Circulatory System

Question 1

True or false? The atria contract simultaneously, and so do the ventricles.

Answer 1

True

Question 2

Describe the path of deoxygenated blood to oxygenated blood and then to rest of body (get valves right!)

Answer 2

• Returns to heart from vena cava
• Pumped into right ventricle through the tricuspid valve
• Pumped to lungs through semilunar valves
• Blood is pumped through the mitral (bicuspid) valve into the left ventricle
• Pumped into aorta and then rest of body

Question 3

What prevent back leakage from the bicuspid and tricuspid valves?

Answer 3

The chordae tendinae that attach to small mounds of muscle (papillary muscles) in their respective ventricles.

Question 4

What are the layers of blood vessels?

Answer 4

• Outer adventitia
• Media (muscle layer)
• Inner intima

Question 5

What is blood pressure? What are its components?

Answer 5

The force exerted by blood against the inner walls of blood vessels (especially arteries).

Systolic: ventricular contraction causing maximal pressure on arteries

Diastolic: Minimal pressure when ventricles relax

Expressed as: systolic/diastolic in mmHg

The pulse pressure is the difference (systolic - diastolic)

Question 6

What are the two components of blood? List the components within each of these.

Answer 6

Plasma:

• Albumin (maintains osmotic pressure and transports substances in blood)
• Globulins (Transport proteins and antibody precursors)
• Fibrinogen (polymerizes from fibrin for blood clotting)

Formed elements:

• erythrocytes
• platelets (thrombocytes)
• white blood cells (leukocytes)

Question 7

What is blood without fibrinogen and other clotting factors?

Answer 7

Serum

Question 8

What are platelets?

Answer 8

Cytoplasmic fragments of large bone marrow cells (megakaryocytes) which are involved in blood clotting by adhering to the collagen of injured vessels, releasing mediators which cause blood vessels to constrict (vasoconstriction)

Calcium ions help signal platelets to aggregate

Question 9

List the granulocyte leukocytes

Answer 9

• Neutrophils (phagocytose bacteria/viruses and are main constituent of pus, first responders)
• Eosinophils (phagocytic and inflammatory)
• Basophils (release heparin and histamine)

Question 10

List the agranulocyte leukocytes

Answer 10

• Lymphocytes

- Monocytes (macrophages when out of blood)

Question 11

What is hematocrit? What is a normal value for adults?

Answer 11

Measures the space in the blood that is occupied with RBCs.

Normally 45%

Question 12

What is hemoglobin (Hb)?

Answer 12

A complex of heme (iron and globin)

Question 13

What is the red colour in muscles due to?

Answer 13

A different form of hemoglobin called myoglobin

Question 14

In capillary beds, what happens when blood pressure is greater than the osmotic pressure? Vice-versa?

Answer 14

When the blood pressure is greater than the osmotic pressure (eg. at arteriole end), filtration of interstitial fluid occurs.

When the blood pressure is less than the osmotic pressure, reabsorption of interstitial fluid occurs (eg. at the venous end)

Question 15

What does the lymphatic system do (in a very broad sense) as a network?

Answer 15

Circulates fluid from the extracellular space (interstitial fluid) to the cardiovascular system

Question 16

How does interstitial fluid enter the lymphatic system? Describe the flow of lymph through the lymphatic system

Answer 16

Through close ended tubes called lymphatic capillaries (lacteals in small intestine). Facilitated by osmotic pressure.

Lymph continues to flow into larger and larger vessels propelled by muscular contraction (esp skeletal) and one way valves. Then the lymph will usually pass through lymph nodes and then into a large vessel (esp the thoracic duct) which drains into one of the large veins, which eventually leads to the right atrium.

Question 17

What is the function of lymph?

Answer 17

• To return leaked protein molecules to the bloodstream

- Microorganisms that invade tissue fluids are carried to lymph nodes (to be dealt with by macrophages and lymphocytes)

Question 18

An intravenous infusion causes a sharp rise in the serum level of albumin. This will most likely cause what to occur to tissue fluid?

Answer 18

Influx of tissue fluid to the bloodstream

Because plasma proteins don’t cross blood vessel walls, albumin does not cross into tissue. However, water can cross these walls. An increase in plasma albumin will upset the osmotic balance because the blood will become hypertonic with respect to tissue. Water will have to flow into the bloodstream to reestablish equilibrium. One of the causes of edema, increased fluid in body tissues, is a decrease in the plasma protein level. This occurs, for instance, in starvation, when the body is forced to use its albumin as an energy source.

Question 19

In the process of osmosis, the net flow of water molecules into or out of the cell depends primarily on the differences in the:

Answer 19

concentration of water molecules inside and outside the cell.

Osmosis is defined as the diffusion of water across a semipermeable membrane moving from an area of higher water concentration (i.e. lower solute concentration = hypotonic) to an area of lower water concentration (i.e. higher solute concentration = hypertonic).