Physiology EXAM 1
know the composition and characteristics of ECF and ICF
- what ions they contain - how changes in these ions or in charge will affect the polarization state of the cell ECF: ✰ Na+: high ✰ K+: low ✰ Cl-: high ✰ anionic proteins & phosphates: low ✰ Ca++: high ICF: ✰ Na+: low ✰ K+: high ✰ Cl-: low ✰ anionic proteins & phosphates: high ✰ Ca++ low
pain sensations
-nociceptors detect pain - free nerve endings, all tissues except brain and spinal cord - mechanical, thermal, or polymodal responsive - pain pathways: 1) spinal reflex pathway 2) ascending pathway to the brain (diverging circuit example) - referred pain
cell that synapses with sensory neurons
-non-neural receptors -most special senses receptors are cells that release neurotransmitter onto sensory neurons, initiating an action potential ex: hair cell
afferent sensory systems
-sensory pathways detect -neural pathways conduct to CNS
sensory receptor cells
-some regenerate: olfaction (note these are PNS neurons); taste -both regenerate from dedicated basal cells -others do NOT (in humans): photoreceptors, hair cells
threshold for odor detection
-very low: only a few molecules need present to be perceived as an odor -define adaptation: as decreasing sensitivity; olfactory receptors adapt quickly
define unit of Hertz (Hz)
1 cycle per second
2 somatic sensory pathways
1) crossover in spinal cord (synapse in dorsal horn): coarse touch, temperature, nociception (*some nociception are reflexes that do not involve brain) 2) ascend to medulla and cross over: fine touch, proprioception, vibration sensory pathways synapse in thalamus, sensations are perceived in the primary somatic sensory cortex
"natural" suppression mechanisms
1) mechanical somatic sensation and the gate theory of pain 2) endogenous analgesia systems: specific areas of the brain can release endogenous opioids (neuropeptides) with morphine-like action to block neurotransmitter release and promote inhibitory postsynaptic potentials
path of light through the retina
1. Ganglion cell layer -axons of optic nerve -ganglion cell 2. Bipolar cell layer 3. Photoreceptor cell layer -cone -rod
7 classes of neurotransmitters
1. acetylcholine 2. amino acids (glutamate, glycine) 3. amines (dopamine, serotonin, epinephrine) 4. purines (ATP) 5. gases (NO) 6. lipid derived (endocannabinoids) 7. neuropeptides
explain how the Na+/K+ ATPase along with the Na and K leak channels generate a negative resting potential
1. sodium ions bind high affinity sites 2. ATP hydrolysis: attachment of phosphate group changes protein conformation, release Na+ 3. conformation changes increases affinity of potassium sites: K+ binds and P released 4. return to original shape, K+ released because we have a lot of K+ leak channels, we are always losing positive charge and thus have slightly negative charge on the inside
describe 4 major events of sensation
1. stimulation of sensory receptor 2. transduction of the stimulus 3. generation of action potentials 4. integration of sensory input in the CNS
gustatory receptor cell
NOT neurons - modified epithelial cells that synapse with first-order taste neurons of the gustatory pathway
define homeostasis
"standing still" maintaining relatively stable state of conditions in the body
electrical synapse
- gap junctions: tunnels called connexons - bidirectional or one-way flow - speed and synchronization effect
define stimulus adaptation
- slow adapting receptor: TONIC - fast adapting receptor: PHASIC
tectorial membrane
a gelatinous membrane projecting over and in contact with the hair cells of the organ of Corti in the cochlear duct
Eustachian tube
a narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum
amacrine cell
a neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells
ganglion cell
a neuron located in the retina that receives visual information from bipolar cells; its axons give rise to the optic nerve
oligodendrocyte
a type of glial cell that forms myelin in the central nervous system
neuronal regeneration
ability of cells to replicate or repair, typically in PNS -PNS regeneration: steps in process, positive roles of macrophages and Schwann cells -CNS failed regeneration: scar formation, negative environment, debris and glial cell proliferation
define sound waves
areas of compression or rarefraction (high or low pressure) of molecules vibrating
middle ear
auditory ossicles, malleus, incus, stapes, Eustachian tube (connects to pharynx, throat) ✦ air-filled; auditory ossicles transmit and amplify sound vibrations from the eardrum to the inner ear at the oval window
define central nervous system (CNS)
brain and spinal cord
dendrites
branchlike parts of a neuron that are specialized to receive information
define AFFERENT division
brings information from the body (peripheral organs) TO the central nervous system ✷ somatic senses: tactile, thermal, pain, proprioceptive ✷ special senses: smell, taste, vision, hearing, equilibrium
sensory receptors
can be neurons of a non-neural cell: know the identity for each special sense
are body fluids insulators or conductors?
