unit three for physiology

List the components of the “vascular tree” in order of blood flow starting from the heart

1. Arteries: rapid-transit, low-resistance pressure reservoirs

2. Arterioles: primary resistance vessels; control blood flow distribution

3. Capillaries: actual sites of gas, nutrient, and waste exchange

4. Venues: capacitance vessels that release WBCs during infection

5. Veins: low-resistance, high-capacitance vessels

What are the three distinct layers or tunicae of a blood vessel?

1. Tunica Interna: innermost endothelial lining

2. Tunica Media: Middle layer of smooth muscle and elastic fibers; controls vasodilation and vasoconstriction

3. Tunica externa: outermost loose connective tissue; contains the vasa vasorum(vessels of vessels)

Star the mathematical relationship between blood flow(F), pressure gradient (delta P) and resistance (R)

F=delta P/R, flow is directly proportional to the pressure gradient and inversely proportional to resistance

What three factors determine vascular resistance (R) and which is the most significant

1. Blood viscosity(n): directly proportional

2. Vessel Length(L): directly proportional

3. Vessel Radius ( r ): inversely proportional to the fourth power. Radius is the most significant because small changes drastically alter resistance

Differentiate between local and extrinsic control of arteriolar radius

Local/intrinsic: matches blood flow to metabolic needs. Triggered by low o2, high CO2, heat or histamine

Extrinsic: important for regulating systemic blood pressure. Primarily controlled by sympathetic activity (vasoconstriction) and hormones like epinephrine and angiotensin II

How does the body respond to a sudden increase in blood pressure

1. BARORECEPTORS in the carotid sinus and aortic arch detect stretch

2. Signals are sent to the MEDULLA (cardiovascular control center)

3. RESPONSE: decreased sympathetic and increased parasympathetic activity, leading to reduced heart rate, reduced cardiac output, and vasodilation

How do the kidneys respond to low blood pressure (RAAS)?

Low BP stimulates the kidneys to release renin. Renin produces Angiotensin II, which causes:

• vasoconstriction

• Release of Aldosterone (promotes salt/water retention)

• Increase in ADH secretion

• Result: increased blood volume and blood pressure

Define Ultrafiltration and Reabsorption in capillary exchange

• ultrafiltration: fluid moves out of capillaries into interstitial fluid when outward pressure (capillary BP) exceeds inward pressure

• Reabsorption: fluid moves into capillaries when inward driving pressures (plasma-colloid osmotic pressure) exceed outward pressure

What are the four primary causes of Edema (swelling)?

1. Reduced concentration of plasma proteins

2. Increased permeability of capillary walls

3. Increased venous pressure

4. Blockage of lymphatic vessels

Name the five mechanisms thta help return blood to the heart against gravity

1. Venous valves (prevent backflow)

2. Skeletal muscle pump

3. Respiratory pump

4. Sympathetic stimulation (vasoconstriction)

5. Cardiac suction

What are the three distinct layers of centrifuged blood and their approximate percentages?

1. Plasma (55%)

2. Buffy coat (leukocytes and platelets <1%)

3. Erythrocytes (RBCs ~45%)

Define hematocrit

The percentage of blood volume consisting of erythrocytes (RBCs)

What are the three main types of plasma proteins and their primary functions

• albumins: most abundant; maintain osmotic pressure and bind poorly soluble substances

• Globulins: alpha/beta serve as carriers and are involved in clotting; gamma globulins are antibodies

• Fibrinogen: a key factor in blood clotting

Where are the most plasma proteins synthesized?

In the liver with the exception of antibodies (produced by b-lymphocytes)

What anatomical features make erythrocytes efficient at oxygen transport ?

• biconcave shape: increases surface area for diffusion

• Thin membrane: allows for easy diffusion

• Flexible membrane: allows cells to squeeze through small capillaries

• Lack of nucleus/organelles: maximizes space for hemoglobin

What are the two main parts of a hemoglobin molecule

1. Globin: protein portion with two alpha and two beta chains

2. Heme groups: four iron-containing groups that bind oxygen

Besides oxygen, what four other chemicals can hemoglobin bind to?

