Circulatory system

Question 1

Electrical Conduction

Answer 1

1. SA node
2. AV node
3. Bundle of His
4. Purkinje Fibers

Question 2

Atrial kick

Answer 2

Extra blood pumped to ventricles due to atrial systole

Question 3

Function of AV node

Answer 3

Signal delayed here to help ventricles fill up

Question 4

Purkinje fibers: function and what connects these cells

Answer 4

Distribute electrical signal through ventricular muscle. Cells connected via intercalated discs, Gap junctions

Question 5

Lub Dub

Answer 5

1. Lub: 2 AV valves close at the start of systole to prevent backflow into atria
2. Dub: 2 semilunar valves close at end of systole

Question 6

Endothelial cell roles

Answer 6

1. Release chemicals for vasodilation and vasoconstriction
2. Allow WBC to pass through vessel wall and into tissues
3. Release chemicals when damaged, which help initiate repair and blood clots

Question 7

Vein vs. Artery Cell Composition

Answer 7

Same type of cells, different composition

Question 8

Volume of blood in arteries vs. veins

Answer 8

Volume of arterial blood less than vein. Total volume passing through either side of heart per time same

Question 9

3 Portal syistems

Answer 9

1. Hepatic portal system: walls of gut and capillary beds of liver
2. Hypophyseal portal system: hypothalamus to capillary bed in anterior pituitary
3. Renal portal system: glomerulus to efferent arteriole before surrounding nephron (vasa recta)

Question 10

Circulation of: Nutrients (carbs, amino acids, fats), Waste, Hormones

Answer 10

1. Carbs and amino acids: absorbed into capillaries of small intestines, enter systemic circulation via Hepatic portal system
2. Fats: absorbed into lacteals of small intestine. Enter systemic circulation via thoracic duct.
3. Wastes (CO2, ammonia, urea): enter bloodstream by traveling down concentration gradient, eventually to kidney
4. Hormones: usually by exocytosis

Question 11

Hydrostatic force

Answer 11

Force per unit area that blood exerts against vessel walls

Question 12

Oncotic pressure

Answer 12

“sucking” pressure generated by solutes as they attempt to draw water into bloodstream

Question 13

Coagulation steps

Answer 13

1. Platelets come in contact with exposed collagen, release contents and begin to aggregate
2. Coagulation factors (by liver) sense tissue factor, initiate complex activation cascade
3. Prothrombin activated to thrombin by thromboplastin
4. Thrombin converts fibrinogen to fibrin
5. Fibrin forms small fibers that aggregate and cross-link like a net
6. Clot broken down by plasmin (from plasminogen