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Structure And Function Of Living Organisms > Respiratory systems > Flashcards

Respiratory systems Flashcards

1
Q

What is partial pressure

A

pressure of a single gas in a gas mixture

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2
Q

What factors affect the rate of diffusion

A

partial pressure gradient, diameter of the gas molecules, temperature, solubility of the gas in liquid, thickness of the gas exchange surface, surface area

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3
Q

Ficks law to calculate rate of diffusion

A

diffusion coefficient x surface area x (partial pressure difference/thickness of interface)

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4
Q

What does the respiratory system consist of

A

specialized body surfaces for gas exchange, mechanisms to ventilate the environmental face of this surface, mechanisms to perfuse the internal face of this surface

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5
Q

What is required when an organisms does not have a specialized system

A

thin, moist integument

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6
Q

What features do respiratory organs have

A

large surface area, thin barrier, a partial pressure difference that forces O2 in and CO2 out

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7
Q

What features do animals in liquid environments have

A

gills are highly branched and folded extensions to maximise surface area, thin tissue, new medium flows continuously over surfaces

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8
Q

What features do animals in gaseous environments have

A

Invaginations (protects the respiratory surface), increased internal surface area, thin tissue (minimizes diffusion path length)

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9
Q

What does the trachea branch into

A

bronchus then bronchioles than alveoli for gas exchange

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10
Q

where is the diaphragm located

A

between the thorax and abdomen

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11
Q

Function of the dead space

A

Transfer of gases to/from alveoli, warming and humidify in inspired air, filtration and removal of foreign material(protection - muscus/cilia)

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12
Q

what is tidal ventilation

A

the volume of air moved in and out while breathing

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13
Q

What are the consequences of tidal ventilation

A

Incoming air mixes with ‘used’ gas, reserve provides reservoir of O2, dead space does not participate in gas exchange

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14
Q

what does air entering the lungs ventilate

A

both the dead space and the alveoli

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15
Q

how do you calculate the minute ventilation of the entire lung

A

dead space volume + amount of fresh air available for gas exchange

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16
Q

How do you calculate the amount of fresh air available for gas exchange

A

(tidal volume-dead space) x breathing rate

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17
Q

how do you calculate the tidal volume

A

dead space volume + amount of fresh air available for gas exchange

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18
Q

How can the amount of fresh air available for gas exchange be increased

A

increasing the tidal volume or by increasing the respiratory frequency

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19
Q

How do birds maximise gas exchange

A

Using unidirectional airflow so incoming air does not mix with stale air

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20
Q

What is the primary role of the respiratory system

A

Meet the metabolic demands of the organism

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21
Q

What is ventilation

A

Convection of respiratory medium over the gas exchange surfaces (active or passive) which maintains a partial pressure gradient at the respiratory interface

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22
Q

Intrapleural space at rest

A

pressure is lower than surroundings inside the space creating a pressure gradient for the alveoli

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23
Q

Lungs at rest

A

expand to fill thoracic cavity because intrapleural pressure is negative (with respect to atmospheric pressure)

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24
Q

What is functional residual capacity

A

The volume remaining in the lungs after a normal, passive exhalation.

