HES 111 midterm I Flashcards
What is the endocrine system?
A series of organs throughout the body that secrete horomones in response to stimulus
Name some bodily functions the endocrine sytsem is involved in?
metabolism, reg of gene expression, growth, reproduction
What are the two categories of endocrine organs and what are some examples in each
Endocrine: ant pit, thyroid, parathyroid, thymus, adrenal corte, pancreas, ovaries/testes
Neuroendocrine: hypothalamus, pineal gland, post pit, adrenal medulla
What are the 4 neuroendocrine organs?
Hypothalamus, adrenal medulla, post pit and pineal gland
what must a horomone bind to to exert action?
Its receptor
What is the difference between a hormone and neurotransmitter?
Hormone travel in bloodstream and secreted by endocrine gland. - long distance
Neurotransmitter - travel across synaptic cleft, secreted by neuron - short
BOTH: bind to a rececptor on a cell
What is a neurohormone?
a hormone secreted into blood by neuroendocrine cells (neurons)
What are the 2 main classes of hormones? Examples?
- amino acid based
- amines: epinephrine, norep (deriv of tyrosine), depamine, thyroid
- Peptide: insulin, GH - Lipid based
- Steroids: etrogen, testosterone, cortisol
How do the 2 classes of hormones behave differently
how they travel in blood, how target. cells recognize/receive, half life
Are amino acid based hyrdophobic or phyllic and where does it bind?
Hydrophyllic, binds on plasma membrane of target cell
Are steroid hormones hydrophobic or phyllic, where do they bind?
Hydrophobic — pass thru plasma membrane and bind in the cytosol in the nucleus of target cells
Both steroid and peptide horomones trigger a ________ response. Steroid horomone usually involve modification of…
INTRAcellular response, gene expression
How are hormones eliminated?
- Taken up by target cell
- Broken down (metabolized by liver) —- eliminated via kidneys
what does rate of hormone elimination depend on?
structure, and wether its bound to a carrier protein
what is hormone half life?
time taken for hormone concentration to reduce by half in the blood
Are hydrophobic/phyllic horomones bound to carrier proteins? How does this effect half life?
Hydrophobic (steroids) are bound to carrier proteins (albumin) so they have longer half lives (min–hrs)
What are 3 ways that hormone secretion is regualted
Other horomones, other molecules (eg ca), glucose (glucose uptake by pancreatic cell triggers insulin secretion, neurotransmitters (symp neurons trigger epinephrine, norepinephrin)
Where do the horomones produced in the hypothalamus go? What is directed in the hypothalamus?
to the post. pit, directs horomones from ant pit
What 2 horomones does hypothal produce for secretion by___
post pit: anti-diuretic horomone (ADH) – to kidneys – water reabsorption back into blood
Oxytocin – uterus and mammary gland: uterine contraction and milk release
What type of horomones (made by hypothalamus) trigger release from the ant pit?
TROPIC - a hormone that triggers release of another horomone
What are 5 tropic horomones released by hypothalamus?
thyroid releasing hormone, corticotropin releasing hormone, prolactin releasing hormone, gonado-tropin releasing horomone, GH releasing hormone
what does prolactin releasing horomone lead to?
prolactin releasing hormone — prolactin — mammary gland –milk production
what is the path of thyroid releasing hormone?
thyroid releasing hormone — thyroid stim hormone – thyroid gland ( thyroid stim and secretion)
Path of corticotropin releasing hormone?
triggers adrenocorticotropic horomone then to adrenal cortext which secretes cortisol and aldosterone
Path of gonadotropin releasing horomone
lutenizing horomone and follicle stim horomone — to the female and male gonads —
IN FEMALE: Synth and secretion of estrogen, progesteron, follicle maturation, ovulation
IN MALE: synth, prep and seretion of testosterone
Path of growth horomone releasing hormone
Growth hormone secretion — liver, adipose tissue, muscle tissue, boen and cartillage, — involved in metabolic processes that release energy for fuel rpod incr blood glucose and promote growth.
What is the main function of the growth hormone?
Regulate growth of target tissues
short term effects are… What is the goal of short term effects?
Metabolic – fat breakdown, new glucose in liver, inhibit gluc uptake in skel muscle
GOAL: Make glucose + fatty acids available for use for fuel and growth
What is the long term effect of GH?
Tropic effect - Trigger release of Insulin-like growth factor (IGF)
Where are thyroid and parathyroid glands located
Thyroid - ant neck, superficial to trachea
Parathyroid - post surface of thyroid
what are the 3 tiers of horomone control form the hypothalamus?
