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MCAT biology > chapter 9 > Flashcards

chapter 9 Flashcards

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1
Q

pathway of air through the body?

A
  • enters the nostrils or the oral cavity
  • travels down to the pharynx
  • travels down to larynx
  • down the trachea
  • down to the bronchi into successively smaller segments known as secondary bronchi, tertiary bronchi, and bronchioles
  • then into the alveoli where gas exchange occurs
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2
Q

what does the nasal cavity contain?

A
  • contains mucous membranes and hairs known as vibrissae that filter particulate matter
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3
Q

what is the function of the epiglottis?

A
  • the switch point that separates the respiratory and digestive systems
  • it is a cartilagenous tissue that covers the larynx during the act of swallowing, shunting food into the esophagus
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4
Q

what houses the vocal cords and how do they work?

A
  • the larynx contains the vocal cords which vibrate to produce sounds when air is pushed through them and are consciously controlled during speaking
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5
Q

what does the trachea have?

A
  • the epithelium of the trachea is lined with goblet cells which produce mucus and the epithelial cells are ciliated
    • particulate matter and microbes that are still present in the air are trapped in the mucus, and the cilia pushes the mucus upwards where it becomes phlegm that can be expelled or swallowed
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6
Q

what are alveoli covered with?

A
  • surfactant which is a film that reduces surface tension, allowing the alveoli to remain inflated when the lung is compressed during exhalation
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7
Q

what is the thoracic cavity?

A
  • it contains the lungs and the heart and is protected by the rib cage
    • the lungs do not adhere directly to the thoracic cavity
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8
Q

the lun is covered by a serous membrane known as?

A
  • the pulmonary pleura while an outer membrane, known as the parietal pleura is what adheres to the thoracic cavity
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9
Q

when fluid accumulates in the pleural space, what happens?

A
  • pleural effusion
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10
Q

if air enters the pleural space, what happens?

A
  • pneumothorax
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11
Q

what is the main driver of breathing?

A
  • the diaphragm- the muscle at the bottom of the thoracic cavity that separates it from the abdominal cavity below
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12
Q

when the diaphragm contracts, what happens?

A
  • the thoracic cavity expands which causes the parietal pleura to expand, causeing a pressure gradient that in turn causes the pulmonary pleura and the lungs to expand
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13
Q

what happens to the pressure inside the lungs when they expand?

A
  • the pressure within them decreases. this decreased pressure compared to the external environment causes air to rush into the respiratory tract (negative pressure respiration)
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14
Q

what is passive exhalation?

A
  • the simple relaxation of the diaphragm is enough to cause the lungs to contract, increasing the pressure and expelling air
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15
Q

what is active exhalation?

A
  • when the muscles between the ribs and abdominal mucles can be used to force air out more intensely and quickly
    • usually occurs during exercise but if it occurs at rest, could be a sign of respiratory disease
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16
Q

what occurs during gas exchange?

A
  • blood runs through the alveolar capillaries and is separated by a wall only one cell thick from the air that is being breathed in
  • the deoxygenated blood being returned to the lungs is rich in carbon dioxide and poor in oxygen, while the air being breathed in is rich in oxygen and relatively poor in carbon dioxide
  • therefore, oxygen and carbon dioxide simply diffuse down their respective concentration gradients
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17
Q

Describe this chart?

A
  • the tidal colume is the volume of air contained in a normal breath
  • the expiratory reserve volume is the amount of additional air that can be exhaled after a normal exhalation
  • the inspiratory reserve volume is the amount of additional air that can be inhaled after a normal inhalation
  • the total lung capacity is the most air that can be possibly present in the lungs after inhaling as deeply as possible
  • the residual volume is the air that remains in the lungs after breathing out as much as possible
  • the vital capacity is the difference between the TLC and RV
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18
Q

The respiratory system plays a role in what kind of immune response?

A
  • the innate immune system
    • the ciliated cells and mucus throughout the respiratory tract help trao particulate matter and pathogens
    • antibiotic proteins known as defensins are secreted in the respiratory tract
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19
Q

the respiratory system also plays a role in?

A
  • thermoregulation
    • extensuve capillary beds are present in the nasal cavity and trachea and can either expand or contract to allow more or less blood to pass through them
    • when more blood passes through vessels close to an interface with the external environment, more heat can be radiated (vasodilation)
    • when less blood is circulated through such vessels, heat is conserved (vasoconstriction)
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20
Q

Carbon dioxide participates in an equilibium with?

A

carbonic acid and the bicarbonate ion

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21
Q

what can occur if the pH of the blood strays away from normal?

A
  • acidemia/acidosis when the pH goes below 7.35
  • alkalmeia/alkalosis when the pH goes above 7.45
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22
Q

too much carbon dioxide in the blood indicates that?