conductors
papillae
elevations on the tongue where taste buds are found, provide a rough texture to the upper surface of the tongue
photoreceptor
light
what are the CNS glia cell types?
oligodendrocyte, microglial cell, astrocyte, ependymal cell
olfactory (I) nerves
on each side of nose, bundles of axons of olfactory receptor cells form the right and left olfactory (I) nerves
voltage gated channels
open and close in response to changes in membrane potential
mechanically gated channels
open and close in response to physical deformation of receptors ➣ particular pressures applied
taste pore
opening in the taste bud
microglial cell
phagocytic glial cell that removes waste products from the central nervous system
synapse anatomy
presynaptic cell, postsynaptic cell, synaptic cleft, axodendritic, axosomatic, axoaxonic
basal cells of olfactory system
stem cells that continually undergo cell division to produce new olfactory receptor cells, which live for only about two months before being replaced
basal cell of gustatory system
stem cells that produce supporting cells, which then develop into gustatory receptor cells
define receptive field
stimulated physical area, specific group of chemicals, or particular set of sound frequencies that causes a response in that neuron
taste transduction of salty and sour
stimuli (salty, Na+ or sour, H+) enter receptor cell via ion channels ➝ depolarizing receptor potential ➝ voltage-gated Ca++ channels open ➝ synaptic vesicle release ➝ neurotransmitters to first-order taste neuron
what dictates function and behaviors of cells?
structure and composition (features) - size, shape, organelles, gene expression
Schwann cell
supporting cells of the peripheral nervous system responsible for the formation of myelin
supporting cell of gustatory system
surround about 50 gustatory receptor cells in each taste bud
synaptic end bulb
swelling at the end of an axon where neurotransmitter molecules are released onto a target cell across a synapse
what are the somatic senses?
tactile, thermal, pain and proprioceptive sensations *proprioceptive: knowledge about where your body's position is without other senses
taste transduction of sweet, bitter, umami
tastant binds gustatory receptor ➝ activates G protein ➝ 2nd messenger depolarizes cell ➝ Ca++ influx to ICF from a) ECF and b) ER (endoplasmic reticulum) ➝ intracellular Ca++ causes synaptic vesicle release ➝ neurotransmitters bind first-order taste neuron
vestibular apparatus
the receptive organs of the inner ear that contribute to balance and perception of head movement (equilibrium) -fluid-filled and houses receptor organs for equilibrium -non-neural receptors detect changes in body position and speed because forces of gravity and acceleration act on the stereocilia -otolith organs (utricle and saccule) and semicircular ducts and crista
what can pass freely through blood-brain barrier?
water, lipid soluble materials lipid soluble: oxygen, carbon dioxide, caffeine, nicotine, steroid hormones, alcohol, barbiturates, some antihistamines
define resting membrane potential
when a cell is at rest (unstimulated), the voltage that exists across the plasma membrane is the resting membrane potential
epithelial tissue
★ cover external and internal surfaces ★ apical and basolateral sides with discrete functions ★ functions: barrier, absorption, secretion
production and properties of CSF: "sinks"
- arachnoid villi: cobweb fingers that project from the subarachnoid space into venous sinuses - venous sinuses connect with venous return of blood to the heart
production and properties of CSF: sources of "faucets"
- define choroid plexus (in 3rd and 4th ventricle): network of capillaries in ventricle wall surrounded by ependymal cells - CSF made via transepithelial transport: the movement of solutes across epithelial cells - ependymal cells secrete Na+, creates osmotic gradient that draws water into the space - CSF contains no cells, little proteins, lots of ions - ependymal cells are multiciliated: have dozens of cilia - CSF is circulated by the ependymal cells that all line the CNS cavities, through the action of their beating cilia
spinal cord organization
- extend from base of brain stem to base of spine - regions along trunk attach to PNS spinal nerves: cervical, thoracic, lumbar, sacral, coccygeal - forked structure of spinal nerves ➣ they are mixed nerves: sensory AND motor ➣ dorsal (back) carries sensory (afferent) info to CNS ➣ ventral (belly side) carries motor (efferent) info to muscles & glands
thermal sensations
- free nerve endings - TRP (transient receptor potential) channel proteins, heat or cold responsive, chemical responsiveness
tactile sensations
- free nerve endings and encapsulated (corpuscles) and sensory functions - example of Pacinian corpuscle: stimulus transduction
what does the CSF provide?