1: hyporthal releases hormones
2: ant pit releases hormones
3: target organs release hormones
4: effects: hormone levels increase - effects on other cells(return to normal range)
What are the the 3 hormones secreted by thyroid: 2 main functions
T3(triiodothyronine) + T4 (thyroxine) + calcitonin
- Reg metabolism - set basal metabolic rate
- Reg body temp - thru metablism
What does the parathyroid gland secrete? It is secreted in response to_____ so it therefore _____
Parathyroid horomone - secreted in reponse to LOW BLOOD CA so therefore INCREASES blood calcium
3 ways PTH increases blood ca
1) Stimulates osteoclasts – incr ca release
2) increase absorbtion of ca by small intestinee
3) increase reabsorption in kidneys
What does IGF do? Where does it come from? Goal?
(insulin like growth factor)
- affecrs cells: protein synth, division, incr glucose uptake in cells
Long term effect of GH
Goal: growth: during developmental years (GH continues to reg blood glucose and muscl growth thru adulthood)
Calcitonin is secreted by ____ and responds to ____ blood ca therefore the effect ____
Secreted by thyroid hormone, responds to high blood ca by lowering blood ca:
1) inhibits osteoclasts
What neurohormones are secreted by adrenal medulla?
epinephrine and norepinephrine
What type of horomones does the adrenal medulla secrete? what types does the adrenal cortex secrete?
adrenal medulla: neurohormones: epinephrine and norepinephrine
Adrenal Cortex: steroid hormones: aldosterone and cortisol
What does aldosterone do? Secreted by?
Regulation of fluid, elctrolyte and pH balance in blood
secrete by the adrenal cortex
what does cortisol do? secreted bY?
promote catabolic rxns in order to provide fuel for stress response
for ex: gluconeogenesis (gluc production in liver)
protein breakdown
fat breakdown
ALSO Inhibit inflammatory responses
Pancreatic islets consist of what type of cells?
alpha, beta, delta
which cell is insulin produced and secreted from? Secrete in respont to..
B (beta) cells. high blood glucose
what cell is glucagon produced and secreted from
a cells - secreted in response to low blood sugar
What are the two types of membranes surrounding the heart?
fibrous pericardium - outer conn tissue
serous pericardium - inner forms 2 layers
what are the two layers if the serous pericardium
parietal layer: fused to inner surface of fibrous pericardium
visceral layer: inner layer closest to heart wall
pericardial cavity: between 2 layers - filled w serous fluid (pericardial fluid) - lubricant decreases friction as heart beats
Which membrane is a part of the heart wall
visceral pericardium (epicardium)
What are the 3 layers of the heart wall?
epicardium - myocardium - endocardium
what layer of heart wall contains fat deposits
epicardium (visceral pericardium)
what is the main component of wall of the heart? what does it contain
myocardium - contains myocytes (cardiac muscle cells). Also specialized pacemaker cells and conn tissue
what is the innermost layer of the heart?
endocardium - faces lumen of heart chambres: simple squamous epithelium + layers of conn tissue w collagen and elastic fibres
what compartments recieve blood from veins
atria
what part of heart ejects blood into arteries
ventricles
What are the major systemic veins?
sup and inf vena cava
why are ventricles larger w thicker walls
because they are stronger pumps
wharts the major systemic artery
aorta
major vessels of pulm circuit?
r and L pulm arteries and veins
which atria is larger
the right is larger, thinner, more anterior
What are right and left ventricles seperated by?
interventricular septum
what are the valves between the atria and ventricles
Atrioventicular valves (AV valves)
Tricuspid - on right side
Bicuspid/mitral - on left side
What are the valves between ventricles and pulmonary arteries
Semilunar valves (Also tricuspid)
- Pulmonary valves - between r ventricle and pulm trunk
- aortic valve: between left ventricle and aorta
what is the purpose of valves
keep blood flowing in one direction
Blood flows in response to - —- gradients
pressure
what happens when pressure in ventricle is high (greater than aorta or atrium)
Pushes aortic valve open, if greater than atrium closes atrioventricular valves (tricuspid or biscupid(mitral)
what happens when pressure in aorta is greater than ventricle
closes aortic semilunar valve
what happens if pressure in the atrium is greater than ventricle
Opens AV valves
Describe the steps of blood flow thru the heart
1) blood in systemic capillaries delivers oxygen to body
2) systemic veins bring deoexygentaed blood back to right atrium
3) Blood passes to right ventricle thru tricuspid valve
4) then thru pulmonary valve to pulmonary veins (pulmonary trunk)
5) to pulmonary capillaries in lungs where blood becomes oxygenated
6) pulm veins returns oxygenated blood to left atrium
7) blood goes from left atrium thru bicuspid (mitral valve) to left ventricle
8) left ventricle pumps thru aortic valve to aorta
9 ) aorta delivers blood to systemic capillaries and body
what are the two types of cells in the myocardium
myocytes - majority (99%)
pacemaker cells - 1%
what is the source of force production of the heart muscle?
