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MCAT > Bio: Ch 7, 11 > Flashcards

Bio: Ch 7, 11 Flashcards

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MCAT flashcards
1
Q

cardiovascular system consists of

A

muscular 3 chambered heart, blood vessels, blood

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2
Q

heart is composed of ____ muscle

A

cardiac

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3
Q

pulmonary circulation

A

right side of heart accepts deoxygenated blood returning from body and moves it to the lungs by way of pulmonary arteries

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4
Q

systemic circulation

A

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

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5
Q

atria

A

thin walled structures where blood is received from either the venae cavae or pulmonary veins

contract to push blood into ventricles

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6
Q

ventricles

A

thick walled structures that send blood to lungs (rt) and systemic circulation (lt)

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7
Q

atria are separated from the ventricles by

A

atrioventricular valves

bicuspid/mitral (lt) and tricuspid (rt)

(LAB RAT)

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8
Q

ventricles are separated from vasculature by

A

semilunar valves

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9
Q

tricuspid valve

A

valve between rt atrium and rt ventricle

(LAB RAT)

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10
Q

mitral/bicuspid valve

A

valve between lt atrium and lt ventricle

(LAB RAT)

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11
Q
A
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12
Q

pulmonary valve

A

valve that separates rt ventricle from pulmonary circulatory circulation

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13
Q

aortic valve

A

valve that separates left entricle from the aorta

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14
Q

the ___ side of the heart is more muscular than the other side because

A

left

the blood is pumped to the whole body –> higher resistance and pressure

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15
Q

pathway of blood

A

venae cavae (from body) > right atrium > tricuspid valve > right ventricle > pulmonary valve > pulmonary artery > lungs > pulmonary veins > left atrium > mitral valve > left ventricle > aortic valve > aorta (to body)

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16
Q

SA node

A

impulse intiation

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17
Q

systole

A

ventricular contraction

blood is pumped out of ventricles

when AV valves are closed

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18
Q

bundle of His

A

spread signal to interventricular septum

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19
Q

purkinje fibers

A

distribute electrical signal through ventricular muscle

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20
Q

intercalculated disk

A

connect muscle cells

contain many gap junctions directly connecting cytoplasm of adjacent cells

allows for coordinated ventricular contraction

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21
Q

diastole

A

heart is relaxed

blood fills ventricles

semilunar valves are closed

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22
Q
A
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23
Q

electric conduction steps

A
  1. SA node: impulse initiation
  2. atria contract
  3. AV node: pauses signal to allow the ventricles to fill fully
  4. bundle of his
  5. purkinje fibers
  6. ventricles contract
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24
Q

vagus nerve

A

slows down the heart rate

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25
Q

cardiac output

A

CO

total blood volume pumped by a ventricle in a mine

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26
Q

heart rate

A

HR

beats per minute

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27
Q

stroke volume

A

SV

volume of blood pumped per beat

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28
Q

cardiac output eq

A

CO = HR x SV

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29
Q

what does the sympathetic nervous system do to the cardiovascular system?

A

increases heart rate and contractility

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30
Q

what does the parasympathetic nervous system do to the cardiovascular system?

A

decreases heart rate

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31
Q

arteries

A

thick, highly muscular structures with an elastic quality –> allows for recoil and helps to propel blood forward within the system

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32
Q

arterioles

A

small muscular arteries

control flow into capillary beds

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33
Q

capillaries

A

have walls that are one cell thick

sites of gas and solute exchange

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34
Q

veins

A

inelastic, thin walled structures that transport blood to heart

can stretch but do not have recoil capability

compressed by surrounding skeltal muscles and have vales to maintain one way flow

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35
Q

endothelial cells

A

line blood vessels

help maintain vessel by releasing chemicals that aid in vasodilation and vasoconstriction

allow white blood cells to pass through

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36
Q

why do veins have valves?

A

bloodflow in most veins is upward against gravity and pressure is high at the bottom of the veneous column

veins need valves to push blood forward and prevent backflow

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37
Q

superior vena cava

A

returns blood form the body above heart

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38
Q

inferior vena cava

A

return blood from below heart

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39
Q

portal system

A

blood passes thorugh two capillary beds in series

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40
Q

hepatic portal system

A

blood travels from gut capillary beds to liver capillary bed via hepatic portal vein

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41
Q

hypophyseal portal system

A

blood travels from capillary bed in hypothalamus to capillary bed in anterior pituitary to allow for paracrine secretion of releasing hormones

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42
Q

renal portal system

A

blood travels from glomerulus to vasa recta through efferent arteriole

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43
Q
A
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44
Q
A
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45
Q

if all autonomic input to the heart were cut, what would happen?

