Phys 335 Unit 1
List the association areas of the cerebral cortex, and describe the general function of these areas.
Association areas = final destination for afferent input that integrate and process sensory input into perception
mechanism of negative feedback control of body temperature
1.) Stimulus: Decrease in body temp 2.) Temp-sensitive neuron in receptor increases signaling rate and sends signal via afferent pathway 3.) Integrating center compares stimulus to set point of 36C 4.) Signal sent via efferent pathway to contract blood vessel and skeletal muscle (shivering) to decrease heat loss and increase heat production
Describe the functional consequence of stimulation of autoreceptors.
Acts as a negative feedback mechanism. NT released by a neuron will bind to autoreceptor on neuron that released the NT
Explain the concept of "labeled lines" with regard to sensory neural pathways.
Dedicated pathways that carry information about a specific modality from a specific body part to the brain Route A.P. flow
Define depolarization, overshoot, repolarization, and hyperpolarization.
Depolarization: resting potential becomes closer to 0 mV overshoot: membrane potential is above 0 mV repolarization: membrane potential approaches resting membrane potential hyperpolarization: potenital is more negative than resting
Explain how overlapping receptive fields influence acuity.
Overlap helps localize distinct stimuli. Sensory units of nearby neurons have lower A.P. frequency. Area with highest frequency is where the stimulus is located. - Lateral inhibition: Enables localization of stimulus by the central receptor inhibiting receptors at the edge of the stimulus via presynaptic inhibition.
Explain why action potentials normally propagate in only one direction along axons
Refractory periods prevent action potentials from reversing direction
Describe the anatomy of an afferent neuron, detailing which portions are in the peripheral nervous system and which are in the central nervous system.
W/In PNS - sensory receptor membrane, myelinated axon, node of Ranvier, cellbody W/in CNS - axon
Nerve
bundle of afferent and efferent axons to/from different levels of the body. Only in PNS. CNS follow tracts
tight junctions
hold epithelial cells together to acts as barriers that regulate exchange of molecules
Explain how substances not permeable to a pure lipid bilayer are able permeate through real cell membranes.
polar and ionized molecules have low solubility in the lipid bilayer and use special proteins such as ion channels to pass through.
Define receptive field
the area of the body that leads to activity in a particular sensory neuron
Define Physiology
the study of mechanisms of body function at both separate levels and integrated
Explain the mechanism of positive feedback control and give a physiological example
- Changes in the variable accelerate further change and has a terminating event childbirth - oxytocin stimulates posterior pituitary gland of hypothalamus to induce smooth muscle contraction of myometrium which stretches in cervix and release of more oxytocin.
List the structures that make up the central nervous system - Spinal cord
- Dorsal horn (backside, made of gray matter) - Dorsal root: afferent pathway to dorsal horn - Dorsal root ganglion: cell body outside CNS - Ventral horn (front, made of gray matter) - Ventral root: efferent path - Spinal cord: surrounds gray matter, made of white matter
Explain why intracellular fluid and extracellular fluid Na+ and K+ concentrations are different, and state the typical values found in each fluid compartment.
- ECF and ICF have balanced charges - membrane potential only changes if current flows across the membrane - only a small charge difference is needed to establish membrane potential difference is caused by membrane permeability - more leak channels for K+ ICF: Na+: 15 mmol/L K+: 150 mmol/L ECF Na+: 145 mmol/L K+: 5 mmol/L
Detail the functional anatomy of SOMATIC including details such as the number and lengths of neurons, the neurotransmitters released, the neurotransmitter receptors, and the target tissues.
- NT: ACh - receptor: N-AChR - target: skeletal muscle
Detail the functional anatomy PARASYMPATHETIC neuron including details such as the number and lengths of neurons, the neurotransmitters released, the neurotransmitter receptors, and the target tissues.
- NT: ACh - receptor: N-achR and M-AChR - target: smooth/cardiac muscle, glands Long CNS axon terminal sends ACh to N-AChR of short ganglion cell which then sends ACh to M-AChR of target
Detail the functional anatomy SYMPATHETIC neuron including details such as the number and lengths of neurons, the neurotransmitters released, the neurotransmitter receptors, and the target tissues.
- NT: ACh, NE, Epi - receptor: N-AChR, Adrenergic receptor - target: smooth/cardiac muscle, glands Short CNS axon terminals 1.) ACh leaves CNS axon terminal and binds to N-AChR of long ganglion cell. NE released onto adrenergic receptor of target 2.) ACh leaves short CNS axon terminal and binds to N-AChR of adrenal medulla. Epi sent into bloodstream and bind to adrenergic receptor of target
Explain how the terms negative feedback and positive feedback relate to the functions of voltage-gated Na+ and K+ channels.