- mechanical protection: CNS is buoyant, floats in CSF; this provides padding, protection from bruising, also reduces weight and pressures on brain (blood pressure, local pressure on neurons, nerves) - chemical protection: environment for chemical signaling - nutrient delivery, waste exchange: CSF is dynamic: made constantly and flushed out to the circulatory and/or lymph systems
brain
- simple multicellular organisms have nerve nets; increasingly complex brains cluster neurons - evolution of clusters led to forebrain, which in humans dominates the brain; brain is precious and must be sheltered/protected
spinal cord information processing
- spinal cord is highly organized ➣ compartments contain ascending or descending tracts (axons!) ➣ ascending tracts carry sensory info to the brain, descending carry commands to motor neurons - cross section: see compartments as gray matter butterfly shape surrounded by white matter - simple or complex routes ➣ sensory neuron ➝ spinal cord ➝ motor neuron (reflex arc) ➣ sensory neuron ➝ spinal cord (and may cross over) ➝ ascend to brain ➝ descend from brain ➝ motor neuron
protection of the brain
- strategy of many layers with different physical and chemical properties - skin (epidermis, dermis) - cranium - meninges (aka membranes) ➣ dura mater: dense connective tissue ➣ arachnoid mater: loose connective tissue ▶ subarachnoid space ▶ cobweb-like spaces hold the cerebrospinal fluid (CSF) ▶ brain also contains caverns that contain CSF: lateral ventricles (left, right), third ventricle, fourth ventricle (which is continuous with the central canal of the spinal cord) ➣ pia mater: thin membrane directly adherent to brain, spinal cord - neurons of brain ➣ blood-brain barrier (BBB) ➣ glia
chemical synapse
- uses neurotransmitters - know the 7 types of neurotransmitters ⇨ 6 are small molecules: acetylcholine, amino acids, amines, purines, gases, lipids ⇨ 1 is larger, the neuropeptides ⇨ CNS uses many neurotransmitters ⇨ PNS: mainly acetylcholine, norepinephrine, epinephrine
spinal cord protection
- vertebrae - 3 meninges with CSF: dura mater, arachnoid matter, subarachnoid space with CSF, pia mater, and note central canal is a cavity at the very center with CSF, CSF drains to lymphatic along the spine
outer hair cells
-are electromotile: change shape (shorten, elongate) in response to sound -stereocilia project into (endo)lymph and push against tectorial membrane, act as a cochlear amplifier that allows hearing of quiet sounds
smell: olfactory system
-gross anatomical terms: nose, nasal cavity, olfactory epithelium, cranial nerve, olfactory bulb, olfactory tract
mechanical somatic sensation and gate theory of pain
-touch, pressure, or vibration can suppress pain sensations, a concept known as gate control theory of pain -within spinal cord are interneurons that normally inhibit second-order neurons of ascending pain pathways- an action that prevents transmission of pain signals to the brain example: if you bump your foot, your impulse is to rub it; mechanical stimulus in local area provides relief because you stimulate mechanoreceptors and neural circuits are connected; pressure leads to divergence and inhibits nociceptor pathway
inner hair cells
-undergo mechanoelectrical transduction -stereocilia project into (endo)lymph, which is rich in K+ -tip link proteins open mechanically-gated cation channels ➔ K+ from (endo)lymph enters ➔ depolarizing receptor potential ➔ opens voltage-gated Ca++ channels ➔ Ca++ entry causes synaptic vesicle release of neurotransmitters to first-order neuron -tip link proteins can also close mechanically-gated cation channels ➔ K+ not able to enter cell ➔ hyperpolarizing receptor potential
methods for removal of neurotransmitters
1. diffuse out of synaptic cleft 2. enzymatic degradation 3. cell uptake- return to axon terminals for reuse or transported into glial cells
neuron function relies on 4 types of integral membrane proteins, which are membrane channels
1. leak 2. ligand gated 3. mechanically gated 4. voltage gated *know under what conditions are they open or closed
pathway that the cerebrospinal fluid follows beginning from a site of production and ending with a site of reabsorption
SECRETION: choroid plexus in 3rd and 4th ventricles ➞ ependymal cells transport Na+ into space, and water follows (osmotic gradient) ➞ cilia on ependymal cells drives CSF circulation around the brain, spinal cord REABSORPTION: drainage occurs 1) in the brain at arachnoid villi, which project into the venous blood circulation and 2) also via arachnoid villi associated with the spinal cord, but those connect to lymphatics
what are the PNS glia cell types?
