Circulatory Systems

Question 1

What maximizes surface area for gas exchange?

Answer 1

tracheae, gills, and lungs

Question 2

Open circulatory systems

Answer 2

the blood or circulating fluid is not kept separate from the tissue fluid so a pump helps propel the fluid into vessels and the fluid leaves the vessels to trickle through the tissues
-arthropods, mollusks, and other invertebrates use this

Question 3

Pros/cons of open circulatory systems

Answer 3

-pros: work well for circulation of nutrients and waste
-cons: not rapid and efficient for gas exchange if metabolic rate is high

Question 4

Tracheal system

Answer 4

puts a limit on the size of the organism bc passive diffusion of gases down the tubes can only go so far

Question 5

Closed circulatory system

Answer 5

-keeps the blood and tissue fluid separate
-one or more muscular hearts and a branching network of vessels move the blood
-direction of blood flow is controlled by one-way valves

Question 6

Advantages of closed circulatory system

Answer 6

-blood flow, nutrient delivery and waste removal are more rapid
-closed systems can regulate blood flow to specific tissues
-cellular elements and large molecules that aid in transport can be kept within the vessels

Question 7

Components of blood

Answer 7

RBCs, WBCs, and platelets

Question 8

Hematocrit

Answer 8

a measure of the cellular portions as a percentage of the total blood volume

Question 9

Plasma

Answer 9

contains gases, ions, nutrients, proteins, hormones, and other stuff

Question 10

Blood cells

Answer 10

made from pluripotent stem cells in the bone marrow
-lymphocytes, monocytes, erythrocytes, and platelets

Question 11

Erythrocytes

Answer 11

biconcave, flexible discs packed w/ hemoglobin which carries O2

Question 12

Platelets

Answer 12

broken off cell fragments from megakaryocytes (stem cells in bone marrow) that contain enzymes and chemicals necessary for blood clotting

Question 13

Clotting

Answer 13

1. vessel damage
2. vascular spasm
3. platelet activation (plug)
4. conversion of prothrombin to thrombin
5. activates polymerization of fibrinogen into fibrin threads
6. forms a meshwork to stabilize plug and provide a base for scar tissue

Question 14

Hemophilia

Answer 14

genetic disorder in which one or more of the clotting factors do not work

Question 15

Capillary beds

Answer 15

lie between arterioles and venules and exchange materials btwn blood and tissue fluid thru their thin walls

Question 16

Precapillary sphincters

Answer 16

made of smooth muscles at the entrance to capillary beds that regulate blood flow into capillaries

Question 17

fenestrations

Answer 17

fine holes in capillary walls, small molecules leak through but large molecules are retained

Question 18

Blood pressure…

Answer 18

squeezes water and small solutes out of the capillaries

Question 19

Osmotic pressure…

Answer 19

draws water back into the capillary w/ HCO3- and CO2

Question 20

How is blood flow regulated in veins?

Answer 20

contraction of skeletal muscle pushes blood toward heart because one-way valves in veins prevent backflow

Question 21

Varicose veins

Answer 21

when the veins become stretched and valves can no longer do their job > increased blood

Question 22

African lungfish

Answer 22

-modified gill arteries: direct some of the blood coming from the heart to the lung and a new vessel carries oxygenated blood from the lung back to the heart
-divided atria keeps blood streams separate

Question 23

Ventricle and arterial contraction

Answer 23

1. atria contract
2. ventricles contract, AV valves close, pressure in ventricles builds up until aortic and pulmonary valves open
3. blood is pumped out of ventricles into aorta and pulmonary artery
4. ventricles relax, pressure in ventricles fall, pressure is greater in aorta, aortic and pulmonary valves close
5. Ventricles fill back up with blood

Question 24

What is the primary pacemaker of the heart?

Answer 24

sinoatrial node (located at the juncture of the superior vena cava and the right atrium)

Question 25

What does a normal heartbeat begin with?

Answer 25

an AP in the SA that spread through the atrial cells causing them to contract in unison

Question 26

Atrioventricular node

Answer 26

stimulated by depolarization of the atria; generate and conduct APs to the ventricles through Bundle of His (to Purkinje fibers)

Question 27

What do Purkinje fibers do?

Answer 27

evenly distribute the AP throughout the ventricular muscle

Question 28

Why do the ventricles contract after the atria?

Answer 28

because of the delay in action potentials from the SA node and AV node

Question 29

Ventricular muscle cell action potentials (2 phases)

Answer 29

1. initiated by voltage-gated NA+ channels opening
2. voltage-gated Ca2+ channels open and don’t close quickly allowing ventricular muscle cells to continue contracting

Question 30

Atherosclerosis

Answer 30

What: smooth internal lining of arteries becomes damaged and deposits of lipids and cholesterol (plaque) can form; plaque becomes infiltrated w/ fibrous connective tissue and calcium deposits, which makes the artery wall less elastic and narrows the lumen of artery
Result: heart attack or stroke

Question 31

Thrombus

Answer 31

blood clot made of platelets and pieces of plaque broken off

Question 32

Types of strokes

Answer 32

1. Ischemic: an embolus lodges in the brain and block blood flow
2. Hemorrhagic: rupture of a blood vessel in the brain

Question 33

Good cholesterol vs bad cholesterol

Answer 33

good: high-density lipoproteins (reduce deposition of cholesterol in arterial plaques)
bad: low-density lipoproteins (increase deposition)