Physiology Full

Explain the formation, distribution, and functions of cerebrospinal fluid.

(C) Formation: salty solution continuously secreted by the choroid plexus (region on the walls of the ventricles) (D) choroid plexus consists of capillaries and a transporting epithelium derived from the ependyma (E) cells selectively pump sodium and other solutes from plasma into the ventricles (F) creates osmotic gradient that draws water along with the solutes (G) Distribution: from the ventricles, cerebrospinal fluid flows into the subarachnoid space between the pia mater and the arachnoid membrane, surrounding the entire brain and spinal cord in fluid (H) flows around the neural tissue (C) finally absorbed back into the blood by special villi on the arachnoid membrane in the cranium (D) Functions: physical protection and chemical protection buoyancy (Auftrieb) of cerebrospinal fluid reduces the weight of the brain nearly 30-fold lighter weight translates into less pressure on blood vessels and nerves attached to the CNS protection: when there is a blow to the head, the CSF must be compressed before the brain can hit the inside of the cranium BUT water is minimally compressible -> helps CSF cushion the brain cerebrospinal fluid creates a closely regulated extracellular environment for the neurons choroid plexus is selective about transporting substances into the ventricles -> the composition of CSF is different from that of the plasma: concentration of K+ is lower in the CSF, and the concentration of H+ is higher than in plasma concentration of Na+ in CSF is similar to that in the blood CSF contains very little protein and no blood cells CSF exchanges solutes with the interstitial fluid of the CNS and provides a route by which wastes can be removed

LO 10.4.3 Explain how hair cells convert sound energy into an action potential.

- Hair cells, like taste receptor cells, are non-neural receptor cells - apical surface of each hair cell is modified into stereocilia - stereocilia arranged in ascending height (lowest to highest) - stereocilia of the hair cells are embedded in the overlying tectorial membrane - if the tectorial membrane moves, the underlying cilia do as well - When hair cells move in response to sound waves, their stereocilia flex, first one way, then the other - Stereocilia attached to each other by tip links - Tip links attached to gates of ion channels - When the hair cells and cilia are in a neutral position, about 10% of the ion channels are open o low tonic level of neurotransmitter released onto the primary sensory neuron - When waves deflect the tectorial membrane, cilia bend toward the tallest members of a bundle - Tip links cause channels to open, so cations (primarily K+ and Ca2+) enter the cell, which then depolarizes - Voltage-gated Ca2+ channels open, increasing neurotransmitter release, and the sensory neuron increases its firing rate - When tectorial membrane pushes the cilia away from the tallest members, the tip links relax and all the ion channels close - Cation influx slows, the membrane hyperpolarizes, less transmitter is released, and sensory neuron firing decreases Fact: The tectorial membrane vibrations reflect the frequency of the incoming sound wave, the hair cells and sensory neurons must be able to respond to sounds of nearly 20,000 waves per second, the highest frequency audible by a human ear

LO 10.6.4 Explain signal processing in the retina and in the visual cortex.

- Signals pass from photoreceptors through bipolar neurons to ganglion cells, with modulation by horizontal & amacrine cells o Horizontal cells à synapse with photoreceptors & bipolar cells, to mediate lateral inhibition in the retina (enhances stimulus location & contrast) o Amacrine cells à modulate information flowing between bipolar cells & ganglion cells - Bipolar Cells o Glutamate release from photoreceptors onto bipolar neurons begins signal processing o two types of bipolar cells § light-on (ON bipolar cells) § light-off (OFF bipolar cells) o ON bipolar cells are activated in the light when glutamate secretion by photoreceptors decreases § in the dark, ON bipolar cells are inhibited by glutamate release o OFF bipolar cells are excited by glutamate release in the dark § in the light, with less glutamate, OFF bipolar cells are inhibited o using different glutamate receptors, one stimulus (light) creates two different responses with a single neurotransmitter o whether glutamate is excitatory or inhibitory depends on the type of glutamate receptor on the bipolar neuron § ON bipolar cells have a metabotropic glutamate receptor called mGluR6 that hyperpolarizes the cell when the receptor binds glutamate in the dark • when mGluR6 is not activated, the ON bipolar cell depolarizes § OFF bipolar cells have an ionotropic glutamate receptor that opens ion channels and depolarizes the OFF bipolar cell in the dark o Bipolar cell signal processing is also modified by input from the horizontal and amacrine cells - Ganglion Cells o bipolar cells synapse with ganglion cells = the next neurons in the pathway o lie on the surface of the retina, where their axons are the most accessible to researchers o each ganglion cell receives information from a particular area of the retina, known as visual fields o visual field of a ganglion cell near the fovea is quite small à only a few photoreceptors are associated with each ganglion cell à visual acuity is greatest in these areas o at the edge of the retina à multiple photoreceptors converging onto a single ganglion cell results in vision that is not as sharp o Visual fields of ganglion cells are roughly circular & are divided into sections § a round center and its doughnut-shaped surround § allows each ganglion cell to use contrast between the center and its surround to interpret visual information • strong contrast between the center and surround elicits a strong excitatory response (a series of action potentials) or a strong inhibitory response (no action potentials) from the ganglion cell • weak contrast between center and surround gets an intermediate respons § two types of ganglion cell visual fields § two predominant types of ganglion cells in the primate retina account for 80% of retinal ganglion cells • Large magnocellular ganglion cells/ M cells à more sensitive to information about movement • Smaller parvocellular ganglion cells/ P cells à more sensitive to signals that pertain to form and fine detail (e.g. texture of objects in the visual field) § melanopsin retinal ganglion cell • acts as a photoreceptor to relay information about light cycles to the suprachiasmatic nucleus, which controls circadian rhythms - Processing beyond the retina o binocular zone = central portion of the visual field, where left and right sides of each eye's visual field overlap o the two eyes have slightly different views of objects in this region à the brain processes and integrates the two views à creates three-dimensional representations of the objects o our sense of depth perception (whether one object is in front of or behind another) depends on binocular vision o Objects that fall within the visual field of only one eye are in the monocular zone à are viewed in two dimensions o Once axons leave the optic chiasm à some fibers project to the midbrain à where they participate in control of eye movement or coordinate with somatosensory and auditory information for balance and movement o most axons à project to the lateral geniculate body of the thalamus à where the optic fibers synapse onto neurons leading to the visual cortex in the occipital lobe o lateral geniculate body is organized in layers that correspond to the different parts of the visual field, which means that information from adjacent objects is processed together § this topographical organization is maintained in the visual cortex, with the six layers of neurons grouped into vertical columns o Within each portion of the visual field, information is further sorted by § form, color, and movement. o The cortex merges monocular information from the two eyes to give us a binocular view of our surroundings o Information from on/off combinations of ganglion cells is translated into § sensitivity to line orientation in the simplest pathways § or into color, movement, and detailed structure in the most complex o each of these attributes of visual stimuli is processed through a separate pathway, creating a network whose complexity we are just beginning to unravel

Describe different patterns for neurotransmitter synthesis, recycling, release, and termination of action.

- Synthesis: - takes place in the nerve cell body and in the axon terminal - polypeptides must be made in the cell body because axon terminals do not have the organelles needed for protein synthesis - large propeptide that results is packaged into vesicles along with the enzymes needed to modify it - vesicles then move from the cell body to the axon terminal by fast axonal transport - inside the vesicle: propeptide is broken down into smaller active peptides - smaller neurotransmitters (acetylcholine, amines, purines) are synthesized and packaged into vesicles in the axon terminal - enzymes needed for their synthesis are made in the cell body and released into the cytosol - dissolved enzymes are then brought to axon terminals by slow axonal transport - Release: Second model of release: - kiss-and-run pathway - synaptic vesicles fuse to the presynaptic membrane at a complex: fusion pore - fusion opens a small channel that is just large enough for neurotransmitter to pass through - instead of opening the fused area wider and incorporating the vesicle membrane into the cell membrane, the vesicle pulls back from the fusion pore - returns to the pool of vesicles in the cytoplasm - Termination of action: Recycling:

LO 10.3.2 Describe the receptors, sensory transduction, and neural pathways for the five primary taste sensations.

- Taste=Gustation closely linked to olfaction - Taste is a combination of 5 sensations: Sweet (triggered by presence of organic molecules) Sour (triggered by presence of H+) Salty (triggered by presence of Na+) Bitter (triggered by presence of organic molecules + possibly toxic components) Umami (triggered by presence of organic molecules) - receptors for taste are located primarily on taste buds on tongue and are scattered in oral cavity - One taste bud is composed of 50-150 taste receptor cells (TRCs -> different types) Type I: glia-like support cells Type II: receptor cells Type III: presynaptic cells Basal cells - taste cell is a non-neural polarized epithelial cell tucked down into the epithelium - tiny tip protrudes into the oral cavity through a taste pore - apical membrane of a taste cell is modified into microvilli to increase surface area - substance must first dissolve in the saliva and mucus of the mouth - formed ligand interacts with an apical membrane protein - initiation of a signal transduction cascade - release of chemical messengers from TRC - activation of primary sensory neurons (gustatory neurons) - axons run through CN VII, IX, X to medulla where they synapse - sensory information then passes through thalamus to gustatory complex and is integrated Sweet, Bitter and Umami Taste - Type II taste receptor cells - G protein-coupled receptors (GPCR) - Receptors activate G protein Gustducin - Activates multiple signal transduction pathways o Some release Ca2+ o others open cation channels and allow Ca2+ to enter the cell - Calcium signals initiate ATP release from the type II cells - ATP acts as a paracrine signal on both sensory neurons and neighboring presynaptic cells - creates complex interactions Sour Taste 5. Type III presynaptic cells 6. H+ acts on ion channels of the presynaptic cell and initiates depolarization 7. Serotonin release by exocytosis excites the primary sensory neuron Salt Taste 8. Type I: glia-like support cells 9. Na+ enters the taste receptor cell through an apical ion channel and causes depolarization 10. Primary sensory neuron fires action potential

Explain the changes in ion permeability and ion flow that take place during an action potential.

- electrical current passes down the axon - voltage-gated ion channels in the axon membrane open sequentially - additional Na+ entering the cell reinforce the depolarization - action potential does not lose strength over distance

Draw and describe the parts of a neuron and give their functions.

- long processes that extend outward from the nerve cell body: dendrites and axons - dendrites: receive incoming signals - axons: carry outgoing information, originate from axon hillock - shape, number, and length of axons and dendrites vary - cell body/ cell soma: includes nucleus and all organelles needed to direct cellular activity -> essential to the well-being of the cell because it contains DNA for protein synthesis - myelin sheath: provides support, acts as insulation around axons and speeds up their signal transmission - sympatic cleft: filled with extracellular matrix whose fibers hold the presynaptic and postsynaptic cells in position.

Explain the role of myelin in the conduction of action potentials.

- myelinated axons limit the amount of membrane in contact with the ECF - small sections of bare membrane/ nodes of Ranvier alternate with longer segments wrapped in multiple layers of membrane (the myelin sheath) - creates a high-resistance wall that prevents ion flow out of the cytoplasm - conduction of action potentials down an axon is faster in axons with high-resistance membranes so that current leak out of the cell is minimized - myelin sheaths increase the effective thickness of the axon membrane by as much as 100-fold - nodes have a high concentration of voltage- gated Na+ channels - they open with depolarization and allow Na+ into the axon - Na+ entering at a node reinforce the depolarization and restore the amplitude of the action potential - the action potential passes along myelinated segments, conduction is not slowed by channel opening because only the nodes need Na+ channels

Describe and compare absolute and relative refractory periods.

- once an action potential has begun, a second action potential cannot be triggered for about 1-2 msec, no matter how large the stimulus - delay = the absolute refractory period - represents the time required for the Na+ channel gates to reset to their resting positions - second action potential cannot occur before the first has finished - action potentials moving from trigger zone to axon terminal cannot overlap and cannot travel backward - relative refractory period follows the absolute refractory period - during the relative refractory period: some but not all Na+ channel gates have reset to their original positions and K+ channels are still open - Na+ channels that have not quite returned to their resting position can be reopened by a stronger-than-normal graded potential -> the threshold value has temporarily moved closer to zero, which requires a stronger depolarization to reach it - Na+ enters through newly reopened Na+ channels, depolarization due to Na+ entry is offset by K+ loss through still-open K+ channels - any action potentials that fire during the relative refractory period will be of smaller amplitude than normal - refractory period distinguishes action potentials from graded potentials - if two stimuli reach the dendrites of a neuron within a short time: successive graded potentials created by those stimuli can be added - if two suprathreshold graded potentials reach the action potential trigger zone within the absolute refractory period: second graded potential has no effect because the Na+ channels are inactivated, cannot open again so soon - refractory periods limit the rate at which signals can be transmitted down a neuron - absolute refractory period ensures one-way travel of an action potential from cell body to axon terminal by preventing the action potential from traveling backward

5.7 The Resting Membrane Potential 152. LO 5.7.1 Explain what it means for a cell to have a resting membrane potential difference.