Schwann
oval window
a small, membrane-covered opening between the middle ear and inner ear into which the footplate of the stapes fits
astrocyte
a star-shaped glial cell with numerous processes (extensions) that run in all directions -most numerous -maintain BBB -maintain chemical environment
cochlea
a winding, cone-shaped tube forming a portion of the inner ear and containing the organ of Corti
process of synaptic signaling
action potential ➝ depolarization opens Ca++ voltage-gated channels ➝ Ca++ triggers vesicle/membrane fusion ➝ neurotransmitter release
special senses
afferent division of sensory input for the nervous system
define intensity
amplitude
define action potential
arise at a trigger zone, typically axonal hillock ✺ ultimately propagate along the axon; regenerated away from axon ✺ when Na+ flows in, local current flow triggers voltage-gated Na+ channels in adjacent membrane to open ✺ involve voltage-gated channels - voltage-gated channels: Na+ and K+ - location, amplitude, all-or-nothing, distance traveled - know sequence of ion flow, ion permeability, and cycle of each gate opening/closure - define the refractory period (incapable of responding) ➣ absolute: Na+ open and then close ➣ relative: Na+ are resting; stronger stimulus than normal needed to trigger action potential because not all the gates are reset and K+ gates are open (losing + charge) - propagation: regenerative nature - conduction: continuous, saltatory - stimuli can be subthreshold, threshold, suprathreshold - effect of chemical factors on electrical activity: K+, Na+, Ca++ - clinical application: how conduction is altered in demyelinating diseases
define taste aversion
avoidance of foods that upset the digestive system -because of taste projections to the hypothalamus and limbic system, there is a strong link between taste and pleasant or unpleasant emotions; sweet foods evoke reactions of pleasure, while bitter ones cause expressions of disgust
olfactory tract
axons of mitral cells form the olfactory tract; some of the axons project to the olfactory cortex in temporal lobe where conscious awareness of smell occurs
visual pathway to the brain
axons of retinal ganglion cells from the optic (III) nerves ➔ meet at optic chiasm ➔ crossover of axons ➔ visual information from the right visual field goes to left side of brain AND visual information from left visual field all goes to the right side of the brain ➔ optic tract ➔ thalamus ➔ connects to the primary visual cortex of the occipital lobe
law of mass balance
balance of input and metabolic production with output via excretion or metabolic removal
mechanoreceptor
bend, stretch, pressure
diencephalon
between brain - thalamus, pineal gland, hypothalamus, pituitary gland
lipid component of cell membrane
bilayer = fluid mosaic model: sea of lipids with protein rafts (75% phospholipids, 20% glycolipid, 5% cholesterol- percentage impacts water permeability)
endogenous analgesia systems
can suppress pain: triggered by extreme stress/trauma -people experiencing severe damage but not feeling any pain
define neuronal plasticity
capacity of the nervous system to modify itself, functionally and structurally, in response to experience and injury example: networks change; connections change by sprouting new dendrites or altering synaptic contacts example: changes at the cellular level (e.g. macromolecules, like protein expression)
ligand gated channels
channel that opens when a neurotransmitter attaches ➣ particular molecule must be there as a key
leak channels
channels that are always open and allow ions to move along their gradient ➣ random, leak across just based on opening and closing; molecules move with respect to electrochemical gradients
chemoreceptor
chemicals in air (sense of smell), fluid
odorants
chemicals that bind to and stimulate the receptors in the olfactory cilia
limbic system
cingulate gyrus, hippocampus, amygdala; the emotional brain
auditory pathway
cochlear branch of vestibulocochlear nerve ➔ brainstem ➔ thalamus ➔ primary auditory cortex -information from each cochlea goes to the left and right auditory cortex (information sharing!)
capillary in BBB
composed of epithelial cells with many tight junctions TIGHT JUNCTION: interlocking protein complexes; seals adjacent cells to solute flow
define perception
conscious awareness and interpretation due to involvement of the cerebral cortex *sensory info that does not go to the cerebral cortex is unconsciously processed: e.g. sensing of blood pressure sent to the cardiovascular center of medulla
define sensation
conscious or subconscious awareness of changes in the external or internal environment ex: touch, heat
pigmented layer
consists of epithelial cells that contain melanin
blue cone
contain blue-sensitive pigment -absorbs light at wavelength of 420 nm
green cone
contain green-sensitive pigment -absorbs light at wavelength of 530 nm
red cone
contain red-sensitive pigment -absorbs light at wavelength of 560 nm
pericytes in BBB
contractile cells that wrap capillaries to promote and maintain tight junctions with their secretions
define feedback system
controlled variable ➞ monitored by receptors ➞ control center ➞ effectors ➞ response
what allows the 2 hemispheres of the brain to communicate?
