Cardiovascular Lecture

Question 1

Description of heart

Answer 1

4 chambered muscular pump circulating blood throughout the body

Question 2

Location of heart

Answer 2

enclosed within a tough fibrous connective tissue sac (fibrous pericardium) inside the mediastinum (connective tissue partition separating thoracic cavity into right and left halves)

Question 3

Regions of heart

Answer 3

Base and apex

Question 4

• Base

Answer 4

–> top of the heart where the large vessels enter and exit

Question 5

• Apex

Answer 5

bottom of the heart, formed by left ventricle

Question 6

Chambers

Answer 6

• Atria
  o Blood receiving chambers
  o Auricle
• Ventricles
  o Blood expulsion chambers
  o Papillary muscles

Question 7

Partitions

Answer 7

• Interatrial septum –> thin wall of cardiac muscle separating right and left atria
• Interventricular septum –> thick wall of cardiac muscle separating R and L ventricles

Question 8

Composition of cardiac skeleton

Answer 8

fibrous rings, fibrous trigone, membranous portion

Question 9

Location of cardiac skeleton

Answer 9

– within the myocardium
- Fibrous rings line interior of the right and left AV, pulmonary, and aortic ostia
- Trigone (triangular mass) located within the base of heart between fibrous rings, ascending aorta, and the pulmonary trunk
- Membranous portion extends as a sheet within the interventricular septum for a short distance

Question 10

Function of cardiac skeleton

Answer 10

– provides independent site of attachment for atrial and ventricular myocardium. Prevents free-flow of electrical impulses between atria and ventricles, provides attachments for fixed portions of heart valves

Question 11

• Specialized cardiac cells and fibers

Answer 11

self-excitable

Question 12

• Sinoatrial (SA) node

Answer 12

collection of cells located near the junction of superior (cranial) vena cava and right atrium

Question 13

SA node function

Answer 13

referred to as the “pacemaker” because it initiated and maintains
heartbeat. Has the fastest rate of depolarization/repolarization of electrical
conduction system. Maintains a rate of 60-100 beats/min. Supplied by
postganglionic parasympathetic and sympathetic stimulation

Question 14

• Atrioventricular (AV) node

Answer 14

collection of cells located in the wall of the right atrium near the base of the interatrial septum

Question 15

AV node function

Answer 15

second fastest rate of depolarization/repolarization. Can take over for
SA node if needed. Maintains rate of approx. 50 beats/min. Supplied by
postganglionic parasympathetic and sympathetic stimulation.

Question 16

Atrioventricular bundle (bundle of his)

Answer 16

consists of AV node and fibers projecting from it. Fibers pass into the interventricular septum a short distance before splitting into right and left bundle branches. Bundle branches descend to the midway point of the septum, then give ruse to Purkinje fibers.

Question 17

• Purkinje cells and fibers

Answer 17

Descend to the apex of the heart, then turn to course upward through the outer ventricular walls

Question 18

Purkinje cells and fibers function

Answer 18

cells and nuclei are larger than myocardial cells. Contain more
glycogen, making them more resistant to hypoxia than myocardial cells. Can take
over for AV node if needed. Maintains rate of 30-40 beats/min

Question 19

Valves

Answer 19

sheet-like extensions of fibrous connective tissue covered by endocardium

Question 20

What are the 4 valves?

Answer 20

Tricuspid valve
Pulmonary valve
Mitral valve
Aortic valve

Question 21

• tricuspid valve

Answer 21

located between the right atrium and the right ventricle.

Question 22

• pulmonary valve

Answer 22

located between the right ventricle and the pulmonary artery.

Question 23

• mitral valve

Answer 23

located between the left atrium and the left ventricle

Question 24

• aortic valve

Answer 24

located between the left ventricle and the aorta.

Question 25

Function of heart valves

Answer 25

The valves prevent the backward flow of blood. These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one-way inlets of blood on one side of a ventricle and one-way outlets of blood on the other side of a ventricle.