1) The resting part of the name comes from the fact that this electrical gradient is seen in all living cells, even those that appear to be without electrical activity. In these "resting" cells, the membrane potential has reached a steady state and is not changing. 2) The potential part of the name comes from the fact that the electrical gradient created by active transport of ions across the cell membrane is a form of stored, or potential, energy, just as concentration gradients are a form of potential energy. When oppositely charged molecules come back together, they release energy that can be used to do work, in the same way that molecules moving down their concentration gradient can do work. The work done by electrical energy includes opening voltage-gated membrane channels and sending electrical signals. 3) The difference part of the name is to remind you that the membrane potential represents a difference in the amount of electrical charge inside and outside the cell. The word difference is usually dropped from the name, as noted earlier.

LO 5.1.4 List the rules for determining osmolarity and tonicity of a solution.

1. Assume that all intracellular solutes are nonpenetrating. 2. Compare osmolarities before the cell is exposed to the solution. (At equilibrium, the cell and solution are always isosmotic.) 3. Tonicity of a solution describes the volume change of a cell at equilibrium. 4. Determine tonicity by comparing nonpenetrating solute concentrations in the cell and the solution. Net water movement is into the compartment with the higher concentration of nonpenetrating solutes. 5. Hyposmotic solutions are always hypotonic. ; 5.2 Transport Processes 131

6.3 Novel Signal Molecules 175. LO 6.3.1 List five ways calcium acts as an intracellular messenger.

1. Calcium binds to calmodulin -> altering enzyme/transporter activity or gating of ion channels 2. Calcium binds to other regulatory protein -> altering movement of contractile/ cytoskeletal proteins (e.g. Ca2+ binds to troponin initiating muscle contraction in a skeletal muscle cell) 3. Calcium binds to regulatory protein -> triggering exocytosis of secretory vesicles (e.g. calcium signal leads to release of insulin from pancreatic β cells) 4. Calcium binds to ion channels -> altering gating state (e.g. Ca2+ -activated K+ channel in nerve cells) 5. Calcium enters into fertilised egg -> initiating development of embryo.

List three chemical classes of hormones and give an example of each.

1. Peptide hormones: Insulin, parathyroid hormone 2. Steroid hormones: Estrogen, androgens, cortisol 3. Amine Hormones (Tyrosine Derivates): (Nor) Epinephrine, dopamine (catecholamines), Thyroxine (Thyroid hormone).

LO 6.5.2 List the seven steps of a reflex control pathway in the order in wich they occur.

1. Stimulus: disturbance or change that sets pathways in motion stimulus may be a change in temperature, oxygen content, blood pressure or regulated variables. 2. Sensor: sensory receptor, that continously monitors ist enviroment for particular variable. 3. Input signal: sensor sends input (afferent) signal tot he integrating center for reflex when sensor is activated by change. 4. Integrating center: compares input signal with the setpoint or desired value of the variable. If variable has moved out of acceptable range, integrating center initiates output signal. 5. Output signal: output (efferent) signal is and electrica signal and/ or chemical signal that travels to target. 6. Target: target or effector ist he cell or tissue that carries out the appropriate response. 7. Response: brings the variable back within normal limits.

6.5. Homeostatic Reflex Pathways. LO 6.5.1 List Cannon's four postulates of homeostatic control and give an example of each.

1. The nervous system has a role in preserving the ``fitness´´of the internal enviroment. - NS coordinates/integrates blood volume, osmolarity, blood pressure, body temeratureand other parameters 2. Some systems of the body are under tonic control (tonos, tone). - Tonically controlled system: minute-to-minute regulation of blood vessel diameter by nervous system è increased NS input decreases diameter, decreased NS input increases diameter - Amount of neurotransmitter determines vessel's response: more neotransmitter means stronger response 3. Some systems oft he body are under antagonistic control. - Systems not under tonic control are under antagonistic control by hormones or NS - In NS controlled pathways: neurons from different divisions have opposing effetcs: o Chem. signals from sympath. division increase heart rate while chem. Signals from parasymp. division decrease heart rate (antagonistic to each other) o Insulin & glucagon are antagonistic hormones 4. One chemical signal can have different effects in different tissues. - Depending on receptor and intracellular pathway of target cell o Epinephrine constricts or dilates blood vessels, depending on vessels receptors (alpha- or beta2- adrenergic receptors)

LO 10.1.3 Explain how the central nervous system is able to determine modality, location, intensity, and duration of a stimulus.

11. Each receptor type is most sensitive to particular modality of stimulus. Each sensory modality is subdivided into qualities. For example colorvision can be subdevided into red, blue and green according to wavelength that stimulate the different visual receptors. Additionally, the brain associates a signal from a specific group of receptors with a specific modality. This 1:1 receptor-sensation association is called labeled line coding 12. Location of stimulus is coded according to which respective fields are activated. Imput from adjacent sensory receptor is processed in adjacent regions of the cortex.Example: touch receptors in hand project to a specific area of cerebral cortex. Exception: neurons in ears are sensitive to different frequencies of sound, no receptive fields & no location. Brain uses timing of receptor activation to compute the location. Brain registers the different times of stimuli to reach two sides of auditory cortex. Lateral inhibition: detection of location of stimulus through suppression of stimulus by close secondary neurons to lateral secondary neurons. Nearer neurons suppress the activation of further neurons. • Stimulus intensity is coded in two types: number of activated receptors and frequency of action potentials coming from these receptors (frequency coding). As stimulus increases in intensity, additional receptors are activated. CNS translates number of active receptors into a measure of stimulus intensity. As stimulus intensity increases, receptor potential amplitude increases in proportion, frequency of action potentials in sensory neurons go up to maximum. • Duration of stimulus is coded by duration of action potentials in sensory neuron. Longer stimulus generates longer series of action potentials in primary neuron. Persisting stimulus leads to adaption of some receptors.

Explain and give examples of emergent properties of neural systems in humans and other organisms.

2. neurons in the nervous system link together to form circuits that have specific functions 3. most complex circuits of the brain: billions of neurons are linked into intricate networks that converge and diverge 4. they create an infinite number of possible pathways 5. signaling within these pathways creates thinking, language, feeling, learning, and memory 6. these behaviors make us human 7. plasticity of human brain networks: easily restructure themselves as the result of sensory input, learning, emotion, and creativity 8. the brain can add new connections when neural stem cells differentiate

Explain the behavioral state system and how it is related to the diffuse modulatory systems and the reticular activating system.

25) three systems that influence output by the motor systems of the body: 26) (1) the sensory system: monitors the internal and external environments and initiates reflex responses 27) (2) cognitive system: resides in the cerebral cortex ; is able to initiate voluntary responses 28) (3) behavioral state system: resides in the brain ; governs sleep-wake cycles and other intrinsic behaviors 29) information about the physiological or behavioral responses created by motor output feeds back to the sensory system, which in turn communicates with the cognitive and behavioral state systems 30) behavioral state system is an important modulator of sensory and cognitive processing 6. many neurons in regions of the brain outside the cerebral cortex (parts of the reticular formation in the brain stem, hypothalamus, limbic system) -> diffuse modulatory systems 7. originate in the reticular formation in the brain stem and project their axons to large areas of the brain 8. four modulatory systems that are generally classified according to the neurotransmitter they secrete: noradrenergic (norepinephrine), serotonergic (serotonin), dopaminergic (dopamine), and cholinergic (acetylcholine) 9. regulate brain function by influencing attention, motivation, wakefulness, memory, motor control, mood, and metabolic homeostasis 10. function of the behavioral state system: control of levels of consciousness and sleep-wake cycles = reticular activating system

Starting at the skull and moving inward, name the membranes and other structures that enclose the brain.

3. Three layers of membrane/ the meninges lie between the bones and tissues of the CNS. These membranes help stabilize the neural tissue and protect it from bruising against the bones of the skeleton. 4. Starting from the bones and moving toward the neural tissue, the membranes are (1) the dura mater, (2) the arachnoid membrane, and (3) the pia mater. 5. The dura mater is the thickest of the three membranes. It is associated with veins/ sinuses that drain blood from the brain through vessels or cavities. 6. The middle layer, the arachnoid membrane, is loosely tied to the inner membrane, leaving a subarachnoid space between the two layers. 7. The inner membrane, the pia mater, is a thin membrane that adheres to the surface of the brain and spinal cord. Arteries that supply blood to the brain are associated with this layer. 8. The final protective component of the CNS is extracellular fluid, which helps cushion the delicate neural tissue.

LO 10.4.2 Describe the anatomical pathway for sound transmission from the cochlea to the auditory cortex.

3. cochlea composed of three parallel, fluid-filled channels Vestibular Duct (scala vestibuli) Cochlear Duct (scala media) Tympanic duct (scala tympani) 4. vestibular and tympanic ducts are continuous with each other 5. connect at the tip of the cochlea as helicotrema 6. Perilymph fills the vestibular and tympanic ducts (similar in ion composition to plasma) 7. Endolymph fills the cochlear duct (similar to intracellular fluid with high concentrations of K+ and low concentrations of Na+) 8. cochlear duct contains the organ of Corti, composed of hair cell receptors and support cells 9. organ of Corti sits on the basilar membrane (responsible for pitch) 10. covered by tectorial membrane 11. membranes move in response to fluid waves

LO 11.1.4 Describe the structure and secretions of the adrenal medulla

31) Adrenal medulla 11. Is a specialized neuroendocrine tissue associated with the sympathetic nervous system 21. Secretes epinephrine into blood (N) Forms the core of the adrenal glands (sit on top of the kidneys) (K) Each adrenal gland is actually 2 glands of different embryological origin that fuse during development 19. The adrenal cortex (outer portion) is a true endocrine gland of epidermal origin that secretes steroid hormones 20. The adrenal medulla, which forms the small core of the gland, develops from the same embryonic tissue as sympathetic neurons and is a neurosecretory structure 29. Preganglionic sympathetic neurons project from the spinal cord to the adrenal medulla, where they synapse 30. postganglionic neurons lack the axons that would normally project to target cells instead, the axonless cell bodies, called chromaffin cells, secrete the neurohormone epinephrine directly into the blood 31. in response to alarm signals from the CNS, the adrenal medulla releases large amounts of epinephrine for general distribution throughout the body as part of a fight-or-flight response

11.2 The Somatic Motor Division 368 LO 11.2.1 Describe the structure of the neuromuscular junction.

32. Neuromuscular junction (NMJ) Is the synapse of a somatic motor neuron on a muscle fiber It has 3 components ---the motor neuron's presynaptic axon terminal filled with synaptic vesicles and mitochondria ---the synaptic cleft ---the postsynaptic membrane of the skeletal muscle fiber includes extensions of Schwann cells, that form a thin layer covering the top of axon terminals On the postsynaptic side of the neuromuscular junction, the muscle cell membrane that lies opposite the axon terminal is modified into a motor end plate a series of folds that look like shallow gutters Along the upper edge of each gutter, nicotinic ACh receptor (nAChR) channels cluster together in an active zone between the axon and the muscle, the synaptic cleft is filled with a fibrous matrix whose collagen fibers hold the axon terminal and the motor end plate in the proper alignment the matrix also contains acetylcholinesterase (AChE), enzyme that rapidly deactivates ACh by degrading it into acetyl and choline

Describe how nervous systems increase in complexity from Cnidarians to mammals.