1. Carbon dioxide

2. Carbon monoxide

3. Nitric oxide

4. Acidic hydrogen ions

Describe the role of erythropoietin

It is a hormone produced by the kidneys in response to low oxygen levels; it stimulates the bone marrow to produce more red blood cells

Name the two categories of leukocytes and the cells within them

Polymorphonuclear granulocytes: neutrophils, eosinophils, basophils

Match the leukocyte to its primary function

Neutrophil: phagocytosis; defense against bacterial infection

Eosinophil: allergic reactions and combatting multicellular parasites

Basophil: releases histamine (allergic reactions) and heparin (anti-coagulation)

Differentiate between B-lymphocytes and T-lymphocytes

• B-lymphocytes: produce antibodies for humoral immunity

• T-lymphocytes: destroy toxic cells; provide cell-mediated immunity against viruses and cancer

What are the three steps of hemostasis?

1. Vascular spasm: vasoconstriction

2. Platelet plug formation

3. Blood coagulation: clotting

What is the final step in the clotting cascade that creates the “mesh”?

Thrombin catalyzes the conversion of soluble fibrinogen into insoluble fibrin threads

How is a clot dissolved once it is no longer needed?

The enzyme plasmin breaks down fibrin; it is activated from plasminogen by factors like Factor XII or tissue plasminogen activator (tPA)

Differentiate between a thrombus and an embolus

A thrombus is an intravascular clot attached to the vessel wall; an embolus is a freely floating clot

Define Anemia and list three specific types

A condition where blood carries below-normal oxygen levels. Types include:

• nutritional: iron or B12 deficiency

• Aplastic: bone marrow failure

• Parietal: kidney disease/EPO deficiency

• Hemolytic: RBC lysis (sickle cell or malaria)

Explain the universal donor and universal accepter blood types

• universal donor: type o because it contains no A or B antigens

• Universal Acceptor: Type AB because it produces no anti-a or anti-b antibodies

What is erthyroblastosis ?

A hemolytic condition occurring when an Rh- mother develops antibodies against an Rh+ fetus, potentially attacking the RBCs of the subsequent RH+ pregnancies

What is the definition of Immunity?

The body’s ability to protect itself by resisting or eliminating potentially harmful foreign invaders or abnormal cells

What are the three common targets of the immune system?

1. Pathogenic bacteria

2. Viruses

3. Cancer cells

Define virulence

A pathogen’s ability to cause severe damage to the host, or its “disease-producing power”

List the characteristics of Innate Immunity

• non-specific

• First line of defense

• Immediate response

• No memory

List the characteristics of adaptive immunity

• highly specific

• Late response

• Has memory

• Considered the “ultimate weapon”

What are the four various forms of innate immunity

1. Inflammation

2. Interferon

3. Natural killer cells

4. Complement system

What do pattern recognition receptors recognize

They recognize pathogen associated molecular patterns (PAMP) in pathogens

Name the five major events that occur during inflammation

1. Localized vasodilation

2. Increased capillary permeability

3. Localized edema (swelling)

4. Walling off the inflamed area

5. Emigration of leukocytes

Define margination and diapedesis

• margination: immune cells sticking to the inner endothelial lining of capillaries

• Diapedesis: stuck leukocytes leaving the vessel to reach the site of infection

How does Interferon protect healthy cells?

It acts as a “whistle blower” by stimulating the synthesis of enzymes that degrade viral messenger RNA, thereby interfering with viral replication

Where do B-cells and T-cells mature?

• B-cells: bone marrow

• T-cells: thymus

Distinguish between humoral and cell mediated immunity

• humoral (B-cell mediated): involves antibody-mediated immunity

• Cell mediated (T-cell mediated): involves cytotoxic immunity where t-cells bind directly with targets

Name the five subclasses of antibodies (immunoglobulins) and their functions

• IgM: first responder in early stages of infection

• IgG: most common; acts as an opsonin to enhance phagocytosis against bacteria

• IgE: attaches to mast cells/basophils; involved in allergic reactions and parasite defense

• IgA: present in mucus membranes, milk, and tears

• IgD: bound to mast cells/basophils; function in allergic reactions

What are the two types of MHC glycoproteins and which T-cells do they bind?

