physiology review session topics Flashcards
discuss homeostasis and what it means to be in a dynamic steady state
homeostasis is our bodys way of maintaining balance; however our state is constantly changing so we maintain a dynamic steady state
give an example of homeostasis
your body knows if you are dehydrated via chemo and osmoreceptors; the primary 2 mechanisms for dehydrations are adh hormone from posterior pituitary and aldosterone to increase fluids in body
bodily homeostasis summarized
nutrients in the ECF, removal of metabolic end products, regulation of body functions, protection of the body, and reproduction
negative feedback
response to a reaction where the response slows or stops the reaction; ex is the thyroid hormone; once thyroid levels at a certain point the system inhibits its own production
positive feedback
when the changing feature is enhanced by the feedback system, ex is childbirth; afferent signals sent to brain during contractions and oxytocin sent to amplify contractions
feed forward control system
initiates a response in anticipation of change; ex is your respiratory rate increases when you start running even tho u are not tired yet in anticipation of the need for extra oxygen
what does the nernst equation do?
determines membrane potential for a specific ion
integral proteins
embedded in the plasma membrane and can span entire membrane
peripheral proteins
positioned only on ecf or cytoplasm side of membrane
glycoproteins
membrane proteins that have carbohydrates attached on outer surface of plasma membrane only
desmosomes
‘riveting’ junctions that anchor adjacent cells, found in tissue that undergoes significant stretching
CADHERINS- critical to maintaining this bond
gap junctions
connecting tunnels formed by connexons; usually found in smooth and cardiac muscle, nonselective and permit direct transfer of signaling molecules between cells
tight junctions
firmly bond adjacent cells to each other and are commonly found in epithelial tissue.
prevent undesirable leaks
KISS sites-made up of claudins that form tight seals at luminal border
VDAC
mitochondria voltage dependent anion channel; functions as gatekeeper for the entry and exit of mitochondrial metabolites; key player in mitochondria mediated apoptosis
goldman hodgkin katz equation
calculates a membrane potential for multiple ions
how does the extracellular messenger (1st messenger) binding to a receptor initiate an intracellular response?
- opening or closing chemically gated receptor channels by binding to them
- activating second messenger systems by binding to a g protein coupled receptor and messenger binding to receptor enzyme complex which activates tyrosine kinase
describe kinase cascade that is associated with the second messenger system
cAMP= a second messenger that can further influence the cell
protein kinase= enzyme that phosphorylates a protein; phosphorylated proteins can then result in further biological effects in the cell *dependant on actions of cAMP
what is resting membrane potential?
constant membrane potential present in cells of all tissues when they are at rest
depolarization
Na channels open and membrane potential increases
repolarization
potassium ion channels open to bring membrane potential back down after it was depolarized
hyperpolarization
when membrane potential is somewhere below resting membrane potential
why can an action potential not move backwards?
refractory period
acetylcholine
-from choline and acetyl coa
-major NT of PNS (excitatory)
-motor= supplies skeletal muscle
-parasympathetic= supplies smooth and cardiac muscle as well as endocrine glands
inhibitory synapse
when NT or NT receptor open K or Cl channels and inhibit signal
excitatory synapse
these signals prompt the sharing of AP between neurons by Na of Ca channels and membrane potential gets close to threshold
threshold potential
threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
what do receptors do?
transduce one form of energy into electrochemical energy
multiple sclerosis
autoimmune disease caused by production of antibodies that target oligodendrocytes; de myelinates axons
monoamine NT
derived from amino acids
monoamine NTs dervied from tyrosine
epinephrine, norepinephrine, and dopamine
monoamine NT derived from tryptophan
serotonin
Parkinsons disease
tremors, shakes, uncontrollable mvmts bc muscles are inhibited from contracting due to lack of dopamine
glutamate
-PAIN NEUROTRANSMITTER
-major excitatory neurotransmitter
-binds to NMDA receptors and allows Ca into neurons which makes dorsal horn cells more excitable and LESSENS FURTHER INJURY
substance P
-pain neurotransmitter
-activates ascending pathways that transmit nocioceptive signals to higher levels for further processing
-UNIQUE TO PAIN FIBERS A FIBERS AND C FIBERS
pain inhibitory pathway
-supresses transmission in pain pathways as they enter spinal chord
-depends on presence of opiate receptors (endorphin, enkepahlins, and dynorphin)
-in periaqueductal gray matter neurons are on afferent pathway and inhibit substance P
cones
opsin, green blue and red, help us see trichromatic vision
rods
contain rhodopsin, dark light sensitive, ‘bleaching effect’ when eyes get adjusted to dark again photopigment color has to regenerate
what happens after light gets refracted by the cornea?
it then moves to the pupil and then to get refracted more by the fovea
what photopigments is the fovea primarily made of?
cones
how does the iris control how much light is let into the pupil?