4) all animals have the ability to sense and respond to changes in their environment 5) unicellular organisms have no obvious brain or integrating center -> they use the resting membrane potential that exists in living cells and many of the same ion channels as more complex animals to coordinate their activities 6) first multicellular animals to develop neurons: jellyfish and sea anemones 7) their nervous system is a nerve net composed of sensory neurons, connective interneurons, and motor neurons that innervate muscles and glands 8) they respond to stimuli with complex behaviors, but without input from an identifiable control center 9) same basic principles of neural communication apply to jellyfish and humans 10) electrical signals/ action potentials and chemical signals passing across synapses (the same in all animals) 11) difference in species: the number and organization of the neurons 12) Picture b) primitive flatworms: the beginnings of a nervous system, the distinction between central nervous system and peripheral nervous system is not clear ; a rudimentary brain consisting of a cluster of nerve cell bodies concentrated in the head, or cephalic region ; two nerve cords come off the primitive brain and lead to a nerve network that innervates distal regions of the flatworm body 13) Picture c) segmented worms/ annelids/ the earthworm: more advanced central nervous system ; clusters of cell bodies are no longer restricted to the head region, occur in fused pairs/ ganglia along a nerve cord ; simple reflexes can be integrated within a segment without input from the brain ; complex reflexes controlled through neural networks ; researchers use leeches (a type of annelid) to study neural networks and synapse formation because the neurons in these species are 10 times larger than human brain neurons, and the networks have the same organization of neurons from animal to animal 14) nerve cell bodies clustered into brains persist throughout the more advanced phyla and become increasingly more complex 15) advantage to cephalic brains: heads of most animals is the part of the body that first contacts the environment as the animal moves -> as brains evolved, they became associated with specialized cephalic receptors, such as eyes for vision and chemoreceptors for smell and taste 16) in insects: specific regions of the brain are associated with particular functions 17) more complex brains are associated with complex behaviors: the ability of social insects like ants and bees to organize themselves into colonies, divide labor, and communicate with one another 18) octopus has the most sophisticated brain development and behavior among the invertebrates 19) in vertebrate brain evolution, the most dramatic change is seen in the forebrain region: the cerebrum 20) Picture d) in the fish: the forebrain is a small bulge dedicated mainly to processing olfactory information about odors in the environment 21) Picture e) in birds and rodents: part of the forebrain has enlarged into a cerebrum with a smooth surface 22) Picture f) in humans: the cerebrum is the largest and most distinctive part of the brain, with deep grooves and folds ; the part of the brain that allows reasoning and cognition 23) cerebellum: a region of the hindbrain devoted to coordinating movement and balance 24) birds and humans have well-developed cerebellar structures

Define gray matter, white matter, tracts, and nuclei in the CNS.

4. Gray matter consists of unmyelinated nerve cell bodies, dendrites, and axons. The cell bodies are assembled in an organized fashion in both the brain and the spinal cord. They form layers in some parts of the brain and in other parts cluster into groups (nuclei) of neurons that have similar functions 5. White matter is mostly myelinated axons and contains very few cell bodies. Its pale color comes from the myelin sheaths that surround the axons. Bundles of axons that connect different regions of the CNS are tracts. Tracts in the central nervous system are equivalent to nerves in the peripheral nervous system.

Describe the structure and functions of the blood-brain barrier.

4. Structure: highly selective permeable brain capillaries 5. the endothelial cells form tight junctions with one another 6. junctions prevent solute movement between the cells 7. tight junction formation is induced by paracrine signals from adjacent astrocytes whose foot processes surround the capillary 8. Function: to isolate the body's main control center from potentially harmful substances in the blood and from blood-borne pathogens (bacteria) 9. selected membrane carriers and channels to move nutrients and other useful materials from the blood into the brain interstitial fluid 10. other transporters move wastes from the interstitial fluid into the plasma 11. any water-soluble molecule that is not transported on one of these carriers cannot cross the blood-brain barrier

Explain how the following structures are organized in the spinal cord: ascending and descending tracts, columns, dorsal root ganglia, dorsal and ventral horns, dorsal and ventralroots,propriospinaltracts,spinal nerves.

5. The spinal cord is divided into four regions: cervical, thoracic, lumbar, and sacral 6. each spinal region is subdivided into segments 7. each segment gives rise to a bilateral pair of spinal nerves 8. just before a spinal nerve joins the spinal cord, it divides into two branches/ roots 9. dorsal root of each spinal nerve: carry incoming sensory information 10. dorsal root ganglia (swellings found on the dorsal roots just before they enter the cord): contain cell bodies of sensory neurons 11. sensory fibers from the dorsal roots synapse with interneurons in the dorsal horns of the gray matter 12. dorsal horn cell bodies are organized into two distinct nuclei, one for somatic information and one for visceral information 13. ventral root carries information from the CNS to muscles and glands 14. ventral horns of the gray matter contain cell bodies of motor neurons that carry efferent signals to muscles and glands 15. ventral horns are organized into somatic motor and autonomic nuclei 16. efferent fibers leave the spinal cord via the ventral root 17. cross section: the spinal cord has a butterfly- or H-shaped core of gray matter and a surrounding rim of white matter 18. White matter can be divided into a number of columns composed of tracts of axons that transfer information up and down the cord • ascending tracts take sensory information to the brain • they occupy the dorsal and external lateral portions of the spinal cord • descending tracts carry mostly efferent (motor) signals from the brain to the cord • they occupy the ventral and interior lateral portions of the white matter • propriospinal tracts remain within the cord

Explain how the body can be in osmotic equilibrium but electrical and chemical disequilibrium.

Active transporters pump molecules against their concentration gradient, and selectively permeable membranes keep solutes contained on one side- both of these processes result in electrical and chemical disequilibrium. However, water is able to move freely between cells and the extracellular fluid and distribute itself until water concentrations are equal throughout the body—in other words, until the body is in a state of osmotic equilibrium.

Explain the role of the following in learning and memory: short-term memory, memory traces, working memory, associative and nonassociative learning, and habituation and sensitization.

Associative learning occurs when two stimuli are associated with each other, such as Pavlov's classic experiment in which he simultaneously presented dogs with food and rang a bell. After a period of time, the dogs came to associate the sound of the bell with food and began to salivate in anticipation of food whenever the bell was rung. Another form of associative learning occurs when an animal associates a stimulus with a given behavior. An example would be a mouse that gets a shock each time it touches a certain part of its cage. It soon associates that part of the cage with an unpleasant experience and avoids the area. Nonassociative learning is a change in behavior that takes place after repeated exposure to a single stimulus. This type of learning includes habituation and sensitization, two adaptive behaviors that allow us to filter out and ignore background stimuli while responding more sensitively to potentially disruptive stimuli. In habituation, an animal shows a decreased response to an irrelevant stimulus that is repeated over and over. For example, a sudden loud noise may startle you, but if the noise is repeated over and over again, your brain begins to ignore it. Habituated responses allow us to filter out stimuli that we have evaluated and found to be insignificant. Sensitization is the opposite of habituation, and the two behaviors combined help increase an organism's chances for survival. In sensitization learning, exposure to a noxious or intense stimulus causes an enhanced response upon subsequent exposure. For example, people who become ill while eating a certain food may find that they lose their desire to eat that food again. Sensitization is adaptive because it helps us avoid potentially harmful stimuli. At the same time, sensitization may be maladaptive if it leads to the hypervigilant state known as post-traumatic stress disorder (PTSD). Memories are stored throughout the cerebral cortex in pathways known as memory traces. Some components of memories are stored in the sensory cortices where they are processed. For example, pictures are stored in the visual cortex, and sounds in the auditory cortex. When a stimulus comes into the CNS, it first goes into short-term memory, a limited storage area that can hold only about 7 to 12 pieces of information at a time. Items in short-term memory disappear unless an effort, such as repetition, is made to put them into a more permanent form. Working memory is a special form of short-term memory processed in the prefrontal lobes. This region of the cerebral cortex is devoted to keeping track of bits of information long enough to put them to use in a task that takes place after the information has been acquired. Working memory in these regions is linked to long-term memory stores, so that newly acquired information can be integrated with stored information and acted on. Working memory allows us to collect a series of facts from short- and long-term memory and connect them in a logical order to solve problems or plan actions. Long-term memory is a storage area capable of holding vast amounts of information. The processing of information that converts short-term memory into long-term memory is known as consolidation. Consolidation can take varying periods of time, from seconds to minutes. Information passes through many intermediate levels of memory during consolidation, and in each of these stages, the information can be located and recalled. intermediate levels of memory during consolidation, and in each of these stages, the information can be located and recalled. The process involves changes in neuronal excitability or synaptic connections in the circuits involved in learning. In some cases, new synapses form ; in others, the effectiveness of synaptic transmission is altered through long-term potentiation or through long-term depression. These changes are evidence of plasticity and show us that the brain is not "hard-wired."

LO 6.2.4 Explain how cascades and signal amplification play a role in signal transduction.

Cascades • Many intracellular signal pathways are cascades • Signal molecule (stimulus) converts receptor (inactive molecule A) into active form signaling cascade starts -> active A converts inactive molecule B into active B -> active B converts inactive molecule C into active C -> until at final step substrate is converted into product • Blood clotting as important example of extracellular cascade Signal amplification • In signal transduction pathways transformation of original signal AND amplification - one signal molecule into multiple second messenger molecules • First messenger ligand combines with receptor -> receptor-ligand complex activates amplifier enzyme -> amplifier enzyme activates several molecules -> in turn molecules each activate several molecules as cascade proceeds -> by the end effects of ligand amplified much more than in 1:1 ratio between each step • Body profits by enabling small amount of ligand to create large effect

LO 6.2.3 Name and describe four major groups of cell surface receptors.

Cell surface receptor (= embedded membrane protein) - „extracellular receptor" <-> Intracellular receptor {Each receptor exhibits a different way of signal transduction} 1. Receptor channel • Most rapid intracellular response to activation of receptor channel • One way of triggering ion-mediated cell signaling • Extracellular ligand binding -> channel opens or closes -> increasing or decreasing ion permeability -> change in cell's membrane potential thereby creating electrical signal -> altering voltage-sensitive proteins • E.g. acetylcholine-gated monovalent cation channel of skeletal muscle - muscle contraction 2. G protein-coupled receptor • Large & complex family of membrane-spanning proteins crossing phospholipid bilayer seven times • Cytoplasmic tail of receptor protein linked to 3-part membrane transducer G protein • Inactive G protein bound to GDP -> exchanging GDP for GTP activates G protein -> activated G protein opens ion channel in membrane or alters enzyme activity on cytoplasmic side of membrane • Most common amplifier enzymes for G protein-coupled receptors are adenylyl cyclase & phospholipase C 3. Catalytic receptor • Receptor-enzymes with receptor region on extracellular side of cell membrane and enzyme region on cytoplasmic side: • Extracellular binding region & intracellular enzyme region as parts of same protein molecule, e.g. insulin receptor or enzyme region as separate protein activated by ligand binding, e.g. cytokine receptors • Ligand binding -> activates intracellular enzyme • Include protein kinases, e.g. tyrosine kinase or guanylyl cyclase 4. Integrin receptor (=catalytic receptor) • Membrane-spanning proteins classified as catalytic receptor & in addition have properties not associated with classic receptors • Bind to proteins of ECM or ligands on extracellular side of membrane and attach to cytoskeleton via anchor proteins inside cell • Ligand binding -> activates intracellular enzyme or alters organization of cytoskeleton • Mediate blood-clotting, wound repair, cell adhesion & recognition in immune response and cell movement during development. Plus summary of basic signal transduction:

LO 6.5.4 Describe some examples of complex reflex pathways with more than one integrating center.

Complex reflex pathways with more than one integrating center: 1. Simplest combines neural reflex with classic endocrine reflex. - Ex.: control of insulin release - Pancreatic beta cells monitor blood glucose concentr. directly, but are also controlled by nervous system - During meal: food in stomach streches walls of digestive tract, sends input signal to brain - Brain sends excritatory output signals to beta cells, which then release insulin - These signals take place before food has been absorbed and blood glucose levels have gone up - Therefore this pathway hast wo integrating centers (brain and beta cells) 2. Most complex neuroendocrine pathways include a neurohormone and two classic hormones. Typical fro some hormones released by ant. pituitary gland (endocrine gland), located below brain - only one receptor and input pathway - brain is first integrating center and neurohormone is first output pathway - endocrine target of neurohormone is the second integrating center, its hormone ist he second output pathway - second endocrine gland ist he third integrating center, its hormone is the third output pathway - target of last signal in sequence is the effector

LO 10.6.2 Trace the pathway for vision from the retina to the visual cortex.

Cornea à pupil à lens à retina (light-sensitive lining of the eye, contains photoreceptors) à neurons of visual pathway form optic nerve & exit at optic disk à optic chiasm (some fibers cross opposite side) à synapse in lateral geniculate body (thalamus) à visual cortex (occipital lobe)

LO 5.3.1 Explain the differences between diffusion in an open system and diffusion across biological membranes

Diffusion in an open system has no barriers to molecular movement, and the molecules spread out to fill the entire system. Diffusion of cologne within a room is an example of diffusion taking place in an open system. Diffusion can also take place between two compartments, such as the intracellular and extracellular compartments, but only if the partition dividing the two compartments allows the diffusing molecules to cross. If a cell membrane is permeable to a molecule, that molecule can enter or leave the cell by diffusion. If the membrane is not permeable to that particular molecule, the molecule cannot cross.

