Bio 163 Exam 2

which part of the conduction system is responsible for atrial systole?

SA node

when considering SA node cells, what event is occurring right before the cells reach threshold?

sodium is leaking into the cells

the closure of which valves produces the second heart sound?

pulmonary and aortic semilunar valves

Endurance athletes typically have lower resting heart rates compared to non-athletes, even though both bodies require the same cardiac output. When an endurance athlete trains, one of the results is increasing the amount of proteins in cardiac muscle cells, resulting in stronger contractions. Considering cardiac output, how does the athlete’s stroke volume compare to the non-athlete’s?

the athlete has a larger stroke volume

Skeletal muscle sarcomeres tend to have an **optimal** resting length while cardiac muscle sarcomeres tend to have a **shorter than optimal** resting length (see arrow). What will happen to the sarcomere length as the heart fills (stretches) with blood?

sarcomeres reach optimal length

what will happen to the amount of tension (y-axis) generated by the sarcomere as EDV increases in the heart

tension will increase (stronger contraction)

Rigorous exercise results in more blood returning to the heart (rather than pooling in vessels). This contributes to higher EDV. If a person has an EDV of 300 mL, what is the resulting stroke volume?

150 mL

A patient with normal baseline contractility of the heart has an EDV of 60 mL. He is treated with the positive inotropic agent *dopamine*. What is his new SV?

47 mL

After recovering and returning to normal contractility, this same patient with a baseline EDV of 60 mL is treated with the negative inotropic agent *acetylcholine*. What is his new SV?

18 mL

The EDV of two female patents of similar body mass and height is measured. Patient 1 has and EDV of 110 mL. Patient 2 has an EDV of 85 mL. Both patient shave an equal ESV. Which patient has a larger stroke volume?

Patient 1

The EDV of two female patents of similar body mass and height is measured. Patient 1 has and EDV of 110 mL. Patient 2 has an EDV of 85 mL. Both patient shave an equal ESV. Which patient has more cross-bridges between thick and thin filaments in the cardiac sarcomeres prior to ventricular systole?

Patient 1

Efferent neurons activated b the cardioaccelatory center are ____ neurons of the sympathetic system.

visceral motor

Which of the following neurotransmitters do preganglionic sympathetic fibers use to communicate with sympathetic ganglia?

a. acetylcholine

b. norepinephrine

c. dopamine

d. glucose

acetylcholine

Blood vessels are lined by endothelial cells. What type of tissue are these cells?

epithelial

Which of the two vessels on this slide is an artery?

B

Which type of artery can withstand the highest pressure?

a. elastic

b. arteriole

c. muscular

a. elastic

In general, where are arterioles located?

close to the capillary beds

which order of capillaries represents least permeable to most permeable?

continuous → fenestrated → sinusoidal

What types of molecules travel through the endothelial cells of capillaries without the help of membrane proteins?

CO2

Patients on dialysis for kidney failure need reliable vascular access for 4 hours, 3 days a week. The walls of veins are normally too thick to be punctured repeatedly with large-bore needles, so an AV fistula procedure is often performed, in which an artery in the forearm is diverted and directly attached to a vein. The vein then thickens over time, making it appropriate for repeated needle sticks. An AV fistula is an example of a(n) **__**.

anastamsis

what is an anastamosis?

a __cross-connection__ between adjacent channels, tubes, __fibers__, or other parts of a network

A patient visits a physician for a second opinion about a diagnosed heart murmur affecting the right AV valve. Heart murmurs can be caused by valve prolapse (the valve turns inside out). Which of the following findings would most likely be present if one of the AV valves was damaged?

a murmur during the first heart sound

which set of neurons represents sensory input to the cardiovascular control centers?

1 (green neurons)

are the green neurons visceral or somatic sensory input?

visceral

if blood pressure starts to decrease, baroreceptors will _____ their rate of firing action potentials to the brain

decrease

The red visceral motor neuron (2) results in the secretion of acetylcholine. The blue neurons (3) result in the secretion of norepinephrine. Which is part of the parasympathetic nervous system?

red

When do baroreceptors increase their action potentials?

elevated blood pressure

What is the response to elevated sensory input?

decreased cardiac output

Which of the following situations will result in the release of acetylcholine from postganglionic visceral motor neurons associated with the heart?

a. a decrease of action potentials from baroreceptors during rest

b. a decrease in arterial blood pressure

c. an increase of action potentials from baroreceptors during rest

b. being attacked by a lion

c. an increase of action potentials from baroreceptors during rest

In a particular tissue there is more solute in capillaries compared to the surrounding tissue. Which way will the water diffuse due to this osmotic pressure?

from the tissue into the capillary

What do you observe about blood hydrostatic pressure across a capillary bed (green box)

it starts high then drops

The majority of capillaries (continuous and fenestrated) are leaky (see arrows above) - fluid can exit and enter. This is based on pressure gradients (including osmotic pressure). At a capillary bed, if the pressure in that part of the capillary is greater than the pressure in the tissue, which way will fluid move?

into the tissue

Capillary hydrostatic pressure is 32 mmHg, interstitial fluid hydrostatic pressure is 1 mmHg capillary osmotic pressure is 25 mmHg, and interstitial fluid osmotic pressure is 2 mmHg. Calculate the net filtration pressure

8 mmHg

*Wuchereria bancrofti* is a tropical, parasitic worm that lives in lymphatic vessels and causes their blockage as the parasite grows. What is one result of this infection?

retention of fluid in tissues

Where is pressure the highest?lowest during ventricular ejection

higher in the ventricles compared to the atria and arteries, and atrial pressure is lower than the veins

What is the pressure gradient during atrial systole?

pressure is higher in the atria compared to the ventricles

What occurs during atrial systole

the SA node is depolarized and causes the atria to contract, forcing blood into the ventricles

What is the second phase of the cardiac cycle?

atrial systole

Where is pressure the highest during the quiescent period?

pressure is highest in the vessels compared to the chambers

What occurs during the quiescent period?