corpus callosum; band of white matter that connects the hemispheres (axons)
crista in semicircular ducts
cupula, hair cell, stereocilia, tip link proteins, mechanically gated K+ channels, (endo)lymph
define and identify the following cell type, their characteristics, and their functions: NEURON AND ITS PARTS
dendrites, soma, axon, node of Ranvier, axon hillock, trigger zone, axon terminal, synaptic end bulb, axonal transport, white matter, gray matter
otolith organs (utricle, saccule)
detect linear acceleration, deceleration; vertical acceleration, deceleration, head tilt transduction: tip link proteins on stereocilia will open and close mechanically gated ion channels as movement occurs
outer ear
ear (pinna), auditory canal, eardrum (tympanic membrane) ✦ collects sound waves and; tympanic membrane (eardrum) vibrates and transmits vibrations to middle
tympanic membrane
eardrum; thin, semitransparent structure between the external auditory canal and middle ear; when sound waves strike it, it vibrates and then transmits vibrations to middle ear
stimulus modality
encoded by sensory receptor and neural pathway = "labeled lines" ❊ thalamus = relay station example: taste is perceived when a stimulus activates a gustatory receptor and its path to the gustatory cortex in the insula region of the brain example: smell is perceived when a stimulus activates an olfactory cortex in the temporal lobe of the brain
define lateral inhibition
enhances contrast and makes a stimulus easier to perceive
midbrain
eye movement
define cerebral lateralization, give examples
functional areas in the cerebral hemispheres that are NOT symmetrical concentrated on LEFT: ✪ language, verbal, mathematic skills; "analysis" ✪ examples: reasoning, numerical/scientific skills, spoken & written language, use and understanding sign language concentrated on RIGHT: ✪ spatial skills, "creative" ✪ examples: music and artistic awareness, space and pattern perception, recognizing faces, patterns, emotional content of language, odor discrimination
neural circuits
functional group of neurons that process information - characteristics can include: divergence, convergence, reverberate, parallel - neuron modulation: excitatory, inhibitory - summation of postsynaptic potentials: spatial, temporal - clinical application: neural circuits blocked using drugs that modulate voltage-gated channels, ex. novocaine and lidocaine
ependymal cell
glial cell that lines membranes within the brain and spinal cord and helps form cerebrospinal fluid
what can pass with regulated passage through blood-brain barrier?
glucose and other water-soluble substances example: glucose transporter proteins in the membrane quickly move glucose to the brain; brain needs a lionshare of glucose in our bodies for its anaerobic metabolism
regions of gray and white matter
gray matter: cortex, basal ganglia, limbic system white matter: corpus callosum
visual sensory system
gross anatomical terms: retina, optic (III) nerve, optic chiasm, optic tract
taste: gustatory system
gross anatomical terms: tongue, papillae, taste bud
insula
gustatory cortex
gustatory pathway to the brain
gustatory receptor cell ➝ first-order taste neurons ➝ axon in one of three cranial nerves, facial (VII), glossopharyngeal (IX), or vagus (X) ➝ go to gustatory nucleus in medulla ➝ project to 3 places: thalamus, limbic system, or hypothalamus from thalamus ➝ gustatory cortex: where we get our conscious awareness and discrimination of taste activating different combinations of gustatory receptor cells is thought to code for unique tastes in our brain
complex sensory neuron
have nerve endings enclosed in connective tissues capsules ex: Pacinian corpuscle that senses touch
basal ganglia
help control movement and muscle tone
stimulus location
how sensitive various areas of the body are; how innervated, how big the receptor fields are, if there is any overlap ❊ 2 point discrimination ❊ acuity: sharpness of perception example: back has big receptor fields that do not overlap; body does not know the exact place; lack acuity with big sensory receptors example: hand has very small sensory fields, lots of overlap, body can discriminate and tell where stimulus is example: auditory uses timing! -uses timing differences to localize sound
how does the body perceive a wide range of tastes (not just 5)?
hypothesis is based on integration in the brain: patterns of activity based on patterns/combinations of activated gustatory receptor cells
first order taste neuron
in the nuclei of three different cranial nerves, situated in medulla oblongata
photoreceptor cell layer
include rods and cones, sensory receptors that detect light and convert it into receptor potentials
is cell membrane an insulator or conductor?
