Cardiovascular System

Question 1

Functions of the Cardiovascular System (4)

Answer 1

1. Maintain blood flow (cardiac output)
2. Deliver O2, nutrients, hormones, electrolytes, H2O to peripheral tissues
3. Remove waste products, including CO2
4. Maintain thermoregulation and glomerular filtration rate (urine output)

Question 2

How do permeability and pressure relate within vessels?

Answer 2

Inversely in arteries (capillaries have least pressure and are most permeable, large arteries have highest pressure and are least permeable).
Directly in veins (low permeability and low pressure)

Question 3

NL vascular pattern

Answer 3

artery > arteriole > metarteriole > capillaries > venule > vein

Question 4

Endocardium

Answer 4

Endothelial lining of the heart chambers surface. Covers surface of valves.

Question 5

Subendocardium

Answer 5

Contains thin layer of CT. Purkinje fibers are found here.

Question 6

Myocardium

Answer 6

Cardiac muscle mass

Question 7

Epicardium

Answer 7

Visceral (outer) layer of pericardial sac. Covered with mesothelium (simple squamous epithelium),has a thin layer of CT and a layer of adipose. Mesothelial cells secrete serous fluid to lubricate movement of the epicardium.

Question 8

All about Purkinje fibers…

Answer 8

In subendocardium, they are cardiac muscle cells joined by intercalated discs. Specialized for impulse conduction rather than contraction. Larger than contractile cardiac muscle fibers, with large amounts of lightly stained glycogen filling most of cytoplasm. Myofibrils at periphery.

Question 9

Intercalated discs

Answer 9

Interdigitating processes where cardiac muscle cells are held together, using desmosomes. Longitudinal sections have gap junctions that form electrical synapses, allowing contraction signals to pass from cell to cell as a single wave.

Question 10

Characteristics of the myocardium

Answer 10

cross striated
central nucleus
intercalated discs (gap junctions, desosomes)
Lipofuscin
sarcoplasmic reticulum
MANY mitochondria

Question 11

Cardiac skeleton

Answer 11

4 dense bands of CT. Structural support.

Question 12

Fibrous trigon

Answer 12

Part of cardiac skeleton, triangular mass that connects aortic arterial ring and L & R atrioventricular rings. Undergoes osseous differentiation and forms Os Cordis in cattle.

Question 13

Types of vessels

Answer 13

Elastic arteries
Muscular arteries
Arterioles
Capillaries (continuous, fenestrated, sinusoidal)
Venules
Veins
Lymphatics

Question 14

Tunica intima

Answer 14

innermost tunic of vessels, endothelium, internal elastic membrane, subendothelial CT (between endothelium and elastic membrane)

Question 15

Tunica media

Answer 15

middle tunic of vessels, smooth muscle and elastic lamellae/fibers

Question 16

Tunica adventitia

Answer 16

outermost tunic of vessels, CT (collagen), may contain blood vessels, nerves, capillaries

Question 17

Hemostasis

Answer 17

arrest bleeding by vasoconstriction/coagulation, or surgically

Question 18

Vascular endothelium role in hemostasis

Answer 18

NL: anti-thrombotic and pro-fibrinolytic
Injury: pro-thrombotic and anti-fibrinolytic

Question 19

Vascular endothelium role in perfusion

Answer 19

Nitric Oxide relaxes and causes vasodialation

Endothelin causes vasoconstriction

Question 20

Vascular endothelium role in inflammation

Answer 20

Regulates traffic of inflammatory cells
Produces pro-inflammatory cytokines
Controls angiogenesis and tissue repair

Question 21

Veins vs arteries (characteristics)

Answer 21

Tunica media of veins is thinner, and smooth muscle fibers have an irregular orientation.
Veins are irregularly shaped and may have valves.
Internal elastic lamina is not seen in veins.

Question 22

Elastic Artery characteristics

Aorta

Answer 22

Tunica intima - endothelium and loose CT
Tunica media - consists of repeating elastic lamellae
Tunica adventitia - has vasa vasorum to supply nutrients to tunica media

Question 23

Muscular arteries characteristics

Femoral artery

Answer 23

Tunica media is primarily smooth muscle and is thickest tunic.
Round appearance
Prominent internal elastic membrane

Question 24

Vascular smooth muscle in tunica media

Answer 24

circumferentially arranged, regulate diameter and tone (vasodilation and constriction)

Question 25

Arterioles characteristics

Answer 25

<6 layers of smooth muscle.
Greatest effect on BP
Nuclei bulge into lumen
No internal elastic membrane in the smallest arterioles

Question 26

Metarteriole

Answer 26

terminal vessel with precapillary sphincters that regulate flow to the capillary bed

Question 27

Pericytes (Rouget cells)

Answer 27

mesenchymal-like contractile cells surrounding capillaries and venules, with tight junctions.
facilitate communication with endothelial cells.
have own basal lamina.
Proliferate after injury - may be replacement stem cell source. Important for angiogenesis (new vessel formation)

Question 28

Capillaries

Answer 28

Thin walled tubules
mesenchymal origin
made of 1 endothelial cell rolled into the tube
exchange between blood and surrounding tissue
7-9um diameter, 0.25-1mm length. can be up to 5-10cm long.

Question 29

Fenestrations

Answer 29

Pores in membrane of endothelial cell of capillary wall. Increase transport in certain capillaries.

Question 30

Continuous capillaries

Answer 30

most common
muscle, brain, bone, lung
BBB and blood-testis barrier
basal lamina

Question 31

Fenestrated capillaries

Answer 31

in tissues with substantial fluid exchange

intestinal villi, choroid plexus, ciliary process, glomerular capillaries

Question 32

Discontinuous (sinusoidal) capillaries

Answer 32

large molecules can exit (RBC in spleen)
hepatic and splenic sinusoids, bone marrow
enlarged, irregular lumen
discontinuous and fenestrated endothelium
basal lamina may be absent

Question 33

Podocytes

Answer 33

cells in Bowman’s capsule in the kidneys, wrap around glomerular (fenestrated) capillaries

Question 34

Venules characteristics

Answer 34

"postcapillary venules"
very leaky
no smooth muscle
leukocyte dispedesis (mvmt out of circulatory system and toward site of injury/infection)
5mm Hg pressure

Question 35

Veins characteristics

Answer 35

Large, wide lumen, irregular shape, thin walls
Valves present in large and medium
Thin tunica media
Tunica adventitia is thickest tunic
Large veins may have vasa vasorum

Question 36

Lymphatic vessels characteristics

Answer 36

Very thin wall, very low pressure
May contain valves
No RBCs, appear clear
anchoring fibrils pull endothelial cells apart, fluid enters