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