- POSITIVE: A depolarizing stimulus opens Na+ channels which increases Na+ permeability. Increased flow of Na+ leads to more depolarization and continues to increase influx of Na+ until a stop mechanism inactivates Na+ channels. - NEGATIVE: Depolarization of Na+ leads to opening of K+ channels which increases K+ permeability out of the cell. Repolarization of membrane potential continues to open K+ channels until hyperpolarization occurs and K+ channels slowly close.
List the structures that make up the peripheral nervous system.
- Spinal nerve: extend from spinal cord receive and send out signals 1.) cervical (8) neck, arms, hands, shoulders 2.) thoracic (12) chest, upper abdomen 3.) lumbar (5) lower abdomen, hips, legs 4.) sacral (5) lower GI, genitals 5.) Coccygeal (1) tailbone
Explain the general functions of the thalamus
- acts as a synaptic relay station for sensory pathways in their way to cerebral cortex - participates in control of skeletal muscle coordination - key function in awareness *selective processing
Define action potentials, and describe how they are different from graded potentials.
- all or none large rapid depolarizations and repolarizations of P.M. that can occur at high frequencies and travel long distances along axons or other excitable membranes - must reach a threshold value before A.P. is fired. *Depend on conc. gradient (Na+/K+) and membrane potential - CANNOT be summated, not graded by stimulus size, don't decrease with distance - have absolute and relative refractory periods - generated by Voltage-gated ion channels *Na+ channels open and close rapidly (inactivated by gate) ** K+ channels open and close slowly - One A.P doesn't change Na+/K+ gradients
Differentiate between carrier-mediated transport and ion channel diffusion.
- both ion channels and carrier-mediated transporters show chemical specificity, but differ in the number of molecules or ions crossing the PM. Ion channels move more ions than carrier proteins moving molecules (transporter must change shape, ion channel doesn't) - both have different transporters or channels for different molecules and ions
Define feedforward control, and describe an example of when this occurs in the body.
- changes in regulated variables are anticipated and prepared for before they occur skin neurons detect temp change and signal brain to adjust blood vessels and muscles before outside temp can cause internal body temp change
Connective cells/tissue explain their general functions.
- connect, support structures of body -blood is a fluid connective tissue because it connects the body systems together bringing the needed oxygen, nutrients, hormones and other signaling molecules, and removing the wastes -forms extracellular matrix consisting of proteins and polysaccharides that act as a scaffold for cellular attachment, transmit chemical messengers to regulate activity, migration, growth and differentiation
Explain the general functions of the brainstem
- contains all the axons in neurons passing b/w spinal cord, forebrain, and cerebellum - contains reticular formation, its integrating centers - nuclei for cranial nerves III - XII
Explain the general functions of the cerebellum
- coordinates movements, posture and balance - participates in some learning
parasympathetic nervous system
- day to day activities/relaxed situations - "rest and digest" - activate processes that help during resting state and inhibit processes that aid physical exertion * decrease heart rate - cranial to sacral
Describe how pain pathways are modulated by higher centers, therapies, and drugs such as morphine and anti-inflammatory agents.
- descending inputs from the brainstem stimulate dorsal horn interneurons to release opioids. Presynaptic opiate receptors inhibit NT release from ascending afferent neuron and post synaptic receptors. Morphine works similar.
facilitated diffusion
- down conc. gradient until conc. on both sides are equal - transporter moves solute - not coupled to ATP - Glucose transporter - cant move up gradient
Define dual innervation and give some examples.
- effects on organs are typically opposite - both are tonically active: neither system is entirely shut off - axons of preganglionic sympathetic neurons tend to be short because they project to a nearby structure, whereas the axons of the postganglionic neurons are long - parasympathetic preganglionic axons are long, postganlionic axons are short - NT released from varicosities ex: speeding and slowing of heart rate, opening and closing of sphincters of the GI tract
List some variables of the extracellular fluid that are homeostatically regulated
- glucose - O2 and CO2 - waste - water, salts, ions - pH - temp - BP * change occurs bc of external environment (cold, famine, drought, etc) ** Activities of cells
Describe the main factor determining permeability of substances through a pure lipid bilayer, and list substances that are permeable and some that are not.
