Histology

Question 1

Endocardium

Answer 1

Internal lining of the heart chambers

Consist of three types of cells

• endothelium (closest to the chambers)
• fibroelastic CT
• subendocardium (closest to the surface of the heart)

Question 2

Myocardium

Answer 2

Middle layer of tissues comprised primarily of contractile cardiac myocytes
- actually does the contracting of the heart

Question 3

Epicardium

Answer 3

External layer of the heart and consists of two layers

• subpericardium: areolar and adipose CT supporting the coronary arteries/veins/nerves/lymph vessels to the heart.
• visceral pericardium: mesothelium layer that produces a lubricating serous fluid contained within the pericardial cavity.

Question 4

Heart murmur

Answer 4

Regurgitation of blood through a prolapsed valve

Question 5

Stenosis

Answer 5

Narrowing of a valve through scar tissue of plaque buildup

Question 6

Ischemia

Answer 6

Reduction and/or loss of oxygenated blood flow to the tissues due to obstruction of hemorrhages of coronary arteries

Question 7

Angina

Answer 7

Visceral cardiac pain caused from a myocardial ischemia

Question 8

MI (heart attack)

Answer 8

Damage/necrosis of myocardial tissue caused by ischemia

Question 9

Tunica intima

Answer 9

Internal lining of the lumen of the vessel

Consist of endothelium and sub endothelium

Question 10

Tunica media

Answer 10

Middle layer of tissues composed primarily of concentric layers of smooth muscle fibers arranged helically.

Consist of smooth muscle, elastic fibers

Question 11

Tunica externa

Answer 11

External layer of the vessels composed of loose CT

Contain type 1 collagen and elastic fibers

Also contain autonomic nerve fibers (mainly sympathetics)

Question 12

Vasa vasorum

Answer 12

Blood vessel supply of blood to keep the healthy

Primarily only present in larger and medium vessels

Question 13

Functional roles of endothelium

Answer 13

Monitors and mediated the bidirectional exchange of molecules between blood and tissues

Controls local clot formation

Regulates local vascular tone and blood flow

Facilities local inflammation and immune responses

Promotes proliferation of cells within a vascular wall and white blood cells.

Question 14

Blood pressure

Answer 14

Cardiac output x stroke volume + total peripheral resistance

Question 15

Systemic hypertension

Answer 15

High blood pressure Through the systemic circuit. Can be secondary or primary.

Secondary = chronic hypertension via renal or endocrine dysfunctions

Primary = essential or idiopathic chronic hypertension do to environmental/lifestyle factors

Question 16

Aortic dissection

Answer 16

A tear in the tunica intima layer of the aorta that overtime causes complete dissection the aorta if not treated,

Question 17

Cardiac Skelton

Answer 17

Prominent areas of fibrous dense irregular CT found in the endocardium and myocardium

used as landmarks to separate atria from ventricle, form AV valves and the interventricular/ intratrial septa

Functions:

• electrical insulation between atria and ventricles (coordinate heartbeat)
• attachment points for cardiac muscle
• anchors and supports heart valves

Question 18

What valves are chorda tendonae found in?

Answer 18

AV valves (bicuspid/tricuspid)

Question 19

Differences in contractile apparatus in cardiac myocytes vs skeletal muscle myocytes

Answer 19

Cardiac has

• more mitochondria
• less Sarcoplasmic reticulum
• presence of fat

Question 20

Atrial natriuretic peptide/factor

Answer 20

Polypeptide hormones found primarily in the right atrium that decrease blood pressure via initiating vasodilation and antagonize the renin-angiotensin system

Question 21

SA node vs AV node

Answer 21

SA node

• found in the right atria near the SVC
• sets atria pace and is the prime initiator of the contraction

AV node

• found on the floor of the right atria near the septum
• sets the ventricular pace and sends the conduction through the AV bundles

Question 22

Why cant cardiac cells regenerate?

Answer 22

They do not possess satellite cells like skeletal muscles do

Question 23

Layers of blood vessels from deep to superficial

Answer 23

Tunica intima

• endothelium
• subendothelium

Tunica media

Tunica externa (adventitia)

Question 24

Difference in layer of arteries vs veins

Answer 24

Arteries

• no valves
• tunica media is thickest layer of vessel
• small tunica externa

Veins

• valves
• tunica externa (adventitia) is thickest layer of vessel

Question 25

Continuous capillaries

Answer 25

Most common type of capillary bed

Most restrictive with exchange, causes molecules to have to diffuse through transportation

Present in muscles, CT, lungs, exocrine glands, nervous tissue

Overlapping endothelium cells prevent paracellular transport

Very defined basement membrane

Question 26

Fenestrated capillaries

Answer 26

Found in kidneys, intestines, choroid plexus and exocrine glands

Endothelial cells still overlap, however they have numerous small openings with a thin diaphragm which allow easier diffusion

Possess a uniform basement membrane

Question 27

Discontinuous capillaries

Answer 27

Rarest kind of capillaries found in liver, spleen, bone marrow

Endothelial cells have large holes without diaphragms which causes discontinuous endothelium layers

Discontinuous basement membrane

Largest diameter capillaries

Question 28

Molecules that directly control vasoconstriction

Answer 28

Endothelium 1-3

Thromboxane A2

Prostaglandin

Question 29

Molecules that directly control vasodialation

Answer 29

Nitrous oxide

Prostacyclin

EDHF