insulator
thalamus
integrating center and relay station for sensory and motor information
medulla oblongata (medulla)
involuntary functions, control heart rate, breathing, sense blood pressure, sense toxins in blood and will stimulate vomit reflex
what molecules are impermeable to cell membrane?
ions, large uncharged polar molecules
define selective permeability
know what can pass the cell membrane and what cannot
cell body
largest part of a typical neuron; contains the nucleus and much of the cytoplasm
cerebrum
largest part of the brain, the "seat of intelligence", walnut appearance with gyri and sulci - 2 hemispheres - frontal lobe, parietal lobe, temporal lobe, occipital lobe, insula
hypothalamus
links nervous and endocrine systems, secretes hormones
neural stem cells
located in lateral ventricles, hippocampus and make new neurons throughout life!
stimulus intensity and duration
longer or stronger stimuli release more neurotransmitter -intensity encoded by frequency of action potentials
neurogenesis
making of new neurons -drives CNS, PNS development -limited in adult brain...but does occur!
types of sensory receptors
mechanoreceptor, thermoreceptor, photoreceptor, chemoreceptor, nociceptor
define graded potential
membrane potential changes that vary in amplitude depending on the stimulus ✺ typically occur on dendrites or the cell body ✺ stronger stimuli affect more membrane proteins and cause graded potentials of higher amplitude ✺ summation: graded potentials can add up when stimuli happen close together - mechanical and ligand-gated channels - location, amplitude, distance traveled, depolarize, hyperpolarize - summation, no refractory period - local current flow, decremental nature
brain stem
most ancestral, primitive part of brain - midbrain, pons, medulla, reticular formation
convergence
movement of the two eyes so that both are directed toward the object being viewed, for example, tracking a pencil moving toward your eyes -the nearer the object, the greater the degree of convergence needed to maintain binocular vision; coordinated action of the extrinsic eye muscles brings about convergence
white matter
myelinated axons
reticular formation
netlike white and gray matter within brain stem that regulates arousal from sleep, consciousness (awake state), muscle tone and posture, pain modulation
bipolar cell
neurons that convey signals from photoreceptors to ganglion cells
bipolar cell layer
neurons that convey signals from photoreceptors to ganglion cells
ganglion cell layer
neurons that generate action potentials in response to signals from bipolar cells
simple sensory neuron
neurons with free nerve endings; they may have myelinated or unmyelinated axons -want it for sensing acute heat -no other. supporting architecture associated with dendrites
what molecules are highly permeable to cell membrane?
nonpolar molecules
olfactory transduction
odorant ➞ G protein ➞ activate adenylyl cyclase in plasma membrane to produce cAMP from ATP ➞ cAMP opens cation channel ➞ Na+ and Ca++ enter ➞ receptor potential ➞ action potential
chemoreception
olfactory and gustatory
temporal lobe
olfactory cortex, auditory cortex, auditory association area
olfactory pathway to the brain
olfactory receptor cell in olfactory epithelium ➞ cranial nerve (I) ➞ synapse with mitral cell at glomerulus in olfactory bulb ➞ olfactory tract ➞ to a) olfactory cortex ➞ cerebral cortex and b) limbic system -each mitral cell receives inputs from one type of olfactory receptor cell
macula in otolith organs
otoliths, otolithic membrane, hair cell, stereocilia, tip link proteins, mechanically gated K+ channels -heavy crystals dragged by gravity; drags goopy membrane, causes deformation of stereocilia --> mechanical changes --> electrical changes
structure of rod and cone photoreceptor cells
outer segment, discs, inner segment, synaptic terminal mechanism: photopigments absorb light energy; their consequent structural change triggers signal transduction events that cause release of neurotransmitter
define referred pain
pain that is felt at a site remote from the place of origin -occurs because both somatic sensory and visceral sensory neurons often converge on second-order neurons of the same ascending pathway to the brain -since the brain is more accustomed to receiving sensory input from somatic sensory neurons than from visceral sensory neurons, it may incorrectly interpret pain from a visceral organ as having a somatic origin
olfactory bulb
parts of brain containing glomeruli that contain axons of olfactory receptor cells that converge onto mitral cells (second order neurons of olfactory pathway)
define frequency
pitch
phototransduction