- hydrophobic core of bilayer determines permeability permeable - hydrophobic (lipid soluble) and small polar substances - O2, CO2, ethanol, FA - nonpolar, have similar permeabilities for all molecules nonpermeable - hydrophilic substances, large polar molecules and charged ions - need ion channel or transport protein
proteins of PM
- ion channels - enzymes - signal receptors - cytoskeletal anchors - cell recognition
Name the receptors that allow us to sense temperatures, describe how they work, and explain the effects of menthol, capsaicin, and ethanol.
- no myelination on axons - actual temperature sensors are ion channels with different temp ranges in TRP protein - ion channels can be opened by chemical ligands. - menthol makes you cold - capsaicin and ethanol make you warm
List what is detected by mechanoreceptors, and state names of a few of these receptor types.
- pressure, stretch, touch, muscle tension -meissner's corpuscle -merkel's corpuscle -free neuron ending -pancinian corpuscle -ruffini corpuscle
Explain the relative importance of the specific neurotransmitter released presynaptically and the receptor mechanisms occurring postsynaptically in determining whether a synapse is excitatory or inhibitory.
- receptor or ion channel determines whether an IPSP or EPSP develops but some NT elicit one or the other.
Explain the general functions of the hypothalamus
- regulates anterior pituitary gland function - regulates water balance - participates in regulation of autonomic nervous system - regulates eating and drinking behavior - reproductive behavior - reinforces certain behaviors - generates body temp, circadian rhythm - participates in emotional behavior *master command center
Define graded potentials, and list five important properties they possess
- short distance signals that rely only on local flow of ionic currents - proportional to the size of the stimulus - decrease with distance from the stimulus site (b/c K+ leaks out) - can be depolarizing or hyperpolarizing - can summate with each other
Epithelial cells and tissue explain their general functions.
- specialized for selective secretion and absorption of ions and organic molecules; protection -located on surface of body or individual organs -rest on protein layers called basement membrane -held my tight junctions
Muscle cells/tissue explain their general functions.
- specialized to create mechanical force for movement -skeletal muscle: attached to bone and produce movement via contractions under voluntary control -cardiac muscle: in heart, contract to pump blood, involuntary -smooth muscle: make up walls of tubes in body and move things under contraction, involuntary
List the five major somatic sensations.
- touch - pressure - temperature - pain - body position and movement
mediated transport systems
- transported solute binds to specific site on transporter protein. A conformational change exposes the solute to the other side of the PM. - molecules move in either direction - flux depends on: 1.) solute conc. 2.) affinity of transporters for solute 3.) number of transporters in membrane 4.) rate at which conformational change occurs
Describe the general anatomy and characteristics of autonomic neurons
- two neuron chain between CNS and effector organ - effector organs are smooth or cardiac muscles, glands, or GI neurons - can lead to excitation or inhibition of the effector organ depending on receptor - operates largely outside conscious control - divided into sympathetic and parasympathetic
active transport
- uses ATP to move solute up gradient - substance binds to transporter - "pumps" - max flux reached when specific transporters are saturated primary: - hydrolysis of ATP by transporter provides E secondary: - ion movement down gradient is coupled to another molecule - Na+ moves to ICF while other molecule moves up gradient - Na+ is transported back out by primary active transport - ceasing of ATP would inhibit primary and secondary transport
List four properties that distinguish action potentials from graded potentials.
1.) A.P are all or none 2.) A.P are not graded by stimulus size 3.) A.P cannot summate due to refractory period 4.) A.P do NOT decrease with distance; they propagate over long distances for signal transmission
List the presynaptic events involved in neurotransmitter release at chemical synapses.
1.) A.P propagates down axon to terminal 2.) Voltage-gated Ca 2+ channels open and allow influx. Ca 2+ bind to synaptotagmin which binds to SNAREs to hold vesicles onto PM. 3.) Ca2+ induced exocytosis of synaptic vesicles 4.) Neurotransmitter diffuses across synaptic cleft 5.) NT binds to post synaptic receptor 6.) NT removed from synaptic cleft
List two ways that stimulus intensity is encoded by afferent neurons.
1.) A.P. frequency 2.) Recruitment of neighboring afferent neurons lead to A.P.s in them * A strong stimulus applied at a specific location activates sensory units around it
List the structures that make up the central nervous system - Brain
1.) Forebrain: - Cerebrum (frontal, parietal, occipital, temporal lobe) - Diencephalon (thalamus, hypothalamus) 2.) Brainstem - Midbrain - Pons - Medulla oblongata (reticular formation) 3.) Cerebellum
State the names and locations of the four lobes that comprise the cerebrum
1.) Frontal lobe (front) 2.) Parietal lobe (mid top) 3. Temporal lobe (mid bot) 4. Occipital lobe (back) *All in forebrain
List eight ways that synaptic transmission can be altered by drugs and diseases.