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25
Functional residual capacity at rest
Increased compared to when someone is exercising or standing
26
When does ventilation occur
When active muscle force is applied to the relaxed respiratory system
27
What happens during inspiration
Active process where the volume of thorax increases, the diaphragm contracts and external intercostal muscles contract
28
What does the increased volume of the thorax lead to
decreases intrapleural pressure, alveoli expand (pressure decreases because the molecules are further apart). Barometric pressure gradient(alveolar pressure < atmospheric pressure). Air flows into the lungs until alveolar pressure = atmospheric pressure.
29
What is Boyle's law
P1V1 = P2V2
30
Describe expiration
Passive process, diaphragm relaxes, external intercostal muscles relax, elastic recoil of the lungs and chest wall reduce volume of the thorax
31
What does a decrease in the volume of the thorax lead to
Increased pressure in the intrapleural pressure. The alveoli recoil as pressure is released (pressure inside increases as molecules are now more compressed) P alveoli > P atmosphere. Air expelled from the lungs
32
Summarise inspiration
Alveolar pressure < atmospheric pressure. Air moves into the lungs. Expiration is the opposite
33
Compliance formula
Change in volume/ change in pressure
34
How is the stretchiness measured
by the compliance so how much the pressure increases
35
On an FRC x pressure graph why does inspiration cause the curve to deviate right
resistive forces which oppose airflow: airway resistance, pulmonary tissue resistance (friction between lungs and chest wall), inertia of the air and tissues
36
Why is airway resistance important
Means greater pressure has to be generated for airflow because the air has to flow through a system of narrow tubes
37
Function of pleural fluid
Minimizes friction between the lungs and chest
38
On a FRC x pressure graph why does expiration cause the curve to deviate left
because resistive forces assist airflow: elastic recoil of lungs and chest wall, surface tension in alveoli, expiration can be active during forces exhalation (internal intercostal and abdominal muscles contract)
39
What is the ventilation in birds like
lung volume changes less than in mammals, air moves through lungs from interconnected air sacs (don't participate in gas exchange but provide continuous air flow), laminar flow across the lungs, negative pressure pump (one way movement of air)
40
What is laminar flow
type of fluid (gas or liquid) flow in which the fluid travels smoothly or in regular paths
41
What is the ventilation like in frogs
air is forced into the lungs and then emptied by abdominal contraction
42
What is the air movement like in insects
airway penetrate each body segment, allowing diffusion. Abdominal muscles 'pump' air through tracheae
43
Describe the water movement across gills
Energy is required to 'pump' water across the gills. Water 'pulled' across gills when opercular activity expands and opercular flaps open. Water 'pushed' over gills when fish close their mouth
44
Features of laminar flow
slow flow rate, parallel stream lines
45
What is Poiseuille's law
Flow rate = (pressure gradient x pi x (airway radius)^4) / (8 x viscosity of liquid x airway length)
46
resistance formula
pressure gradient / flow rate
47
What is resistance proportional to
1 / (airway radius)^4
48
What are the features of turbulent flow
high flow rate, disorganised stream lines
49
What are the features of transitional flow
intermediate flow rate, eddy current (swirling of a fluid and the reverse current)
50
What causes airway resistance to decrease
increasing the volume of conducting airways
51
Why does resistance decrease as the lung expands
connective tissue pulls on bronchioles, so their diameter expands and airway resistance falls
52
What happens to airway resistance when we breathe out
Bronchioles recoil, so lung volume is reduce and airway resistance rises rapidly because radial traction is relieved
53
What is dynamic compression
Occurs at low lung volume or when intrathoracic pressure > alveolar pressure (forced expiration). Airways are compressed and may close. Occurs during active expression
54
What affects bronchial smooth muscle tone
nervous activity, hormones or external factors
55
What is bronchioconstriction and what causes it
increased airway resistance caused by irritant (reflex constriction of trachea, large bronchi), parasympathetic stimulation, fall in PCO2, asthma
56
What is bronchiodilation and what causes it
lowered airway resistance, caused by autonomic stimulation (circulation catecholamines), sympathomimetic agents (beta 2 agonists)
57
How can infection increase airway flow resistance
inflammation of the tissue lining of the upper airways. Overproduction/accumulation of mucus
58
Elastic properties of the lungs
when inflated lungs can recoil or collapse back to resting volume. Elastic recoil is determined by elastic properties of lung tissue and surface tension in the alveoli. Elastin and collagen fibers in alveolar wall and around blood vessels and bronchi. Network of fibers allow distension, but recovers geometry when pressure is released
59
What problems does the air-fluid interface in alveoli cause
attractive forces in liquid (surface tension) oppose expansion by inspired air, promotes collapse of smaller alveoli, causes transudation of fluid from capillaries
60
What minimises air-fluid interface problems in alveoli
Surfactant
61
What is pulmonary surfacant
Phospholipoprotein screwed from type II alveolar cells, lowers the surface tension in the liquid layer. Prevents alveolar collapse at low pressures. Present in air breathing animals and some fish
62
When is compliance reduced
when surface tension is increased (decreased production of surfactant)
63
Features of the pulmonary circulation system
gas composition in arteries and veins is opposite to those in systemic circulation. Low pressure. Artery walls are thin and contain little smooth muscle. Low vascular resistance
64
Vascular resistance formula
(input pressure-output pressure)/blood flow
65
Why are there higher rates of flow at the bottom of the lungs
Due to decreasing perfusion and ventilation going from the bottom to the top of the lungs due to the effects of gravity
66
Ventilation in an upright individual
interpleural pressure is greater (more negative) at the apex. Atmospheric pressure (Palv) is constant
67
Perfusion in an upright individual
Blood pressure greater at the base Pa>Pv>Palv (at the base, opposite at the apex). Distribution affected by posture, exercise and diet.
68
What is Va:Q
the amount of air that reaches your lungs divided by the amount of blood flow in the capillaries in your lungs
69
What does a Va:Q value of 0 mean
Blood passing through the lung without coming in to contact with alveolar air
70
What does a Va:Q value of infinity mean
anatomical dead space, or ventilated alveoli that are not perfused
71
what is important to optimise gas exchange
local matching of ventilation and perfusion
72
What are the mechanisms to defend Va:Q matching
modulation of blood flow rather than ventilation, vasoconstriction by low PO2 (hypoxia). Blood is directed away from poorly - ventilated area
73
What influences the transfer of O2
diffusion across the red blood cell membrane and combination with haemoglobin
74
What is cooperative binding
when one oxygen binds to Hb, a chemical change makes it easier for more oxygen to bind to Hb
75
What causes the bohr shift to occur
Higher Pco2, [H+], temperature, 2-3 BPG
76
which capillaries have a lower average resting partial pressure of O2
systemic capillaries
77
What is haemocyanin
Cu containing molecule, packaged in cells
78
Which molecules have a higher affinity than haemoglobin
myoglobin and foetal Hb
79
CO2 chemical combination in plasma
CO2+H2O <-> H2CO3 <-> H+ + HCO3- <-> H+ + CO32-
80
What do guard cells control
air and water movement. Open in direct response to K+ influx and increased turgor pressure
81
What control breathing in mammals
neural networks: brainstem (cellular control), sends signals to respiratory muscles (effectors), then to receptors (sensor) which sends signals back to the brain
82
Where to breathing patterns start
medulla to spinal cord to respiratory muscles
83
Name the receptors in the lung
stretch receptors, juxta-pulmonary "J" receptors, irritant receptors, proprioreceptors (position/length sensors)
84
Central chemoreceptors
Located near ventolateral surface of the medulla, sensitive to pH CSF (index of PCO2), slow response time and relatively insensitive to change in PO2
85
Peripheral chemoreceptors
in carotid and aortic bodies (high blood flow). Responds rapidly, detect oscillations during breathing
86
What causes increased breathing rate
Decreases PO2, increased [H+] and increased PCO2
87
What is hypoxia
Low levels of oxygen
88
What is hypercapina
abnormally high CO2
89
What is the diving reflex in mammals
triggered by cold water on the face, reduced heart rate, increased peripheral vasoconstriction, lactate accumulation in muscle, energy conservation (delayed increased PCO2)

Structure And Function Of Living Organisms (10 decks)

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