A

heart would continue beating at the intrinsic of the pacemaker (SA node)

they would be unable to change their heart rate via the sympathetic or parasympathetic nervous system, but the heart would not stop beating

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46
Q

plasma

A

liquid portion of blood

aqueous mixture of nutrients, slats, respiratory gases, hormones, and blood proteins

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47
Q

categories of the cellular portions of blood

A

erythrocytes, leukocytes, platelets

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48
Q

blood cells are formed from

A

hematopoietic stem cells

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49
Q

erythrocytes lack ____ because…

A

mitochondria, nucleus, and organelles

to make room for hemoglobin

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50
Q

hemoglobin

A

protein that binds four molecules of oxygen

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51
Q

hematocrit

A

percentage of blood composed of erythrocytes

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52
Q

erythrocyte

A

specialized cell designed for oxygen transport

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53
Q

why are red blood cells biconcave?

A

assists them in travelling through capillaries

increases cell’s surface area, which increases gas exchange

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54
Q

how do blood cells generate ATP

A

rely on glycolysis for ATP, with lactic acid as main byproduct

(cannot carry out oxidative phosphorylation)

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55
Q

leukocytes

A

white blood cells

part of immune system

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56
Q

leukocytes

types

A

granulocytes and agranulocytes

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57
Q

granulocytes/granular leukocytes

+ex

A

play role in nonspecific immunity -> contain compounds that are toxic to invaders

neutrophils, eosinophils, basophils

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58
Q

agranulocytes

+ex

A

play role in immunity

lymphocytes and monocytes

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59
Q

lympthocytes

A

important in specific immune response

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60
Q

specific immune response

A

body’s targeted fight against particular pathogens

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61
Q

thrombocytes/platelets

A

cell fragments from megakaryocytes

blood clotting

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62
Q

hematopoiesis

A

production of blood cells and platelets

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63
Q

thrombopoietin

A

secreted by liver and kidney and stimulates mainly platelet develop

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64
Q

blood antigens

A

A, B, O, Rh factor (D)

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65
Q

blood antigens dominance

A

A and B are codominant

i (O) recessive

Rh+ is dominant

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66
Q

universal donors

A

type O blood

don’t produce any antigens

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67
Q

universal recipients

A

type AB

don’t produce any antibodies

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68
Q

B+ blood can recieve blood from to

A

B+, B-, O+, O-

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69
Q

B+ blood can donate to

A

B+, AB+

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70
Q

why cell types contain nuclei and which do not?

A

nuclei: leukocytes
none: erythrocytes, platelets

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71
Q

blood pressure

A

force per unit area that is exerted on walls of blood vessels by blood

divided into systolic and diastolic components

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72
Q

blood pressure must be high enough to ___, but it must be low enough to ___

A

high enough to overcome the resistance created by arterioles and capillaries

low enough to avoid damaging the vasculature and surrounding structures

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73
Q

sphygmomanometer

A

measures blood pressure

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74
Q

blood pressure is maintained by

A

baroreceptor and chemoreceptor reflexes

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75
Q

low blood pressure promotes ___ and ___ release

A

aldosterone and ADH

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76
Q

high blood osmolarity promotes ___ release

A

ADH

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77
Q

high blood pressure promotes ____ release

A

ANP

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78
Q

gas and solute exchange in capillaries relies on

A

concentration gradients

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79
Q

gas and solute exchange in capillaries

A

capillaries are leaky

conc gradients

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80
Q

blood vessels

hydrostatic pressure

A

pressure of the fluid within the blood vessel

psuhes fluid out at arteriole end of capillary

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81
Q

blood vessels

osmotic pressure

A

due to proteins

draws fluid back into vessel at venule end

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82
Q

largest drop in blood pressure occurs

A

across the arterioles

important bc capillaries cannot withstand so much pressure

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83
Q

the longer a blood vessel is, the ___ resistance it offers

A

more

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84
Q

the larger the cross sectional area of a blood vessel, the ___ resistance it offers

A

less

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85
Q

baroreceptors

A

detect changes in mechanical forces on the walls of the vessel

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86
Q

chemorecetpors

A

sense when osmolarity of the blood is too high, which could indicate dehydration

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87
Q

oxygen saturation

A

percentage of hemoglobin molecules carrying oxygen

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88
Q

cooperative binding in oxygen

A

each successive oxygen bound to hemoglobin increases the affinity of the other subunits, while each successive oxygen released decreases the affinity of the other subunits

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89
Q

in lungs, there is a ___ partial pressure of oxygen, resulting in…

A

high

loading of oxygen onto hemoglobin

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90
Q

in tissues, there is a ___ partial pressure of oxygen, resulting in

A

unlading of oxygen onto hemoglobin

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91
Q

carbon dioxide is largely carried in blood in the form of

A

carbonic acid, bicarbonate, and hydrogen ions

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92
Q

what can cause a right shift in the oxyhemoglobin dissociation curve? what does this result in?

