Physio exam review Flashcards
What is the consequence of a septal defect between the L and R ventricles?
Blood flow from L to R because the L ventricle is under much greater pressure than the right.
What is the difference in pressure between the L and R atria?
Zero. If there is a septal defect in the atria, there is no blood flow between the two chambers.
What prevents the mitral and tricuspid valves from everting to lower pressure regions in the atria during ventricular systole?
Chordae tenineae
Which has a greater volume, the right or the left heart?
They are equal
What is the pressure in the left atrium while standing?
Sub-atmospheric, -2 to -4 atm. This makes it easy for blood to return from the lungs to the heart.
Which muscles in the heart keep the valves from everting?
The papillary muscles prevent eversion in conjunction with the chordae tendineae.
What prevents mitral regurgitation?
Chordae tendineae
What is the ultimate fate of the valve leaflets after a myocardial infarction?
A myocardial infarction causes dilation of the heart muscles (they become loose), which increases their size. However, the leaflets remain the same size and, therefore, regurgitation occurs.
What is the most posterior structure in the heart?
Left atrium
What makes up most of the anterior surface of the heart?
Right ventricle
What other vessels following the aortic valve would be compromised in the case of a clogged aortic valve?
Coronary arteries –> They supply blood to the myocardium.
Which valves are larger and why? The AV valves, or the aortic and pulmonary valves?
The AV valves are larger. The aortic and pulmonary are smaller because they are send the same volume of blood through a smaller opening and thus achieving a greater velocity.
Give the relative percentages of blood output to organs
Renal 25%, GI 25%, Muscles 25%, Cerebral 15%, Coronary 5%, and skin 5%.
Why does the brain require such a relatively high percentage of cardiac output?
Because it does not store glucose and needs a continuous flow.
Do arteries have valves? Veins?
Arteries NO. Veins YES, one-way valves.
Where is blood found at its highest velocity?
Aorta
Which blood vessels have the greatest surface areas?
Capillaries
Which blood vessels hold the greatest volume of blood?
Veins, 2/3
Which blood vessels exert the greatest control of BP? Why?
Arterioles, because they display the greatest change in size. Capillaries don’t change size, arteries don’t change size, veins change SLIGHTLY, but not as much as arterioles.
Through which blood vessels does the greatest drop in blood pressure occur?
Arterioles.
What is the only part of the vasculature that moves? What receptors mediate this movement?
Arterioles. Alpha-1 receptors constrict, Beta-2 receptors dilate.
If the pressure can be dropped at the ____ of a system, the total flow will go up.
At the END of a system –> Blood flow = (Arterial pressure - VENOUS PRESSURE)/Vascular resistance. NOTE how increasing the pressure at the beginning of the system WITHOUT reducing the end pressure will DECREASE TOTAL FLOW.
What is the range of cycles per second the human voice is capable of, in Hz?
300-
Define autoreceptor and what they do
Alpha 2 receptors on the sympathetic postganglionic nerve terminals. They are activated by norepinephrine from presynaptic nerve terminals and INHIBIT FURTHER RELEASE of norepinephrine from the SAME TERMINAL.
Define “heteroreceptors” and what they do
Alpha 2 receptors found on the parasympathetic postganglionic nerve terminals in the GI tract. Norepinephrine is released from sympathetic postganglionic fibers that synapse on these parasympathetic postganglionic nerve terminals. When activated by norepinephrine, the alpha 2 receptors cause inhibition of release of Ach from the parasympathetic nerve terminals. IN THIS WAY, the SNS indirectly inhibits GI function by inhibiting the parasympathetic activity.
What substance(s) activate alpha 1 receptors?
Equally sensitive to epi and nor, HOWEVER, only norepinephrine released from adrenergic neurons is present in high enough concentrations to activate alpha 1 receptors.
What is the general action, mechanism of action, and G protein for the following:
- ) Alpha 1
- ) Alpha 2
- ) Beta 1
- ) Beta 2
1.) Alpha 1: Excitatory (constricting), increase IP3 and intracellular [Ca2+], Gq.
2.) Alpha 2: Inhibitory (relaxing), inhibition of adenylyl cyclase and thus decrease cAMP, Gi.
3&4.) Beta 1 AND Beta 2 (they have the same action): Stimulation of adenylyl cyclase and thus decrease cAMP, Gs.
