Exam 1 Flashcards
Physiology
study/logic of nature; study of the function of something
Homeostasis
maintenance of a stable internal environment despite the external environment
Physiology
homeostasis is maintained
Pathophysiology
homeostasis isn’t maintained
Claude Bernard
believed that keeping an “internal milieu” of the four “humors” is a prereq for good health
Walter Cannon
coined the term homeostasis
Pavlov question
why the contents of stomach are acidic and when they reach the duodenum it becomes alkyl
Cranial nerve X
vagus nerve; communicates and recieves info from many areas of thoracic and abdominal cavities
Afferent
towards the brain
Efferent
away from the brain
Pavlov hypothesis
the vagus nerve controlled the liver and pancreas ducts working together
Be able to draw and label the ducts and important parts of the liver and pancreas as well as what is found moving through the ducts
:)
Bayliss and Starling hypothesis
believed the nervous system didn’t affect the change of pH. thought there were cells in the small intestine producing a hormone
Bayliss and Starling Experiment 1 description
tedious dissections of dogs to remove branches of the vagus nerve in the liver, pancreas, small intestine while keeping the vasculature intact. an acidic solution was dripped into the duodenum
Bayliss and Starling Experiment 1 results
when the acidic solution was added the pancreatic duct started to contract and bicarbonate solution moved into the duodenum
Bayliss and Starling Experiment 1 faults
they didn’t think they got all of the afferent and efferent vagus nerve
Bayliss and Starling Experiment 2 description
scraped parts of the duodenal mucosa, added some acid, filtered, and injected the solution into the veins of a dog
Bayliss and Starling Experiment 2 results
the pancreatic duct constricted and the bicarbonate solution was released
Secretin
discovered by Bayliss and Starling; made by cells lining the duodenum when the concentration of hydrogen ions increase; secreted into the blood to result in the pancreatic duct contracting and releasing bicarbonate solution
Parts of a homeostatic mechanism
receptor, control center, effectors
Cholecystokinin
made by cells of the duodenum to cause the cholecyst to contract and release bile which relaxes the sphincter of oddi and cause enzyme rich solution to be released from the pancreas
Merocrine
secrete product through exocytosis of secretory vacuoles; no part of the cell is lost in the process
Merocrine example
sweat gland
Apocrine
there are apical regions which are pinched off during secretion leading to cells partially losing cytoplasm during secretion
Apocrine example
sweat glands found in axillary and inguinal regions
Holocrine
dislodged cells from the basement membrane is secreted leading to the entire cell being lost
Holocrine example
sebaceous glands of the skin
Endocrine
ductless
Endocrine example
secretin
Exocrine
have ducts
Cytogenous
release of entire viable cells
Cytogenous example
seminiferous tubules releasing sperm cells
Autocrine
cell releases signal which works on those surrounding it as well as itself
Paracrine
cell releases signal which only works on neighboring cells
Neurocrine
neuron releases neurotransmitter to one target cell
Jusxtaposed cells
what happens to one cell will happen to the cell that is juxtacrine to the other
Growth factors will be converted to
arachidonic acid
Arachidonic acid final product
will be converted into something else which when added with cyclooxygenase will yield prostaglandin, thromboxane, and leukotrisne
Prostaglandin
primary pain signal that the body produces; found in most all cells
How to create pain medication
could inhibit cyclooxygenase through a NSAIDs way or using cortisol to block the creating of arachidonic
NSAIDs
nonsteroidal anti-infammatory drug
Asprin and Thromboxane
thromboxane is created by platelets; aspirin inhibits its creation which also decreases the chance of blood clots
Nitric Oxide
most important to cardiovascular physicology; will is a vasodilator
Norepinephrine
made by the brain and adrenal glands; released in response to stress. Will cause BP to increase by contracting vascular smooth muscle causing cardio output to increase. Will cause Bronchial smooth muscles to relax. this happens due to different transduction pathways between vascular smooth muscle and bronchial smooth muscles
Sodium
primary cation within body fluid
Average person’s division of body fluid
42L is divided about 2/3 is found intracellular, about 1/4 is found interstitial, the rest is found intravascular
Interstitial
space between cells
Concentration of substances within the body fluid between the different spaces
is similar
Viscosity and plasma
plasma is more viscous than the fluid found in the interstitial space
Dynamic constancy and set point
homeostasis will keep the body’s physiological systems within a set range of numbers which will have constant fluctuation throughout the day
Arterial oxygen and calcium levels set point
has a tighter range of numbers than any other set points
Ghrelin set point
300-700pg/ml; primary orexigenic signal
Set point for fasting glucose level
90mg/dL
Pituitary gland