A

results in decreased affinity for oxygen

  1. high PaCO2
  2. high [H+]/low pH
  3. high temp
  4. high [2,3-BPG]
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93
Q

coagulation results from

A

activation cascade

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94
Q

coagulation cascade steps

A
  1. endothelial lining of a blood vessel is damaged
  2. collagen and tissue factor underlying the endothelial cells are exposed
  3. results in formation of a clot over damaged area
  4. platelets bind to collagen and stabilized by fibrin
  5. clots broken down by plasmin
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95
Q

clots

A

composed of coagulation factors (proteins) and platelets

prevent blood loss

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96
Q

coagulation factors are secreted by

A

liver

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97
Q

coagulation factors

A

sense tissue factor and initiate a complex activation cascade

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98
Q

fibrin is activated by

A

thrombin

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99
Q

plasmin

A

breaks down clots

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100
Q

fibrin

A

stabilizes clots

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101
Q

where should you look on the oxyhemoglobin dissociation curve to determine the amount of oxygen that has been delivered to tissues?

A

drop in y value (% hemoglobin saturation)

102
Q

what direction does the oxyhemoglobin dissociation curve shift as a result of exercise?

A

right

represents hemoglobin’s decreased affinity for oxygen, which allows more oxygen to be unloaded at the tissues

103
Q

What is the role of the Chordae Tendinae and Papillary Muscles?

A

The Papillary Muscles contract to pull on the valves via the Chordae Tendinae during a ventricular contraction. This helps prevent blood from flowing back into the Atria from the Ventricles.

104
Q

Place the following layers of the heart in order from inside to out.

I. Endocardium
II. Pericardium
III. Myocardium

(A) I > II > III
(B) II > I > III
(C) I > III > II
(D) II > III > I

A

(C) I > III > II

From inside to outside: Endocardium –> Myocardium –> Pericardium

In questions like these, if you can understand the prefix meanings, it’s a lot easier. For instance, “endo” means inside or within.

105
Q

Which of the following structures is known for connecting cardiac muscle cells and ensuring this coordination in contracting?

(A) The AV Node
(B) The bundle of His
(C) Interventricular Septum
(D) Intercalated Discs

A

(D) Intercalated Discs

The Intercalated Discs are known for connecting cardiac muscle and ensuring coordination while contracting.

106
Q

Which of the following appropriately maps the pathway of Electrical Conduction in the heart?

I. Neural Input
II. Bundle of His
III. AV Node
IV. SA Node
V. Purkinje Fibers

(A) I > II > III > IV > V
(B) I > IV > III > II > V
(C) IV > III > II > V
(D) I > II > IV > V

A

(C) IV > III > II > V

The Electrical Conduction Pathway in the heart is:

  1. SA Node
  2. AV Node
  3. Bundle of His
  4. Purkinje Fibers
107
Q

CRB If neural input is not needed by the SA Node for generating contractions normally, then why is the SA Node innervated?

A

The SA Node can be affected by neural input to either speed up or slow down the rate of contraction!

108
Q

CRB True or false? The depolarization wave spreading from the SA Node also causes the atria to contract, increasing cardiac output by up to 30%.

A

True. The depolarization wave spreading from the SA Node also causes the atria to contract, increasing cardiac output by up to 30%.

109
Q

Which of the following is the proper description of the Frank-Starling Mechanism, which also affects Cardiac Output?

(A) Stretching the heart will increase stroke volume and cardiac output, so filling the heart with less blood will increase the Cardiac Output.
(B) Heartrates can increase to increase Cardiac Output, but only to a point of diminishing returns.
(C) Stretching the heart will increase stroke volume and cardiac output, so increasing Venous Return will increase Cardiac Output.
(D) Increased Cardiac Output can stress the heart, so Venous Return is always kept to the minimum necessary to power life.

A

(C) Stretching the heart will increase stroke volume and cardiac output, so increasing Venous Return will increase Cardiac Output.

110
Q

Match the following terms with their respective function.

(1) Pulmonary Capillaries
(2) Systemic Capillaries

(A) Blood loses oxygen and gains carbon dioxide
(B) Blood loses carbon dioxide and gains oxygen

A

(1) Pulmonary Capillaries – (B) Blood loses carbon dioxide and gains oxygen
(2) Systemic Capillaries – (A) Blood loses oxygen and gains carbon dioxide

Pulmonary circulation entails blood exchanging CO2 for O2. Systemic circulation entails delivering O2 to the cells of the body in exchange for CO2.

111
Q

Which of the following occur during the first heart sound (AKA Lub), also called S1.

I. Mitral & Tricuspid valve close
II. Mitral & Tricuspid valve open
III. Pulmonary & Aortic valve open
IV. Pulmonary & Aortic valve close

(A) I only
(B) I and IV only
(C) I and III only
(D) II and IV only

A

(C) I and III only

During S1, the mitral and tricuspid valves close (which causes the “Lub” sound) and the pulmonary and aortic valves open.

