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Biology > The Cardiovascular System > Flashcards

The Cardiovascular System Flashcards

1
Q

What is pulmonary circulation?

A

Right side of the heart receives deoxygenated blood and sends it to the lungs thru pulmonary arteries

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2
Q

What is systemic circulation?

A

Left side of the heart receives oxygenated blood thru pulmonary veins from lungs and pumps it out to rest of body thru aorta

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3
Q

What do the atria do? What does the left atrium connect to/receive vs. the right?

A

Atria receive blood

  • Right from venae cavae, deoxygenated blood
  • Left from pulmonary veins, oxygenated blood
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4
Q

What is the purpose of valves? What are the two atrioventricular valves? The two semilunar valves?

A

Valves prevent backflow and generate allow heart to create pressure within ventricles needed to propel blood thru circulation

  1. AV valves: separate atria from ventricles
    - Right: tricuspid
    - Left: mitral or bicuspid
  2. Semilunar valves: separate ventricles from vasculature
    - Right: pulmonary valve
    - Left: aortic valve
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5
Q

Why is the left side of the heart more muscular than the right?

A

The left side is sending out blood that must travel a long distance, so BP must be maintained very far away

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6
Q

What does it mean that cardiac muscle has myogenic activity?

A

It can contract without any neurological input. Neuro input just helps it slow down or speed up.

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7
Q

What is the path of electrical conduction in the heart?

A
  1. SA node (right atrium) generates 60-100 signals/min, causing both atria to contract at the same time
    - Atrial systole causes increased atrial pressure, forcing a little more blood into ventricles (5-30% of cardiac output, called atrial kick)
  2. Signal reaches AV node (junction of A and V): signal is delayed here to allow ventricles to fill to the max
  3. Signal then travels down bundle of His and its branches in the interventricular septum
  4. Signal travels to Purkinje fibers, which distribute signal thru muscle cells, which are connected by intercalated discs (gap junctions with connecting cytoplasm for coordinated contraction)
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8
Q

What is the normal human heart rate?

A

60-100 beats per minute

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9
Q

Which nerve provides parasympathetic signals to the heart?

A

Vagus nerve

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10
Q

What is systole?

A

First half of heartbeat in which ventricles contract, AV valves close, and blood is pumped out to the body; high pressure

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11
Q

What is diastole?

A

Second half of heartbeat in which ventricles relax, semilunar valves close, and blood from atria fills ventricles; low pressure

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12
Q

What is cardiac output, and how is it calculated? What is the normal CO in humans?

A

Total blood volume pumped by a ventricle in a minute
CO = HR x SV
HR is heart rate, SV is stroke volume (vol of blood pumped per beat)
-about 5 L/min in humans

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13
Q

Describe arteries.

A
  • Carry oxygenated blood away from the heart
  • Major arteries - aorta (largest), coronary, subclavian, etc. carry blood to different peripheral tissues
  • Branch into arterioles, which become capillaries that go thru tissues
  • Have much more smooth muscle than veins and are elastic, creating resistance to blood flow (which left ventricle must push against)
  • Elastic recoil and high pressure forces blood forward
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14
Q

Describe veins.

A
  • Carry deoxygenated blood to heart, empty into superior and inferior venae cavae to right side of heart
  • Capillaries join together to become venules, which join to form veins
  • Can stretch to accommodate large quantities of blood
  • Large veins contain valves to prevent backflow as blood is traveling against gravity in legs back to heart
  • Lack of smooth muscle means they need to rely on skeletal muscle contraction to force blood up against gravity
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15
Q

What types of cells line vessels, and why?

A

Endothelial cells

  • release chemicals that aid in vasodilation/constriction
  • allow WBCs to pass thru wall during inflammation
  • release chemicals for blood clots for repair
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16
Q

Which 2 arteries contain deoxygenated blood?

A

Pulmonary arteries and umbilical arteries

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17
Q

Describe capillaries.