myocytes
what generates spontaneous, rythmic action potentials
pacemaker cells
do pacemaker cells contribute to the contractile force of the heart
no - just a signal for myocyte contraction
what joins myocytes together?
intercalated discs
what connects pacemaker cells to contractile cells?
Intercalated discs
what are intercalated discs made of?
Desmosomes: hold the cells together
Gap junctions; allow ions to pass rapidly form one call to another
What are the steps of the cardiac conduction system?
1) SA node generates AP potentaial which spreads to atrial cells and AV node
2) after AV node delay, AP goes to AV bundle and then to right and left bundle branches
3) ap spreads from bundle branches along purkinje fibers to contractile cells of ventricles
What is the purpose of the delayed conduction thru the AV node?
Allows atria to fully depolarize (and contract) before the ventricles, giving ventricles time to fill up w blood.
steps of pacemaker action potentails
1) Slow initial depol phase: HCN channels open in response to membrane hyperpolarization –> this leads to more Na+ in then K+ out leads to depolarization to threshold
2) Full depol Phase: Ca2+ via ca channels leads to depol phase
3) Repol phase: K+ out via K+ channels, repolarization
4) Min potential phase: HCN open again in resp to hyperpol from K+ flowing out and cycle repeats
What inititiates the HCN channels to open in pacemaker action potentials
during the final phase K+ flow out and hyperpolarize opening HCN channels
Action potentials are transmitted from ___ to ___ through _____
from pacemaker cells to myocytes thru gap junctions
what are the steps of myocyte action potentials
1) rapid depolarization phase: Na+ rushes into cell via Na+ channels
2) initial repolarization phase: Na+ channels close, K+ open, K+ leaves causing some repolarization
3) plateau phase: Ca2+ comes, via opening og ca channels, in while K+ is going out, causing balance:
- Lengthens AP to 200-300: Keeps HR slow enough to allow time for heart to fill w blood before next contraction
4) Repolarization phase: Na+ and Ca2+ channels closee as K+ continue to exit = repol
What does the plateau phase allow for in myocyte action potentials?
allows enough time for the heart to fill w blood before the next contraction and prevents tetanus (another AP)
what does chronotropic mean?
Heart rate
Does the parasmpathetic ns have a positive or negative chronotopic effect?
negative
Does sympathetic nervous system have a positive or negative chronotropic effect
positive
does contraction and relaxation of the myocytes need to be in perfect synchrony?
Yes. and facilitate filling and blood flow from atria ventricles, and then out via the aorta or
pulmonary arteries
what is preload?
The amount of stretch of the sarcomeres in the ventricular muscle cells (myocytes). Before contraction
What is the perfect sequency an synchrony a result of? (3 reasons)
1) delay at av node
2) gap unction allow eletrical signal to spread quick thru myocytes
3) orientation of myocytes
How does increased preload affect blood pressure?
Increase in preload increases edv –>incr SV, Incr CO, Incr blood pressure
where are the electodes on a 3 lead ecg
RIght arm (-, -) , left arm( +, -), left leg (+, +)
What are the 3 diffferent waves of the ECG and what does each represent
P wave - atrial depolarization
QRS complex - Ventricular depolarization (masking atrial repol)
T wave - Ventricular repolarization
What does the R-R interval represent on an ECG
duration of cardiac cycle
what does P-Q represent
duration of atrial repol and AV node delay
What does Q-T interval represent?
entire duration of ventricular action potential
what does the s-t segment represent
ventricular plateau phase
The cardiac cycle describes not electrical events but ____ events of the heart
mechanical
what rep contraction what rep relaxation of heart
contraction - systole
relaxation- diastole
Do atrial and ventricular systoles and diastoles occur at same or different times why?
The occur at different times due to the AV node delay.
Do both sides of the heart work at different times or simulataneosly
simulataneosly
what are the 4 main phases of the cardiac cycle
filling, contraction, ejection, relaxation
What horomone binds inside a cell and why?