112
Q

Which of the following occur during the second heart sound (AKA Dub), also called S2.

I. Mitral & Tricuspid valve close
II. Mitral & Tricuspid valve open
III. Pulmonary & Aortic valve open
IV. Pulmonary & Aortic valve close

(A) I only
(B) I and IV only
(C) I and III only
(D) II and IV only

A

(D) II and IV only

During S2, the pulmonary and aortic valves close (which causes the “Dub” sound) and the mitral and tricuspid valves open.

113
Q

Which of the following statements about Venules is true?

(A) Venules are larger than Veins.
(B) Venules lead to the Veins.
(C) Venules have lower blood pressure than Veins.
(D) At least two of the above statements are true.

A

(B) Venules lead to the Veins.

The order of bloodflow goes capillary > Venule > Larger Vein.

114
Q

The heart is pumping the blood out, so arteries are under ____ pressure with ____ volume. Veins are under ____ pressure with ____ volume.

(A) High; Low; High; Low
(B) High; Low; Low; High
(C) High; High; Low; Low
(D) High; High; High; High

A

(B) High; Low; Low; High

Arteries have high pressure and low volume.
Veins have low pressure and high volume.

115
Q

High resistance would result from vasoconstriction or vasodilation?

A

Vasoconstriction would cause a high resistance.

116
Q

Increasing which of the following could increase Blood Pressure?

I. The force of Cardiac Contractions
II. The rate of Cardiac Contractions
III. Increasing Precapillary Sphincter Diameters

(A) I and II only
(B) I and III only
(C) II and III only
(D) I, II and III

A

(A) I and II only

Each of the following could increase Blood Pressure:

I. The force of Cardiac Contractions
II. The rate of Cardiac Contractions
III. Decreasing Precapillary Sphincter Diameters

117
Q

Which of the following relationships between Systolic and Diastolic Pressure is accurate in a healthy adult?

(A) Systolic Pressure > Diastolic Pressure
(B) Systolic Pressure = Diastolic Pressure
(C) Systolic Pressure < Diastolic Pressure
(D) More than one of the above answers is possible

A

(A) Systolic Pressure > Diastolic Pressure

As a sign that the heart is effectively pumping blood, Systolic Pressure must be higher than Diastolic Pressure in a healthy adult.

118
Q

Which of the following are present inside the blood vessel under normal conditions, floating around with blood cells?

I. Platelets
II. Collagen
III. Fibrin

(A) I and II only
(B) II and III only
(C) III only
(D) I only

A

(D) I only

Of the following choice, only platelets are floating around in the blood vessel with blood.

Collagen is present outside of the blood vessel.

Fibrinogen is found inside the blood vessel under normal conditions, not fibrin.

119
Q

True or False? While red blood cells do not have a nucleus, their precursors do.

A

True. While red blood cells do not have a nucleus, their precursors do.

120
Q

In a normal adult, blood has the least amount of:

(A) Plasma
(B) White Blood Cells
(C) Red Blood Cells
(D) Water

A

(B) White Blood Cells

Less than 1-percent of blood is made up of white blood cells and platelets.

121
Q

Which of the following cannot be found in the Plasma Layer?

(A) Antibodies
(B) Electrolytes
(C) Platelets
(D) Clotting Factors

A

(C) Platelets

Blood Plasma is composed of:
90% Water
8% Proteins (Albumin, Antibodies, etc)
2% Hormones, Electrolytes, and Nutrients

Platelets and White Blood Cells are found in the Buffy Coat Layer.

The Red Blood Cell Layer only contains Red Blood Cells. But don’t forget that Hemoglobin and other proteins are found within Red Blood Cells.

122
Q

True or False? The only way for oxygen to be transported in the blood is through hemoglobin.

A

False. A very small percentage of oxygen will diffuse right into the plasma.

123
Q

Which of the following are reasons for oxygen delivery into the tissues?

I. High partial pressure of oxygen in the tissues
II. H+ competes with oxygen for hemoglobin
III. CO2 competes with oxygen for hemoglobin

(A) I only
(B) II only
(C) II and III only
(D) I, II, and III only

A

(C) II and III only

H+ and CO2 compete with oxygen for hemoglobin, decreasing the affinity of oxygen for hemoglobin, causing oxygen to be released into the tissues.

The partial pressure of oxygen is LOW in the tissues, which is another reason why oxygen diffuses into the tissues.

124
Q

In which direction, right or left, does the below reaction move when oxygen delivery to the tissues is occurring? What about when carbon dioxide is being delivered to the lungs?

CO2 + H20 <=> H2CO3 <=> HCO3 + H+

A

The equation is moving to the right during oxygen delivery to the tissues. This is due to the increasing amount of CO2 entering from the blood stream.

