LQB185 Chapter Notes - Chapter 20: Heart Valve, Papillary Muscle, Pulmonary Circulation

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20.2 Heart Valves and Circulation of Blood

➢ As each chamber of the heart contracts, it pushes a volume of blood into

a ventricle or out of the heart into an artery.

➢ Valves open and close in response to pressure changes as the heart

contracts and relaxes.

➢ Operation of the Atrioventricular Valves (AV)

- Tricuspid and Bicuspid valves make up the atrioventricular valves

- When the AV is open the rounded ends of the cusps project into

the ventricle (inwardly sucked onwards). Subsequently the

ventricles are relaxed, the papillary muscles are relaxed making

the chordae tendinous go slack and blood moves from a higher

pressure in the atria to a lower pressure in the ventricles

- When ventricles contract, the pressure of the blood drives the

cusps upward until their edges meet and close the opening. At

the same time the papillary muscles contract which pulls on and

tightens the chordae tendinous. This prevents the valve cusps

from everting (opening).

➢ Operation of the Semilunar Valves (SL)

- Aortic and Pulmonary valves make up the Semilunar valves

- Each oes cusps are split ito  flaps. The AV ol hae  flaps

- SL valves allow ejection of blood from the heart into arteries but

prevent backflow of blood into ventricles.

- Cusps project into the lumen of the artery

- When ventricles contract, pressure builds inside chamber thus

stimulating the valves to open.

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- When the ventricles relax, blood starts to backflow toward heart.

Blood fills the valve cusps causing the free edges of the SL to

contract and close entry.

➢ Systemic and Pulmonary Circulations

- Input of one becomes the output of the other

- Left side of the heart is the pump for systemic circulation:

receives red oxygenated blood from the lungs.

- Right side of the heart is the pumps for pulmonary circulation:

receives all the dark-red deoxygenated blood returning from the

systemic circulation.

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➢ Coronary Circulation

- Nutrients are not able to diffuse in the heart.

- The Myocardium has its own network of blood vessels (the

Coronary circulation).

- Coronary Arteries branch from the ascending aorta and encircle

the heart

- When heart is contracting, blood flows in the coronary arteries is

squeezed shut then when the heart relaxes the high pressure of

blood propels blood through the coronary arteries, into capillaries

and into coronary veins.

➢ Coronary Arteries

- Left and right arteries branch from the ascending aorta and supply

oxygenated blood to the myocardium.

- Left supples anterior interventricular branch

- Right supples posterior interventricular branch

➢ Coronary Veins

- Blood -> arteries of the coronary circulation -> capillaries (delivers

oxygen and nutrients to heart muscles and collects carbon dioxide

and waste) -> coronary veins.

- Deoxygenated blood from myocardium drains into the Coronary

Sinus -> empties into the right atrium.

- Carrying blood into the coronary sinus are:

1. Great cardiac vein

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Document Summary

As each chamber of the heart contracts, it pushes a volume of blood into a ventricle or out of the heart into an artery. Valves open and close in response to pressure changes as the heart contracts and relaxes. Tricuspid and bicuspid valves make up the atrioventricular valves. When the av is open the rounded ends of the cusps project into the ventricle (inwardly sucked onwards). Subsequently the ventricles are relaxed, the papillary muscles are relaxed making the chordae tendinous go slack and blood moves from a higher pressure in the atria to a lower pressure in the ventricles. When ventricles contract, the pressure of the blood drives the cusps upward until their edges meet and close the opening. At the same time the papillary muscles contract which pulls on and tightens the chordae tendinous. This prevents the valve cusps from everting (opening). Aortic and pulmonary valves make up the semilunar valves. Each o(cid:374)e(cid:859)s cusps are split i(cid:374)to (cid:1007) flaps.

Related Questions

1) The external layer of the heart wall is the

Multiple Choice

endocardium.

myocardium.

epicardium.

parietal pericardium.

2) Check all that are characteristics of cardiac muscle.

Check All That Apply

Cells are long and cylindrical.

Cells are short and branching.

Cells have multiple nuclei at the periphery of the cell.

Cells have one or two nuclei in the center of the cell.

They are composed of thick and thin filaments.

The functional contractile unit is the sarcomere.

3) Match the chamber of the heart with the structure(s) from which it receives blood.

Coronary sinus

Pulmonary veins

Right atrium

Left atrium

Match each of the options above to the items below.

Right atrium

Right atrium Open choices for matching

Right ventricle

Right ventricle Open choices for matching

Left atrium

Left atrium Open choices for matching

Left ventricle

4) The less extensive distribution of T-tubules contributes to the more delayed onset and prolonged contraction of cardiac muscle tissue compared to skeletal muscle tissue.