A
  • Single endothelial cell layer
  • Easy diffusion of gases, nutrients, wastes
  • Damaged capillaries can cause bruising
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18
Q

Which 2 veins carry oxygenated blood?

A

Pulmonary and umbilical veins

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19
Q

Describe the steps of circulation in the body.

A
  1. Deoxygenated blood in superior and inferior vena cava enters the right atrium
  2. Travels through tricuspid valve to right ventricle
  3. On contraction, blood from the right ventricle passes thru the pulmonary valve into the pulmonary arteries, where it travels to lungs
  4. Gas exchange in lung capillaries make oxygenated blood
  5. Oxygenated blood travels thru pulmonary venules –> veins to left atrium
  6. Travels thru mitral valve to left ventricle
  7. On contraction, left ventricle sends blood thru aortic valve into aorta
  8. From aorta, blood enters arteries –> arterioles –> capillaries –> exchange occurs
  9. Blood enters venules –> veins –> SVC or IVC for return to right atrium
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20
Q

What are the three portal systems in the body?

A

Capillary beds thru which blood passes before returning to heart

  1. Hepatic portal system: blood from gut capillary beds passes thru hepatic portal vein before reaching liver capillary beds
  2. Hypophyseal portal system: blood leaving hypothalamus cap bed travels to anterior pituitary cap bed for paracrine secretion of hormones
  3. Renal portal system: blood leaving glomerulus travels thru arteriole to nephron cap bed (vasa recta)
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21
Q

What is the composition of blood?

A

55% liquid, 45% cells

  • Plasma: liquid portion; nutrients, salts, gases, hormones, proteins
  • Cells: erythrocytes, leukocytes (much less than RBCs, only 1% of blood normally), platelets
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22
Q

What is the function of RBCs?

A
  • To transport oxygen thruout the body
  • Contain millions of hemoglobin molecules, each of which can bind 4 oxygen molecules, so one RBC has 1 billion oxygen molecules
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23
Q

What are some features of RBCs?

A
  • biconcave - this helps them travel thru tiny capillaries and increases their surface area
  • lose organelles when they mature to make space for hemoglobin
  • rely on glycolysis for ATP with lactic acid as by-product (don’t consume O2 they carry)
  • have no nuclei, so can’t divide - survive for 120 days before being phagocytized and recycled by liver and spleen
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24
Q

What measurements are taken during a blood test to gauge RBC health?

A
  1. Hemoglobin: g/dL, normal at 13.5-17.5 for men, 12-16 for women
  2. Hemocrit: how much of the blood sample consists of RBCs, normal is 41-53% for men and 36-46% for women
25
Q

What is the function of WBCs? How many types are there?

A
  • defense against pathogens, foreign cells, cancer

- 2 types

26
Q

What are granulocytes?

A
  • end in -phils
  • contain cytoplasmic granules that contain toxic material released thru exocytosis
  • involved in inflammation, allergies, pus formation, destruction of bacteria/parasites
27
Q

What are the subtypes of agranulocytes?

A

Lymphocytes and monocytes

28
Q

What are lymphocytes?

A
  • involved in specific immune response: body’s targeted fight against particular pathogens
  • some are primary responders against infection
  • others maintain long-term memory bank of pathogen recognition
  • many vaccines work by training these guys
29
Q

Where does lymphocyte maturation take place, and what are the resulting cells called?

A
  1. bone marrow - B-cells - antibody generation

2. thymus - T-cells - kill virally infected cells and activate other immune cells

30
Q

What are monocytes?

A
  • phagocytize foreign material
  • stockpiled by organs, once they leave bloodstream and enter organ, called macrophages
  • microglia in nervous system, osteoclasts in bone, Langerhans cells in skin
31
Q

What are thrombocytes?

A
  • platelets
  • cell fragments released from megakaryocytes, cells in bone marrow
  • assist in blood clotting
  • present in high concentration
32
Q

What triggers hematopoiesis? What are the two most notable ones?

