7 Mammalian Gas Exchange Flashcards

1
Q

what is the need for a gas exchange system (GES) in multicellular organisms?

A

low SA:vol ratio

large diffusion distance

high metabolic rate

∴ diffusion rate too low to sustain aerobic respiration

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2
Q

what is the definition of a tissue?

A

a group of one or more cell types that are specialised and working together for a particular function

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3
Q

what is the definition of an organ?

A

a group of one or more tissue types that are specialised to carry out specific function(s)

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4
Q

what is the definition of an organ system?

A

a collection of organs with particular function

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5
Q

what are the component parts of the GES?

A

lungs, trachea, bronchi, bronchioles, larynx, mouth, diaphragm

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6
Q

why is a rich blood supply required for the lungs?

A

maintains a steep concentration gradient for gas exchange of O(2) and CO(2)

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7
Q

what is the diameter of an alveolus?

A

~ 200 - 300 um

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8
Q

what is the purpose of surfactant in the alveoli?

A

makes the lining moist ∴ reduces surface tension and prevents the alveoli sticking together during exhalation

easier for O(2) to dissolve and diffuse into the blood

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9
Q

what is the purpose of smooth muscle in the bronchi and bronchioles?

A

to control the diameter of the lumen during inhalation and exhalation

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10
Q

what is the purpose of ciliated epithelial cells?

A

to keep the airway free of debris by wafting mucus and its contents up the trachea to be swallowed or expelled as sputum

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11
Q

what is the purpose of goblet cells?

A

to secrete mucus (a glycoprotein) to trap pathogens and other foreign objects

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12
Q

what is the purpose of cartilage in the trachea?

A

to provide support to keep the airway open during inhalation as the pressure in the thorax decreases

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13
Q

what happens during inhalation?

A

intercostal muscles: contract

ribcage: up and out
diaphragm: contracts and flattens

thorax pressure: decreases

thorax volume: increases

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14
Q

what happens during exhalation?

A

intercostal muscles: relax

ribcage: down and in
diaphragm: relaxes and domes

thorax pressure: increases

thorax volume: decreases

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15
Q

name three factors that contribute to lung size

A

body size (and ∴ gender)

physical activity level

general health

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16
Q

what is roughly the capacity of the lungs?

17
Q

what is the definition of tidal volume?

A

the volume of air that moves in and out of the lungs during a normal breath

18
Q

what is the definition of vital capacity?

A

the maximum amount of air that can be forcibly expelled from the lungs following breathing as deeply as possible

~ 3 - 5 dm^3

19
Q

what is the definition of residual volume?

A

the volume of air remaining in the lungs after a maximal expiratory effort

20
Q

what is the definition of dead space?

A

the volume of non-exchange surfaces in the breathing system

21
Q

what is definition of pulmonary ventilation?

A

the amount of air exchanged with the environment per minute

22
Q

how is pulmonary ventilation calculated?

A

p.v. = tidal volume x breathing rate

23
Q

what is FEV(1)?

A

{forced expiratory volume}

the volume of air that can be breathed out in the first second of forced exhalation

24
Q

how is FEV(1) calculated?

A

FEV(1) = (4.3 x height - 0.029 x age) - 2.49

25
what is PEFR?
{peak expiratory flow rate} the maximum rate of forcing air out through the mouth
26
what is the use of PEFR?
used to diagnose pulmonary disorders
27
what can cause respiratory arrest?
obstruction of trachea or bronchi drug overdose asthma attack severe pneumonia severe shock heart attack
28
how is respiratory arrest treated?
expired air resuscitation then CPR