What happens when Beta 1 receptors are activated in the kidney?
Renin is secreted, which activates angiotensin (constricts blood vessels). Also increases secretion of ADH and aldosterone. Essentially, IT INCREASES BLOOD PRESSURE.
What compound phosphorylates proteins at the end of the Alpha 1 mechanism?
Protein kinase C
In the final step for the mechanism of action for Beta 1&2, what action does adenylyl cyclase perform?
It catalyzes the conversion of ATP to cAMP.
Where is norepinephrine primarily released from?
Postganglionic sympathetic adrenergic nerve fibers.
What action does Beta 2 stimulation have on its target tissues?
Relaxation/dilation. Dilates vessels to skeletal muscle (for fight or flight), dilates GI tract wall (so it doesn’t squeeze shit out), dilates bladder wall (so it doesnt squeeze peepee out), and dilates bronchioles (so you can breathe more better).
Describe the effects of catecholamines on alpha 1&2, and beta 1&2 receptors.
Alpha 1: Nor and epi equipotent, though compared to beta receptors, it is relatively insensitive. HIGHER CONCENTRATIONS of catecholamines are necessary to activate alpha 1. Physiologically, the only way to achieve such high levels is when norepinephrine is released from postganglionic sympathetic nerve fibers, NOT when it (nor OR epi) is systematically released from the adrenal medulla.
Alpha 2: ? Book doesn’t say.
Beta 1: Reacts equally well to norepinephrine from postganglionic sympathetic nerve fibers, and from epinephrine from nerve fibers.
Beta 2: Preferentially activated by epinephrine. Therefore, epi released from adrenal medulla is expected to activate Beta 2, whereas norepinephrine released from sympathetic nerve endings is not.
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What is the mechanism of action for nicotinic receptors?
When Ach binds to BOTH alpha subunits (it has 2 alpha, 1 beta, one delta, and one gamma), the associated ion channel opens, allowing Na+ to flow iN, and K+ to flow out. This depolarizes the membrane.
Where are nicotinic receptors found?
Motor end plate of skeletal muscle, and on all postganglionic neurons of both the SNS and PSNS, AND on chromaffin cells of the adrenal medulla.
What is the coupled enzyme in alpha 1 receptors? After the G protein subunit activates it, what happens to complete its actions?
Phospholipase C.
- ) This enzyme then catalyzes the liberation of IP3 and diacylglycerol from PIP2.
- ) IP3 then causes the release of Ca2+ from intracellular stores in the ER or SR, increasing the intracellular [Ca2+].
- ) Together, the Ca2+ and diacylglycerol activate PROTEIN KINASE C, which phosphorylates proteins.
- ) These phosphorylated proteins execute the final physiologic actions.
Which, if any, sympathetic effector organs are muscarinic receptors found on? Where else?
Sweat glands. Also, heart, GI tract, bladder, bronchioles, and male sex organs.
What are the three (3) mechanisms of action for muscarinic receptors? Be specific and give example for the unusual one!
There are three (3):
- ) Exactly like alpha 1.
- ) Like alpha 2? (inhibit adenylyl cyclase and lower intracellular cAMP).
* **3.) Alter physiologic processes with DIRECT ACTION ON THE G PROTEIN with NO SECOND MESSENGER–> E.G. Muscarinic receptors in the SA node, when activated by Ach, produce activation of a Gi protein (alpha 2 style) and release of the alpha i subunit, WHICH BINDS DIRECTLY TO K+ CHANNELS OF THE SA NODE. When this happens, the K+ channels open and SLOW THE RATE OF DEPOLARIZATION OF THE SA NODE, thus DECREASING THE HEART RATE.
For the following sense receptors, give: Location, what it senses, adaptive speed, and phasic or tonic:
- ) Hair receptor
- ) Merkel’s
- ) Pacinian
- ) Ruffini’s
- ) Meissner’s
- ) Tactile disc
- ) Hair: Hairy skin. Senses velocity, direction. Rapid, PHASIC.
- ) Merkel’s: Non-hairy skin. Senses vertical indentation. Slow, TONIC. VERY SMALL RECEPTIVE FIELD. Response proportional to stimulus.
- ) Pacinian: Subcutaneous, intramuscular. Senses vibration, tapping. Very rapid, PHASIC. VERY LARGE STRUCTURE, opens sodium channels on its own.
