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Histology > Cardiovascular Lecture > Flashcards

Cardiovascular Lecture Flashcards

1
Q

Description of heart

A

4 chambered muscular pump circulating blood throughout the body

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2
Q

Location of heart

A

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

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3
Q

Regions of heart

A

Base and apex

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4
Q
  • Base
A

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

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5
Q
  • Apex
A

bottom of the heart, formed by left ventricle

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6
Q

Chambers

A
  • Atria
    o Blood receiving chambers
    o Auricle
  • Ventricles
    o Blood expulsion chambers
    o Papillary muscles
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7
Q

Partitions

A
  • Interatrial septum –> thin wall of cardiac muscle separating right and left atria
  • Interventricular septum –> thick wall of cardiac muscle separating R and L ventricles
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8
Q

Composition of cardiac skeleton

A

fibrous rings, fibrous trigone, membranous portion

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9
Q

Location of cardiac skeleton

A

– 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

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10
Q

Function of cardiac skeleton

A

– 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

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11
Q
  • Specialized cardiac cells and fibers
A

self-excitable

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12
Q
  • Sinoatrial (SA) node
A

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

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13
Q

SA node function

A

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

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14
Q
  • Atrioventricular (AV) node
A

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

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15
Q

AV node function

A

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.

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16
Q

Atrioventricular bundle (bundle of his)

A

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.

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17
Q
  • Purkinje cells and fibers
A

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

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18
Q

Purkinje cells and fibers function

A

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

19
Q

Valves

A

sheet-like extensions of fibrous connective tissue covered by endocardium

20
Q

What are the 4 valves?

A

Tricuspid valve
Pulmonary valve
Mitral valve
Aortic valve

21
Q
  • tricuspid valve
A

located between the right atrium and the right ventricle.

22
Q
  • pulmonary valve
A

located between the right ventricle and the pulmonary artery.

23
Q
  • mitral valve
A

located between the left atrium and the left ventricle

24
Q
  • aortic valve
A

located between the left ventricle and the aorta.

25
Q

Function of heart valves

A

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.

26
Q

Heart cycle

A

Systole and Diastole

27
Q

Systole

A
  • Contraction phase of the cardiac cycle
  • Atria contract in unison
  • Ventricles contract in unison
28
Q

Diastole

A
  • Relaxation phase of cardiac cycle
  • Atria relax in unison
  • Ventricles relax in unison
29
Q

Complete heartbeat (cardiac cycle

A

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.

30
Q

Endocardium

A
  • 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
31
Q

Myocardium

A
  • 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)
32
Q

Epicardium (visceral pericardium)

A
  • 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
33
Q

Explain how blood flows through the heart.

A
34
Q

Arteries

A

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.

35
Q

Elastic arteries

A

(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

36
Q

Muscular arteries

A

(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

37
Q

Small arteries

A

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

38
Q

Arterioles

A
  • Endothelial cell layer
  • 1-2 smooth muscle layers
  • Tunica adventitia
  • Regulate blood flow to capillaries
39
Q

Capillaries

A

–> 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
40
Q

Venules

A

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

41
Q

Veins

A

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.

42
Q

Lymphatic vessels

A

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.

43
Q

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

A

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.

Histology (15 decks)

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