A
  • the bidy needs more oxygen to power aerobic respiration and makes the blood too acidic
    • the NS detects this through chemoreceptors that detect acidic conditions. when stimulated, they cause the respiratory rate to increase which causes CO2 to be expelled form the body while allowing more oxygen in
    • this shifts the balance of the bicarbonate equilibrium away from H+ and increases the pH of blood
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23
Q

if the pH of the blood is too high (alkaleima), what happens?

A
  • the rate of respiration decreases allowing carbon dioxide to build up, and thereby re-acidifying the blood
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24
Q

What is blood plasma?

A
  • Plasma is the largest part of your blood. It, makes up more than half (about 55%) of its overall content. When separated from the rest of the blood, plasma is a light yellow liquid. Plasma carries water, salts and enzymes, proteins, hormones, etc.
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25
Q

what is plasma volume?

A
  • connected to hydration and blood pressure
  • greater plasma volume is correlated with higher blood pressure levels
  • less plasma volume levels mean lower blood pressure
  • drhydration is also associated with low plasma volume and low blood pressure
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26
Q

plasma volume is regulated by the endocrine system and excretory system. which hormones play a role?

A
  • aldosterone and ADH that increase fluid retention
    • aldoesterone increases sodium reabsorption in the DCT and collecting duct of the nephron which drives water reabsorption through osmosis
    • ADH acts directly on the collecting duct in the npehron to increase water reabsorption
    • ANP decreases the plasma volume by decreasing sodium absorption
27
Q

what is the buffy coat?

A
  • contains leukocytes (WBC and are major component of innate immune system) and platelets (fragments of cells that allow the blood to clot)
28
Q

if a blood vessel ruptures, platelets react with what to form a clot?

A
  • collagen, thrombin, vitamin K and calcium
    • prothrombin to thrombin
    • fibrinogen to fibrin
29
Q

what is the hematocrit layer composed of?

A
  • erythrocytes (RBC) which carry oxygen to the different tissues of the body
30
Q

erythrocytes are created in the bone marrow in response to?

A
  • erythropoietin, a hormone that is released from the kidney when RBC levels are low
    • only engage in anaerobic respiration as they have no nucleus or mitchondria
31
Q

erythrocytes also express a variety of glycoproteins on their surface (blood type system) which is an example of?

A
  • codominance
32
Q

what is the Rh factor?

A
  • found on different gene and does not exhibit codominance, instead it involves a single antigen that is either present (+) or absent (-)
  • independent from the ABO blood type system
33
Q

what are the chambers of the heart?

A

right and left atria

left and right ventricle

34
Q

what is the path of blood?

A
  • deoxygenated blood returns to the right atrium via the superior and inferior venae cave and the coronary sinus, which drains the coronary veins
  • from there it is pumped to the right ventricle through the tricuspid valve
  • then it foes to the pulmonary arteries through the pulmonary semilunar valves
  • after becoming oxygenated, it is returned to the heart via pulmonary veins, and enters the left atrium
  • it is pumped through the bicuspid valve from the left atrium to the left ventricle
  • the left ventricle pushes the blood into the circulation through the aortic semilunar valves into the ascending aorta
35
Q

the valves in the heart function to ensure that?

A
  • blood only flows in one direction
    • Atrioventricular valves and semilunar valves
    • bicuspid valve is aka the mitral valve
36
Q

what do the terms systole and diastole refer to?

A
  • systole refers to when the heart is contracting
  • diastole is used to refer to when the heart is relaxed
    • 120/80 mmHg
37
Q

what are the 3 types of blood vessels?

A
  • arteries
  • capillaries
  • veins
38
Q

how are arteries defined?

A
  • move blood away from the heart
39
Q

how are capillaries defined?

A
  • tiny blood vessels where gas exchange takes place
40
Q

how are veins defined?

A
  • carry blood back toward the heart
41
Q

in the systemic circulayion, which supplies blood to the tissues of the body, arteries supply oxygenated blood, but in the pulmonary circulation, which specializes in gas exchange, the pulomary arteries carry?

A
  • deoxygenated blood away from the heart to get reloaded with oxygen in the lungs and then the pulmonary veins return the newly oxygenated blood to the body
42
Q

arteries carry high-pressure blood so they have?

A
  • thick muscular walls which can dilate or constrict
43
Q

how does thermoregulation work in arteries?

A
  • vasoconstriction of the arteries near the skin is used to conserve heat in a cole environment
  • vasodilation of the arteries is used to dissipate excess heat
    • vasodilation can also be used to supply more oxygenated blood to specific tissues in response to neurological control
44
Q

As arteries branch off from each other, they develop into smaller, more numerous?

A
  • arterioles
    • blood pressure drops quickly between the arterioles and capillaries
45
Q

how many erythrocytes can pass through a capillary at a time?