1.) Increase leakage of NT from vesicle 2.) Increase NT release into cleft 3.) block transmitter release 4.) Inhibit NT synthesis 5.) block cleft or intracellular enzyme metabolize NT 6.) bind to receptor on postsynaptic cell to block NT or mimic NT 7.) inhibit or stimulate second-messenger activity 8.) block NT reuptake
List the reason why postsynaptic potentials are relatively brief.
1.) NTs rapidly bind and unbind from receptors 2.) NTs are taken back into presynaptic terminal by reuptake or transported into nearby glial cells 3.) NTs diffuse away from synaptic cleft 4.) NTs can be enzamatically destroyed into inactive substances.
List three general mechanisms causing the termination of postsynaptic potentials.
1.) Neuromodulators can interact with receptors on either pre/post synaptic cells to modify effectiveness of synapse transmitting signal 2.) Inhibition by decreasing Ca 2+ influx into presynaptic cell 3.) Drugs can block cleft, block transmitter release, bind to receptor to block NT, enzymatic metabolism of NT, inhibit second-messenger activity within postsynaptic cell.
five components of a negative feedback system connect the deviation of a variable from normal to the correction of that deviation
1.) Stimulus acts on a receptor that regulates variable changes from its normal value 2.) A receptor detects the stimulus and sends message via afferent pathway (nerves or hormones) 3.) Integrating centers compare to set point by communicating w. the brain through groups of neurons and glands. 4.) Signal sent out via efferent pathway to effector cells, tissue, organ systems 5.) Response occurs and opposes initial change moving back to towards normal value and inhibits stimulus
List the five regions of the spinal cord from top to bottom, state the number of spinal nerves associated with each, and explain what information is carried by spinal nerves.
1.) cervical (8) neck, arms, hands, shoulders 2.) thoracic (12) chest, upper abdomen 3.) lumbar (5) lower abdomen, hips, legs 4.) sacral (5) lower GI, genitals 5.) Coccygeal (1) tailbone
Explain the general functions of the cerebrum
1.) contains cerebral cortex: participates in perception; generation of skilled movement; reasoning, learning, memory 2.) contains subcortical nuclei, basal nuclei: participates in coordination of skeletal muscle activity, and limbic system: participates in emotion, behavior, some learning 3.) contains interconnecting pathways
List eight factors that can affect how we perceive sensory information.
1.) receptor adaptation 2.) emotion 3.) personality 4.) experience 5.) filtering by thalamus 6.) damaged pathways 7.) drugs 8.) disease
Explain how color vision occurs
3 types of cones in eye that absorb light at different wavelengths -combination of their firing frequencies is perceived as color
Define sensory unit.
A single afferent neuron with all of its receptor endings
Define the absolute and relative refractory periods, and describe an experiment you could use to determine those periods.
Absolute: No matter how strong a stimulus is, neuron can't fire an A.P. Relative: A.P may fire but it will be smaller b/c K+ efflux repolarizes cell and lower number of Na+ channels open.
List cell types with which neurons form chemical synapses, and state the major difference between electrical and chemical synapses with regard to speed.
Cell types for chemical synapses: muscle and gland cell - electrical synapses receive direct cell-to-cell contact and conduct signals very quickly. - chemical synapses diffuse across synaptic cleft which is slower than electrical synapse.
explain why cells of multicellular organisms become specialized
Cells differentiate to have specialized functions differentiated cells form tissues and different tissues form organs that perform specific functions
List the two major anatomical divisions of the nervous system
Central Nervous System Peripheral Nervous System
Explain the mechanism and significance of long-term potentiation
Contributes to learning and memory 1. A.P sent down to presynaptic axon terminal. Vesicles containing glutamate are created 2. vesicle binds to PM and release glutamate into cleft where it binds to AMPA and NMDA receptors. 3. Na+ entry in AMPA receptor channel depolarizes the postsynaptic cell by 20-30 mV. 4. depolarization drives Mg 2+ ion out of pore of NMDA receptor to allow influx of Ca 2+ ions. 5. Ca 2+ influx activates second-messenger system leading to increase Na+ and Ca 2+ influx in post synaptic cell by retrograde signaling which leads to long lasting increase in glutamate receptor and sensitivity 6. lasting increase in glutamate synthesis and release continues. Ethanol impairs process acutely by blocking NMDA receptors.