controls almost all aspects of physiological processing; master gland of the endocrine system; located within the sella turcica of the sphenoid bone of the skull
ACTH
adrenocorticotropic hormone; will act on the adrenal glands to cause them to release cortisol
HPA axis: ACTH
the pituitary gland will release CRH which will release corticotropin which will release ACTH who will act on the adrenal glands to cause them to release cortisol
CRH
cortiocotropin releasing hormone
Cortisol
glucocorticoid; released under conditions of stress; will increase levels of blood glucose which will increase the amount of energy available for the muscles and nerve cells
Cortisol set point and ACTH
will fluctuate throughout the day; a few hours before you awake ACTH will slowing rise increasing cortisol levels so that when you are awake there is energy available; other than that the levels of cortisol and ACTH are within normal rage
Be able to draw the graphs of glucose, ghrelin, ACTH/cortisol
Negative feedback
opposite response to some initial stimulus
Hypothermia negative feedback
first the body will try to conserve heath through: to constrict the skin blood vessels to draw blood away from the surface of the skin and not activate the sweat glands and curling the body up. if the first steps don’t work the body will try to produce heat through shivering which when the skeletal muscles contract they need ATP to do so. (1 glucose molecule is converted to 34% ATP and the rest heat)
Metabolic and molecular pathways negative feedback
the product of a pathway will bind to a rate limiting enzyme through competitive/noncompetitive/allosteric inhibition which will change the binding site. ex/ phosphofrutokinase
Blood glucose negative feedback
when it increases beta cells will increase insulin. when it decreases alpha cells will increase glucagon
HPT and T4 negative feedback
hypothalamus releases TRH which will effect the pituitary gland to release TSH which will tell the thyroid to increase the production of T4 and T3 but especially T4. The failure of having iodine will lead to T3 and T4 to being contstructed incorrectly and therefore the negative feedback loop will not complete causing the pituitary gland to continue producing TSH. As T3 and T4 concentration increases the thyroid follicles will increase in order to hold all of it leading to goiters
Thyroid follicles
will surround the colloid and store thyroid hormones
Thyroid hormones
make it easy and efficient for cells to generate ATP
TRH
thyrotropin releasing hormone
TSH
thyroid stimulating hormone
Positive feedback
initial stimulus is reinforced; rare due to leading to not maintaining variables within a set range
Hemostasis and positive feedback
after being cut the body will start the blood clotting cascase. thrombin will be ultimately be produced to create a blood clot which in turn increases the molecules used to create thrombin
Hemostasis and negative feedback
the production of thrombin will lead to ceasing of blood loss
Parturition and positive feedback
Contractions of the myometrium will cause the relase of oxytocin (a posterior pituitary hormone) which will cause more uterine contractions
Parturition and negative feedback
child birth signifies the end of gestation
Resetting set points - fever
hypothalamus will increase body temperature and mechanisms are enacted to keep it at a higher level in order to make the body inhospitable for illness
Resetting set points - body temp
due to lower amount of movement at night body temperature is set to a lower set point
Resetting set points - iron levels
during infection iron levels will decrease in order to withold the iron from bacteria who can use it to produce energy
Endogenous
comes from within
Entrainable
can be reset but the body will be given reminders
Zeitgeber
natural time giver, the sun
Circadian rhythms
based off of the sun, the pineal gland will secrete melatonin, levels are highter around the time you go to sleep and decrease a few hours before you wake up; about 24 hour length cycle
Phase shifting
circadian rhythm shifting as age increses
Hamsters and circadian rhythm experiment
with constant dim light there’s no zeitgeber and therefore activity isn’t confined to when the light is on; the activity shifts each day due to the circadian rhythms not being exactly 24 hours long
Suprachiasmatic nucleus
within the hypothalamus
Suprachiasmatic nucleus (SCN) and circadian rhythm
the belief was that the SCN wasn’t connected to other parts of the brain like other regions are and therefore it was releasing some type of endocrine signal which directs other parts of the brain
SCN experiment 1 description
A Halasz knife was used to cut around the SCN of rodents leaving their cells intact while stopping any neuralogical signals from coming in or leaving
SCN experiment 1 results
the rodent’s circadian rhythm wasn’t changed at a ll
SCN experiment 2 descritpion
the SCN of rodents were lesioned and fetal SCN cells were encapsulated with a nuclear membrane which only allowed molecules to move through diffusion across it
SCN experiment 2 results
the circadian rhythms were able to return to normal after the SN was lesioned and prior to the fetal SCN cells were put in place; this implies that thte cells of SCN were creating a diffisuable signal which controlled the circadian rhythm