circular (contract) and radial (dilate) muscles
rhodopsin
g coupled protein receptor found in rods that converts light into an electric signal
eustachian tube
connects middle ear to pharynx
describe how mechanical energy goes to electrochemical energy when discussing sound transmission
1- tympanic membrane vibrates when struck by sound waves
2-middle ear transfers vibrates to oval window via ossicles (stapes, malleus, incus)
3-waves in cochlear fluid set basilar membrane in motion
4- receptive hair cells are bent as basilar membrane is deflected up and down (ORGAN OF CORTI)
5-mechanical deformation of specific hair cells is transduced into neural signals that get transmitted into auditory cortex for sound perception
inner hair cells
transform mechanical energy into electrical impulses in the auditory nerve; open Na channels
outer hair cells
-change length depending on membrane potential
-lengthen for hyperpolarization and shorten for depolarization
-amplifies motion of basilar membrane and amplifies response of inner hair cells
-makes inner hair cells more sensitive
tectorial membrane
top layer of the organ of corti and plays a critical role in hearing restoration
cochlear implants
-implant has 22 open contacts spread along the wire to stimulate specific areas of the cochlea
-electrode is inserted through round window and threaded into the scala tympani
-the electrode contacts the spiral ganglion bodies, bypassing the damaged hair cells
describe the two types of deafness
-conductive deafness= impairment of any mechanism that normally conducts soundwaves through the inner or middle ear
-sensorineural deafness= inner ear dysfunction, especially of cochlea; dysfunction of any part of the brain that processes signals
vomeronasal organ
-located in nose next to vomer bone
-detect phermones
*phermones are nonvolatile chemical signals passed subconciously from one individual to another
where do photoreceptors synapse?
they synapse on bipolar cells which synapse on ganglion cells which form the optic nerve
ON vs OFF bipolar cells
ON center cells= depolarized by light and hyperpolarized by dark
OFF center cells= hyperpolarized by light and depolarized by dark
*on center more glutamate w light
*off center more glutamate w dark
glaucoma
when aqueous fluid builds up in your eye and pressure increases pressing on optic nerve because canal of schlemm is not draining properly
macular degeneration
-doughnut vision
-when macula (part of retina) is damaged and impairs your sharp, straight ahead vision
afferent somatosensory pathways (visceral vs sensory)
visceral afferent=transmits subconscious input
sensory afferent=transmits conscious input
1st, 2nd, 3rd order neurons
1st-peripheral receptor that first detects stimulus
2nd- in spinal chord or medulla and synapses with third order neuron
3rd-originates in thalamus and travels to ultimate destination
efferent pathway (motor) primary and secondary neurons
primary or upper= originate in cerebral cortex and travel down brain stem or spinal chord
secondary or lower= begin in spinal chord and travel to target tissue
describe receptor adaptation
desensitize by reducing number of receptors on the cell
phasic vs tonic receptors
phasic=sensory receptor that adapts quickly to a stimulus (getting in hot tub)
tonic=sensory receptor that adapts slowly to a stimulus (construction noise)
lateral inhibition
Lateral inhibition refers to the capacity of excited neurons to reduce the activity of their neighbors. Neurons that are firing inhibit the stimulation of surrounding. Accordingly, only the neurons that are most stimulated and least inhibited respond.
slow vs fast pain
slow= dull pain (unmyelinated C fibers)
fast=accute and sharp pain (myelinated A fibers)
vestibular apparatus in the inner ear
-contains semicircular canals and otolithic organs
-semicircular canals detect acceleration and deceleration
-otolithic organs detect linear movement and how to hold head relative to gravity
central vs peripheral vertigo
central=Caused by lesions or disorders
(stroke, M.S.) of brainstem vestibular connections or
cerebellum. Often chronic or permanent
peripheral=more severe than central, caused
by disturbance to vestibular apparatus or vestibular
nerve. Generally paroxysmal, shorter in duration, and
accompanied by deafness or tinnitus
what is benign “paroxysmal” vertigo caused by?
caused by loose calcium deposits (crystals or “ear rocks”) in what are called the semicircular canals of the inner ear; also think about nstygamus
How do you know which semi circular canal is triggering vertigo?
Dix-Hallpike Maneuver – movement of head in order to trigger an episode and reveal which semi-circular canal is causing the trouble
how does the hypothalamus interact with the anterior pituitary gland?
Through Hypophyseal portal system. This is a capillarities system that flow between hypothalamus and pituitary gland. Hypothalamus secretes hormones into this system that signals pituitary gland to secrete hormones.
How does the hypothalamus interact with the posterior pituitary gland?
it communicates with the posterior pituitary via action potentials traveling down axons that connect the hypothalamus to the posterior pituitary *NEURAL; *hypo tract
NEUROHYPOTHYSIS
What is the function of the hypothalamic-hypophyseal portal system?
The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands.
Structurally, how are the hypothalamohypophyseal tract and the hypophyseal portal veins different?