A

one at a time to ensure enough time for gas exchange

46
Q

after moving through the capillaries, deoxygenated blood moves into?

A
  • venules which drain into veins whcih then gather into the venae cavae before returning to the heart
47
Q

what carries the low pressure blood?

A
  • veins and have much thinner walls
  • they have valves that allow blood flow in one dirction
    • muscles also help with this
48
Q

blood vessels are lined with?

A
  • endothelial cells, which are structurally similar to epithelial cells with the exception that they contain the protein vimentin, rather than keratin
  • they play a major role in vascular physiology including functioning as a selective barrier between blood vessels and the rest of the tissue of the body as well as mediating inflammation, vasodilation and vasoconstriction, blood clottinh and angiogenesis (the development of new blood vessels)
49
Q

how does the heart contract?

A
  • it can set its own rhythm which is controlled by the SA node which periodically send out action potentials
    • gap junctions between teh cardiac muscle cells allow the action potential to propagate throughout the tissue causing contraction
    • the action potential flows from the SA node to the atria, but not into the ventricles because of a layer of insulating tissue. this causes the atria to contract, pushing blood forward into the ventricles
    • the AV node allows the action potential to pass through the ventricles after the atria contracted, The ventricles must then contract together, so the signal is sped through the bundle of His and the Purkinje fibers to all the muscle cells of the ventricles
50
Q

the rhythym of the heart is regulated by both the?

A
  • nervous and endocrine system
    • the autonomic nervous system regulates the heart (para and sympathetic)
    • hormones like epinepherine and norepinepherine can increase heart rate
51
Q

A pressure differential is used to drive flow through a netowrk of tubes that provide resitance. the equation for this is?

A

Q= deltaP/R

  • Q is the flow through the system (equivalent to the cardiac output for the systemic circulation)
  • deltaP is the overall change in pressure
  • R is the peripheral resistance (the resistance provided by the blood vessels)
    • RQ=P given constant flow, resistance and deltaP are proportional to each other (increase R, P goes up too)
    • analagous to V=IR where V for electric potential is analogous to deltaP, I for electric current is analogous to Q (blood flow) abd R is used for resistance in both contexts
52
Q

How does high altitude affect blood pressure?

A

The higher you travel, the less oxygen you take in with each breath. The body responds to this by increasing the heart rate and the amount of blood pumped with each beat. As a result, there is a temporary increase in blood pressure until the body adapts to the lower oxygen levels

53
Q

what is the continuity equation?

A

A1v1=A2v2

54
Q

blood pressure throughout the body from largest to least?

A
  • aorta
  • elastic arteries
  • muscular arteries
  • arterioles
  • capillaries
  • venules
  • medium and large veins
  • venae cavae
55
Q

what is hydrostatic and oncotic pressure and what happens if they dysregulate?

A
  • hydrostatic pressure is the “pushing” pressure due to the force of water on its container
  • the oncotic pressure is the “pulling” pressure due to the presence of solutes in a soltuons
    • the hydrostatic pressure drops as you move from the arterial end of the capillary bed to the venous end, but the oncotic pressure remains pretty constant
    • therefore, the hydrostatic pressure pushes water into the interstitial tissue and the oncotic pressure pulls it back in on the venous end
    • dysregulation of this process due to excessibe hydrostatic pressure or insufficient oncotic pressure can lead to edema
56
Q

Hemoglobin has 2 forms:

A
  • T state- low affinity for oxygen
  • R state- high affinity
57
Q

when oxygen binds to the first heme group, it shifts the hemoglobin from?

A
  • T form to R form facilitating further binding (cooperative)
58
Q

what is the Bohr effect?

A
  • The Bohr Shift describes the movement of the oxygen dissociation curve to the right of normal. This occurs due to increased levels of carbon dioxide, such as when a person increases their exercise level, which causes an increased concentration of carbonic acid to be formed.
59
Q

What causes the hemoglobin curve to shift to the left?

A
  • high pH
  • low BPG
  • low temperature
60
Q

what cuases the hemoglobin curve to shift to the right?

A
  • low pH
  • high BPG
  • high temperature
61
Q

how is carbon dioxide excreted?

A
  • The enzyme carbonic anhydrase converts carbon dioxide gas to carbonic acid (H2CO3)
  • carbonic acid then dissociates into bicarbonate and H+; since bicarbonate ion is charged, it moves freely though the aqueous blood
  • carbon dioxide as a gas is exhaled in gas exchange in the lungs, where it diffuses down its concentration gradient and out of the body
62
Q

fetal hemglobin has a?

A
  • greater affinity for oxygen because it is less strongly affected by 2.3-BPG so this allows fetal hemoglobin to “take” oxygen from maternal hemoglobin
63
Q
A

MCAT biology (12 decks)

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