- ) Ruffini’s: Hairy skin. Skin stretch, joint rotation. Slow, TONIC. LARGE receptive field.
- ) Meissner’s: Non-hairy skin. Two-point discrimination, tapping, flutter. Rapid, PHASIC.
- ) Tactile disc: Hairy skin. Vertical indentation of skin. Slow, TONIC. VERY SMALL RECEPTIVE FIELD.
Give the structure (i.e. where it crosses) and function (what senses it carries) for 1.) Dorsal column, and 2.) Anterolateral (spinothalamic) system.
- ) Dorsal column: Crosses at brain stem (IPSILATERAL to side of perception). Carries fine touch, vibration, and proprioceptive sensations.
- ) Anterolateral (spinothalamic) system: Crosses at spinal cord (CONTRALATERAL to side of perception). Carries pain and temperature sensation.
What does “lateral inhibition” allow for?
Greater focus and precision of sense. SO YOU CAN TELL WHERE STIMULUS IS COMING FROM.
Blood vessel compliance is highest when…
They hold a large volume at a low pressure. C = V/P
List 4 anatomical structures with high compliance (fill rapidly with little change in pressure).
List 2 with low compliance (fill slowly with LARGE increase in pressure)
High compliance: Lungs, veins, lymphatics, stomach.
Low compliance: Skull, old arteries
What is a consequence of low compliance in blood vessels?
Hypertension
Compliance is the opposite of…
Elasticity: To retain shape and increase pressure
What does high compliance essentially mean in words?
That you can take a lot of volume without a big change in pressure
What happens to pressure and compliance as you go from arteries to veins?
Decreasing pressure, increasing compliance.
What does high compliance do to BP?
Keeps BP low
Where is the site of compliance change in blood vessels?
Arterioles
What is pulse pressure, what does it reflect?
Difference between systolic and diastolic pressure. It reflects stroke volume (amount of blood ejected in a single beat).
High compliance = ______ pulse pressure
Low
Give eq more MEAN arterial pressure
Diastolic + 1/3 pulse pressure
Is the mean pulse pressure closer to systole or diastole? Why?
Diastole, because diastole lasts longer.
All valve lesions (e.g. aortic stenosis, atherosclerosis) give you….
CHF, SOB
What happens to pressure in LV during aortic stenosis? What is normal?
Normal is NO PRESSURE GRADIENT BETWEEN LV and AORTA, i.e. both are 120. IT IS NOT NORMAL TO HAVE A PRESSURE GRADIENT ACROSS VALVES!!!
During aortic stenosis, LV pressure > Aorta pressure
Aortic stenosis (blocked valve) does what to pulse?
Delays the exit of blood and delays pulse because the stenotic valve is in the way.
What does the valve pressure gradient tell you?
How bad your aortic stenosis is
What does a murmur indicate?
Delayed closing of the valve. Diastolic crescendo murmur.
What is an aortic regurgitation, what does it cause?
Blood spills backwards, dilates LV, extra high EF, and greater pulse pressure. It causes a decrescendo murmur.
Describe the compliance of pulmonary circulation
High compliance, low pressure. Because lungs are soft.
The SA node is the pacemaker because….
It is faster than the other nodal tissues. They could do it, but they are too slow.
What is the relationship of action potential to refractory period?
Longer action potential = longer refractory period
What is the effect of high BP on the heart?
Cardiomyopathy, stretched and damaged internodal pathways. The heart will stretch the pathways and cause atrial fibrillation, because it stops before it gets to ventricles.
Why can you live with Afib? What causes it?
Because ventricular filling is mostly passive. Only 10-20% of cardiac output is from atrial contraction. But you can get clots due to hemostasis.
It is caused by malfunctioning SA node, UNLESS THERE IS NO P-WAVE, in which case it would originate in the INTERNODAL PATHWAYS.
Which bundle branch block is more pathologic, L or R?
Left.
Describe the action of sodium/potassium ATPase
3 Na+ out, 2 K+ in. Ungated K+ channels = more K+ going out.
The membrane resting potential is closer to the equilibrium potential of _____ because ____
K+ because it has ungated channels.
What causes repolarization?
K+ leaving causes negative inside. Voltage gated potassium channels
Why is there a plateau needed in atrial, ventricular, and Purkinje AP’s? What causes it?