Lipid based/steroid molecules because they are hydrophobic therefore can pass thru membrane
if BP drops below normal range waht happens in terms of symp ns
Increased activity of sup ns
What happens during the ventricular filling phase?
Blood flows down the pressure gradient from atria to ventricles.
Atria in systole
Ventricles in diastole
AV valves open
semilunar valves are closed
Isovolumetric contraction Phase
ventricular systole
atrial diastole
all valves closed
what the state of the atria and ventricles during ventricular ejection. Which valves open and closed. FLow of blood?
ventricles in systole
atria in diastole
AV valves closed
SL valves open
Blood is ejected into pulm artery and aorta
What is end diastolic volume?
total amount of blood in ventricles at the end of ventricular diastole
At rest how much blood is pumped into each ventricle
70ml
what is end systolic volume? How much is it at rest
the amount of blood remaining in ventricle at the end of ventricular ejection
at rest about 50ml
what the state of the atria and ventricles during isovolumetric Relaxation:. Which valves open and closed. FLow of blood?
ventricles in diastole
atria in diastole
all valves closes
blood is not being ejected or enter - remains constant
what is stroke volume?
Volume of blood ejected out of left ventricle in one heart beat
what is cardiac output
volume of blood pumped out of left ventricle in one minute (L/min)
What is venous return>
volume of blood returning to heart in one min
whats the formula for SV? Resting is?
EDV-ESV. 70mL
What is formula for CO? whats resting?
SV x HR - 70x70 = 4900ml (around 5 L)
What are the 3 main factors that affect stroke volume?
Preload, contractility, afterload
What is preload?
amount of stretch of sarcomeres in ventricular myocytes before contraction - det by EDV
How does preload affect SV? 2 factors that influence edv?
Higher preload = Higher volume of blood in ventricle (EDV) = more stetch on ventricle myocytes and more potential for actin-myosin overlap e
1) length of time ventricle spends in diastole
2) amount of bood returning to heart from systemic circuit (venous return)
How does contractility increase SV?
- Greater force of contraction = more blood ejected = lower ESV = greater SV
what are inotropic agents?
agents that affect contractility
What is afterload?
the force ventricle must overcome in order to eject blood into arteries
How does afterload increase SV?
Lower afterload = ventricle pumping against lower resisistane = lower ESV
What happens to the three factors that affect stroke volume when stroke volume decrease?
low preload (muscle cells less stretched) , low contractility (heart contracts more weakly), high afterload (ventricle pumping against a higher resistance)
What are chronotropic agents?
Factors that influence HR
Under normal conditions what determines HR?
The rate at which SA node generates AP
What is a positive chronotropic agent? what does it include?
ANything that increases rate at which SA node fires (incr HR)
includes sympathetic nervous system, horomones, elevated body temp
What is a negative chronotropic agent? and examples
Anything that decrease the rate of SA nod firing
included parasympathetic nervous system and decreased body temp
How does sympathetic NS reg Cardiac output
Epinephrine and norepinephrin incr HR and contractility of myocytes which increases SV and HR. positive chronotropic and Inotropic effect.
How does parasympathetic NS regulate CO?
Acetylcholine targets SA node and decreases HR
- Negative chronotropic effectf
what are presuure resevoirs
arteries
what are volume resevoirs
veins
What is the site of variable resistance
the arterioles
are there more arteries or veins
veins
what holds more blood, arteries or veins?
veins hold much more blood than arteries (70%)
what are the wall layers of arteries and veins from innermost to outermost
innermost - tunica intima
middle - tunica media
outer - tunica externa
what layer of the arteries and veins contains smooth muscle?
tunica media
what does contraction of the arteries or veins lead to vs relaxation?
contraction –> vasoconstiction –> decreased diametre
Relaxation –> vasodilation —> increases diameter
veins have ____ wals, ____ elastic fibres, ____ smooth muslcle and ____ lumen
Most arteries have much thicker _______ (wall) and more ___ laminae (due tonhigher bp the ssee)
VEINS = thinner walls, less elastic fibres, less smooth muscle, larger lumen
Most arteries have much thocker tunica media more internal and external elastic laminae.
Whats a main role of tunica media
controlling blood flow and blood pressure
what is the fucntion of elastic arteries? primarily made up of?
Condict blood under high pressure to organs. Elastic laminae.
what type of arteries are pulmonary arteries
elastic
what arteries reg bP and control blood flow to organs?
muscular arteries
wha tunics are arterioles made of?
all 3
what is the main function of arterioles?
control blood to tissues, feed capillaries
Main fucntion of venules?
drain capillary beds
main function of veins
return blood to heart
what are the three types of capillaries?
continuous, fenestrated, sinusoidal
what is the least leaky capillary type? Joined by tight junctions
continuous - msucle tissue
which type of capillary is moderately leaky?
fenestrated
which type of capillary is the leakiest?