The chambers are in diastole, and (both) are filling with blood. SA nodes are depolarizing

_____ path are associated with heart rate

visceral motor

what do chemoreceptors do?

sense chemical changes (carbon dioxide or O2 level) in the blood and inform the brain centers

What do baroreceptors do?

sense physical sensory changes (pressure and arterial wall stretch) and informs the brain center

what do proprioreceptors do?

receives sensory input from the muscles/tendons and informs the brain on changes in physical activity

What do the cardioinhibitory neurons secret?

acetylcholine (think parasympathetic)

Interneurons of the cardioinhibitory center will _____ heart rate

decrease

the cardioaccelatory center neuron secrete what?

Norepinephrine (think sympathetic)

What is the main function of the semilunar (aortic and pulmonary) valves?

to prevent back flow from the arteries back into the ventricles during isovolumetric relaxation

what does the T wave represent?

isovolumetric relaxation

what does the ST segment represent

ventricular ejection

what does the QRS complex represent?

isovolumetric contraction

what’s the average heart rate

about 75 bpm

True or false:

During the quiescent period, blood is only passively filling the atria

false: the ventricles are also passively being filled

which stage of the cardiac cycle helps to fill ventricles to the maximum blood volume?

atrial systole

True or False:

In the heart, blood will flow from areas of high pressure to areas of low pressure

true

how does the body maintain blood pressure at rest?

Sensory input must be gathered and CNS must integrate that input. Then it will send a motor output to negate any changes away from homeostasis

What are the three main variables that affect blood pressure

* cardiac output
* resistance of vessels
* blood volume

what is Mean Arterial Pressure

the average pressure of the vessels leaving the heart

diastolic pressure

the pressure during ventricular relaxation

systolic pressure

pressure during ventricular contraction

What is blood pressure

the force blood exerts on the arterial wall

what are the two exceptions to the “normal” blood flow?

a portal system or anastomosis

what is a portal system?

when blood vessels travel to two capillary beds before Turing to the heart

what is anastomosis?

alternate blood route to bypass a capillary or vessels converging to the same location

what is the “normal” flow of blood

heart → artery → capillary and gas exchange → vein → heart

what are varicose veins?

when blood pours into the veins of lower limbs and causes veins to stretch

what’s the respiratory pump?

when the pressure from respiration forces blood through the vessels

what’s the muscular pump?

when veins rely on compression from nearby muscles to push blood

what are back flow valves?

folds of the tunica intima that ensure one day flow of the blood toward the heart

reabsorption

net movement of water into capillaries

filtration

net movement out of capillaries

what occurs during ventricular ejection?

the ventricles fully contract while the atria are in systole. Blood is forced into the arteries, and atria are passively being filled w blood

what is phase 4 of the cardiac cycle called?

ventricular ejection

systole

contraction

diastole

relaxation

pressure gradient is the difference in what?

the difference between the pressures of two regions (p1-p2)

pressure depends on the ____ of the space it occupies

volume

what are veins and the different types

vessels that deliver blood to the heart

types are:

* large veins
* small veins
* venules

what is phase 1 of the cardiac cycle called?

the quiescent period

what is the cardiac cycle?

one complete contraction and relaxation

If baroreceptors send more action potentials to the brain than normal the brain interprets that as _____ pressure

high

where are the dendrites of baroreceptors located?

the carotid sinuses and aortic arch

what’s the structural class of baroreceptors?

unipolar

what’s the function classification of baroreceptors?

visceral sensory

True or False:

baroreceptors send action potentials to the brain

true

True or False:

an increase in cardiac output will help to raise blood pressure

true

what events are considered visceral motor actions

the release of acetylcholine from cardioinhibitory neurons and neurons stimulating the release of epinephrine and norepinephrine

what’s the stimulus that causes the depolarization of baroreceptors?

the stretch of the arterial walls triggering mechanically gated channels in the membrane

increasing heart rate is a ______ response

sympathetic

parasympathetic visceral motor response

occurs when blood pressure is too high and causes a decrease in HR and vasodilation

sympathetic visceral motor response

occurs when blood pressure is too low, causes and increased heart rate and vasocontriction

interneurons of the cardioaccelatory center will ______ heart rate

increase

what are the cardiovascular control centers

cardioaccelatory and inhibitory centers

vasomotor center

what is a center?

a collection of interneurons that receive sensory input and create a motor output to alter that function

visceral motor responses are initiated from interneurons in “ _______”

brain centers

what does the P wave represent?

atrial systole

what do positive inotropic agents do?

increase contractility

where is pressure the highest/lowest during isovolumetric contraction

pressure on the aorta/pulmonary arteries are still greater than the ventricles

what occurs during isovolumetric contraction?

atria are in diastole, and the ventricles begin to depolarize/contract

what is phase 3 of the cardiac cycle called?

isovolumetric contraction