process by which light energy is converted into a receptor potential in the outer segment of a photoreceptor ✦ rods are sensitive in low light and release neurotransmitter in that condition! light ➔ isomerizes cis-retinal ➔ trans-retinal separates from photopigment on the disc ➔ this activates a G protein on the disc membrane ➔ G protein triggers graded potentials that cause neurotransmitter release via Ca++ entry ➔ bipolar cell experiences graded potentials ➔ ganglion cell has action potential
astrocytes in BBB
processes press against capillaries to promote and maintain tight junctions with their secretions
microvilli
projections that increase the cell's surface area - project from each gustatory receptor cell to the tongue's surface through the taste pore
supporting cells of olfactory system
provide physical support to the olfactory receptor cells and help detoxify chemicals that come in contact with olfactory epithelium
suppression of pain sensations
provision of drugs -analgesic: drug that causes analgesia, pain relief that occurs without affecting other modalities of sensation or consciousness (aspirin, ibuprofen) -anesthetic: drug that causes anesthesia, absence of all modalities of sensations, including pain sensations; general anesthetic is a drug that affects the entire body and results in loss of consciousness, local anesthetic is a drug that affects only a small area of the body and does not result in loss of consciousness (novocaine, lidocaine)
metabotropic receptors
receptors that are associated with signal proteins and G proteins -signal is transduced by a second messenger: SLOWER RESPONSE
ionotropic receptors
receptors that are coupled to ion channels and affect the neuron by causing those channels to open -FASTER RESPONSE
hyposmia
reduced ability to smell; aging contributes to this as there is a gradual loss of olfactory receptor cells coupled with their slower rate of replacement as we age
pons
relay station between cerebrum and cerebellum; coordinate breathing with medulla
direction of visual processing
retina, optic nerves, optic chiasm, optic tracts, lateral geniculate bodies, optic radiations, visual cortex
semicircular canals (contains ducts)
rotational acceleration, deceleration -3 at right angles to each other -enlarged chamber of duct = ampulla that contains a sensory structure, the crista
5 unique gustatory receptor cells
salty, sour, sweet, bitter, umami (savory) - found in all the taste buds: all tastes can be detected in all tongue areas
cerebellum
second largest part of brain; coordinates movement
pituitary gland
secretes hormones that affect other glands and organs
pineal gland
secretes melatonin to regulate circadian rhythm
inner ear
semicircular canal, vestibule, cochlea, oval window, round window, labyrinth, lymph, tectorial membrane, basilar membrane, cochlear duct, organ of Corti with inner and outer hair cells, vestibulocochlear (VIII) cranial nerve ✦ series of cavities; hearing, equilibrium
nociceptor
sensitive to stimuli that damage, we perceive it as pain
4 attributes of sensory coding
sensory coding: how the CNS tells the difference among all the input stimuli - modality, definition of labeled line - location, definition of acuity ➣ 2-point discrimination ➣ timing ➣ lateral inhibition - intensity - duration
parietal lobe
sensory cortex, sensory association area
3 types of neurons
sensory neuron, interneuron, motor neuron
olfactory receptor cells
sensory neurons that respond to olfactory stimuli ✬ nonmotile cilia extend from dendrite of olfactory receptor cell, sites of olfactory transduction ✬ within the plasma membranes of olfactory cilia are olfactory receptor proteins that detect inhaled chemicals ✬ chemosensing property of olfactory cilia on olfactory receptor cells ✬ each olfactory receptor cell expresses 1 olfactory receptor protein all over its cilia ✬ approximately 400 unique olfactory receptor proteins and 400 unique olfactory receptor cells
taste buds
sensory organs in the mouth that contain the receptors for taste -each taste bud has all the types of gustatory cells; not restricted to one region
bony labyrinth
series of cavities in the temporal bone of the cranium; contains perilymph
3 types of sensory receptors
simple sensory neuron, complex sensory neuron, cell that synapses with sensory neurons
frontal lobe
skeletal muscle movement, motor cortex
pinna
skin-covered flap of cartilage located on each side of the head; collects sound waves and directs them into external auditory canal
what molecules are moderately permeable to cell membrane?
small uncharged polar molecules; cross via gaps as lipids move, # of gaps depends on the amount of cholesterol
what are the special senses?
