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MCAT BIO my flashcards > Pulmonary Circulation > Flashcards

Pulmonary Circulation Flashcards

1
Q

Pulmonary circulation

A

Right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries; constitutes the first pump.

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2
Q

Systemic circulation

A

Left side of the heart receives oxygenated blood from the left side of the lungs by way of the pulmonary veins and forces it out of the body through the aorta.

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3
Q

Atria

A

Thin-walled structures where blood is received from either the venae cavae (deoxygenated blood entering the right heart) or the pulmonary veins (oxgyenated blood entering the left heart)

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4
Q

Ventricles

A

Atria send blood to the ventricles, which contract to send blood to the lungs (right ventricle) and the systemic circulation (left ventricle).

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5
Q

Are atria or ventricles more powerful

A

Ventricles are more muscular, allowing for more powerful contractions that are necessary to push blood through the rest of the body.

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6
Q

Atrioventricular valves

A

Separates atria from ventricles

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7
Q

Semilunar valves

A

Separates ventricles from vasculature. Includes pulmonary and aortic valves, and have 3 leaflets each.

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8
Q

Tricuspid valve

A

Valve between right atrium and right ventricle

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9
Q

Mitral/bicuspid valve

A

Valve between left atrium and left ventricle

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10
Q

Pulmonary valve

A

Separates right ventricle from the pulmonary circulation

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11
Q

Aortic valve

A

Separates left ventricle from the aorta

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12
Q

Electrical pathway, in order of excitation, of the heart

A

The sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His (AV bundle) and its branches, and the Purkinje fibers

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13
Q

SA node

A

Where impulse initiation occurs in the heart : generates 60-100 signals per minute without requiring any neurological input.
Small collection of cell located in the wall of the right atrium.
As depolarization wave spreads from SA node, it causes the 2 atria to contract simultaneously.

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14
Q

Atrial systole

A

Contraction, results in an increase in atrial pressure that forces a little more blood into the ventricles.

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15
Q

Atrial kick

A

Additional volume of blood squeezed into ventricles; accounts for about 5-30 percent of cardiac output

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16
Q

AV node

A

Sits at the junction of the atria and ventricles. Signal is delayed here to allow the ventricles to fill completely before they contract.

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17
Q

Purkinje fibers

A

Distribute the electrical signal through the ventricular muscle

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18
Q

Intercalated discs

A

May contain many gap junctions directly connecting the cytoplasm of adjacent cells: allows for coordinated ventricular contraction.

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19
Q

Systole

A

Ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles

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20
Q

Diastole

A

Ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles.

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21
Q

Cardiac output

A

The total blood volume pumped by a ventricle in a minute. The volumes of blood passing through each side must be the same

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22
Q

Equation for cardiac output

A

Cardiac output (CO) is the product of heart rate (HR, beats/minute) and stroke volume (SV, volume of blood pumped/beat).

CO = HR x SV

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23
Q

Pathway of Circulation

A

Right atrium –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary artery –> lungs –> pulmonary veins –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta –> arteries –> arterioles –> capillaries –> venules –> veins –> venae cavae –> right atrium

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24
Q

How many portal systems are there in the heart and what do they do

A

There are 3; blood will pass through 2 capillary beds in series before returning to the heart

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25
Q

Hepatic portal system

A

Blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver

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26
Q

Hypophyseal portal system

A

Blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones

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27
Q

Renal portal system

A

Blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta.

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28
Q

Plasma

A

The liquid portion of blood, an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins.

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29
Q

What are the 3 main categories that make up the cellular portion of blood

A

Erythrocytes, leukocytes, and platelets

30
Q

Why are red blood cells biconcave

A

The shape assists them in traveling through tiny capillaries

Shape increases the cell’s surface area, which increases gas exchange.

31
Q

What do mature red blood cells lack compared to other cells, and why

A

They lack nuclei, mitochondria, and other membrane-bound organelles.
This lack of organelles makes space for molecules of hemoglobin.
Lack of mitochondria means that red blood cells do not consume the oxygen it carries before delivering it to peripheral tissues.

32
Q

How do red blood cells generate ATP

A

They rely entirely on glycolysis, with lactic acid (from fermentation) as the main by-product.

33
Q

What does hematocrit measure

A

How much of the blood sample consists of red blood cells, given as a percentage.

34
Q

Leukocytes

A

Usually comprise less than 1 percent of total blood volume: are a crucial part of immune system.

35
Q

Leukocytes are generally categorized into what 2 classes

A

Granulocytes and agranulocytes

36
Q

Granulocytes

A

Neutrophils, eosinophils, and basophils.
Contain cytoplasmic granules that contain a variety of compounds that are toxic to invading microbes.
Involved in inflammatory reactions, allergies, pus formation, and destruction of bacteria and parasites.

37
Q

Agranulocytes

A

Consist of lymphocytes and monocytes; do not contain granules that are released by exocytosis.`

38
Q

Lymphocytes

A

Important in the body’s specific immune response; lymphocytes that mature in the bone marrow are referred to as B-cells –> those that mature in the thymus or T-cells.