The equation is moving to the left during carbon dioxide delivery to the lungs. This is due to the decreasing amount of CO2 in the blood stream.

These two scenarios are based on Le Chatlier’s Principle.

125
Q

During inhalation in the lungs, the partial pressure of carbon dioxide is _______, and the partial pressure of oxygen is _________.

(A) high, high
(B) high, low
(C) low, low
(D) low, high

A

(D) low, high

During inhalation in the lungs, the partial pressure of carbon dioxide is low, and the partial pressure of oxygen is high.

126
Q

Draw the oxygen-hemoglobin dissociation curve. What is on the y-axis? What is on the x-axis? What is the shape of the curve and why?

A

The y-axis is the percent saturation of hemoglobin with oxygen.

The x-axis is the partial pressure of oxygen.

The curve is sigmoidal due to the cooperativity effect.
Once one oxygen binds to hemoglobin, it is easier for the remaining oxygens to bind, until there are no more spots for oxygen.

127
Q

Draw the carbon dioxide-hemoglobin dissociation curve. What is on the y-axis? What is on the x-axis? What is the shape of the curve and why?

A

The y-axis is the percent saturation of hemoglobin with carbon dioxide.

The x-axis is the partial pressure of carbon dioxide.

The curve is a straight line because there is no cooperativity in the binding of CO2 to hemoglobin.

128
Q

What antigens do people with Blood Type A contain? What antibodies do people with Blood Type A contain? People with Blood Type A may receive a blood donation from individuals of which blood types?

A
129
Q

Why does a person with Blood Type A have antibodies against Antigen B but not against Antigen A?

A

A person with Blood Type A will generate antibodies against foreign antigens because these are likely part of an invader. For this reason, people with blood type A will generate antibodies against Antigen B (an antigen not found in its own body) and not against Antigen A (an antigen found in its own body).

130
Q

Why can’t a person with Blood Type A receive blood from a person with Blood Type B?

A

The recipient with Blood Type A contains Anti-B Antibodies in their bloodstream. If they received a blood donation from a donor with Blood Type B, the Anti-B Antibodies in the recipient’s bloodstream would attack the donor’s blood cells since they have Antigen B on them. This results in serious inflammation and stress within the recipient’s bloodstream.

131
Q

What antigens do people with Blood Type O contain? What antibodies do people with Blood Type O contain? People with Blood Type O may receive a blood donation from individuals of which blood types?

A
132
Q

main types of muscle

A

skeletal, smooth, cardiac

133
Q

skeletal muscle

function

A

support and movement

propulsion of blood in venous system

thermoregulation

134
Q

skeletal muscle

structure

A

striated

polynucleated

135
Q

skeletal muscle

types

A

red fibers, white fibers

136
Q

skeletal system is under ___ control

A

somatic/voluntary

137
Q

red fibers

A

aka slow twitch fibers

have high myoglobin content

carry out oxidative phosphorylation

138
Q

white fibers

A

aka fast twitch fibers

have less myoglobin

carry out anaerobic metabolism

139
Q

smooth muscle

A

respiratory, reproductive, cardiovascular, and digestive system

capable of more sustained contractions than skeletal muscle

can display myogenic activity

140
Q

smooth muscle

structure

A

nonstriated

uninucleated

141
Q

smooth muscle is under ___ control

A

autonomic

142
Q

myogenic activity

A

do not require nervous system input to contract

(still respond to nervous input)

143
Q

cardiac muscle

A

contractile tissue of the heart

can display myogenic activity

144
Q

cardiac muscle is under ___ control

A

autonomic

145
Q

cardiac muscle

structure

A

striated

uninucleated (sometimes binucleated)

cells connected with intercalated discs

146
Q

sarcomere

A

basic contractile unit of striated muscle

made of thick (myosin) and thin (actin) filaments

147
Q

tonus

A

constant state of low level contraction

seen in blood vessels

148
Q

all muscles require ____ for contraction

A

Ca2+

149
Q

thick filaments

A

organized bundles of myosin

150
Q

thin filaments

A

organized bundles of actin

contain troponin and tropomyosin

151
Q

titin

A

acts as a spring and anchors actin and myosin filaments together, preventing excessive stretching of the muscle

152
Q

Z-lines

A

define the boundaries of sarcomere

153
Q

M-line

A

located in middle of sarcomere

M - middle

154
Q

I-band

A

contains only thin filaments

(I is a thin letter)

155
Q

H-zone

A

contains only thick filaments

(H is a thick letter)

156
Q

A-band

A

contains the thick filaments in their entirety

only part of sarcomere that maintains a constant size during contraction

157
Q

during contraction, which parts of sarcomere change and how?