LO 6.4.2 Explain the role of up-regulation, down-regulation, and pathway termination in modulating cell responses to receptors and their ligands. .

Down regulation: - decrease in receptor number - cells ability to remove receptors from membrane by endocytosis - goal: less response of target cell even though signal molecule concentration is high - quicker than down regulation: desensitization o binding chemical modulator to receptor protein § ex.:adrenergic receptors desensitized by phosphorylation of receptor up-regulation: - in decreased concenration of ligand, up-regulation by target cell to keep normal level response - target cell inserts receptors into membrane - more receptors make target cell more responsive - ex.: damaged neuron, unable to release normal amount of neurotransmitter è up-regulation of target cell pathway termination: - ability of cell to tell when siganl is over - Ways of stopping receptor activity: o degradation of extracellular ligand by extrac. Enzymes (breakdown of ACTH) o removing chemical messengers by transporting into neighboring cells o once ligand is bound to receptor: endocytosis of receptor-ligand complex § ligand removed intracellular, receptor returns to membrane (exocyto.).

Describe motivation and emotion and how they are related to brain function.

Emotion and motivation are two aspects of brain function that represent an overlap of the behavioral state system and cognitive system. The pathways involved are complex and form closed circuits that cycle information among various parts of the brain, including the hypothalamus, limbic system, and cerebral cortex. The most commonly described emotions, which arise in different parts of the brain, are anger, aggression, sexual feelings, fear, pleasure, contentment, and happiness. The limbic system, the region of the amygdala, is the center of emotion in the human brain. When the amygdala is artificially stimulated in humans, as it might be during surgery for epilepsy, patients report experiencing feelings of fear and anxiety. Experimental lesions that destroy the amygdala in animals cause the an-imals to become tamer and to display hypersexuality. The amygdala is the center for basic instincts such as fear and aggression. The pathways: Sensory stimuli feeding into the cerebral cortex are constructed in the brain to create a representation (perception) of the world. After information is integrated by the association areas, it is passed on to the limbic system. Feedback from the limbic system to the cerebral cortex creates awareness of the emotion, while descending pathways to the hypothalamus and brain stem initiate voluntary behaviors and unconscious responses mediated by autonomic, endocrine, immune, and somatic motor systems. Motivation is defined as internal signals that shape voluntary behaviors. Some of these behaviors, such as eating, drinking, and having sex, are related to survival. Others, such as curiosity and having sex (again), are linked to emotions. Some motivational states are known as drives and generally have three properties in common: (1) they create an increased state of CNS arousal or alertness, (2) they create goal-oriented behavior, and (3) they are capable of coordinating disparate behaviors to achieve that goal. Motivated behaviors often work in parallel with autonomic and endocrine responses in the body. For example, if you eat salty popcorn, your body osmolarity increases. This stimulus acts on the thirst center of the hypothalamus, motivating you to seek something to drink. Increased osmolarity also acts on an endocrine center in the hypothalamus, releasing a hormone that increases water retention by the kidneys. In this way, one stimulus triggers both a motivated behavior and a homeostatic endocrine response. Some motivated behaviors can be activated by internal stimuli that may not be obvious even to the person in whom they are occurring. Eating, curiosity, and sex drive are three examples of behaviors with complex stimuli underlying their onset. We may eat, for example, because we are hungry, the food looks good or we do not want to hurt someone's feelings. Many motivated behaviors stop when the person has reached a certain level of satisfaction, or satiety, but they may also continue despite feeling satiated. Animal studies have shown that pleasure is a physiological state that is accompanied by increased activity of the neurotransmitter dopamine in certain parts of the brain. Drugs that are addictive, such as cocaine and nicotine, act by enhancing the effectiveness of dopamine, thereby increasing the pleasurable sensations perceived by the brain. As a result, use of these drugs rapidly becomes a learned behavior.

LO 10.1.2 Explain how receptors convert physical stimuli into electrical signals using the following terms: transduction, threshold, adequate stimulus, receptive field, receptor potential.

First step is transduction: conversion of stimulus energy into information able processed by nervous system. In many receptors, opening and closing of ion channels converts chemical, mechanical, thermal or light energy directly into change in membrane potential. Other transduction mechanisms include signal transduction and second messenger systems that initiate change in membrane potential. Each sensory receptor has adequate stimulus, a particular form of energy it is most responsive to. Ex.: thermoreceptor is more sensitive to temperature changes than to pressure. Besides their specificity, receptors can also respond to most other forms if intensity is high enough. Ex.: photoreceptors respond to light, but blow to the eye can cause "seeing stars", a mechanical energy stimulating photoreceptors. Threshold is the minimum stimulus (minimum depolarization) needed to cause action potential. • Stimulus opens/closes ion channels in receptor membrane (directly or indirectly with second messenger) ; • Opening results in Na+ or other cation influx into receptor , depolarizing the membrane ; • In few cases: stimulus causes hyperpolarization when K+ leaves the cell. • In case of vision: stimulus (light) closes cation channel to hyperpolarize the receptor Change in sensory receptor potential is a graded potential called receptor potential. The somatic sensory and visual neurons of the receptors can only be activated by stimuli falling into their specific are which is called the receptive field of the neuron. These receptive fields overlap with each other.

LO 11.1.2 Compare and contrast the anatomy and chemical communication of the sympathetic and parasympathetic branches.

How, then, do the two autonomic branches differ anatomically? The main anatomical differences are (1) the pathways' point of origin in the CNS and (2) the location of the autonomic ganglia. most sympathetic pathways (red) originate in the thoracic and lumbar regions of the spinal cord. Sympathetic ganglia are found primarily in two ganglion chains that run along either side of the bony vertebral column, with additional ganglia along the descending aorta. Long nerves (axons of postganglionic neurons) project from the ganglia to the target tissues. Because most sympathetic ganglia lie close to the spinal cord, sympathetic pathways generally have short preganglionic neurons and long postganglionic neurons Many parasympathetic pathways originate in the brain stem, and their axons leave the brain in several cranial nerves Other parasympathetic pathways originate in the sacral region (near the lower end of the spinal cord) and control pelvic organs. In general, parasympathetic ganglia are located either on or near their target organs. Consequently, parasympathetic preganglionic neurons have long axons, and parasympathetic postganglionic neurons have short axons. Parasympathetic innervation goes primarily to the head, neck, and internal organs. The major parasympathetic tract is the vagus nerve (cranial nerve X), which contains about 75% of all parasympathetic fibers. The Autonomic Nervous System Uses a Variety of Chemical Signals Chemically, the sympathetic and parasympathetic branches can be distinguished by their neurotransmitters and receptors, using the following rules 26. Both sympathetic and parasympathetic preganglionic neurons release acetylcholine (ACh) onto nicotinic cholinergic receptors (nAChR) on the postganglionic cell. 27. Most postganglionic sympathetic neurons secrete norepinephrine (NE) onto adrenergic receptors on the target cell. 28. Most postganglionic parasympathetic neurons secrete acetylcholine onto muscarinic cholinergic receptors (mAChR) on the target cell. Exceptions: A few sympathetic postganglionic neurons, such as those that terminate on sweat glands, secrete ACh rather than norepinephrine. These neurons are therefore called sympathetic cholinergic neurons.

LO 5.7.2 Explain how changes in ion permeability change membrane potential, giving examples.

In most cases, membrane potential changes in response to movement of one of four ions: Na+, Ca2+, Cl -, and K+. The first three are more concentrated in the extracellular fluid than in the cytosol, and the resting cell is minimally permeable to them. If a cell suddenly becomes more permeable to any one of these ions, then those ions will move down their electrochemical gradient into the cell. Entry of Ca2+ or Na+ depolarizes the cell (makes the membrane potential more positive). Entry of Cl - hyperpolarizes the cell (makes the membrane potential more negative). When the membrane is more permeable to K+, it leaks out, and cell hyperpolarizes until it reaches the equilibrium potential for K+.

6.2 Signal Pathways 168. LO 6.2.1 Explain the general sequence of events that follow lipophilic ligand binding to intracellular receptors.

Lipophilic ligand passes through plasma membrane & binds to intracellular receptor changing gene expression Lipophilic signal molecule enters cell by simple diffusion trough phospholipid bilayer of cell membrane -> lipophilic ligand binds to cytosolic receptor or nuclear receptor -> activation of intracellular receptor (A) -> turns gene on and directs the nucleus to making new mRNA -> mRNA provides template for synthesis of new proteins (B) -> turns gene off and represses gene activity „Slow Response" [Some lipophilic signal molecules also bind to cell membrane receptors in addition to intracellular receptor].

LO 6.2.2 Describe the general sequence of events that follow lipophobic ligand binding to a cell surface receptor.

Lipophobic ligand binds to receptor on or within plasma membrane initiating intracellular signaling cascade Lipophobic signal molecule remain in extracellular fluid -> lipophobic ligand binds to receptor protein on cell membrane -> activation of membrane receptor (=channel - (A) or other receptor molecule - (B)) (A) -> opens or closes channel -> altering ion flow across membrane (B) -> turns on associated proteins -> starting intracellular cascade of second messengers (= signal transduction) -> last second messenger acts on intracellular target creating a response „Fast response".

6.1 Cell-to-Cell Communication 165 LO 6.1.1 Describe three forms of local communication and two forms of long-distance communication.

Local communication via: 1. Direct transfer of electrical and chemical signals between adjacent cells through protein channels creating cytoplasmic bridges gap junctions -> different isoforms of connexions forming gap junctions - gap junction selectivity simplest form of cell-to-cell communication 2. Contact-dependent signals occurring when surface molecules on one cell membrane bind to surface molecules on another cell's membrane with cell adhesion molecules acting as receptors occurs in immune system and during growth & development 3. Paracrine signals acting on cells close by and autocrine signals acting on cell secreting it by diffusing through interstitial fluid e.g. histamine as paracrine signal released from damaged cells Long-distance communication via: 1. Electrical signals pass along neurons until reaching cell end -> translation into chemical signal secreted by neuron neurocrine molecules used by nervous system 2. Chemical signals hormones secreted into blood & distributed all over body by circulation -> only cells with receptor for hormone are target cells used by endocrine system.

LO 5.1.3 Compare and contrast molarity, osmolarity, osmolality, osmotic pressure, and tonicity.

Molarity (M), is defined as number of moles of dissolved solute per liter of solution (mol/L). However, using molarity to describe biological concentrations is misleading the important factor for osmosis is the number of osmotically active particles in a given volume of solution, not the number of molecules. Biological solutions we express the concentration as osmolarity, the number of osmotically active particles (ions or intact molecules) per liter of solution. (molarity (mol/L) * number of particles/molecule (osmol/mol) =osmolarity (osmol/L) Osmolality is concentration expressed as osmoles of solute per kilogram of water. Tonicity is a physiological term used to describe a solution and how that solution would affect cell volume if the cell were placed in the solution and allowed to come to equilibrium. The pressure that must be applied to the piston to exactly oppose the osmotic movement of water into compartment B is known as the osmotic pressure of solution B. (See the diagram above)

5.6 Epithelial Transport 149. LO 5.6.1 Explain transcellular transport, paracellular transport, and transcytosis as they apply to epithelial transport.

Movement across an epithelium, or epithelial transport, may take place either as paracellular transport, through the junctions between adjacent cells or as transcellular transport through the epithelial cells themselves. Transcellular transport uses a combination of active and passive transport mechanisms. Transcytosis, which is a combination of endocytosis, vesicular transport across the cell, and exocytosis. In this process, the molecule is brought into the epithelial cell via receptor-mediated endocytosis. The resulting vesicle attaches to microtubules in the cell's cytoskeleton and is moved across the cell by a process known as vesicular transport. At the opposite side of the epithelium, the contents of the vesicle are expelled into the interstitial fluid by exocytosis.

LO 10.2.3 Explain how pain and itch are mediated by nociceptors, and describe the neural pathways for pain.