Question 26

Heart cycle

Answer 26

Systole and Diastole

Question 27

Systole

Answer 27

- Contraction phase of the cardiac cycle - Atria contract in unison - Ventricles contract in unison

Question 28

Diastole

Answer 28

- Relaxation phase of cardiac cycle - Atria relax in unison - Ventricles relax in unison

Question 29

Complete heartbeat (cardiac cycle

Answer 29

timing: takes about 0.8 seconds Phase 1 --> 0.1 sec = atria contract. Ventricles relax. AV valves are open. Pulmonary and aortic valves are closed Phase 2 --> 0.3 sec = atria relax. Ventricles contract. All valves closed for the first part. Pulmonary and aortic valves open for the latter part Phase 3 --> 0.4 sec = quiescent period. Relaxation of all chambers. All valves closed during first part. AV open during latter part.

Question 30

Endocardium

Answer 30

- Innermost layer of the heart consisting of a serous membrane - Adhered to the deep surface of the myocardium - Has some elastic fibers to accommodate movement of the heart

Question 31

Myocardium

Answer 31

- Middle layer of the heart - Composed of cardiac muscle cells - Varies in thickness depending on location (thinnest at atrial walls; thickest at left ventricular wall)

Question 32

Epicardium (visceral pericardium)

Answer 32

- Outermost layer consisting of a serous membrane (single layer of epithelial cells connected to a basement membrane by a small amount of connective tissue) - Adhered to surface of myocardium

Question 33

Explain how blood flows through the heart.

Answer 33

Question 34

Arteries

Answer 34

distribute oxygen-rich blood to your body. Arteries, part of your circulatory (cardiovascular) system, are the blood vessels that bring oxygen-rich blood from your heart to all of your body's cells. They play a crucial role in distributing oxygen, nutrients and hormones throughout your body.

Question 35

Elastic arteries

Answer 35

(larger) o Relatively thick tunica intima o Flat, elongated endothelial cells o Collagenous and elastic fibers, smooth muscle cells in subendothelial layer o Inconspicuous internal elastic membrane o Tunica media is thick with multiple layers of elastic, and smooth muscle cells

Question 36

Muscular arteries

Answer 36

(medium) o Thinner tunica intima than elastic arteries o Sparse endothelial layer o Prominent and wavy internal elastic membrane o Tunica media is nearly all smooth muscle

Question 37

Small arteries

Answer 37

o Endothelial cell layer and basal lamina o More than 2 smooth muscle layers o External elastic membrane is often distinct o Typical tunica adventitia

Question 38

Arterioles

Answer 38

- Endothelial cell layer - 1-2 smooth muscle layers - Tunica adventitia - Regulate blood flow to capillaries

Question 39

Capillaries

Answer 39

--> Capillaries are delicate blood vessels that exist throughout your body. They transport blood, nutrients and oxygen to cells in your organs and body systems. Capillaries are the smallest blood vessels in your vascular system. - Single endothelial cell layer and basal lamina - RBCs pass through one at a time - Efficient at exchange of gases and metabolites

Question 40

Venules

Answer 40

are the smallest veins and receive blood from capillaries. They also play a role in the exchange of oxygen and nutrients for water products. There are post-capillary sphincters located between the capillaries and venules

Question 41

Veins

Answer 41

have two main purposes. One purpose is to collect oxygen-poor blood throughout your body and carry it back to your heart. The other purpose is to carry oxygen-rich blood from your lungs to your heart.

Question 42

Lymphatic vessels

Answer 42

are the network of capillaries (microvessels) and a large network of tubes located throughout your body that transport lymph away from tissues. Lymphatic vessels collect and filter lymph (at the nodes) as it continues to move toward larger vessels called collecting ducts.

Question 43

Describe how tissue fluid is formed at capillary beds, then collected and returned to the venous system by the lymphatic system.

Answer 43

Tissue fluid is formed at the arteriole end of the capillary where there is large hydrostatic pressure from the left ventricle of the heart. This hydrostatic pressure within the capillary is greater than the pressure in the fluid surrounding the capillaries, therefore forcing the fluid out of the capillaries. Most of the lymphatic vessels have valves like those in veins to keep the lymph, which can clot, flowing in the one direction (toward the heart). Lymphatic vessels drain fluid called lymph from tissues throughout the body and return the fluid to the venous system through two collecting ducts.