A

H-zone, I-band, distance between Z-lines, and distance between M-lines decrease

158
Q

myofibrils

A

sarcomeres attached end to edn

159
Q

myocyte/muscle fiber

A

contains many myofibrils

160
Q

myofibrils are surrounded by ___

A

sarcoplasmic reticulum

161
Q

sarcoplasmic reticulum

A

modified endoplasmic reticulum

contains high conc of Ca2+ ions

162
Q

sarcolemma

A

cell membrane of myocyte

163
Q

t-tubules

A

connected to sarcolemma and oriented perpendicularly to myofibrils

allow action potential to reach all parts of the muscle

164
Q

muscle contraction steps

A
  1. acetylcholine released from neuromusclar junction
  2. acetylcholine binds to receptors on sarcolemma –> depolarization
  3. depolarization spreads to t-tubules –> Ca2+ ions released
  4. Ca2+ binds to troponin –> shift in tropomyosin and exposure of myosin binding sites on actin
  5. myosin heads bind to exposed sites on actin –> sarcomere shortens –> cross bridges form and pull actin along thick filament –> contraction
165
Q

muscle relaxation steps

A
  1. acetylcholine degraded by acetylcholinesterase –> terminates the signal and allows Ca2+ to be brought back into SR
  2. ATP binds to myosin head, allowing it to release from actin
  3. sarcomere returns to original width
166
Q

simple twitch

A

all or nothing response of muscle cells

consists of a latent period, contraction period, and relaxation period

167
Q

motor end plate

A

nerve terminal in neuromsucular junction

168
Q

motor unit

A

motor neuron and all of the myocytes innervated by the neuron’s axon terminals, including the neuromuscular junctions between the neuron and the fibers

169
Q

actin myosin cross bridge cycle

A
170
Q

sliding filament model

A

repetitive binding and releasing of myosin heads on actin filaments allows the thin filament to slide along thick filament, causing sequential shortening of sarcomere

171
Q

latent period

A

time between reaching threshold and onset of contraction

actional potential spreads along muscle and allows for calcium to be released from SR

172
Q

frequency summation

A

addition of multiple simple twitches before the muscle has an opportunity to fully relax

173
Q

tetanus

A

simple twitches that occur so frequently that the muscle is unable to relax at all

174
Q

oxygen debt

A

difference between the amount of oxygen needed and the amount present

175
Q

muscle cells have additional energy reserves to…

A

reduce oxygen debt and forestall fatigue

176
Q

additional energy reserves that muscle cells have include:

A

creatine phosphate and myoglobin

177
Q

creatine phosphate

A

transfer a phosphate group to ADP, forming ATP

178
Q

myoglobin

A

heme containing protein that is a muscular oxygen reserve

binds oxygen with a high affinity

muscles use them to keep aerobic metabolism going when muscles run out of oxygen

179
Q

which zone or band in the sarcomere does not change its length during muscle contraction? why?

A

A-band - entire length of myosin filemnt

filaments do not change length, but instead slide over each other –>A band maintains a constant length

180
Q

endoskeletons

A

internal skeletons

181
Q

exoskeletons

A

external skeletons

182
Q

human skeletal system can be divided into:

A

axial and appendicular skeletons

183
Q

axial skeleton

A

consists of structures in midline

skull, vertebral column, rib cage, hyoid bone

184
Q

appendicular skeleton

A

consists of the bones of the limbs, pectoral girdle, pelvis

185
Q

bone is derived from

A

mesoderm

186
Q

compact bone

A

provides strength

dense

187
Q

spongy/cancellous bone

A

has lattice-like structure consisting of trabeculae

188
Q

trabeculae

A

bony points

189
Q

cavities between trabeculae are filled with

A

bone marrow

190
Q

red marrow

A

filled with hematopoietic stem cells

191
Q

yellow marrow

A

composed primarily of fat and is relatively inactive

192
Q

long bones

A

contain shafts called diaphyses that flare to form metaphyses and terminate in epiphyses

193
Q

epiphysis contains

A

epiphyseal (growth) plate

194
Q

epiphyseal plate

A

causes linear growth of bone

195
Q

periosteum

A

layer of connective tissue that surrounds the bone

196
Q

ligaments

A

bone to bone

197
Q

tendons

A

bone to muscle

198
Q

bone matrix

A

has organic components (collagen, glycoproteins, peptides) and inorganic components (hydroxyapatite)