Define convergence and divergence with regard to neuronal pathways, and explain the functional significance of each.
Convergence: ONE presynaptic branch stemming from axon terminals of MULTIPLE neurons converge onto ONE postsynapse of another neuron Divergence: ONE neuron with multiple presynaptic branches diverge to meet multiple postsynaptic branches of MANY neurons. *Divergence allows one neuron to communicate with many other neurons in a network. **Convergence allows a neuron to receive input from many neurons in a network
Draw the cells involved in neurotransmission of the "ON" bipolar cell pathway under conditions when no light is striking the photoreceptor, and also what occurs when light strikes the photoreceptor.
DARK: 1.) Rod or cone cGMP level is high and photoreceptor is depolarized 2.) Glutamate released and hyperpolarizes bipolar cell 3.) No excitatory NT released onto ganglion cell 4.) no APs in brain LIGHT 1.) cGMP level falls, photoreceptor is hyperpolarized. 2.) Bipolar cell depolarizes spontaneously 3.) Excitatory NT released onto ganglion cell that fires AP
Explain how the functions of voltage-gated Na+ channels and voltage-gated K+ channels produce a typical neuronal action potential.
During resting potential, both ion channels are closed. Opening of Na+ channels depolarize the cell which causes (+) feedback to open more Na+ channels rapidly which leads to overcome threshold and overshoot. Inactivation gate closes Na+ channel leading to repolarization and hyperpolarization because K+ channels close slowly. When K+ channels close, the membrane potential returns to resting state.
Define homestasis
Dynamic mechanisms that maintain physiological variables in the internal environment within predictable ranges that are compatible with cell survival.
List the major fluid compartments of the body, indicate the volumes of each in an average-sized person
ECF (33%) - Interstitial fluid: 11 L - Plasma: 3 L ICF (67%) - ICF: 26 L - Fluid in RBC: 2 L *Barriers b/w ICF and ECF create compartmentalization and regulate what substances pass through
Define excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP).
EPSP: Graded potential making it more likely an A.P will fire IPSP: Graded potential making it less likely A.P will fire
List the postsynaptic events occurring during signaling at excitatory and inhibitory synapses.
EPSP: ligand-gated receptor opens when NT binds and allows net influx of Na+ into cell to cause depolarization IPSP: NT binds to receptor and either opens channels for K+ efflux or Cl- influx *Type 1 cell: Cl- prevents depolarization ** Type 2 cell: Hyperpolarization caused by K+ or Cl-
State whether EPSPs and IPSPs are graded potentials or action potentials
EPSPs and IPSPs are graded potentials. When an EPSP summates enough it can depolarize the cell and fire an A.P IPSP summate to hyperpolarize a cell.
Define gray matter and white matter and compare their distributions in the brain and spinal cord.
Gray matter: composed of cell bodies White matter: tracts of myelinated axons Brain: gray matter = outside layer of cerebral cortex ; subcortical nuclei white matter = inside cerebral cortex Spinal cord: gray matter = inside spinal cord white matter = surround gray matter
Ohm's Law
I = V/R
Explain how a spinal cord injury could result in loss of pain and temperature information from one side of the body and loss of fine touch discrimination from the other side of the body.
If an injury occurs
Describe in detail the mechanism of phototransduction occurring within a photoreceptor cell, explaining what processes dominate when light is striking the cell and what processes dominate when light is not striking the cell.
In dark, cGMP is high, retinal is bound to opsin, channels open, and membrane is depolarized (Guanylyl cyclase is most active component in dark). - when photons strike, retinal dissociates, phosphodiesterase activity is activated, cGMP is reduced, channels close and cell repolarizes.
Explain how the distance between two points affects the time to reach diffusion equilibrium, and how that influences the size of cells.
Increase in distance decreases diffusion rate cells are small because a larger size makes diffusion more difficult
Describe what happens to receptor potentials and action potentials as the intensity of stimulation of a sensory unit increases.
Increasing intensity of stimulation the receptor potential in the sensory endings increases and frequency of A.P in sensory neuron axon increases
Differentiate between "metabotropic" and "ionotropic" receptors in neurons.
Metabotropic: Linked to G-protein which activates a secondary-messenger which goes on to open ion channels. Ionotropic: Ligand-gated transmembrane channels that can "open" or "close" to allow ions to pass.
Define neuromodulator, describe its general mechanism of action, and give an example.