SCN firing rates
cells of the SCN were put in culture and the firing rates were recorded; they followed an about 24 hour rhythm and peaked at different times due to the vast amount of other physiological processes that are regulated by the circadian rhythm
action potential
cells changing the charge of their insides with respect to the houtside
retinohypothalamic pathway
pathway within the eyes that respond to light
Visually impaired and circadian rhythm
most visually impaired peolpe can keep circadian rhytjms while other cases leads to unmaintainable circadian rhythm
Ganglion cells
the primary job of sending information about light to the SCN
Clock genes
discovered first in fruit flies, the protein that’s trasnscribed will enter the nucleus and supress the gene. as the levels decrease and the inhibitor will be removed to allow the gene to express itself
SCN and clock genes
within the SCN there’re clock genes which will signal the pienal gland, when you’re awake the SCN clock genes will inhibt which doesn’t allow for signals to pass to the pineal gland and no melatonin is produce
Jet lag
takes about 4-5 days for the zeitgerber to remind the SCN and reset the circadian rhythm
Ultradian
rhythms less than a day
Infradian
rhythms longer than a day
Circlunal
rhythms about the length of the cycle of the moon
Anticipatory homeostasis
the body anticipates the need for change in order to keep homeostatic conditions before the environmental change occurs
Drug withdrawl
symptoms are opposite of how the drug effects the body due to the body trying to keep homeostasis
Drug overdose and anticipatory homeostasis
taking a drug at the same place, at the same time, with the same people leads to the body to physchologically learn and in turn anticipatory homeostasis will occur; by changing the environment the body isn’t cued in on what’s happening and anticipatory homeostaisis will not occur and the body will be susceptible to overdosing
gernalizations of homeostatic control systems
balancing inputs and outputs, negative feedback is a hallmark of normal physiology, there’s a range of normal values, set points can be reset, there’s a heirarchy of control systems so if the body needs to keep homeostasis by shutting down body systems it will (ex/ heat stroke)
Baroreceptro reflex
carotid sinuses within the aortic arch will snese the presser and stretching/distension of the vessels
Baroreceptor reflex - afferant pathways
vagus nerve and glossopharingeal
Baroreceptor reflex - integrating center
nucleus of the solitary tract (NTS) within the medulla oblongata found within the brain stem
Medulla oblongata
in charge of most reflexes
Influencers of blood pressure
cardiac output and peripheral resistance
Cardiac output
heart rate multiplied by stroke volume
Average cardiac output
average resting heart rate is 70; average stroke volume is 0.07L leading to an average cardiac output of 5L/min
Peripheral resistance
how dilated vessels are
To lower BP how to change cardiac output
change cardiac output by lowering heart rate or lowering stroke volume through lowering the amount of water within the blood
Baroreceptor reflex pathway
the carotid sinuses will send signals down the X and IX nerves towards the NTS. Once recieved the NTS will signal to the CVLM, SON, and NA. CVLM will signal to the RVLM which will lead multistep sympathetic nervous system response. SON will send a signal to the posterior pituitary gland to either inhibit or make ADH. NA will cause a parasymphetic nervous system response.
Carotid sinuses
baroreceptors found within the internal carotids; has a baseline of activity but when BP changes the activity of the receptors will fluctuate based on the change
CVLM
caudal ventrolateral medulla
RVLM
rostral ventrolateral medulla
NA
nucleus ambiguus; found within the medulla
SON
supraoptic nucleus within the hypothalamus
ADH
antidiuretic hormone; aka vasopressin
Parasympathetic pathway and X
there are connections of the vagus nerve within the parasympathetic pathway; through mechanical stimulation of the vagus nerve it can mimic the effector signals of the barorecepter reflex and lower BP
Baroreceptor reflex - when BP is high
there’s a lot of distension within the vessels and the carotid sinus receptors will increase in activity and send signals from the X and IX nerve to the NTS. The NTS will send signals to the CVLM to inhibit RVLM and therefore inhibiting the activity of the sympathetic nervous system. NTS will then activate NA which will activate the main parasympatheitc nervous system towards the heart lowering the heart rate. NTS will inhibit SON to not release vasopressin
SON and ADH
SON will send a signal to the posterior pituitary gland to cause the gland to create ADH
Baroreceptor reflex - when BP is low
disinhbition will occur as there’re no inhibitors and activation of the effectors SON and CVLM will occur
Homeostasis of chemical substances
loss of substances has to equal the gain of substances
Pool
can either store net gain substances or could be incorporated into other molecules
Net loss of chemical substances
can happen through metabolism and other excretions
Reccommended daily intake of sodium
2300mg
If sodium levels increase