Structurally, the tract is composed of axons of neurons that extend from the hypothalamus to the posterior pituitary; the portal veins are blood vessels that extend from the hypothalamus to the anterior pituitary.
What are the primary roles of the cerebellum?
balance, muscle tone, coordination of voluntary muscle activity, and motor learning
what NT is involved in the inhibition of muscles?
acetylcholine and dopamine
what NT are involved in emotion and behavior?
norepinephrine, dopamine, and serotonin
List the 3 dopaminergic pathways
1- nigrostriatal system
2- tuberoinfundibular system
3- mesolimbic/mesocrotical system
nigrostriatal system
-modulates voluntary movements
-neurons in substantia nigra and terminals in striatum of basal ganglia
tuberoinfundibular system
-secretes hypothalamic regulatory factors into hypophyseal portal system
-within hypothalamus
mesolimbic/mesocortical system
-modulates behavior responses, particularly motivation and drive
-located in ventral tegmental area of midbrain
-axons to limbic system, hippocampus, and medial prefrontal cortex
what antidepressents manipulate noradrenergic pathways and how do it work?
MAOIs- inhibits reuptake of NTs which results in increased concentration of NT that elevate mood
cerebrum
-most complex and has key role in most sophisticated neural functions
-gyri and sulci
-left and right cerebral hemisphere
what connects cerebral hemispheres?
-corpus callosum
-commissures are bundles of nerves that cross midline and interconnect reciprocal areas of hemispheres
what are the 4 major lobes of the cerebral cortex and their functions?
occipital lobe- vision
temporal lobe- hearing
parietal lobe- somatosensory (tactlie info) and perception of awareness of position and mvmt of body
frontal lobe-voluntary motor activity, speaking ability, elaboration of thought
primary motor cortex (located in frontal lobe)
-voluntary mvmt of skeletal muscles
-primarily controls muscles on contralateral side
-voluntary decision making controlled by supplementary motor area, premotor area, posterior parietal cortex
Broca’s area
governs speaking ability
Wernicke’s area
-language comprehension
-responsible for formulating coherent patterns of speech
reward system
when stimulated areas of limbic system provide pleasurable feelings
nucleus accumbens
site of action of ALL addictive drugs
How do SSRIS, MAOIs, and SNRIs work?
they keep the desired NT within synapse longer, increasing effectiveness
insular cortex
-forms the floor of the lateral sulcus
- important for gustatory and sensorimotor processing, risk-reward behavior, autonomics, pain pathways, and auditory and vestibular functioning
ependymal cells
-in ventricles of brain
-form and circulate CSF
-have cilia
-act as neural stem cells for formation of new glial cells and neurons in the hippocampus
microglia
-immune defense cells in CNS
-when resting they are wispy and branched but when activated they become swollen and migrate
*overactive microglia can contribute to alzheimers
astrocytes
-glue of the CNS
-guide neurons during fetal brain development
-aid in BBB
-important in repair of brain injuries and neural scar formation (stops signals when needed tho and can stop nerve repair in CNS)
-take up excess K from ECF in brain
-enhance synaptic formation VIA GLIOTRANSMITTERS
-clear toxins from brain via glymphatic system
oligodendrocytes
-form insulating myelin sheaths around axons in CNS
-increase signal transmission speeds
describe communication in astrocytes
-signals pass thru ecf via gap junctions
-astrocytes have receptors for glutamate which causes influx of Ca that triggers release of ATP
discuss glymphatic system
-brain washing (astrocytes clearing metabolic byproducts)
-allows exchange of solutes between CSF and ISF
-facilitate this by AQUAPORINS
Alzheimer’s disease
-memory loss
-abnormally altered nonadrenergic, serotonergic, and cholinergic pathways
-3 neuropathalogic changes
1 neurodegeneration
2 amyloid plaques
3 neurofibrillary tangles
significance of TAU proteins and alzheimers
make neurofibrillary tangles
amyloid plaques and alzheimers
excess B-amyloid protein that is folded in between nerve cells
are hormones produced in anterior or posterior pituitary?
they are produced in anterior; they are released in posterior but not produced
what is the melanocrotin system?
critical neural system in (ACCRUATE NUCLEUS) hypothalamus underlying control of body weight and other functions
POMC neurons
neurons in accruate nucleus (arc) that act as anorexigenic neurons which decreases food intake
Neuropeptide Y (NPY) and Agouti-related protein (AgRP)
appetite stimulating (orexigenic) neurons in ARC
fungal meningitis
People can get sick if they breathe in fungal spores. People get meningitis if the fungal infection spreads from the lungs to the brain or spinal cord. Fungal meningitis does not spread between people. The fungus Candida can also cause meningitis.
hormones in the anterior pituitary
-oxytocin=stimulates uterin contractions during burth
-arginine= stimulates growth hormone and vasopressin
-vasopressin=regulatory hormone