It is needed so the heart has time to pump blood. It is caused by the longer APs in the heart, and they get longer as you move down the nodal pathway, e.g. SA node = 150ms, Purkinje = 300ms. Compared to 1-2ms for nerves and skeletal muscle.
Why does cardiac muscle need a long refractory period?
So you don’t have another part of the heart contract before the ventricles are empty. Also, the AP’s could propagate in both directions and the heart would not beat in a sequential manner.
The “rate of rise of the upstroke” (the rate of change in the membrane potential as a function of time) is greatest, i.e. the rate of rise in the upstroke is fastest, when resting membrane potential is _____, it is slowest when _____
most negative, i.e. HYPERPOLARIZED (e.g. -90mV) because of electrochemical gradient.
Slowest when resting membrane potential is less negative, i.e. DEPOLARIZED.
List the steps of normal action potential.
- ) Resting potential is established at approx. -70mV and K+ conductance is high and it diffuses out of leak channels down its concentration gradient. At rest, Na+ conductance is low. v
- ) Upstroke: AP causes depolarization of cell membrane (-60mV) and Na+ channels open allow influx of Na+ = further depolarization to 65mV.
- ) Repolarization: After upstroke, Na+ channels SLOWLY close in response to depolarization, this ends upstroke. Also, depolarization opens K+ channels and an outward flow of K+ repolarizes membrane.
4.) Hyperpolarization: For a brief period after repolarization, K+ conductance remains high and membrane potential is driven towards K+ eq potential as K+ continues outwards. Eventually, K+ conductance returns to resting levels and the cell membrane depolarizes slightly back to resting membrane potential.
Where do calcium channel blockers work?
Vascular reactivity in peripheral blood vessels, L-type calcium channels in the heart.
What do calcium channel blockers do in the heart?
They allow repolarization.
Rapid depolarization in nodal tissue is based on _____?
Calcium
What is phase 4 in nodal tissue unstable? When does calcium enter?
It is constantly depolarizing due to funny Na+ channels. They start at -65mV and shut off at -45mV (threshold for phase zero) to allow calcium to flow in.
What speeds and slows phase 4 of nodal action potential?
Sympathetic (Nor/Epi) SPEEDS phase 4, Beta-1 agonist
Para (Ach) SLOWS phase 4, M2 agonist
Which drugs SLOW conduction through the AV node?
Beta blockers, calcium channel blockers, or digoxin
What ultimately determines the heart rate?
The rate of phase 4 depolarization.
How does the heart ensure that each AP will be followed by another?
The funny channels (If) are turned on by repolarization from the preceding action potential.
What is the spinal level of the SNS?
T1-L3, thoracolumbar
What are the levels of the PSNS?
CN 3, 7, 9, 10 and S2-S4. Craniosacral.
Steps for photoreception in rods
- ) light converts 11-cis rhodopsin to All-trans rhodopsin (photoisomerization)
- ) Metarhodopsin is formed
- )Metarhodopsin activates G protein (transducin)
- ) Transducin activates phosphodiesterase
- ) Phosphodiesterase causes cGMP levels to decrease
- ) Decreased cGMP closes Na+ channels (decreased inward Na+ current) = HYPERPOLARIZATION
- ) Hyperpole causes decrease of either excitatory or inhibitory neurotransmitter:
- ) Excitatory neurotransmitter–> response of bipolar or horizontal cell to light is hyperpolarization
- ) Inhibitory –> response is depolarization of bipolar or horizontal cell.
* Inhibition of inhibition is excitation*
Choroid is between the ____ and _____. What does it do? What is its visible portion? Anterior portion of the choroid is the____
Between Sclera and Retina —> outer to inner: S C R
It FEEDS the retina
Visible portion is IRIS
Anterior portion is the SCLERA
Visual acuity is highest at the ____ where light is focused at the _____
Macula, fovea
The ____ connects the choroid with the iris
Ciliary body
State if the effect is produced by increased, or decreased inhibition:
- ) On center, off surround
- ) Off center, on surround
- ) Decreased inhibition (produces excitation)
2. ) Increased inhibition
Contraction or relaxation of the ciliary muscle increases focal length? Makes it thicker?