True or False

5) The cells of the ___________ act as the heart's pacemaker, which establishes the pace for cardiac activity.

Multiple Choice

atrioventricular (AV) node

sinoatrial (SA) node

atrioventricular (AV) bundle

Purkinje cells

6) Match the cardiac vein with its description.

Travels close to the right marginal artery

In posterior interventricular sulcus

In anterior interventricular sulcus

In the posterior portion of cornary sulcus

Match each of the options above to the items below.

Great cardiac vein

Great cardiac vein Open choices for matching

Middle cardiac vein

Middle cardiac vein Open choices for matching

Small cardiac vein

Small cardiac vein Open choices for matching

Coronary sinus

7) Parasympathetic innervation to the heart comes from the medulla oblongata via the left and right ___________ nerves.

8) Check all that are components of the sympathetic innervation of the heart.

Check All That Apply

Cervical sympathetic ganglionCervical sympathetic ganglion

Spinal cordSpinal cord

Vagus nerve (CN X)Vagus nerve (CN X)

Cardiac nerveCardiac nerve

Sympathetic postganglionic axon

9) Check all that occur during ventricular contraction.

Check All That Apply

The AV valves open to allow blood to enter the ventricles from the atria.The AV valves open to allow blood to enter the ventricles from the atria.

The semilunar valves remain closed to prevent backflow of blood into the ventricles.The semilunar valves remain closed to prevent backflow of blood into the ventricles.

The semilunar valves open to allow blood to flow into the large arteries.The semilunar valves open to allow blood to flow into the large arteries.

The AV valves close to prevent backflow of blood into the atria.

1. Which of the following is the correct sequence of bloodflow?

a. heart --> atery --> arteriole --> capillary -->vein --> venule --> heart

b. heart --> vein --> venule --> capillary -->arteriole --> artery --> heart

c. heart --> artery --> arteriole --> capillary -->venule --> vein --> heart

d. heart --> artery --> venule --> capillary -->arteriole --> vein --> heart

e. heart--> artery --> capillary --> arteriole -->venule --> vein --> heart

2. What are the functions of the elastic fibers that are foundin the walls of ateries? (there may be more than one answer)

Select one or more:

a. they allow the artery to stretch and then recoil back to itsoriginal shape as blood is forcegully pumped from the heart intothe arteries

b. they allow arteries to lengthen as the volume of blood in thearteries increase

c. they help maintain a steady blood pressure during thedifferent phases of heart contraction

d. they smooth out the walls of the arteries to preventturbulent blood flow

3. Which of the following are functions of the lymphatic system?(there may be more than one answer)

Select one or more:

a. help fight infections and cancer

b. allows excess interstitial fluid (fluid found between thecells in your tissues) to get dumped back into your blood

c. brings large molecules from fat digestion into thebloodstream so that they can be processed and stored

d. all of the above are functions of the lymphatic system

4. Which of the following blood vessels bring newly oxygenatedblood from the blood vessels in the lungs back to the heart so thatthe heart can pump it to the rest of the body?

Select one:

a. aorta

b. inferior vena cava

c. pulmonary vein

d. pulmonary artery

5. Which of the following mechanisms help blood fight gravity sothat, for instance, it can return from blood vessels in your feetback into your heart? (there may be more than one answer)

Select one or more:

a. breathing allows the pressure in your chest to decrease andallow blood to flow up towards your heart

b. as you walk, the skeletal muscles in your legs contract andsqueeze the veins; since veins have valves, blood flows up anddoesn't backflow back down

c. the force of blood flowing out of the heart and into thearteries pushes all of the blood along, causing blood to return tothe heart

d. precapillary sphincters open to allow blood to flow backtowards the heart

6. The tricuspid and bicuspid/mitral valves prevent backflow ofblood from the atria into the ventricles.

Select one:

True

False

7. The following sequence represents the correct order of bloodflow through the heart:

inferior and superior vena cava --> right atrium --> rightventricle --> pulmonary artery --> lungs --> pulmonaryvein --> left atrium --> left ventricle --> aorta

Select one:

True

False

8. Capillaries are as wide as one red blood cell.

Select one:

True

False

9. The purpose of the coronary arteries is to bring oxygenatedblood to the walls of the heart so that the muscles in the heartwalls can contract.

Select one:

True

False

10. Vasodilation refers to the narrowing of blood vessels.

Select one:

True

False

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LQB185 Chapter Notes - Chapter 20: Heart Valve, Papillary Muscle, Pulmonary Circulation

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