Nocireceptors are neurons with free nerve endings. They respond to string noxious stimuli (chemical, mechanical, thermal) which cause/ potentially cause tissue damage. They are found in skin, joints, muscles, bones, various internal organs, not in CNS. Activation of nocireceptors initiates adaptive, protective response: discomfort from overuse of muscles/ joints warns to take easy + avoid damage. Afferent signals from nocireceptors carried to CNS in two types of primary sensory fibers: A-delta fibers and C fibers. Most common sensation is pain, but when histamine or other stimulus activates subtype of C fibers, sensation of itch comes up. Pain: subjective perception ; brains interpretation of sensory information coming from pathways of nocireceptors ; highly individual & multidimensional, vary with person's emotional state ; - Fast pain: described as sharp & localized ; rapidly transmitted to CNS by small, myelinated A-delta fibers. - Slow pain: described duller & more diffuse ; carried on small, unmyelinated C fibers ; - Timing distinction between them most obvious when stimulus originates far from CNS (toe). First, quick stabbing sensation (fast pain), followed shortly by dull throbbing (slow pain). Itch (pruritus): only from nocireceptors in skin ; characteristic for many rashes and other conditions ; aalso symptom for some systemic disease: multiple sclerosis, hyperparathyroidism, diabetes mellitus. Antagonistic interaction between them: when itching, you scratch à small pain interrupts itch. Nocireceptor pathways: Primary sensory neurons of nocireceptorsterminate in dorsal horn of spinal cord. Their activation follows two pathways: - Reflexive protective responses, integrating at level of spinal cord (spinal reflexes) These responses initiate rapid unconscious responses automatically removing stimulated area from source of stimulus. (Pulling back hand from hotplate) Primary nocireceptor neurons synapse onto interneurons (spinal reflex) or secondary neurons projecting to brain. - Ascending pathways to cerebral cortex becoming conscious sensation (pain or itch) Secondary sensory neurons cross body's midline in spinal cord, ascending to thalamus & sensory areas of cortex. Pathways also branches to lambic system & hypothalamus Pain may accompanied by emotional distress (suffering) and autonomic reactions (nausea, vomiting, sweating) Chronic pain is greater than nociceptor activation indicate, it reflects damage or long-term changes to nervous system à results from long-term potentiation at synapses.

5.5 Vesicular Transport 146 LO 5.5.1 Compare phagocytosis, endocytosis, and exocytosis.

Phagocytosis is the actin-mediated process by which a cell engulfs a bacterium or other particle into a large membrane-bound vesicle called a phagosome. The phagosome pinches off from the cell membrane and moves to the interior of the cell, where it fuses with a lysosome, whose digestive enzymes destroy the bacterium. Phagocytosis requires energy from ATP. Endocytosis, differs from phagocytosis in two important ways. First, in endocytosis the membrane surface indents rather than pushes out. Second, the vesicles formed from endocytosis are much smaller. In addition, some endocytosis is constitutive that is, it is an essential function that is always taking place. In contrast, phagocytosis must be triggered by the presence of a substance to be ingested. Endocytosis is an active process that requires energy from ATP. In exocytosis, intracellular vesicles move to the cell membrane, fuse with it, and then release their contents to the extracellular fluid. Cells use exocytosis to export large lipophobic molecules, such as proteins synthesized in the cell, and to get rid of wastes left in lysosomes from intracellular digestion. Exocytosis is a constitutive process (always taking place), and requires ATP for energy.

Describe the parts of a synapse and their functions.

Presynaptic cell: neuron that delivers a signal to the synapse - Postsynaptic cell: the cell that receives the signal - Synaptic cleft: narrow space between two cells - majority of synapses in the body are chemical synapses - presynaptic cell releases a chemical signal that diffuses across the synaptic cleft and binds to a membrane receptor on the postsynaptic cell - CNS contains electrical synapses - the presynaptic and postsynaptic cells are connected by gap junction channels - gap junctions allow electrical current to flow directly from cell to cell - communication at electrical synapses is bidirectional and faster than at chemical synapses

Describe the role of the following in synaptic communication: ionotropic and metabotropic receptors, neurotransmitters and neuromodulators, fast and slow synaptic potentials, excitatory and inhibitory postsynaptic potentials.

Receptor-channels mediate rapid responses by altering ion flow across the membrane, so they are also called ionotropic receptors. Some ionotropic receptors are specific for a single ion, such as Cl-, but others are less specific, such as the nonspecific monovalent cation channel. • G protein-coupled receptors mediate slower responses because the signal must be transduced through a second messenger system. GPCRs for neuromodulators are described as metabotropic receptors. Some metabotropic GPCRs regulate the opening or closing of ion channels. • Neurotransmitters and neuromodulators act as paracrine signals, with target cells located close to the neuron that secretes them. (Neurohormones, in contrast, are secreted into the blood and distributed throughout the body.) • If a molecule primarily acts at a synapse and elicits a rapid response, we call it a neurotransmitter, even if it can also act as a neuromodulator. • Neuromodulators act at both synaptic and nonsynaptic sites and are slower acting. • Some neuromodulators and neurotransmitters also act on the cell that secretes them, making them autocrine signals as well as paracrine signals. • A neurotransmitter combining with its receptor sets in motion a series of responses in the postsynaptic cell. Neurotransmitters that bind to G protein-coupled receptors linked to second messenger systems initiate slow postsynaptic responses. • Some second messengers act from the cytoplasmic side of the cell membrane to open or close ion channels. Changes in membrane potential resulting from these alterations in ion flow are called slow synaptic potentials because the response of the second messenger pathway takes longer than the direct opening or closing of a channel. The response itself lasts longer, usually seconds to minutes. • Neurotransmitters acting on GPCRs may also modify existing cell proteins or regulate the production of new cell proteins. • Fast synaptic responses are always associated with the opening of ion channels. The neurotransmitter binds to and opens a receptor-channel on the postsynaptic cell, allowing ions to move between the postsynaptic cell and the extracellular fluid. The resulting change in membrane potential is called a fast synaptic potential because it begins quickly and lasts only a few milliseconds. • If the synaptic potential is depolarizing, it is called an excitatory postsynaptic potential (EPSP) because it makes the cell more likely to fire an action potential. • If the synaptic potential is hyperpolarizing, it is called an inhibitory postsynaptic potential (IPSP) because hyperpolarization moves the membrane potential away from threshold and makes the cell less likely to fire an action potential.

LO 10.1.1 Describe the different types of receptors for somatic and special senses.

Sensory receptors vary in complexity, ranging from branched endings of single sensory neuron to complex nonneuronal cells acting as sensors. Neural and nonneuronal receptors develop from the same embryonic tissue. Simplest sensory receptor have neuron with free nerve endings. Complex receptors have nerve endings encased in connective tissue. Simple and complex neuronal receptor axons can be myelinated or unmyelinated. Most special senses receptors are cells releasing neurotransmitter onto sensory neurons, initiating action potential. Example: hair cell, found in ear. Special senses: vision, hearing, taste, smell, equillibrium Somatic senses: touch, temperature, pain, itch (nociception), proprioception (awareness of body movement and position in space) Proprioception: conscious or unconscious Receptors can be devided into four major groups, based on type of stimulus to which they are most sensitive. Chemoreceptors respond to chemical ligand that bind to receptor (taste, smell) Mechanoreceptors respond to various forms of mechanical energy, including pressure, vibration, gravity, acceleration, sound (hearing, touch, for example), stretching (baroreceptors: vessel stretch) Thermoreceptors respond to temperature Photoreceptors respond to light (vision)

5.4 Protein-Mediated Transport 136 LO 5.4.1 Compare movement through channels to movement on facilitated diffusion and active transport carriers

Simple diffusion across membranes is limited to lipophilic molecules, but the majority of molecules in the body are either lipophobic or electrically charged need the help of membrane proteins, a process called mediated transport. Facilitated diffusion occurs when a molecule moves down its concentration gradient, and net transport stops when concentrations are equal on both sides of the membrane. If protein-mediated transport requires energy from ATP or another outside source and moves a substance against its concentration gradient, the process is known as active transport.

10.2 Somatic Senses LO 10.2.1 Trace the pathways for somatic sensation from receptor to the somatosensory cortex.

Somatic senses receptors are present in skin an viscera. - Receptor activation triggers action potentials in primary sensory neuron. Primary sensory neurons in PNS are pseudounipolar neurons, their nerve cell bodies lie in dorsal root ganglia along the spinal cord. - Axon terminals synapse in CNS onto interneurons serving as second sensory neurons. Location - Neurons associated with receptors for nociception, temperature & coarse touch synapse onto secondary mneurons shortly after entering spinal cord. - Fine touch, vibration and proprioceptive neurons have long axons projecting up the spinal cord to the medulla. - All secondary sensory neurons cross midline of body ; sensation from left side are processed in right hemisphere of brain & vice versa. p Secondary neurons for nociception, temperature & coarse touch cross midline in spinal cord, then ascend to brain. Fine touch, vibration, proprioceptive neurons cross midline in medulla. - In thalamus, secondary sensory neurons synapse onto tertiary sensory neurons, that project to somatosensory region of cerebral cortex. - Additionally, many sensory pathways send branches cerebellum for coordinating balance & movement - Somatosensory cortex recognizes where ascending sensory tract originate. Each sensory tract has corresponding region of cortex (sensory field).

LO 10.2.2 Describe the different types of somatosensory receptors.

Somatosensory receptors are the most common receptors in body ; they respod to forms of physical contact like: stretch, steady pressure, fluttering or stroking movement, vibration, texture. They're found in skin and deeper body regions. p Pacinian corpuscles: respond to vibration ; some of the largest receptors ; composed of nerve endings encapsulated in connective tissue layers ; found in subcutaneous skin, muscles, joints & internal organs ; they are rapidly adapting phasic receptors q Meissner's corpuscles: respond to flutter and stroking movements ; synapse with nerve endings encapsulated in connective tissue ; superficial layers of skin ; rapid adaption (phasic receptors) r Ruffini corpuscles: stretch of skin ; deep layers of skin ; synapse with nerve endings encapsulated in connective tissue ; slow adaption ( tonic receptors) s Merkel receptors: steady pressure and texture ; superficial layers of skin ; synapse with epidermal cell synapses with enlarged nerve ending ; slow adaption (tonic receptor) t Free nerve endings (thermoreceptors): temperature, stimuli, hair movement ; located around hair roots and under surface of skin ; synapse with unmyelinated nerve endings

6.4 Modulation of Signal Pathways. LO 6.4.1 Apply concepts of specificity, competition, affinity, and saturation to receptors and their ligands.

Specificity and competition: multiple ligands for one receptors - different ligand molecules with similar structures may bind to same receptor - ex.: neurotransmitter norepinephrine & neurohormone epinephrine both bind to adreergic receptors ability of receptor to bind both ligands demonstrates it's specificity - epinephrine & norepinephrine also compete with each other for receptors binding sites Adrenergic receptors come in two major isoforms: alpha and beta - Alpha isoform has higher affinity for norepinephrine - Beta2 ifoform has higher affinity for epinephrine Agonists and Antagonists - After ligand binding to receptor: one oft wo events occur o Ligand activats receptor & elicit response o Ligand occupies binding site/ prevets response - Competing ligand binding & elicing response: agonist of primary ligand - competing ligand binding & blocking activity : antagonist of primary ligand one ligand may have multiple receptors - for most signal molecule: target cell response depends on receptor or associated intraellular pathways, not on the ligand - some ligands bind to different receptor isoforms in different tissues: o epinephrine binds to different adrenergic receptors in two tissues § epinephrine on alpha receptors in intestinal blood vessels: è vasoconstriction § epinephrine on beta2- receptors in skeletal muscle blood vessels: è vasodilation Saturation: fact of reaching maximum rate of protein activity due to limited number of protein molecules in a cell - can be observed with enzymes, transporters receptors - ability to respond to chemical signals is limited by number of receptors fort hat signal.

LO 5.4.2 Apply the principles of specificity, competition, and saturation to carrier- mediated transport

Specificity refers to the ability of a transporter to move only one molecule or only a group of closely related molecules. One example of specificity is found in the GLUT family of transporters, which move 6-carbon sugars A transporter may move several members of a related group of substrates, but those substrates compete with one another for binding sites on the transporter. For example, GLUT transporters move the family of hexose sugars, but each different GLUT transporter has a "preference" for one or more hexoses, based on its binding affinity. Sometimes the competing molecule is not transported but merely blocks the transport of another substrate. The rate of substrate transport depends on the substrate concentration and the number of carrier molecules.

LO 11.1.3 Describe the synthesis and breakdown of autonomic neurotransmitters.

The primary autonomic neurotransmitters, acetylcholine and norepinephrine, can be synthesized in the axon varicosities Both are small molecules easily synthesized by cytoplasmic enzymes. Neurotransmitter made in the varicosities is packaged into synaptic vesicles for storage. The concentration of neurotransmitter in the synapse is a major factor in autonomic control of a target: more neurotransmitter means a longer or stronger response. The concentration of neurotransmitter in a synapse is influenced by its rate of break- down or removal. Neurotransmitter activation of its receptor terminates when the neurotransmitter (1) diffuses away, (2) is metabolized by enzymes in the extracellular fluid, or (3) is actively transported into cells around the synapse. The uptake of neurotransmitter by varicosities allows neurons to reuse the chemicals.