the body needs 3 days to return to homeostasis in the mean time the osmolarity of the blood is increased leading to high stroke volume
Questions to ask about any homeostatic response
what is the variable being measured, what are the receptors and where are they, what’s the integrating center and where, what’re the effectors and how do they work
Membrane potential
potential difference in distribution of charges in membrane due to the unequal distribution of charges outside vs inside the cell
Membrane potential of every cell
is negative, fewer positive charges on the inside the cell membrane relative to the outside
Excitable cells
cells that can flip the charge from outside to the inside, neurons and muscle cells
Variables of excitable cells
dependent on permeability of the cell membrane, cells with more abundance of voltage gated ion channels have larger permeabilities
Current
movement of ions through an ion channel
Sodium extracellular concentration
145 mmol/L
Sodium intracellular concentration
15 mmol/L
Chloride extracellular concentration
100 mmol/L
Chloride intracellular concentration
7 mmol/L (dependent on the type of cell)
Potassium extracellular concentration
5 mmol/L
Potassium intracellular concentration
150 mmol/L
Goldman-Hodgkin-Katz equation
calculates resting membrane potential, equals -70 millivolts
Pk
1
PNa
0.04
PCl
0.45
Membrane permeabilities for potassium vs sodium
for potassium it is 25% more permeable than for sodium due to potassium channels being more leaky
Two compartments: Compartment A with 0.15M of NaCl and Compartment B with 0.15M KCl, there’s a membrane between the compartments and two potassium ion channels
when the channels open there’s a flux due to concentration gradiant of potassium leading to compartment A gaining positive charge and compartment B losing positive charge creating a potential difference. Then a flux due to electrostratic gradient will occur and potassium will start to move back to compartment B as it’s attracted to the negative charge. Equilibrium potential of potassium is reached when the flux forces become equal in magnitude but opposite in direction. There’s not an equal amount of potassium between each comparment nor equal in charge but the fluxes will be equal
Nernst equation
Eion=(61/Z)log(C0/C1) Z=valance charge of ion C0=concentration on the outside C1= concentration on the inside
Calculates the voltage at which there would be no movement of ions given the membrane was permeable for only that ion and equilibrium potential was reached
61/Z from Nernst equation comes from
RT/ZF R=gas constant, T=temp constant, F= Fereday’s constant
ENa
60 millivolts
EK
-90 millivolts
ECl
-70 millivolts
Resting membrane potential and equilibrium potential of potassium
isn’t surprisingly close to eachother because when the cell is at rest the ion channel for potassium is leaky
Sodium Potassium pumps
3 sodium move out for every 2
Depolarizing
loss of negative potential charge, charges moves towards zero, membrane potential doens’t become positive
Overshoot
reversing the polarity of membrane potential, only excitable cells can do this, in order for this to happen a lot of sodium has to mvoe in and a lot of potassium has to move out which is an energetically expensive action, almost as cells do this they will repolarize
Repolarizing
cells getting back to resting potential
Hyperpolarizing
more negative than resting potential
Action potential
uses voltage gated ion channels, happens in only exictable cells, only depolarizes, will have the same amplitude magnitude and duration throughout the membrane
Sodium channel
has amnio acid residue aka inactivation gate that will swing into the channel after it opens, the channel will go from closed to open to inactivated state which will then go back to a closed state, it cannot be opened if in an inactivated state
Potassium channel
will go from closed to open and open to closed
Sodium and potassium channels
have the same stimulus to open the channels which doesn’t make sense because it wouldn’t chagne the charge of membranes when used for action potential but it’s alright because potassium is slower to respond than sodium
Graded potential
change in variable amplitude and duration which is conducted decrementally, occurs in all cells, depends on ligand gated channels or mechanically gated channels
Ligand gated sodium channel - graded potential
when the chemical stimulus binds the channel opens up and sodium will move inside the cell (concentration gradient). Sodium will then also start to move out with the help of a potassium pump scattered nearby the channel opening. As the amount of sodium entering increases the duration it takes to move it back out will increase which leads to the decrement of the cell membrane. As sodium is being pumped out the positive charge will be spread around the channel where sodium is entering which leds to an increasingly negative membrane potential as you move away from the channel.
Amplitude of graded potential
dependent on the intensity of the stimulus, a high intentsity stimulus means there’s a lot of the ligant present which also leads to a longer duration for the membrane needs to pump the sodium back out
Hyperpolarization
potential becomes more negative than the resting level