• Class I MHC: found in all cells; recognized by CD8+ cytotoxic t-cells

• Class II MHC: found in antigen-presenting cells (macrophages, B cells, dendritic cells); recognized by CD4+ Helper T cells

How do cytotoxic T-cells destroy infected cells

They secrete perforin (pokes holes in the cell) and granzymes (induces apoptosis)

How does the body maintain self-tolerance

1. Clonal deletion: permanently deleting B and T cells that react to self-antigens during development in the thymus

2. Clonal anergy: inactivating cells that escape deletion

Distinguish between immunodeficiency and autoimmune diseases

• immunodeficiency: the system fails to respond adequately to foreign invasion

• Autoimmune: the system fails to recognize self-antigens and attacks its own tissues

What causes the symptoms of immediate hypersensitivity(allergies)?

Allergens bind to IgE antibodies on mast cells, which then release Histamine

What are two types of cardiac muscle cells and what are their primary roles?

• auto rhythmic cells (1%): initiate and conduct action potentials responsible for contraction

• Contractile cells (99%): perform the mechanical work of pumping

Describe the ion movements during the action potential of a contractile cell

• rapid rise: Na+ influx through fast sodium channels

• Plateau phase: slow ca2+ entry through L-type channels coupled with reduced k+ efflux

• Resting potential: maintained by leaky k+ channels

Why is a long refractory period (250 sec) critical in cardiac muscle?

It prevents summation of contraction and tetanus, ensuring the heart has time to alternate between contraction and relaxation.

List the autorhythmic tissues of the heart and their normal firing rates

• SA node: 70-80 bpm (normal pacemaker)

• AV node: 40-60 bpm

• Bundle of His & Purkinje fibers: 20-40 bpm

Define Systole and diastole

-systole: contraction and emptying of the heart

Dissolve: relaxation and filling of the heart

What causes the two normal heart sounds (“lub-dup”)?

• first heart sound (lub): closure of the AV valve

• Second heart sound (dup): closure of the semilunar valves

What is isovolumetric ventricular contraction?

A brief period at the start of systole where all valves are close; ventricular pressure rises while volume remains constant

What is the formula for cardiac output (CO)?

CO+HR (Heart Rate) x SV (Stroke Volume)

How does parasympathetic stimulation affect the heart?

• decreases heart rate by releasing acetylcholine

• Increases k+ permeability, hyperpolarizing the SA node and slowing depolarization

Define the Frank-Starling law of the heart

It is the intrinsic relationship where an increase in venous return (end-diastolic volume) leads to an increase in stroke volume due to increased muscle fiber stretching and contractibility.

What are preload and after load?

• preload: the extent of filling (EDV) before contraction

• Afterload: the arterial blood pressure the heart must pump against

Name the three layers of a blood vessel wall

1. Tunica interna: innermost endothelial lining

2. Tunica media: smooth muscle layer for vasoconstriction/dilation

3. Tunica externa: outermost connective tissue layer

What factors determine vascular resistance (R)?

• Viscosity of blood (direct relationship)

• Vessel length (direct relationship)

• Vessel radius (inverse relationship to the 4th power; the most significant factor)

Why are arterioles considered the “major resistance vessels”?

Their radius is small enough to offer considerable resistance, and they can be adjusted to regulate blood flow to organs and determine mean arterial pressure

What is mean arterial pressure and how is it calculated ?

MAP is the average pressure driving blood into tissues. Formula: MAP= diastolic pressure + 1/3 pulse pressure

Describe the two processes of capillary bulk flow

• ultrafiltration: pressure inside the capillary exceeds outside pressure, pushing fluid out

• Reabsorption: inward-driving pressures exceed outward pressures, pulling fluid back in

What is atherosclerosis?

A progressive disease where plaques (lipid core with a connective tissue cap) form beneath the vessel lining, potentially leading to heart attacks or strokes

List four common causes of edema (swelling).

1. Reduced plasma protein concentration

2. Increased capillary wall permeability

3. Increased venous pressure

4. Blockage of lymphatic vessels