Neuromodulator: Small peptides, co-released with NT and activate secondary-messenger signaling cascades - can interact with receptors on either presynaptic or postsynaptic cells to modify effectiveness of the synapse at transmitting signal * Neuromodulator binds to a metabotropic receptor that activates G-protein to convert GDP to GTP. GTP activates adenyl cyclase that activates cAMP with ATP. Active cAMP initiates a kinase that phosphorylates another protein.
Neuron cells/tissue explain their general functions.
Neuron: initiate, integrate, conduct electrical signals to other cells. electrical signals cause release of NTs functional unit of nervous system
Differentiate between the function of nonspecific and specific ascending neural pathways.
Nonspecific: pathway convergence and notify the brain that something is happening causing general arousal and focusing attention Specific: pathway follow labeled lines that provide detailed info about the modality, location, intensity
Describe the physical structure and chemical composition of a typical cell membrane.
PM forms a selective barrier enclosing the cells machinery - selective gate keeping by proteins embedded into membrane - made of amphipathic lipid bilayer with embedded proteins. *lipid head group is hydrophilic, tails are hydrophobic
Define presynaptic inhibition and presynaptic facilitation, and draw diagrams to explain the mechanisms of each.
Presynaptic inhibition: Decrease depolarization and neurotransmitter release by decreasing Ca 2+ influx Presynaptic facilitation: Increase depolarization and NT release by Ca 2+ influx
Differentiate between the function of rapidly-adapting receptors and slowly-adapting receptors, and state an alternate term for each receptor type.
Rapid (phasic): Rapid decrease in receptor sensitivity decreases frequency and likelihood of A.P. being fired despite stimulus *on/off burst of A.P - clothes pressed on skin Slow (tonic): slow decay of receptor potential during constant stimulus - maintaining upright posture
Name the two general types of photoreceptor cells, and describe their visual properties.
Rods: - periphery of retina - respond to dim light - low acuity - no color vision - 100 cones converge onto 1 ganglion cell cones: - bright light - dense around fovea - high acuity - color vision - both create graded potentials.
Explain the difference between "protein receptor" and "sensory receptor."
Sensory: Activated by a stimulus and transduce information into electrical responses. Protein: Cell surface receptors within the plasma membrane
Differentiate the functions of somatic, visceral, and special sensory neurons, and give examples of what is detected by each.
Somatic: "Aware of" - touch, pressure, cold, position Visceral: "Unaware of" - blood pressure, oxygen levels Special: Vision
With regard to the somatosensory cortex, define somatotopic map and explain the significance of the different sizes of body parts along the map.
Somatotopic map differentiates parts of the brain where specific stimulus are interpreted. Larger size body parts indicate higher sensory unit density
Define receptor potential, and explain where it occurs
Stimulus with enough intensity initiate receptor potentials that summate together to form an A.P occurs in receptor membrane of sensory receptor
Define adequate stimulus.
The "right" stimulus that a receptor responds best to - preferred stimulus of receptor
Define fluid mosaic model.
The fluid mosaic model states that a cell membrane consists of a phospholipid bilayer with proteins embedded throughout. - allows membrane to change shape - cholesterol in bilayer provide structural support and affects fluidity
Define functional unit
The smallest part of something that demonstrates the important properties of the whole - cells
Explain the difference in the relationship between Cl- and the resting membrane potential between cells with chloride pumps and cells without chloride pumps.
Type 1 cell: Na+/K+ set the resting membrane potential. Equilibrium potential of Cl- = RMP (prevent depolarization) Type II cell: Minor Cl- pumping hyperpolarizes the cell
Explain the mechanism of action potential propagation in unmyelinated and myelinated neurons. Define saltatory conduction.
Unmyelinated: Slower, for processes not in a hurry like regulation of digestion Myelinated: Myelin acts as insulator that keeps ions in axon which allows a greater current to pass to node of Ranvier (increases speed). Saltatory conduction: to "hop" from one node to another, increasing conduction velocity
List two factors that determine the propagation velocity of action potentials along neurons.
Velocity increases with: 1.) increasing axon diameter 2.) myelination
Given that lipid bilayers are not very permeable to water, explain how water is able to permeate cell membranes.
