Circulation of Blood

Question 1

What are the four chambers of the heart?

Answer 1

Right and left atrium

Right and left ventricles

Question 2

Which components of the heart supply the pulmonary circulation?
What is the normal path of blood through the pulmonary circulation?

Answer 2

• The R atrium and Ventricle pump blood into the pulmonary trunk and artery into the lungs and pulmonary circulation
• Pulmonary trunk to pulmonary arteries to lung capillaries to pulmonary veins to L atrium

Question 3

Which part of the heart supplies the systemic circulation?
How does the structure of the L ventricle differ from the R?
What is the normal route of blood through the systemic circulation?

Answer 3

• the L atrium and ventricle pump blood into the aorta to the systemic circulation
• the L ventricle is thicker than the R
• Blood returns from pulmonary circulation to L atrium through Mitral valve to L ventricle up through aortic valve into aorta then to Large and small arteries then into arterioles then capillaries picked up by venues then to veins and through the vena cavae to the R atrium

Question 4

What are the component parts of the microcirculation?

Answer 4

Arterioles, Precapillary sphincters, capillaries, venules

Question 5

Describe the structure and function of the 4 component parts of the microcirculation.

Answer 5

• arterioles- small diameter muscular walled arteries
• precapillary sphincters- rings of smooth muscle, control entry of blood from arteriole into each capillary
• capillaries- smallest diameter blood vessel single tube one cell thick of flattened endothelial cells, allows for exchange of nutrients and waste between cells
• venules- smallest diameter vessels that drain blood back to the larger true veins

Question 6

Explain how the Parallel arrangement of blood supplies to different organs allows independent regulation of blood flow.

Answer 6

Arranged like a parallel circuit with branches to each organ system.
Where resistance is lowest (largest diameter of vessels) blood flow is greatest. Allows adaptation to metabolic demands of tissue.

Question 7

Explain how valves open and close.

What is their function?

Answer 7

• They open and close passively due to pressure differences between the different chambers
• they prevent back flow of blood

Question 8

What are the Atrioventricular valves?
Where are they found?
What is their structure?

Answer 8

-The tricuspid valve and the Mitral (Bicuspid) valve
-tricuspid is between R atrium and Ventricle
Mitral is between L atrium and Ventricle
- Tricuspid is three papillary muscles attached by chordae tendineae
Mitral is 2 papillary muscles attached by chordae tendineae

Question 9

What are the 2 semilunar valves?
How do the semilunar valves differ from AV valves?
How is this difference clinically relevant?

Answer 9

-the pulmonary valve between R ventricle and pulmonary trunk
the aortic valve between L ventricle and the Aorta
-More heavy duty, smaller openings and have to withstand higher pressure from the ventricles pumping blood into pulmonary and systemic circulations
-The valves experience more stress and in the long term can become a point of failure in the heart leading to valve incompetence

Question 10

How is cardiac muscle similar to skeletal muscle?

Answer 10

has thick myosin filaments and thin actin filaments

striated

Question 11

Discuss the special features of myocardial cells.

Answer 11

Cells are connected by desmosomes at the intercalated disks

At each disk membranes fuse forming a permeable communicating junction= Gap junction

Question 12

Discuss the term Syncytium and how Gap Junctions play a role.

Answer 12

ions move with ease in the intracellular fluid connecting cardiac cells
action potentials travel easily from one cardiac cell to another
cardiac cells are interconnected so when one cell is excited the AP spreads to all of them