flashcards physiology exam 2

What are the main functions of the cardiovascular system?

1. circulates gases (carbon dioxide & oxygen)

2. circulates nutrients

3. circulates antibodies

4. circulates hormones

5. circulates wastes

6. circulates electrolytes, etc.

7. regulates temperature

8. regulates pH

9. clotting

10. immune response

What are the two main components of blood?

1. plasma (liquid part)

2. formed elements (blood cells & platelets)

What type of tissue is blood?

vascular connective tissue

What is hematocrit?

the percent (%) of whole blood composed of red blood cells (RBCs)

• female (♀): 38–45%

• male (♂): 43–51%

What does temperature regulation involve?

1. taking heat to the skin → radiate out → sweat (540 cal/gram H20).

2. water acts as a “heat sink” with high specific heat (heat capacity).

What is the specific heat of water compared to metals?

H₂O (water) = 1 cal/g°C

Fe (iron) = 0.1 cal/g°C

Al (aluminum) = 0.1 cal/g°C

What is the normal blood pH range and how is it maintained?

pH = 7.35–7.45

Maintained by a buffer system.

What are the three layers seen when blood is centrifuged?

1. Plasma (top layer)

2. Buffy coat (white blood cells + platelets)

3. Erythrocytes (bottom layer)

What are two examples of blood’s role in homeostasis?

• Regulating pH via buffers

• Regulating temperature via heat distribution

What are leukocytes?

White blood cells that defend the body against infection and disease.

What are the two main categories of leukocytes?

1. Granulocytes

2. Agranulocytes

What are the three types of granulocytes?

-neutrophils

-eosinophils

-basophils

What are neutrophils also called?

Polymorphonuclear leukocytes (PMNs)

Describe neutrophils:

1. 60-65% of white blood cells (WBCs)

2. Lysosome-rich and very phagocytic

3. Very migratory

4. Poorly stained granules

5. Faint in blood smears

Describe eosinophils:

1. Granules stain red with eosinophils (acidic dye)

2. Bilobed nucleus

3. Contain lysosomes

4. Active in allergic reactions and parasitic infections

Describe basophils:

1. Approximately 0.5% of white blood cells (WBCs)

2. Granules contain histamine (vasodilator, increases capillary permeability) and heparin (anticoagulant)

3. Granules are not lysosomes

What are the two types of agranulocytes?

1. Monocytes

2. Lymphocytes

Describe monocytes:

1. Largest of all white blood cells

2. 15-20 µm (micrometers)

3. Become macrophages in tissues

4. Very active phagocytes

Describe lymphocytes:

1. Smallest of white blood cells

2. Two main types:

• T lymphocytes- cellular immunity

• B lumphocytes- humoral immunity (produce antibodies)

What are platelets?

• cytoplasmic fragments with no nucleus

• Live about 10 days

• Count: 150,000-300,000 per mm³ of blood

• Important in hemostasis (prevention of bleeding)

What determines blood type?

The presence of surface antigens A and/ or B on red blood cells.

What are the four blood types and their antibodies

What is the Rh factor?

An antigen found on red blood cells

• Rh⁺: has the antigen

• Rh⁻: lacks the antigen

What happens if an Rh⁻ mother carries an Rh⁺ baby?

She may produce anti-Rh antibodies that cross the placenta during a second pregnancy, causing hemolytic disease (erythroblastosis fetalis).

What is RhoGAM used for?

To prevent Rh⁻ mothers from forming anti-Rh antibodies

What are the genetic alleles for the ABO blood group system?

• IA, IB, and i

• IA and IB are codominant (both expressed → type AB)

• i is recessive (only shows when homozygous ii → type O)

What are the possible genotypes for each ABO blood type?

• Type A: IAIA or IAi

• Type B: IBIB or IBi

• Type AB: IAIB

• Type O: ii

What are the Rh factor genotypes?

• Rh⁺: RR or Rr (has the Rh antigen)

• Rh⁻: rr (no antigen)

What dye stains acidic cell structures red or pink?

Eosin, an acidic dye that binds to basic (alkaline) components in cells.

What dye stains basic structures blue or purple?

Methylene blue, a basic dye that binds to acidic components like DNA or granules.

Why are neutrophil granules faint in blood smears?

Because their granules stain poorly with common blood dyes, giving a light or faint appearance under the microscope.

What does hemostasis mean?

Hemostasis means the prevention of bleeding — literally “static blood.” It’s the process the body uses to stop bleeding after injury.

What are the three main steps of hemostasis?