Anterior + posterior pituitary gland structure and function

The anterior pituitary is a true endocrine gland. The Anterior Pituitary Secretes Six Hormones prolactin (PRL), thyrotropin (TSH), adrenocorticotropin (ACTH), growth hormone (GH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) Secretion of all the anterior pituitary hormones is controlled by hypothalamic neurohormones. hypothalamic neurohormones control release of anterior pituitary hormones are usually identified as releasing hormones (e.g., thyrotropin-releasing hormone) or inhibiting hormones (e.g., growth hormone-inhibiting hormone or (somatostatin)). These hormones that control the secretion of other hormones are known as trophic hormones; of the six anterior pituitary hormones, prolactin acts only on a nonendocrine target (the breast). The remaining five hormones have another endocrine gland or cell as one of their targets Pathway; 1. Neurons synthesizing trophic neurohormones release them into the capillaries of the portal system. 2. Portal veins carry the tropic neurohormones directly to the anterior pituitary, where they act on the endocrine cells. 3. 3. Endocrine cells release their peptide set of capillaries for distribution to the target organs. The posterior pituitary, or neurohypophysis, is an extension of the neural tissue of the brain. It secretes neurohormones made in the hypothalamus, a region of the brain that controls many homeostatic functions. The posterior pituitary is the storage and release site for two neurohormones; oxytocin and vasopressin are clustered together in areas of the hypothalamus known as the paraventricular and supraoptic nuclei. · Vasopressin (antidiuretic hormone) or ADH, acts on the kidneys to regulate water balance in the body. · oxytocin - In women, oxytocin released from the posterior pituitary controls the ejection of milk during breast-feeding and contractions of the uterus during labor and delivery Dopamin inhibits Prolaction breast TRH stimulates TSH- Thyriod gland CRH stimulates ACTH adrenal cortex GHRH STIMULATES GH Liver SOMATOSTATIN INHIBITS GH GnRH STIMULATES FSH AND LH Endocrine cells of the gonads

11 Efferent Division: Autonomic and Somatic Motor Control 11.1 The Autonomic Division 356 LO 11.1.1 Describe the physiological role of the autonomic division and its branches.

The autonomic division of the efferent nervous system (or autonomic nervous system for short) is also known in older writings as the vegetative nervous system, reflecting the observation that its functions are not under voluntary control. The word autonomic comes from the same roots as autonomous, meaning self- governing. Another name for the autonomic division is visceral nervous system because of its control over internal organs. The autonomic division is subdivided into sympathetic and parasympathetic branches If you are resting quietly after a meal, the parasympathetic branch is dominant, taking command of the routine, quiet activities of day-to-day living, such as digestion. Consequently, parasympathetic neurons are sometimes said to control "rest and digest" functions. In contrast, the sympathetic branch is dominant in stressful situations, such as the potential threat from the snake. One of the most dramatic examples of sympathetic action is the fight-or- flight response, in which the brain triggers massive simultaneous sympathetic discharge throughout the body The sympathetic and parasympathetic branches of the au- tonomic nervous system display all four of Walter Cannon's properties of homeostasis: (1) preservation of the fitness of the internal environment, (2) up-down regulation by tonic control, (3) antagonistic control, and (4) chemical signals with different effects in different tissues Most internal organs are under antagonistic control, in which one autonomic branch is excitatory and the other branch is inhibitory

5.8 Integrated Membrane Processes: Insulin Secretion 158. LO 5.8.1 Describe the sequence of membrane transport-associated steps that link increased blood glucose to insulin secretion from pancreatic beta cells.

The beta cells of the pancreas synthesize the protein hormone insulin and store it in cytoplasmic secretory vesicles. When blood glucose levels increase, such as after a meal, the beta cells release insulin by exocytosis. Insulin then directs other cells of the body to take up and use glucose, bringing blood concentrations down to pre-meal levels. The beta cell has two gated membrane channels that help control insulin release. One is a voltage-gated Ca2+ channel. This channel is closed at the cell's resting membrane potential. The other is a K+ leak channel (that is, the channel is usually open) that closes when ATP binds to it. It is called an ATP-gated K+ channel, or KATP channel. Following a meal, plasma glucose levels increase as glucose is absorbed from the intestine Step 1. Glucose reaching the beta cell diffuses into the cell with the aid of a GLUT transporter. Increased glucose in the cell stimulates the metabolic pathways of glycolysis and the citric acid cycle, Step 2: ATP production increases, and ATP binds to the KATP channel, the gate to the channel closes, preventing K+ from leaking out of the cell Step 4. Retention of K+ depolarizes the cell Step 5. Voltage-sensitive Ca2+ channels to open Step 6. Calcium ions enter the cell from the extracellular fluid, moving down their electrochemical gradient. The Ca2+ binds to proteins that initiate exocytosis of the insulin-containing vesicles, and insulin is released into the extracellular space.

Name the major subdivisions of the cerebrum, cerebellum, diencephalon, and brain stem. Explain their anatomical relationships and give their major functions.

The brain stem • can be divided into white matter and gray matter • some ascending tracts from the spinal cord pass through the brain stem • other ascending tracts synapse there • descending tracts from higher brain centers travel through the brain stem on their way to the spinal cord • pairs of peripheral nerves branch off the brain stem • 11 of the 12 cranial nerves (numbers II-XII) originate along the brain stem • cranial nerves carry sensory and motor information for the head and neck • the brain stem consists of the medulla oblongata, the pons, and the midbrain • fourth ventricle runs through the interior of the brain stem and connects to the central canal of the spinal cord 1.1 The Medulla oblongata 6. the transition from the spinal cord into the brain proper 7. its white matter includes ascending somatosensory tracts that bring sensory information to the brain, and descending corticospinal tracts that convey information from the cerebrum to the spinal cord 8. 90% of corticospinal tracts cross the midline to the opposite side of the body in a region of the medulla/ the pyramids 9. each side of the brain controls the opposite side of the body 10. gray matter in the medulla includes nuclei that control many involuntary functions (blood pressure, breathing, swallowing, vomiting) 1.2 The Pons • a bulbous protrusion on the ventral side of the brain stem above the medulla and below the midbrain • primary function: to act as a relay station for information transfer between the cerebellum and cerebrum • coordinate the control of breathing along with centers in the medulla 1.3 The Midbrain/ mesencephalon - - small area between the lower brain stem and the diencephalon - functions: control of eye movement, relaying signals for auditory and visual reflexes - Cerebellum - the second largest structure in the brain - located inside the base of the skull, above the nape of the neck - most of the nerve cells in the brain are in the cerebellum - function: to process sensory information and coordinate the execution of movement - sensory input into the cerebellum comes from somatic receptors in the periphery of the body and from receptors for equilibrium and balance located in the inner ear - receives motor input from neurons in the cerebrum Diencephalon - lies between the brain stem and the cerebrum - composed of two main sections: thalamus and hypothalamus - two endocrine structures: the pituitary and pineal glands - many small nuclei that make up the thalamus - thalamus receives sensory fibers from the optic tract, ears, spinal cord and motor information from the cerebellum 9. projects fibers to the cerebrum (where the information is processed) 10. the hypothalamus lies beneath the thalamus 11. it is the center for homeostasis 12. contains centers for various behavioral drives 13. the posterior pituitary (neurohypophysis) is a down-growth of the hypothalamus and secretes neurohormones that are synthesized in hypothalamic nuclei 14. the anterior pituitary (adenohypophysis) is a true endocrine gland 15. its hormones are regulated by hypothalamic neurohormones secreted into the hypothalamic-hypophyseal portal system The Cerebrum 16. the largest and most distinctive part of the human brain 17. fills most of the cranial cavity 18. composed of two hemispheres connected primarily at the corpus callosum 19. each cerebral hemisphere is divided into four lobes: frontal, parietal, temporal, and occipital 20. surface has a furrowed, walnut-like appearance, with grooves/ sulci dividing convolutions/ gyri 21. cerebral gray matter three major regions: the cerebral cortex, the basal ganglia, and the limbic system 22. cerebral cortex is the outer layer of the cerebrum ; neurons are arranged in anatomically distinct vertical columns and horizontal layers 23. basal ganglia are involved in the control of movement 24. limbic system surrounds the brain stem ; acts as the link between higher cognitive functions (reasoning) and more primitive emotional responses (fear) 25. major areas of the limbic system: amygdala and cingulate gyrus (linked to emotion and memory) and the hippocampus (associated with learning and memory)

LO 5.1.2 Describe the distribution of body water among compartments and the effect of age and sex on total body water

The intracellular compartment contains about two -thirds (67%) of the body's water. The remaining third (33%) is split between the interstitial fluid (which contains about 75% of the extracellular water) and the plasma (which contains about 25% of the extracellular water). The 70-kilogram Reference Man has 60% of his total body weight, or 42 kg (92.4 lb), in the form of water. Adult women have less water per kilogram because they have more adipose tissue. Large fat droplets in adipose tissue occupy most of the cell's volume, displacing the more aqueous cytoplasm. Age also influences body water content. Infants have relatively more water than adults, and water content decreases as people grow older than 60.

LO 5.2.1 Compare bulk flow to solute movement across membranes.

The most general form of biological transport is the bulk flow of fluids within a compartment. In bulk flow, a pressure gradient causes fluid to flow from regions of higher pressure to regions of lower pressure. As the fluid flows, it carries with it all of its component parts, including substances dissolved or suspended in it. Blood moving through the circulatory system is an excellent example of bulk flow. Solute movement through a membrane is the flow between many different compartments. It is much more selective, and not all molecules can readily pass through.

Describe the stages of sleep.

There are four stages of sleep. REM (stage 1) and Non-rem 1, 2, and 3 that get sequentially deeper Person falls asleep: the state of arousal lessens, the frequency of the waves decreases slow-wave sleep (deep sleep or non-REM sleep, stage 4): on the EEG as presence of delta waves, high-amplitude, low-frequency waves of long duration that sweep across the cerebral cortex ; sleepers adjust body position without conscious commands from the brain to do so rapid eye movement (REM) sleep (stage 1): EEG pattern closer to that of an awake person - low-amplitude, high-frequency wave ; brain activity inhibits motor neurons to skeletal muscles, paralyzing them muscles still move the eyes and control breathing control of homeostatic functions is depressed during REM sleep, body temperature falls toward ambient temperature most dreaming takes place eyes move behind closed lids sleepers are most likely to wake up spontaneously from periods of REM sleep typical eight-hour sleep consists of repeating cycles: first hour: person moves from wakefulness into a deep sleep (stage 4) sleeper then cycles between deep sleep and REM sleep (stage 1), with stages 2- 3 occurring in between near the end of an eight- hour sleep period: sleeper spends the most time in stage 2 and REM sleep

LO 10.1.4 Explain how tonic and phasic receptors adapt to a continuous stimulus.

Two categories of receptors: - Tonic receptors à slowly adapting, fire rapidly action potentials when first activated, then slow and maintain firing as long as stimulus is present. (Baroreceptors, irritant-, tactile receptors, proprioceptors - Phasic receptors à rapidly adapting, fire action potential when first receive stimulus, cease firing if strength of stimulus remains constant. Once stimulus reaches steady state, phasic receptors adapt to steady state and turn off. Allows body to ignore information not important for maintaining homeostasis or well-being. Sense of smell uses phasic receptors (olfactory receptors are a type of phasic receptors). Ex.: olfactory receptors adapt to your fragrance after use, therefore you don't smell it during the day. - once phasic receptor is adapted, only way to create a new signal is to increase intensity of excitatory stimulus or remove stimulus to allow the receptor to reset. - molecular mechanism for sensory receptor adaption depends on receptor type: in some receptors: K+ open causing repolarization & signal stop in others: Na+ quickly inactivate. in others: biochemical pathways change receptor's responsiveness accessory structures may also decrease amount of stimulus reaching receptor. Ex.: ear muscles contract, dampen vibration of small bones (response to loud noises), decreasing sound signal

Growth hormone

Type: Peptide Effect: Up protein synthesis/ Decrease protein catabolism Up fatty acid --> Acetyl CoA/Increase fatty acid catabolism Decrease glucose uptake = Increase blood glucose Decrease gluconeogenesis in liver Encourages bone end growth/ Stop bone mineralisation Increase division of chondrocytes Diabetogenic effects Stimulation: Growth hormone releasing hormone (hypothalamus) starvation (decrease blood glucose and fatty acid) Increased blood amino acid Ghrelin Stress/trauma Exercise Deep sleep Supression: Growth hormone inhibiting hormone Increased blood glucose and fatty acid Decrease blood amino acid Aging Obesity Somatostatin Gigantism: excessive GH during childhood causing proportional growth Acromegaly: excessive GH in adulthood which causes enlargement of cartilaginous parts of bones of hand, feet and cranium. -Soft tissue that can grow will grow. Dwarfism: lack of GH with normal proportions Permisiveness: Somatomedin causes growth of bone but only when growth hormone is there

Compare and contrast graded potentials and action potentials •

Voltage changes across the membrane can be classified into two basic types of electrical signals: graded potentials and action potentials • Graded potentials are variable-strength signals that travel over short distances and lose strength as they travel through the cell. They are used for short-distance communication. If a depolarizing graded potential is strong enough when it reaches an integrating region within a neuron, the graded potential initiates an action potential. • Action potentials are very brief, large depolarizations that travel for long distances through a neuron without losing strength. Their function is rapid signaling over long distances, such as from your toe to your brain.