Water passes through channels called aquaporins - increase in aquaporins increases water permeability - water diffuses down gradient
penetrating molecules
able to pass through membrane in both directions - netflux down a concentration gradient until diffusion equilibrium is reached - at equilibrium netflux = 0 but fluxes exist and are equal magnitude but opposite in direction
List the functions served by cranial nerve XI
accessory efferent: innervates sternocleidomastoid and trapezius muscles in back
Define accommodation reflex, and give a detailed description of how it works in focusing on objects at different distances.
accommodation: changes in the lens shape to adjust for different distances in order that the visual image is focused on the retina ciliary muscle contract or relax to adjust zonular fibers that either flatten or bend the lens. parasympathetic nerves cause ciliary muscles to contract, zonular fibers relax and the lens bends to view close objects
Describe the locations and general functions of afferent neurons, efferent neurons, and interneurons.
afferent neurons are generally in the periphery and have sensory receptors that take in information about the external environment -cell body in PNS, axon terminal in CNS interneurons, their cell bodies and terminals are in the CNS efferent neurons carry info out of CNS to effector cells, cell body in CNS, axon and terminal in PNS 1 afferent neuron: 200K interneuron: 10 efferent neuron
Describe what will occur when there are differing concentrations of nonpenetrating solutes on two sides of a membrane that is permeable to water.
after diffusion equilibrium there are equal concentrations of water on both sides
basement membrane sides
basolateral attaches to epithelial side apical faces the lumen
List the four levels of organization of the human body, from smallest to largest.
cell, tissue, organ, organ system
State the role of the nervous system in maintaining homeostasis.
control system that receives info about internal and external environment, integrates it, and directs activities of cells throughout the body to maintain homeostasis
Define sensory coding.
conversion of stimulus energy into a signal, or pattern of A.P. that convey relevant sensory info to the CNS
Differentiate between the cytoplasm and cytosol of a cell.
cytoplasm: everything contained within the PM including organelles and cytosol cytosol: fluid within the cell
Define hyperopia, describe what causes it, and explain how it can be corrected.
far sightedness short cornea or lens too weak convex lens correction
Homeostasis: Dynamic Constancy
fluctuation in variables change over short period of time but remains relatively constant over long periods of time
List the functions served by cranial nerve IX
glossopharynegal efferent - innervates skeletal muscles involved in swallowing ands parotid salivary gland afferent - transmits info from tastebuds and reciptors in auditory-tube skin, and info from blood pressure receptors and blood gas level via chemorecptors
Define osmotic pressure using a simple example of two fluid compartments separated by a semipermeable membrane.
higher osmalarity = higher osmotic pressure -water moves from low osmotic pressure to high -no osmotic pressure at equilibrium -osmotic pressure: the pressure that would have to be applied to stop water from moving into a compartment
Define cotransport, countertransport, symport, and antiport, and give examples of each
in secondary active transport cotransport/symport: - solute moves in same direction as Na+ countertransport/antiport: - solute moves in opposite direction of Na+
Describe how each of the following factors influences diffusion of a molecule: temperature, mass of the molecule, medium through which molecules are moving, membrane thickness, surface area, concentration difference across a membrane, and permeability of the molecule across a membrane.
increase in temp: increases diffusion rate increase in mass: slows down increase in medium density; slows down SA: increase in SA increases diffusion rate permeability: increase in molecule permeability increases diffusion
Negative feedback
increase or decrease variable being regulated creates response that moves variable in opposite direction *occurs at organ, cellular, and molecular level to minimize changes from set point
List the three general mechanisms of gating of ion channels.
ligand-gated: ligand (NT) binds to protein channel to change shape of channel. voltage-gated: changes in membrane potential can cause movement of certain charged regions on channel protein altering its shape mechanically gated: stretching the membrane
Describe the anatomical differences that result in regions like the lips having very high sensory acuity, while others, like the back of your arm, have very low sensory acuity.
lips have more sensory units with small receptive fields back of arm has fewer units and larger receptive fields
explain how the electrochemical gradient, affects the movement of an ion through a cell membrane.
membrane potential is created by an imbalance of charge on either side of the membrane with a slight negative charge within the cell and positive charges outside the cell concentration differences across the membrane also affect the flux of ions. the direction ions flux depends on the magnitude of both forces. Netflux would be determined by comparing magnitude of opposing forces.
In a cell permeable to more than one ion, explain the role of relative permeability in determining the membrane potential.
more leak channels at rest will bring the membrane potential close to the ion with greater permeability. K+ has more leak channels so it dominates
Define myopia, describe what causes it, and explain how it can be corrected.
near-sightedness long cornea or too strong of lens. -corrected by concave lens
Describe the neuronal pathway carrying pain sensation to the brain, including the neurotransmitters involved and the brain regions where synapses occur.
nocireceptors: pain receptor with no myelinated axons. NT = glutamate and substance P pain stimulus triggers sensory receptors that send a signal to ascending afferent paths to CNS where substance P or glutamate act on thalamus which sends signal to the somatosensory cortex.