1. Vasoconstriction

2. Platelet plug formation

3. Clot formation (with retraction and resolution)

What happens during vasoconstriction?

• Blood vessels constrict to reduce blood flow.

• Platelets release thromboxane, which acts as a vasoconstrictor.

• Von Willebrand factor (vWF) attracts platelets to the site of damage and helps them stick, starting the platelet plug.

What is the role of von Willebrand factor?

It acts like a bridge — it binds exposed collagen fibers at the injury site and attracts platelets, triggering them to attach and start the platelet plug.

What is the function of thromboxane?

Thromboxane is released by platelets and causes vasoconstriction to limit blood loss.

What is platelet plug formation?

The second step of hemostasis — platelets stick to the damaged vessel wall and to each other, forming a temporary seal over the injury.

What chemical makes platelets “sticky”?

ADP (adenosine diphosphate) released by activated platelets makes other platelets sticky, promoting aggregation.

What other chemical activates more platelets during plug formation?

ATP — it helps activate surrounding platelets, creating a positive feedback loop.

How do platelets stick together?

Via fibrin connections — fibrin strands form a mesh that holds platelets together.

What happens in the clot formation stage?

• Fibrinogen (soluble) is converted into fibrin (insoluble).

• This reaction is catalyzed by the enzyme thrombin.

• The fibrin forms a net-like structure that traps red blood cells and platelets, forming a clot.

What enzyme converts fibrinogen to fibrin?

Thrombin

Why is fibrin important in clot formation?

Because it forms the structural mesh of the clot that physically seals the injury.

What happens during clot retraction?

• Actin and myosin in platelets contract, causing the clot to shrink.

• This pulls the wound edges closer together and helps expel serum from the clot.

What happens after the clot retracts?

The vessel begins healing and repair; smooth muscle cells reproduce, helping restore the vessel wall.

Why does the clot eventually need to be removed?

Because once the vessel is healed, the clot becomes unnecessary and could block flow — so it must be dissolved.

What enzyme dissolves the clot?

Plasmin — formed from the inactive precursor plasminogen.

What converts plasminogen into plasmin?

Plasminogen activators, such as tissue plasminogen activator (tPA).

What is the function of plasmin?

It digests fibrin, breaking down the clot (fibrinolysis).

What is thrombosis?

An inappropriate or abnormal clot that forms inside a blood vessel, usually a vein, without injury.

What is a thromboembolus?

A clot that breaks free and travels through the bloodstream — it can block vessels elsewhere, leading to serious conditions like stroke or pulmonary embolism.

What could happen if one of the hemostatic factors is missing?

A bleeding disorder may occur (e.g., hemophilia), since the chain reaction for clot formation cannot complete.

Which proteins and cells are most active during hemostasis?

Platelets, clotting factors, and fibrinogen — all work together to form a stable clot.

What is the myocardium?

The muscular layer of the heart responsible for contracting and pumping blood.

What are the main characteristics of myocardial tissue?

1. Striated like skeletal muscle

2. Small, uninucleated cells

3. T-tubules are present

4. Sarcoplasmic reticulum (SR) is similar to skeletal muscle

5. Calcium (Ca²⁺) comes from both the SR and interstitial fluid

6. Composed of autorhythmic and contractile cells

7. Myogenic (generates its own action potential)

8. Cells connected by gap junctions at intercalated discs

9. Cells are branched

Why is the myocardium said to be striated?

Because it has sarcomeres (repeating actin and myosin filaments) like skeletal muscle.

What is the difference between autorhythmic and contractile cells?

• Autorhythmic cells (1%): Generate their own action potentials (pacemaker cells).

• Contractile cells (99%): Respond to action potentials by contracting and pumping blood.

What makes cardiac tissue myogenic?

It can generate its own electrical impulses without stimulation from the nervous system.

What are intercalated discs?

Specialized junctions that connect cardiac cells; they include gap junctions (for electrical signals) and desmosomes (for mechanical strength).

What is the function of gap junctions in the heart?

They allow ions to flow between cells, enabling synchronized contractions (functional syncytium).

What is the function of desmosomes?

• They anchor cardiac cells together so they don’t pull apart during contraction.

• They are stronger than the cell itself.

What percentage of myocardium is autorhythmic?

About 1%.

What percentage of myocardium is contractile?

About 99%.

List the main parts of the heart’s conduction system.

• SA (sinoatrial) node

• AV (atrioventricular) node

• Bundle of His (AV bundle)

• Bundle branches

• Purkinje fibers