10.3 Chemoreception: Smell and Taste 322 LO 10.3.1 Describe the receptors, sensory transduction, and neural pathways for olfaction.

p Olfactory bulb receives input from primary olfactory neurons in olfactory epithelium q Primary sensory neurons (primary olfactory neurons) Single dendrite extending from cell body to olfactory epithelium o Single axon forming the olfactory nerve o Neurons replaced after 2 months 3. Surface of olfactory epithelium contains knobs (terminals of olfactory sensory neurons) 4. Each knob has non-motile cilia functioning as dendrites embedded in mucus 5. Odorant molecules dissolve in mucus before they bind to odorant receptor protein (G protein-linked membrane receptors) 6. combination of an odorant molecule with its odorant receptor activates a special G protein 7. increase in cAMP concentration opens cAMP-gated cation channels 8. depolarizing the cell and triggering a signal that travels along the olfactory sensory neuron axon to the olfactory bulb 9. Secondary and higher-order neurons project from the olfac- tory bulb through the olfactory tract to the olfactory cortex (bypassing the thalamus) 10. descending modulatory pathways from the cortex terminate in the olfactory bulb 11. reciprocal modulatory connections within and between the two branches of the olfactory bulb 12. olfactory pathways lead to the amygdala and hippocampus, parts of the limbic system involved with emotion and memory -> link between smell and memory

LO 6.3.2 Describe the advantages and disadvantages of gaseous second messenger molecules.

{almost NO information in book} (+) Advantages - Very short half-life (seconds) and breaks down quickly -> enables cell to limit space and time of signal activity. - Diffuse directly into the cell and affect it intracellularly - Diffuses easily to cells in the vicinity -Can be supplemented by the diet (-) Disadvantages -these same gases can be noxious when exogenic like NO and CO • Small reach

Distinguish between electrical and chemical synapses.

• Electrical synapses pass an electrical signal, or current, directly from the cytoplasm of one cell to another through the pores of gap junction proteins. Information can flow in both directions through most gap junctions, but in some current can flow in only one direction (a rectifying synapse). Electrical synapses occur mainly in neurons of the CNS. They are also found in glial cells, in cardiac and smooth muscle, and in nonexcitable cells that use electrical signals, such as the pancreatic beta cell. The primary advantage of electrical synapses is rapid and bidirectional conduction of signals from cell to cell to synchronize activity within a network of cells. Gap junctions also allow chemical signal molecules to diffuse between adjacent cells. • The vast majority of synapses in the nervous system are chemical synapses, which use neurocrine molecules to carry information from one cell to the next. At chemical synapses, the electrical signal of the presynaptic cell is converted into a neurocrine signal that crosses the synaptic cleft and binds to a receptor on its target cell.

Explain what the cellular mechanism of action of a hormone is.

• Hormones bind to target cell receptors and initiate biochemical responses. - one hormone may act on multiple tissues - the effects may vary in different tissues or at different stages of development - e.g. insulin, a hormone with varied effects - in muscle and adipose tissues: altering glucose transport proteins and enzymes for glucose metabolism - in the liver: modulating enzyme activity but no direct effect on glucose transport proteins - in the brain and some other tissues: glucose metabolism is totally independent of insulin • Termination of action: - negative feedback to stop secretion - in the bloodstream: degradation into inactive metabolites by enzymes of the liver and kidneys - metabolites are then excreted in bile or urine - rate of hormone breakdown is indicated by half-life in the circulation - enzymes can degrade peptide hormones bound to cell membrane receptors - some receptor-hormone complexes are brought into the cell by endocytosis -> hormone is digested in lysosomes.

Explain how negative feedback can be used to determine the location of a problem with one gland in a two- or three-gland pathway.

• If cortisol levels are high but levels of both trophic hormones are low, the problem is a primary disorder (Fig. 7.14a). There are two possible explanations for elevated cortisol: endogenous cortisol hypersecretion or the exogenous administration of cortisol for therapeutic reasons. In both cases, high levels of cortisol act as a negative feedback signal that shuts off production of CRH and ACTH. • Figure 7.14b shows a secondary hypersecretion of cortisol due to an ACTH-secreting tumor of the pituitary. The high levels of ACTH cause high cortisol production, but in this example the high cortisol level has a negative feedback effect on the hypothalamus, decreasing production of CRH. The combination of low CRH and high ACTH isolates the problem to the pituitary. • If the problem is overproduction of CRH by the hypothalamus (Fig. 7.14c), CRH levels are higher than normal. High CRH in turn causes high ACTH, which in turn causes high cortisol. This is, therefore, tertiary hypersecretion arising from a problem in the hypothalamus.

Explain permissiveness, synergism, and functional antagonism as they apply to hormones.

• In permissiveness, one hormone cannot fully exert its effects unless a second hormone is present, even though the second hormone has no apparent action (2 + 0 > 2). For example, maturation of the reproductive system is controlled by gonadotropin- releasing hormone from the hypothalamus, gonadotropins from the anterior pituitary, and steroid hormones from the gonads. However, if thyroid hormone is not present in sufficient amounts, maturation of the reproductive system is delayed. Because thyroid hormone by itself cannot stimulate maturation of the reproductive system, thyroid hormone is considered to have a permissive effect on sexual maturation. • Synergism: Two (or more) hormones interact at their targets so that the combination yields a result that is greater than additive (1 + 2 > 3). E.g. epinephrine and glucagon • Two hormones are considered functional antagonists if they have opposing physiological actions. E.g. glucagon and growth hormone raise the concentration of glucose in the blood, and both are antagonistic to insulin, which lowers the concentration of glucose in the blood. Hormones with antagonistic actions do not necessarily compete for the same receptor. Instead, they may act through different metabolic pathways, or one hormone may decrease the number of receptors for the opposing hormone.

Explain the roles of Wernicke's area and Broca's area in written and spoken language.

• Language skills require the input of sensory information (primarily from hearing and vision), processing in various centers in the cerebral cortex, and the coordination of motor output for vocalization and writing. • In most people, the centers for language ability are found in the left hemisphere of the cerebrum. Even 70% of people who are either left-handed (right-brain dominant) or ambidextrous use their left brain for speech. The ability to communicate through speech has been divided into two processes: the combination of different sounds to form words (vocalization) and the combination of words into grammatically correct and meaningful sentences. • Integration of spoken language in the human brain has been attributed to two regions in the cerebral cortex: Wernicke's area at the junction of the parietal, temporal, and occipital lobes and Broca's area in the posterior part of the frontal lobe, close to the motor cortex. • Input into the language areas comes from either the visual cortex (reading) or the auditory cortex (listening). Sensory input from either cortex goes first to Wernicke's area, then to Broca's area. After integration and processing, output from Broca's area to the motor cortex initiates a spoken or written action. • If damage occurs to Wernicke's area, a person may have difficulty understanding spoken or visual information. The person's own speech may be nonsense because the person is unable to retrieve words. This condition is known as receptive aphasia because the person is unable to understand sensory input. • Damage to Broca's area causes an expressive aphasia, or Broca aphasia. People with Broca aphasia understand simple, unambiguous spoken and written language but have difficulty interpreting complicated sentences with several elements linked together. This difficulty appears to be a deficit in short term memory. These people also have difficulty speaking or writing in normal syntax. Their response to a question may consist of appropriate words strung together in random order.

Explain the mechanism of long-term potentiation mediated by AMPA and NMDA receptors.

• Long-term potentiation (LTP) and long-term depression (LTD) are processes in which activity at a synapse brings sustained changes in the quality or quantity of synaptic connections. If synaptic activity persists for longer periods, the neurons may adapt through LTP and LTD. • A key element in long-term changes in the CNS is the amino acid glutamate, the main excitatory neurotransmitter in the CNS. • Glutamate has two types of receptor-channels: AMPA receptors and NMDA receptors. • NMDA receptor at resting membrane potentials, has blocked channel by a gate and a Mg2+ ion. Glutamate binding opens the ligand-activated gate, but ions cannot flow past the Mg2+. If the cell depolarizes, the Mg2+ blocking the channel is expelled, and then ions can flow through the channel. -> NMDA channel opens only when the receptor is bound to glutamate and the cell is depolarized.

Explain how comparative endocrinology is useful for understanding human physiology.

• Many of our models of human physiology are based on research carried out in fish or frogs or rats. For example, the pineal gland hormone melatonin was discovered through research using tadpoles. Many small nonhuman vertebrates have short life cycles that facilitate studying aging or reproductive physiology. Genetically altered mice (transgenic or knock- out mice) have provided researchers valuable information about proteomics.

Name the types and functions of glial cells.

• PNS: Schwann cells and Satellite cells Schwann cells: support and insulate axons by forming myelin Satellite cells: form supportive capsules around nerve cell bodies located in ganglia • CNS: Ependymal cells, Astrocytes, Microglia, Oligodendrocytes Ependymal cells: create a selectively permeable epithelial layer, the ependyma (source of neural stem cells), that separates the fluid compartments of the CNS Astrocytes: highly branched glial cells make up 50% of all cells in the brain they take up and release chemicals they rovide neurons with substrates for ATP production they help maintain homeostasis in the CNS extracellular fluid by taking up K+ and water ends of some astrocyte processes surround blood vessels and become part of the blood-brain barrier Microglia: specialized immune cells they remove damaged cells and foreign invaders Oligodendrocytes: support and insulate axons by forming myelin.

Compare temporal and spatial summation. Compare presynaptic and postsynaptic inhibition.

• Postsynaptic inhibtion: Inhibitorypostsynapticpotential(IPSP)sumswithtwoexcitatorypostsynapticpotentials(EPSPs)topreventanactionpotentialinthepostsnapticcell Presynaptic inhibtion:Oneinhibitoryandtwoexcitatoryneurosnfireandthesummedpotentialistoolowanddoesn'ttriggertheaxonhillock

List the six anterior pituitary hormones, the hormones that control their release, and their primary targets.

• Release: Secretion of all the anterior pituitary hormones is controlled by hypothalamic neurohormones. • The hypothalamic neurohormones that control release of anterior pituitary hormones are usually identified as releasing hormones (e.g., thyrotropin-releasing hormone) or inhibiting hormones (e.g., growth hormone-inhibiting hormone). • Hormones: prolactin (PRL), thyrotropin (TSH), adrenocorticotropin (ACTH), growth hormone (GH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) • Targets: Prolactin to mammary glands. Growth hormone to musculoskeletal system. Thyroid stimulating hormone to thyroid gland. Adrenocorticotropin stimulating hormone to adrenal cortex. Gonadotropins (Leutinising hormone and follicle stimulating hormone) to gonads (ovary and testis)

Explain the four criteria that make a chemical signal a hormone.

• Secreted by a cell/ group of cells: endocrine glands/cells, neurons (neurohormones), immune cells (cytokines) • Secreted into the blood • Transported to distant targets (via blood) • Exert their effect at very low concentrations (nanonmolar 10-9 to picomolar 10-12).

Explain in words how the Goldman- Hodgkin-Katz equation relates to the membrane potential of a cell.

• The Goldman-Hodgkin-Katz (GHK) equation calculates the membrane potential that results from the contribution of all ions (Na+, K+, Cl-) that can cross the membrane. The GHK equation includes membrane permeability values because the permeability of an ion influences its contribution to the membrane potential. If the membrane is not permeable to a particular ion, that ion does not affect the membrane potential.