Define presbyopia, describe what causes it, and explain how it can be corrected.
old vision lens loses flexibility to snap to round shape so close objects can't be focused. bifocal lenses helps correct it
Name the two types of glial cells that form myelin, and differentiate where they are found.
oligodendryte: create the myelin sheath in the CNS schwann cell: create myelin sheath in PNS
List the functions served by cranial nerve II
optic afferent: carries input from receptors in eye
Describe the relationship between homeostasis of ECF, the cells of the body, and the organ systems.
organ systems maintain homeostasis of ECF which is essential fro the survival of cells that make up the organ system.
Explain the difference between molarity (moles per liter) and osmolarity (osmoles per liter).
osmalarity is the total solute concentration of a solution one osmole is = to one mol of solute particles
List the primary sensory regions of the cerebral cortex, and describe the anatomical location and function of each.
parietal lobe: - central sulcus - separates frontal from parietal lobe - somatosensory cortex - gustatory cortex occipital lobe: - visual cortex temporal lobe: -auditory cortex frontal/temporal - olfactory cortex in limbic system
Define acuity
precision of localizing a stimulus - depends on amount of convergence of neuronal input in specific pathway * Increase in receptor field , fewer sensory units and convergence decrease acuity *temp has low acuity
Na+/K+ ATPase pump
primary active transport - moves Na+ from ICF to ECF and K+ in opposite direction - Binding of 3 Na+ molecules activates ATPase activity resulting in conformation change that exposes Na+ to ECF - New conformation allows 2 K+ to bind which dephosphorylates transporter exposing K+ to ICF - net transfer of positive charge out of cell
define diffusion
random thermal movement of molecules from high concentration to low concentration until uniformity is reached - directly through lipid bilayer via protein channel depends on: - temperature - mass of molecule - SA - medium - membrane thickness - distance traveled - conc. diff - permeability of molecules
astrocyte
regulate extracellular fluid in CNS and forms blood brain barrier
Explain how ion channels can have selectivity for the ion(s) that diffuse through them.
selectivity of ion channels depends on channel diameter, charge and polarity, number of water molecules associated with ion.
Define referred pain, and describe the mechanism from which it results.
sensation experienced at a site other than the injured or diseased tissue. -visceral and somatic afferents converge on the same neurons in the spinal cord
Explain the concept of a "set point," and give an example of when a set point might change
set point: change in variable value or range to suit body needs - during a fever, body temp increases to kill pathogen - during exercise, blood flow increases
Differentiate between an "equilibrium" and a "steady state."
steady state: energy added to maintain stable condition equilibrium: relatively constant state that does not require energy to maintain
dorsal column ascending pathways.
stimulus sends A.P on afferent neuron of body movement, limb position, fine touch and pressure receptor and enters through left side dorsal horn. A.P goes up spinal cord and enters brainstem and crosses over the thalamus into right side of somatosensory cortex
anterolateral system ascending pathways.
stimulus sends A.P on afferent neuron of pain or temp receptor and enters through left side dorsal horn. Crossing over occurs within the spinal cord gray matter (anterolateral column) and sends A.P up the spinal cord through the brain stem, reticular formation, thalamus and into the right side of the somatosensory cortex
sympathetic nervous system
sympathetic - prepare body for emergency/stressful situation - "fight or flight" - activates processes facilitating physical exertion and inhibits processes that don't help *increase heart rate, cardiovascular activity, dilate pupils decrease digestion - thoracic to lumbar
Explain what it means to say that "one branch of the autonomic system is discrete, and one is generalized," and state which is which. (Hint: See textbook explanation on page 180).
sympathetic activities are widespread and diffuse, and combat the acute emergencies. The parasympathetic activities are usually discrete and isolated, and provide a comfortable environment
Define synapse, presynaptic neuron, and postsynaptic neuron.
synapse: small gaps between neurons presynaptic neuron: sends a signal at a synapse postsnaptic neuron: receives signal at synapse
Define sensory transduction
the conversion of stimulus energy into a change in the receptor potential of a sensory receptor stimulus to electrical response
Explain why each eye has a "blind spot," and why we don't usually notice it.
the optic disc is on the nose side of retina; it is the site of blood vessel entry/exit and ganglion cell exit - it lacks photoreceptors so photons striking it wont produce an image
List the functions served by cranial nerve X
vagus efferent: innervates skeletal muscle in pharynx and larynx and smooth muscle glands of thorax and abdomen afferent: transmits info from receptors in thorax and abdomen