39
Q

Monocytes

A

Phagocytize foreign matter such as bacteria.

40
Q

What are monoctyes called once they leave the bloodstream and enter an organ

A

Macrophages.

41
Q

Microglia

A

Macrophages in the CNS

42
Q

Langerhans cells

A

macrophages in the skin

43
Q

Osteoclasts

A

macrophages in the bone

44
Q

What are the 2 major antigen families relevant for blood groups

A

ABO antigens and Rh factor

45
Q

Are A and B alleles codominant?

A

Yes

46
Q

Relationship of O allele (i or O) to A and B

A

O allele is recessive to both A and B alleles

47
Q

What are the four blood types

A

A, B, AB, and O

48
Q

Universal donors

A

People with type O blood: because their blood will not cause ABO-related hemolysis in any recipient. HOwever, they can only receive blood from other type O individuals.

49
Q

Universal recipients

A

People with type AB blood: they can receive blood from all blood types.

50
Q

Rh factor

A

A surface protein expressed on red blood cells

51
Q

How to indicate Rh factor on blood type

A

Rh-positive (Rh+) or Rh-negative (Rh-) refers to the presence or absence of a specific allele called D. Can also be indicated with a plus or minus superscript on the ABO blood type (such as O+ or AB-).

52
Q

What type of inheritance does Rh-positivity follow

A

Autosomal dominant inheritance; one positive allele is enough for the protein to be expressed

53
Q

Erythroblastosis fetalis

A

During childbirth: if a woman is Rh- and her fetus is Rh+, she will become sensitized to the Rh factor, and her immune system will begin making antibodies against it. In any subsequent pregnancy where the fetus is Rh+, maternal anti-Rh antibodies can cross the placenta and attack fetal blood cells, resulting in hemolysis of the fetal cells.

54
Q

Sphygmomanometer

A

Measure the gauge pressure in the systemic circulation –> specifically measures the force per unit area exerted on the wall of the blood vessels

55
Q

How is blood pressure expressed

A

It is expressed as a ratio of the systolic (ventricular contraction) to diastolic (ventricular relaxation) pressures.

56
Q

What is considered to be the range of normal blood pressure

A

Between 90/60 and 120/80

57
Q

Where does the largest drop in blood pressure in the body occur

A

It occurs across the arterioles: critical because the capillaries are thin-walled and unable to withstand the pressure of the arterial side of the vasculature.

58
Q

How can Ohm’s law (V = IR) be applied to circulation

A

Change in P = CO x TPR
Where change in P is the pressure differential across the circulation, CO is the cardiac output, and TPR is the total peripheral (vascular) resistance,

59
Q

Oxygen saturation

A

The percentage of hemoglobin molecules carrying oxygen

60
Q

Carbonic anhydrase

A

Catalyzes the combination reaction between carbon dioxide and water to form carbonic acid.

61
Q

Bohr effect

A

When a decrease in hemoglobin’s affinity for oxygen causes a right shift in the oxyhemoglobin curve as a shift to the right.

62
Q

What changes occur in blood due to exercise

A

Increased partial pressure of CO2
Increased [H+]
Increased temperature

63
Q

What are the 2 pressure gradients essential for maintaining a proper balance of fluid volume and solute concentrations in the bloodstream

A

Hydrostatic and osmotic (oncotic) pressures

64
Q

Hydrostatic pressure

A

The force per unit area that the blood exerts against the vessel walls. Generated by the contraction of the heart and the elasticity of the arteries.
Pushes fluid out of the bloodstream and into the interstitium through the capillary walls, which are somewhat leaky by design.

65
Q

Osmotic/oncotic pressure

A

The “sucking” pressure generated by solutes as they attempt to draw water into the bloodstream. Cuz most of the osmotic pressure is attributable to plasma proteins, it is usually called oncotic pressure.

66
Q

Starling forces

A

Balance of opposing pressures (hydrostatic vs oncotic).
At the arteriole end of a capillary bed, hydrostatic pressure (pushing fluid out) is much larger than oncotic pressure (drawing fluid in).
At the venule end of the capillary bed, hydrostatic pressured has dropped below oncotic pressure, and there is net influx of water back into the circulation

67
Q

Edema

A

Accumulation of excess fluid in the interstitium

68
Q

Thoracic duct

A

Channel that returns most lymphatic fluid to the central circulatory system

69
Q

Clots

A

Composed of both coagulation factors (proteins) and platelets, and they prevent (or at least minimize) blood loss.

70
Q

Coagulation factors

A

Mostly secreted by the liver; sense tissue factor and initiate a complex activation cascade.

71
Q

What is the endpoint of the coagulation cascade

A

The activation of prothrombin to form thrombin by thromboplastin. Thrombin can then convert fibrinogen into fibrin. Fibrin forms small fibers that aggregate and cross-link into a woven structure, like a net, that captures red blood cells and other platelets, forming a stable clot over the area of damage.

72
Q

What is the function of plasmin (generated from plasminogen)

A

Breaks down clots.

MCAT BIO my flashcards (15 decks)

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