Explain the relationships between the following terms: current flow, conductance, resistance, Ohm's law.

• The flow of electrical charge carried by an ion is called the ion's current. The net flow of ions across the membrane depolarizes or hyperpolarizes the cell, creating an electrical signal/ action potential. • The high-speed movement of an action potential along the axon is called conduction of the action potential. • Current flow, whether across a membrane or inside a cell, obeys a rule known as Ohm's Law. It says that current flow (I) is directly proportional to the electrical potential difference (in volts, V ) between two points and inversely proportional to the resistance (R) of the system to current flow: as resistance R increases, current flow I decreases.

Compare the structure and function of the anterior and posterior pituitaries.

• The pituitary gland is a lima bean-sized structure that extends downward from the brain, connected to it by a thin stalk and cradled in a protective pocket of bone. • The anterior pituitary gland is a true endocrine gland of epithelial origin. It is also called the adenohypophysis and its hormones are adenohypophyseal secretions. • The posterior pituitary/ neurohypophysis, is an extension of the neural tissue of the brain. It secretes neurohormones made in the hypothalamus. The posterior pituitary is the storage and release site for two neurohormones: oxytocin and vasopressin. The neurons producing oxytocin and vasopressin are clustered together in areas of the hypothalamus, the paraventricular and supraoptic nuclei.

List and give examples of the seven groups of neurocrine secretions.

• acetylcholine • amines: serotonin, histamine, (nor)epinephrine, dopamine • amino acids: glutamate, GABA, glycine • peptides: substance P, opioid peptides (enkephalins, endorphins) • purines: AMP, ATP • gases: NO, CO, H2S • lipids: THC

Name the three most common types of endocrine pathologies.

• hormone excess (mostly due to hypersecretion caused e.g. by adenomas) • hormone deficiency (due to hyposecretion caused by e.g. is insufficient dietary iodine for the thyroid gland to manufacture the iodinated hormone or an atrophy of hormone secreting gland because of disease) • abnormal responsiveness of target tissues to a hormone (caused by abnormal interactions between the hormone and its receptor or by alterations in signal transduction pathways e.g. hyperinsulinemia).

LO 12.1.2 Diagram the sliding FILAMENT theory of contraction (includes contraction cycle)

• myosin cross bridges provide force that pushes actin filament during contraction • myosin binds to to actin, calcium signal initiates power stroke and pushes actin towards center of sarcomere, at end of power stroke myosin unbinds moved actin and binds to new actin for a new contractile cycle • power stroke repeats many times during contraction • energy for power stroke comes from ATP that is hydrolyzed by myosin • when contraction begins in response to calcium signal: troponin C binds reversibly to calcium, forms calcium-troponin C complex • calcium - troponin C complex pulls tropomyosin away & unveils actin's myosin-binding sites. Now myosin cross-bridges can carry out power stroke, actin filaments are moved and contractile cycles repeat until binding sites are covered again • for muscle relaxation: calcium concentration in cytosol must decrease. - relaxation: filaments slide back with aid of titin & elastic connective tissue • starting with rigor state ; myosin head tightly bound to G-actin molecules, no ATP/ADP bound to myosin • 1. ATP binds and myosin detaches ; decreases actin binding affinity for myosin, myosin releases from actin • 2. ATP hydrolysis provides energy for myosin head to rotate and reattach to actin, ADP & Pi remain bound to myosin until it forms 90° angle with long axis of filaments ; then myosin binds new actin that is 1-3 molecules away from where it started • 3. power stroke ; begins after calcium binds to troponin uncovering rest of myosins binding site. Release of Pi allows myosin head to swivel ; cross-bridge tilting from a 90° to 45° angle • 4. Myosin releases ADP at the end of power stroke. With ADP gone ; myosin head again tightly bound to actin in rigor state —> cycle is ready to begin once more as new ATP binds to myosin

LO 10.6.3 Explain how photoreceptors convert light energy into action potentials.

• phototransduction is similar for rhodopsin (in rods) and the three color pigments (in cones) o Rhodopsin is composed of two molecules o opsin, a protein embedded in the membrane of the rod disks o retinal, a vitamin A derivative that is the light-absorbing portion of the pigment • Bleaching = activated retinal no longer binds to opsin & is released from the pigment - In absence of light retinal binds into a binding site on opsin Retinal is activated by only 1 photon of light & changes its shape to a new configuration • electrical signals in cells occur as a result of ion movement between the intracellular and extracellular compartments • rods contain three main types of cation channels cyclic nucleotide-gated (CNG) channels that allow Na+ and Ca2+ to enter the rod • K+ channels that allow K+ to leak out of the rod o voltage-gated Ca2+ channels in the synaptic terminal that help regulate exocytosis of neurotransmitter 1. rod in darkness - rhodopsin is not active ; high cyclic GMP (cGMP) levels ; CNG & K+ channels are open - Na+ & Ca2+ ion influx are greater than K+ efflux à rod stays depolarized to an average membrane potential of -40 mV - Voltage-gated Ca2+ channels are open à continuous (tonic) release of the neurotransmitter glutamate from the synaptic portion of the rod onto the adjacent bipolar cell 2. Light activates rhodopsin - Second-messenger cascade is initiated trough G protein transducin àdecreases the concentration of cGMP à closes CNG channels à cation influx stops or slows - Decrease cation influx & continued K+ efflux à inside of rod hyperpolarizes, glutamate release onto bipolar neurons decreases - Bright light à closes all CNG channelsà stops neurotransmitter release - Dimmer light à causes response that is graded in proportion to the light intensity 3. Recovery phase - After activation à retinal diffuses out of the rod à transported into pigment epithelium à reverts to its inactive form before moving back into rod à in rod it reunites with opsin - Recovery from rhodopsin from bleaching can take some time à major factor in slow adaption of the eye when moving from bright light into dark

10.6 The Eye and Vision 338 LO 10.6.1 Describe the structures of the eye and the role of each structure in vision.

• pupil = opening through which light can pass into the interior of the eye o size varies with the contraction and relaxation of pupillary muscle o appears as black spot in iris • Iris = colored ring of pigment that determine eye color • Lens = transparent disk that focuses light • Zonules = attach lens to ciliary muscle • Anterior chamber (in front of lens) is filled with aqueous humor o Low-protein, plasma-like fluid secreted by the ciliary epithelium supporting the lens • Vitreous chamber (behind the lens) = mostly filled with vitreous body o Clear, gelatinous matrix = helps maintain shape of the eyeball • Sclera = outer wall of the eyeball, composed of connective tissue • Ciliary muscle = contraction alters curvature of the lens • Retina = contains photoreceptors • Fovea = region of sharpest vision • Optic disk (blind spot) = region where optic nerve and blood vessels leave the eye

LO 12.1.1 Draw and label a series of diagrams to show the different levels of organization of skeletal muscle.

• skeletal muscles are composed of muscle fibers (muscle cells) • fibers are cylindrical with multiple nuclei • satellite cells outside the muscles become active in growth / repair (stem cells) • fibers sheathed in connective tissue with adjacent fibers = fascicles —> in between: nerves, collagen, elastic fibers, vessels • attached via tendons to bone • muscle fiber anatomy ; cell membrane = sarcolemma, cytoplasm = sarcoplasm, intracellular structures that contract = myofibrils, sarcoplasmic reticulum ; contains calcium which is essential for contraction • sarcoplasmic reticulum consists of terminal cisternae that store calcium, adjacent to cisternae ; transverse tubules (t-tubules) • t- tubules are continuous with extracellular fluid. 1 t-tubule + 2 adjacent cisternae = triad • t-tubules allow action potentials to rapidly reach the interior of the cell • cytosol contains many glycogen granules and mitochondria (ATP for contraction) Myofibrils are contractile structures • each fibril composed to several types of protein in a repeating structures = sarcomeres • proteins include: thick filament = myosin, thin filament = actin, regulatory proteins: tropomyosin & troponin and 2 giant accessory proteins = titin & nebulin • Myosin: ability to create movement, 2 chains ; heavy & light chains, 250 myosin molecules merge to form a thick filament. Heavy chains = motor domain that uses ATP to create movement + hydrolyze ATP via myosin ATPase + contain binding sites for actin • Actin: globular protein that makes up thin filaments (2x F-actin polymers twisted together), G-actin has single myosin-binding site • when actin & myosin bind ; cross bridges form, they have two states: 1. low-force (relaxed muscles), high-force (contracting muscles) Sarcomere • under light microscope: arrangement of thick and thin filaments in myofibril creates repeating • order, alternating light and dark bands: 1 repeat of pattern forms sarcomere • sarcomere = contractile unit of myofibril with following elements: • Z - disks: one sarcomere composed of 2 Z-disks and the filaments between them. Serve attachment for thin filaments • I - bands: lightest color bands of sarcomere, region only occupied by thin filaments. Z-disk runs through middle of every I band —> each half of an I band belongs to different sarcomere • A band: darkest region, encompasses entire length of thick filament • H-zone: central, lighter region of A-band, occupied by thick filaments only • M line: attachment site for thick filaments, divides A band in half • proper alignment of filaments ensured by titin & • nebulin • Titin: stretches from one Z disk to neighboring M line, has two functions: stabilizes position of contractile filaments, its elasticity returns fibers to resting length • Nebulin: assists titin, inelastic giant protein that lies alongside thin filaments and attaches to Z-disk. Helps align actin filaments

Describe the role of the nervous system in endocrine reflexes.

• stimuli integrated by the CNS influence the release of many hormones through efferent neurons • specialized groups of neurons secrete neurohormones ‣ catecholamines made by modified neurons in the adrenal medulla ‣ hypothalamic neurohormones secreted from the posterior pituitary ‣ hypothalamic neurohormones that control hormone release from the anterior pituitary • two endocrine structures are incorporated in the anatomy of the brain: the pineal and the pituitary gland.

Compare long-loop negative feedback for anterior pituitary hormones to the negative feedback loops for insulin and parathyroid hormone.

• the hormone secreted by the peripheral endocrine gland "feeds back" to suppress secretion of its anterior pituitary and hypothalamic hormones • pathways with two or three hormones in sequence: the "downstream" hormone usually feeds back to suppress the hormone(s) that.

10.5 The Ear: Equilibrium 335 LO 10.5.1 Explain how otoliths and the cupula convey information about movement and head position to the vestibular nerve.

• vestibular apparatus/ membranous labyrinth • is an intricate series of interconnected fluid-filled chambers consists of two saclike otolith organs: the saccule and the utricle tell us about linear acceleration and head position three semicircular canals that connect to the utricle at their bases sense rotational acceleration in various direction • at one end of each canal is an enlarged chamber, the ampulla, which contains a sensory structure known as a crista • crista consists of hair cells and a gelatinous mass: the cupula • that stretches from floor to ceiling of the ampulla, closing it off • hair cell cilia are embedded in the cupula • as the head turns, the bony skull and the membranous walls of the labyrinth move, but the fluid within the labyrinth cannot keep up because of inertia (the tendency of a body at rest to remain at rest) • in the ampullae, the drag of endolymph bends the cupula and its hair cells in the direction opposite to the direction in which the head is turning • if rotation continues, the moving endolymph finally catches up • if head rotation stops suddenly, the fluid has built up momentum and cannot stop immediately the fluid continues to rotate in the direction of the head rotation, leaving the person with a turning sensation if the sensation is strong enough, the person may throw his or her body in the direction opposite the direction of rotation in a reflexive attempt to compensate for the apparent loss of equilibrium otolith organs (utricle & saccule) are arranged to sense linear forces o their sensory structures, called maculae, consist of hair cells (embedded in the otolith membrane) a gelatinous mass known as the otolith membrane calcium carbonate and protein particles called otoliths - bind to matrix proteins on the surface of the otolith membrane - if gravity or acceleration cause the otoliths to slide forward or back, the gelatinous otolith membrane slides with them, bending the hair cell cilia and setting off a signal • maculae of the utricle sense forward acceleration or deceleration as well as head tilt • maculae of the saccule are oriented vertically when the head is erect, which makes them sensitive to vertical forces, such as dropping downward in an elevator • the brain analyzes the pattern of depolarized and hyperpolarized hair cells to compute head position and direction of movement - vestibular hair cells (e.g. those of cochlea) are tonically active and release neurotransmitter onto primary sensory neurons of the vestibular nerve - those sensory neurons either synapse in the vestibular nuclei of the medulla run without synapsing to the cerebellum (the primary site for equilibrium processing) - collateral pathways run from the medulla to the cerebellum or upward through the reticular formation and thalamus