A
  • hormones, growth factors, cytokines
    1. erythropoietin: secreted by kidney and stimulates RBC development
    2. thrombopoietin: secreted by liver and kidney and stimulates platelet development
33
Q

What are antigens, and what are the two major antigen families?

A
  • RBCs express antigen surface proteins, a specific target to which the immune system can react
  • ABO antigens and Rh factor
34
Q

Describe the inheritance properties of ABO antigens.

A
  • A and B alleles are co-dominant, so one can express 1, both, or none
  • blood type AB: IA and IB, or just A and B
  • blood type O: i or O (homozygous recessive)
  • blood type A: IAIA or IAi
  • blood type B: IBIB or IBi
35
Q

Which blood type is the universal donor? The universal acceptor? Why?

A
  • O is universal donor: express neither antigen so will not initiate any immune response/generate antibodies regardless of recipient’s blood type
  • AB is universal recipient: no blood antigen is foreign
36
Q

What is the Rh factor?

A
  • also surface protein on RBCs
  • Rh+ means specific allele called D is present, Rh- means it is absent
  • Rh+ follows autosomal dominant inheritance (just need 1 + allele to express protein)
37
Q

Why does the Rh factor matter for mothers and babies?

A
  • If a woman is Rh- and her baby is Rh+, she will be exposed to fetal blood during birth, and her immune system will start making antibodies against Rh+
  • Fine for the first child, but if the second child is Rh+, maternal anti-Rh antibodies can cross placenta and attack fetal blood cells, causing hemolysis
  • called erythroblastosis fetalis, treated with medicine
38
Q

How does Rh matter in blood transfusions?

A

an Rh+ person can receive Rh+ or Rh- blood, but an Rh- person cannot receive any Rh+ blood

39
Q

What is blood pressure, and how is it measured?

A

BP is a measure of the force per unit area exerted on the wall of the blood vessels, measured with sphygmomanometer

40
Q

What is blood pressure expressed as? What is normal BP?

A
  • Ratio of the systolic (ventricular contraction) to diastolic (ventricular relaxation) pressures
  • Between 90/60 and 120/80
41
Q

Across which vessels occurs the biggest pressure drop?

A

the largest drop in BP occurs across the arterioles (because capillaries can’t stand artery pressure)

42
Q

What does this formula mean: change in P = CO x TPR?

A
  • the pressure gradient across the circulatory system drives cardiac output thru a given vascular resistance
  • change in P is pressure differential, CO is cardiac output, TPR is total peripheral (vascular) resistance
43
Q

What factors decrease vascular resistance?

A
  • shorter blood vessel, larger cross-sectional area
  • arteries are highly muscular so can contract and expand as needed
  • arterioles can also contract to limit the amount of blood entering a cap bed
  • opening cap beds will decrease vasc resistance and increase cardiac output
44
Q

How is BP regulated?

A
  • baroreceptors in vessel walls - neurons that detect changes in mechanical forces; can stimulate vasoconstriction (symp nervous system)
  • chemoreceptors can sense when osmolarity is too high (dehydration), release ADH to increase blood volume and pressure
  • juxtaglomerular cells in kidney stimulate aldosterone release to increase blood vol and pressure
  • if BP too high, sympathetic impulses could decrease so vessels could relax
  • specialized atrial cells secrete hormone called atrial natriuretic peptide (ANP), which aids in loss of salt within kidney (natural diuretic) - but fairly weak
45
Q

How does oxygen get transferred in the blood?

A
  • hemoglobin has 4 subunits, each of which can bind to an oxygen molecule
  • the binding/releasing of oxygen occurs at each unit’s central Fe atom in an oxidation/reduction reaction
46
Q

How is the level of oxygen in the blood measured?

A

oxygen saturation- percentage of hemoglobin molecules carrying oxygen, usually above 97%

47
Q

What is cooperative binding of hemoglobin?