smell, taste, vision, hearing, equilibrium
transmission of sound waves from air to fluid of ear
sound waves in auditory canal ➔ vibrate ear drum ➔ vibration of malleus/incus/stapes bones in air ➔ vibration transferred to membrane of the oval window ➔ creates motion/waves in lymph fluid of cochlea ➔ organ of Corti moves against tectorial membrane as vibration of basilar membrane occurs ➔ ultimately pressure release of the cochlea at the membrane of the round window
proprioceptive sensations
tell you where limbs are located and how they are moving when other senses are not involved ❊ 3 types: muscle spindles, tendon organs, joint kinesthetic receptors
thermoreceptor
temperature
factors under homeostatic control
temperature, pH, fluids, gases, nutrients, electrolytes, hormones
define "polarized state of cells"
the cell is POLARIZED because it exhibits a resting membrane potential
axon hillock
the cone-shaped area on the cell body from which the axon originates -where action potentials start
axon terminal
the endpoint of a neuron where neurotransmitters are stored
axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
horizontal cell
the laterally interconnecting neurons having cell bodies in the inner nuclear layer of the retina of vertebrate eyes -they help integrate and regulate the input from multiple photoreceptor cells
action potential propagation
the movement of an action potential along an axon; in myelinated axons, it occurs via saltatory conduction -continuous is like the space bar, saltatory like the tab key
organ of Corti
the organ of hearing, consisting of hair cells and supporting cells that rest on the basilar membrane and extend into the endolymph of the cochlear duct; aka spiral organ
somatosensory cortex
the sensory homunculus -this map depicts the relative proportion of the sensory receptors in the various parts of the body
axonal transport
the transportation of materials from the neuronal cell body to distant regions in the dendrites and axons, and from the axon terminals back to the cell body -ability to transmit excitability relies on AXONAL TRANSPORT: motor proteins kinesin and dynein hydrolyze ATP to "walk" along microtubules and move cargo (vesicles, organelle, other particles)
function of auditory ossicles
transmit and amplify vibrations from the tympanic membrane to oval window
true or false: a stroke that destroys function of the left visual cortex would destroy the ability to see the right visual field
true
gray matter
unmyelinated axons
equilibrium pathway to brain
vestibulocochlear (VIII) nerve ➔ cerebellum or brainstem ➔ cerebrum
basilar membrane regions
vibrate in high response to high, medium, or low frequency based on their membrane properties
sound transduction in the organ of Corti
vibration of basilar membrane ➔ hair cells move against the tectorial membrane and their stereocilia bend
occipital lobe
visual cortex and visual association area
body fluid maintenance is essential to homeostasis
★ body fluids are 50-60% of human total mass ★ intracellular fluid = ICF - inside cells, 2/3 of body fluids ★ extracellular fluid = ECF - outside cells 1. 80% interstitial: spaces between cells 2. 20% plasma: fluid in bloodstream; analysis of blood composition = litmus for homeostatic state - buffer between cells and the world ★ cell membrane = crucial to regulate homeostasis - serves as wall and possesses numerous gatekeeper functions
define feedforward system
★ controlled variable ➞ monitored by receptors ➞ control center ➞ effectors ➞ prepare for change ★ body is "looking forward," anticipatory sequence of events
nervous tissue
★ detect and respond to environment: convert stimuli to electrical and chemical signals
connective tissue
★ many forms: loose, dense, adipose, cartilage, bone, blood ★ functions: supports and protects organs, stores energy, insulation, transport gas
positive feedback loop
★ sequence of events that promotes/reinforces the change ★ example of cervix stretching and smooth muscle contractions during labor
muscle tissue
★ skeletal, smooth, cardiac ★ functions: body movement, heat, energy storage, organ movement, pump blood
negative feedback loop
★sequence of events that negates/reverses the change ★ example of elevated blood pressure
facts about olfactory pathways
☆ THALAMUS relay center is bypassed ☆ odors can evoke strong emotional responses and memories because action potentials are conducted to cerebral cortex and limbic system
facts about olfactory transduction
☆ threshold for detecting odors is low ☆ olfactory receptors are rapidly adapting sensory receptors (we "get used to" the smells around us)
protein component of cell membrane
✢ integral = pass all the way through ✢ peripheral ✢ glycoproteins
define peripheral nervous system (PNS)
✷ all nervous system outside the CNS ✷ cranial nerves connect brain to body: 12 pairs ✷ spinal nerves connect spinal cord to body: 31 pairs ✷ extensive networks of sensory receptors and wiring to effectors
define EFFERENT division
✷ somatic nervous system: connects to skeletal muscle ✷ autonomic nervous system: connects to all other tissues ➞ sympathetic: fight or flight activities ➞ parasympathetic: rest and digest activities ➞ enteric: gastrointestinal tract
photopigments in discs
✾ consist of opsin (4 different ones, each specific to 1 photoreceptor: 1 rod and 3 cone cells) and retinal (vitamin A derivative) complex ✾ light energy induces isomerization of retinal causes its dissociation from the opsin protein and apparent "bleaching" of the opsin