199
Q

bone is organized into

A

concentric rings called lamellae

around a central haversian/volkman’s canal

200
Q

osteon

A

structural unit of bone

201
Q

lacunae

A

between lamellar rings

where osteocytes reside

202
Q

canaliculi

A

connect lacunae

allow for nutrient and waste transfer

203
Q

bone remodeling is carried out by

A

osteoblasts and osteoclasts

204
Q

osteoblasts

A

build bone

205
Q

osteoclasts

A

resorb bone

206
Q

bones and parathyroid hormone

A

inc resportion of bone –> inc calcium and phosphate conc in blood

207
Q

bones and vitamin D

A

increase resportion of bone –> increased turnover –> production of stronger bone

208
Q

bones and calcitonin

A

increases bone formation

dec calcium concentrations in blood

209
Q

cartilage

A

firm elastic material

avascular and not nucleated

found in areas that require more flexibility or cushioning

210
Q

cartilage is secreted by

A

chondrocytes

211
Q

chondrin

A

cartilage matrix

212
Q

endochondral ossification

A

bone forms from cartilage during fetal life

213
Q

intramembranous ossification

A

bones that form directly from undifferentiated tissue (mesenchyme)

ex skull

214
Q

mesenchyme

A

undifferentiated embryonic connective tissue

215
Q

joints may be classified as

A

immovable or movable

216
Q

immovable joints

A

fused together to form sutures or similar fibrous joints

217
Q

movable joints

A

contain synovial capsule

usually strengthened by ligaments

218
Q

synovial fluid

A

aids in motion by lubricating the joint

219
Q

synovial fluid is secreted by

A

synovium

220
Q

articular cartilage

A

coats the bones in the join to aid in movement and provide cushioning

221
Q

antagonistic pairs

A

muscles that serve opposite functions

when one muscle contracts, the other lengthens

222
Q

origin

A

end of the muscle with a larger attachment to bone (usually the proximal connection)

223
Q

insertion

A

end of the muscle with the smaller attachment to bone (usually the distal connection)

224
Q

synergistic muscles

A

work together to accomplish the same function

225
Q

flexor muscle

A

decreases the angle across a joint

226
Q

extenso muscle

A

increases or straightens the angle across a joint

227
Q

abductor muscle

A

moves a part of the body away from the midline

228
Q

adductor muscle

A

moves a part of th ebody toward the midline

229
Q

what chemical forms most of the inorganic component of bone?

A

hydroxyapatite crystals

230
Q

Which of the following important proteins in muscles have ATPase activity?

I. Actin
II. Myosin
III. Titin

(A) II only
(B) I and II only
(C) I and III only
(D) I, II and III

A

(A) II only

Only Myosin has ATPase activity.

231
Q

The myosin-actin crossbridge cycle consists of 4 main steps in which ATP is altered, resulting in the movement of a myosin head in relation to an actin filament. State what the myosin head does in response to each of the following:

(1) ATP binds to the myosin head.
(2) ATP is hydrolyzed, forming ADP and Pi.
(3) ADP and Pi dissociate from the myosin head.

Bonus: Be sure to use the terms “cocked” and “powerstroke”

A

(1) ATP binds to the myosin head. - The myosin head dissociates from the actin filament.
(2) ATP is hydrolyzed, forming ADP and Pi. - The myosin head cocks forward into its higher energy “cocked” conformation, binding to actin one rung higher than before.
(3) ADP and Pi dissociate from the myosin head. The myosin head does its powerstroke, pulling the actin filament. The myosin head remains attached to the actin filament as it waits for another molecule of ATP to bind and restart the cycle.

Note: This likely feels like a lot to memorize, but the AAMC will test you on it!

232
Q

Which of these steps of myosin-actin crossbridge cycle could not occur if there was no actin?

(A) ATP binds to the myosin head.
(B) ATP is hydrolyzed, forming ADP and Pi.
(C) ADP and Pi dissociate from the myosin head.
(D) None of the above would fail to occur

A

(C) ADP and Pi dissociate from the myosin head.

This is the step that cannot occur if there is no actin, since the ADP dissociates due to conformational changes during the power-stroke that occurs when the myosin head is bound to actin.

233
Q

Why doesn’t the actin filament slip back into its starting position each time the myosin head detaches from the actin?

A

This is due to the fact that there are many myosin heads interacting with the actin filament at a given time.

234
Q

Describe the relationship between Ca2+, tropomyosin, troponin, myosin, and actin.

A

Tropomyosin is wrapped around the actin filament, covering up the mysosin binding sites. Troponin is what holds the Tropomyosin in place on the actin, and when Ca2+ binds to troponin, it will pull tropomyosin away from the binding sites, allowing myosin to bind to the actin filament, allowing the cross-bridge cycle to begin.

235
Q

Via what mechanism does Ca2+ get back into the sarcoplasmic reticulum when it is time for muscle relaxation?

(A) Passive diffusion through the membrane
(B) Secondary active transport
(C) Passive diffusion through the ryanodine channels
(D) Primary active transport

A

(D) Primary active transport

When it is time for muscle relaxation, Ca2+ is transported back into the sarcoplasmic reticulum via a pump that utilizes ATP and is known as the Sarco-Endoplasmic Reticulum Calcium ATPase (SERCA).

236
Q

The role of titin is to anchor _____________ to the ____________.