A
  1. in lungs, oxygen diffuses into alveoli
  2. first oxygen binds to heme group, inducing a conformational shift from taut to relaxed
  3. the shift increases hemoglobin’s affinity for O2 - positive feedback effect with each binding
  4. once filled, the removal of 1 O2 will induce a conformational change, decreasing affinity for O2, so the other subunits release O2 - positive feedback again
    - results in S-shaped hemoglobin dissociation curve
48
Q

How is carbon dioxide transported in the body?

A
  • CO2 exists in blood as a bicarbonate ion (HCO3-)
  • CO2 enters an RBC and carbonic anhydrase catalyzes the combination reaction between CO2 and H2O to form carbonic acid
  • this will dissociate into a proton and HCO3-, which have high solubilities in water
  • in lungs, this reaction reverses, and CO2 can be expelled
49
Q

Describe the Bohr effect.

A
  • increased CO2 production will cause a right shift in the bicarbonate buffer equation, leading to more H+
  • H+ can bind to hemoglobin, reducing its affinity for O2
  • shift in oxyhemoglobin curve to the right (meaning more O2 is being unloaded into tissues)
50
Q

When would the oxyhemoglobin curve shift left?

A
  • decreased CO2, decreased H+, decreased temperature

- fetal hemoglobin (HbF) has a higher affinity for oxygen than adult hemoglobin (HbA)

51
Q

How are carbs, amino acids, and fats transported in the body?

A
  • carbs and amino acids are absorbed into small intestine capillaries and enter systemic circulation via hepatic portal system
  • fats absorbed into lacteals of small intestine, bypassing hepatic portal to enter systemic circulation via thoracic duct; eventually released in lipoproteins, which are water-sol
52
Q

What is hydrostatic pressure?

A
  • force per unit area that the blood exerts against the vessel walls
  • due to contraction of heart and elasticity of arteries
  • blood pressure
53
Q

What is osmotic/oncotic pressure?

A
  • sucking pressure made by solutes as they draw water into the bloodstream
  • mostly because of plasma proteins
54
Q

How are hydrostatic and osmotic pressures balanced?

A
  • at arteriole end of a cap bed, hydrostatic pressure (pushing fluid out) is much larger than osmotic (drawing fluid in), so a net efflux of water from circulation
  • as fluid moves out of vessels, hydrostatic pressure decreases a lot, but osmotic stays the same
  • at venule end, hydrostatic pressure (pushing fluid out) has dropped below osmotic pressure (drawing in), and there is a net influx in of water back into circulation
55
Q

Why is it important to balance Starling forces?

A

movement of solutes and fluids is necessary to avoid edemas, accumulation of excess fluid in interstitiums

56
Q

How is lymphatic fluid returned to circulatory system?

A

travels thru thoracic duct

57
Q

What are clots made of?

A

coagulation factors (proteins) and platelets

58
Q

How do clots form?

A
  1. when vessel endothelium is damaged, it exposes the underlying connective tissue, which contains collagen and a protein called tissue factor
  2. when platelets come into contact with exposed collagen, they sense this as evidence of injury
  3. release their contents and aggregate
  4. coagulation factors (from liver) sense tissue factor and initiate a complex activation cascade
  5. the endpoint of the cascade is the activation of prothrombin to form thrombin by thromboplastin
  6. thrombin can then convert fibrinogen into fibrin, which fill form a fiber net that captures RBCs and platelets to form a clot and eventually a scab
59
Q

What is the process of blood clotting?

A
  1. blood vessels are injured
  2. platelets attach to the matrix that becomes exposed when endothelial cells lining vessels are disrupted
  3. this activates integrin molecules, causing them to adhere to circulating proteins like fibrinogen
  4. form a network of cells and fibers dense enough to plug the injury
  5. clot eventually broken down by plasmin, from plasminogen

Biology (14 decks)

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