Relaxation increases focal length
Contraction makes it thicker
For near vision, ciliary muscle should be _____
For far vision, muscle should be ______
Contracted (thicken)
Relaxed (tighten/flatten)
The macula gets blood from the
Choroid
In the fovea, there are only ____
Cones = high acuity, low sensitivity (better at seeing in light)
Aqueous humor drains in anterior chamber into the ____
Canal of Schlemm
What prevents internal reflections?
Brown melanin
Name layers of retina from inner to outer
Photoreceptor (rod or cone) Horizontal cell Bipolar cell Amacrine cell Ganglion
Why is there a blind spot?
No cones or rods on optic disc
What is far sighted? How to fix?
Near sighted?
Light focused behind retina. Correct with convex lens
Light focused in front of retina. Correct with concave lens.
Photoreceptors directly synapse on
Bipolar cells.
_____ are mixes of ON and OFF signals.
Amacrine cells.
In smooth muscle, calcium binds to ____, which regulates _____.
Calmodulin, myosin light chain kinase
In smooth muscle, no _____ = no actin myosin binding
MLC kinase
_____ and _____ inhibit smooth muscle contraction when _____ is low by binding to ______ to inhibit ______
Calponin and caldesmon inhibit smooth muscle contraction when calcium is low by binding to actin to inhibit myosin ATPase.
Name the three ways to start smooth muscle contraction. They all increase _____.
They all increase calcium by opening SR
- ) Action potential from outside voltage
- ) Ligand gated (from outside)
- ) IP3 opens SR
Give steps of smooth muscle activation
Depole or IPs or Ligand opens SR –> Calcium increases in cell –> Calcium activates calmodulin –> Calmodulin increases MLC kinase
How to diagnose MS
MRI shows plaques around brain and spinal cord
What is the strongest muscle in the 1.) Male 2.) Female
1.) male: Masseter 2.) Female: Uterus
What is the best initial test for myasthenia gravis?
What is the most accurate test?
What is the best initial therapy?
Ach receptor antibodies
Electromyography
Ach inhibitors (alpha 2) to bump up neurotransmitter transmission
Thymectomy if under 60, and immune suppresive meds help
What is myasthenia gravis?
An autoimmune disease that attacks Ach receptors at the NMJ. Antibodies can pass the disease.
10-20% of pts do not have antibodies to Ach receptors
40-70% have muscle specific receptor tyrosine kinase MuSK
What does botulism do? Treatment?
Blocks release of Ach from presynaptic terminal. Death from respiratory failure.
Where do odors bind?
Ciliary receptors on olfactory receptor cells
Fracture of the ____ severs olfactory neurons
Cribiform plate
What gives rise to olfactory receptor cells?
Basal cells.
Give steps to olfactory transduction
Odorant binds to receptor protein Proteins activate Golf Golf activates adenylyl cyclase adenylyl cyclase converts ATP to cAMP cAMP opens Na channels Receptor cell depolarizes AP propagates toward bulb
Which olfactory cells project to higher levels in the brain?
Mitral cells
the 3 semicircular canals contain…
What fills all of the vestibular canals/organs?
An ampula with hair cells covered by cupula
Endolymph
How are the rings of the semicircular canal oriented. Why?
Right angles. Curved to detect angular acceleration.
How does your body detect head spinning? Which direction does fluid travel in relation to your head?
Endolymph stays (lags) and pushes cupula to top of hair cells. Opposite of rotation
What are the mechanoreceptors in the Ampula, Saccule, and utricle? How are they activated?
Kinocilia. Activated (depolarized) when stereocilia move closer (short move closer to large). Moving away is HYPERPOLARIZATION.
- ) ___ provide weight (inertia) for movement.
- ) __ detect linear and vertical acceleration, NOT VELOCITY
- ) _____ detect horizontal movement
- ) Otoliths, head moves but STONES STAY IN PLACE
- ) Saccule
- ) Utricle
What causes benign positional vertigo? How to treat?
immobile otoliths. NO SYMPTOMS WHEN LYING FLAT.
Treat by stopping endolymph production! MECLIZINE
How to treat Meniere’s
Salt restriction and diuretics
What is the dx if you cant directionalize sound?
Perilymph fistula from loud explosion
What is SIADH?
Syndrome of Inappropriate Antidiuretic Hormone: When a person secretes inappropriately high levels of antidiuretic hormone, WHICH PROMOTES WATER REABSORPTION IN THE COLLECTING DUCTS.