(A) myosin, Z-line
(B) myosin, M-line
(C) actin, Z-line
(D) actin, M-line

A

(A) myosin, Z-line

The role of titin is to anchor myosin to the Z-line.

237
Q

True or False? All skeletal muscles are attached to tendons.

A

False. Not every skeletal muscle is attached to a tendon/bone. For instance, the external oblique muscle is attached to a different fibrous tissue known as an aponeurosis.

238
Q

Which of the following muscle types are striated?

What does that mean? What is responsible for giving the muscle a striated appearance?

I. Smooth Muscle
II. Cardiac Muscle
III. Skeletal Muscle

(A) I Only
(B) III Only
(C) I and III Only
(D) II and III Only

A

(D) II and III Only

Cardiac and skeletal muscle are striated. They are striped due to the presence of sarcomeres arranged end-after-end, and the z-lines linking these sarcomeres gives that dark band appearance.

239
Q

Which of the following are characteristics of smooth muscles?

I. Spindle shaped
II. Only 1 nuclei
III. Nuclei located in the periphery of the cell

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(B) I and II only

Smooth muscles are spindle shaped with only one nuclei in the center.

240
Q

Which of the following are characteristics of cardiac muscles?

I. Branched
II. Can be Uninucleate or Multinucleate
III. Nuclei located in the periphery of the cell

(A) I only
(B) III only
(C) I and II only
(D) I, II and III

A

(C) I and II only

Cardiac muscles are branched. They typically have 1-3 nuclei that are located in the center of the cell.

241
Q

Which of the following are ways that the force of contraction could be increased physiologically?

I. Recruiting larger motor units to contract.
II. Increasing the frequency of stimulation.
III. Increasing the activation of the Antagonistic muscles.

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(B) I and II only

Recruiting larger motor units to contract and increasing the frequency of stimulation can increase the force of contraction.

242
Q

Do type 1 or type 2 muscle fibers fatigue easily? Do type 1 or type 2 muscle fibers resist fatigue?

A

Type 2 muscle fibers fatigue easily. Type 1 muscle fibers are fatigue resistant.

243
Q

What is the role of Myoglobin in the muscles? Does it exhibit cooperativity?

A

Myoglobin is the oxygen storage molecule for the muscle. It is not cooperative, because it is made of only one subunit and can only bind one oxygen molecule.

244
Q

Which of the following are sites for Hematopoiesis in adults?

I. Cancellous Bone
II. Compact Bone
III. Metaphysis

(A) I Only
(B) II Only
(C) I and II Only
(D) I, II, and III Only

A

(A) I Only

Cancellous Bone, also known as Spongy Bone, is the site of Hematopoiesis. In adults, this Hematopoiesis occurs in Red Bone Marrow, which is located in the Epiphysis (NOT the Metaphysis).

245
Q

CRB True or false? Hematopoiesis depends upon its own Pluripotent stem cells, called Hematopoietic Stem Cells.

A

False. Hematopoiesis depends upon its own Multipotent stem cells, called Hematopoietic Stem Cells.

246
Q

Draw a Long Bone and label it with the following parts:

(1) Diaphysis
(2) Metaphysis
(3) Epiphysis

A
247
Q

Compare the role of red bone marrow versus yellow bone marrow.

A

Red bone marrow is responsible for hematopoeises while yellow bone marrow is responsible for fat storage.

248
Q

In which part of an osteon will you find lymphatic vessels, blood vessels, and nerves?

(A) haversian canal
(B) lamellae
(C) canaliculi
(D) lacunae

A

(A) haversian canal

You will find lymphatic vessels, blood vessels, and nerves in the haversian canal of the osteon.

249
Q

In which part of an osteon will you find osteocytes?

(A) haversian canal
(B) lamellae
(C) canaliculi
(D) lacunae

A

You will find osteocytes in the lacunae of osteon.

250
Q

Which of the following cells are derived from monocytes?

(A) Osteoprogenitors
(B) Osteocytes
(C) Osteoblasts
(D) Osteoclasts

A

(D) Osteoclasts

Osteoclasts are derived from monocytes.

251
Q

What effect does increased osteoblast activity have on the blood calcium and phosphate levels? What effect does increased osteoclast activity have on the blood calcium and phosphate levels?

A

Increased osteoblast activity will decrease the amount of calcium and phosphate in the bloodstream due to the use of calcium and phosphate in the formation of hydroxyapatite.

Increased osteoclast activity will increase the amount of calcium and phosphate in the bloodstream due to the release of calcium and phosphate from hydroxyapatite.

252
Q

Too little calcium in the blood will result in which of the following?

I. Lethargy
II. Muscle cramps
III. Convulsions

(A) I and II only
(B) II and III only
(C) I and III only
(D) I, II, and III

A

(B) II and III only

Too little calcium in the blood will lead to muscle cramps and convulsions.

MCAT (26 decks)

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