Sinusoidal - cellls can pass thru
what is blood flow thru capillary bed based on?
tissue needs - skel msucles need more o2 more capillary beds
what is blood flow thru tissues regulate dby?
1) opening/closing of precapillary sphincters
2) vasoconstriciton/dilation of arterioles
What is the equation for blood flow?
Blod pressure gradient (deltap)/resistance
- bp gradient creates the blood flow
- the total resistance is the impedence to blood flow
what is the current (I) equation
= voltage gradient (delta v) (delta v)/ Resistance
What is the main determinant of flow rate of blood?
pressure gradient
What is blood pressure?
outward force that the blood exerts on the walls of blood vessels (mmHg)
What are the three things resistance is determined by?
Vessel radius, length, viscocity
What is the velocity of blood flow equation?
1 / cross sectional area
Total cross sectional area increase as artries bracnh into…
smaller vessels
As total cross sectional area increase what happens to velcocity
velocity slows down
where is blood velcocity slowest? why?
in capillaries, to allow more time for effective gas and nutrient exchange
What is systolic pressure - at rest?
pressure of blood against artery wall during systole (120mmHg)
what is Diastolic pressure - at rest?
the pressure of blood against the artery walls during diastole - 80mmHg
what is the pulse pressure?
difference betwee systolic and diastolic BP - Sp-Dp - 120-80 = 40
What dos systemic arterial bp represent?
the driving pressure of blood thru arteries -MAP
what is the MAP equation
MAP = diastolic pressure + 1/3 (systolic pressure – diastolic pressure)
when is pulse pressure gone on the graph? what does the black line mean?
when it reaches the arterioles – cap – venules – to veins– venacavae
black line is MAP
What are the three factors that determine BP?
Peripheral resistance, CO, blood volume
as peripheral resistance increase what happens to BP?
also increases
what are the three things that impact peripheral resistance?
Blood viscocity - more viscous more molecule resistance to motion - blood has high viscocity bc of protein and cells
Blood vessel length - longer blood vessel = gerater Resistance = more pressure to propela long long vessel
Blood vessel radius - as radius increases resitance decreases, so inverse
How does hight blood viscocity impact BP?
more viscous= more resistance to motion = more peripheral resistance = higher BP
what is a reason that resistance in pulm circuit is less than systemic
Blood vessels are longer in systemic so reseitance is grater
How does cardiac output impact BP
Increase in cardiac output leads to increase in BP
How does blood volume imapct BP?
when blood contains more water, volume invrease, increase in blood volume means increase in pressure therfore increase in BP
which circiuit does pressure remain relatively low and stable?
pulmonary
in systemic circuit whre is the highest pressure? where is the lowest
highest is arteries than arterioles, lowest is venules and veins
where does MAP decrease rapidly
arterioles
2 mechanisms of venous return
valves - ensure one way flow
Skeletal muscle pump - skel muscle squeeze deeper veins to propel to heart (vasoconstirciton)
What three systems is BP under regualtion by?
nervous, endocrine and urinary
where is short term maintenance of BP? where is long term maintenance? what sytems?
Short term - nervous ssystem - ANS. - periph resistance and CO ( think HR and SV) - Norepinephrine and epinephrin
Long term - kdineys and endocrine sytem
- increases the water lost as urine changinging blood volume
horomones act on kdiney to manage fluid retention eg ADH
give an example of how the endocrine system plays a role in the cardiovascular.
Endocrine releases ADH (anti-diuretic horomone) which alter fluid retention in the kidney therfore changinf blood volume and impacting blood pressure.
How does Nervous system impact HR?
symp neurons release epinephrine and norepinephrine which increase HR and contractility and therfore cardiac output -
also cause vasocontriviton of arteriooles which increases perip resistance
Which ssytem in the ANS decreases bp and why?
Parasympthetic decrease heart rate decreaseing CO and therefore blood pressure
what are baroreceptors?
specialized mechanoreceptors found in walls of aortic arch and common carotid artery which respond to stretch in the artery wall
where are baroreceptors found?
aortic arch and common carotid artery
what is the baroreceptor reflex (in terms of increase in Bp)
Increased BP –> increased wall stretch –> increaseed firing of AP via cranial nerves of sns –> to medulla for integration –> output to lower bp
where
