Physiology 1 Flashcards

1
Q

External Respiration Definition

A

Sequence of events that leads to the exchange of O2 and CO2 between the external environment and cells of the body

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2
Q

How many steps in external respiration?

A

4

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3
Q

4 steps of external respiration?

A

Ventilation
Gas exchange between alveoli
Gas transport in the blood
Gas exchange at tissue level

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4
Q

Internal Respiration Definition?

A

Intra-cellular mechanism which consumes O2 and produces CO2

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5
Q

Ventilation

A

Mechanical process of moving air between the atmosphere and the alveolar sacs

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6
Q

Gas exchange between alveoli

A

The exchange of O2 and CO2 between the air in the alveoli and the blood in the pulmonary capillaries

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7
Q

Gas transport in the blood

A

The binding and transport of O2 and CO2 in the circulating blood

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8
Q

Gas exchange at tissue level

A

The exchange of 02 and CO2 between blood in the systematic capillaries and the body cells

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9
Q

4 body systems involved in external respiration

A

Respiratory
Circulatory
Nervous
Haematology

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10
Q

Boyles Law?

A

At any constant temperature the pressure exerted by a gas varies inversely with the volume of the gas
(As volume of gas increases the pressure exerted by the gas decreases)

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11
Q

What must happen to intra-alveolar pressure for air to flow into the lungs during inspiration?

A

Must become lower than atmospheric pressure

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12
Q

Intra-alveolar pressure before inspiration?

A

Equivalent to atmospheric pressure

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13
Q

Why do thorax and lungs expand in Inspiration

A

Contraction of Inspiratory muscles

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14
Q

2 forces that hold the lungs and thoracic wall in close opposition?

A

Intrapleural Fluid cohesiveness- water molecules attract each other, pleural membranes stick together
Negative intraplueral pressure- transmural pressure gradient across lung and chest walls

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15
Q

3 pressures important in ventilation?

A

Atmospheric pressure
Intra-alveolar pressure
Intra-pleural pressure

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16
Q

Normal atmospheric pressure?

A

760 mm hg at sea level

17
Q

How is the volume of the thorax increased?

A

Contraction of the diaphragm, flattening out its dome shape

18
Q

What lifts the ribs and moves out the sternum?

A

External intercostal muscle contraction

19
Q

Physiology during inspiration?

A

Elevated Rib cage- Increases side to side dimensions of thoracic cavity
Contraction of diaphragm- increases vertical volume of thoracic cavity

20
Q

Process of Inspiration

A

Chest walls and lungs are stretched
Increase in size of lungs causes decrease in intra-alveolar pressure
Air then enters the lungs down the concentration gradient, until intra-alveolar pressure becomes equal to atmospheric

21
Q

Normal expiration?

A

Passive process brought about by relaxation of the inspiratory muscles

22
Q

Pneumothorax

A

Air in the pleural space

23
Q

What can abolishe the transmeural pressure gradient?

A

A Pneumothorax

24
Q

Symptoms of pneumothorax

A

Shortness of breath, Chest pains

25
Q

Physical signs of pneumothorax?

A

Hyperresonant percusssion

Decreased/absent breath sounds

26
Q

What causes the lungs to recoil during expiration?

A

Elastic connective tissue

Alveolar surface tension

27
Q

Alveolar surface tension?

A

Attraction between water molecules at liquid air interface

28
Q

What reduces alveolar surface tension?

A

Surfactant

29
Q

If alveoli were coated in water alone?

A

Surface tension too much, aveoli would collapse

30
Q

LaPlace’s Law?

A

P=2T/r
P=Inward directed collapsing pressure
T= Surface Tension
r=Radius of the bubble

31
Q

What does LaPlace’s law say?

A

Alveoli with smaller radiuses have a higher tendancy to collapse

32
Q

Pulmonary surfactant?

A

Complex mixture of lipids and proteins secreted by type 2 alveoli

33
Q

How does pulmonary Surfactant work?

A

Lowers alveolar surface tension by interspersing between water molecules lining the alveoli

34
Q

What are developing fetal lungs unable to do until late in pregnancy?

A

Synthesize surfactant = premature babies may not have enough= Respiratory distress syndrome of newborn

35
Q

Factor which helps keep the alveoli open?

A

The alveolar interdependence

36
Q

Alveolar Interdependence

A

If an alveolus starts to collapse, the surrounding alveoli are stretched and then recoil exerting expanding forces in the collapsing alveolus to keep it open.

37
Q

Forces keeping alveoli open?

A

Transmural pressure gradient
Pulmonary surfactant
Alveolar Interdependence

38
Q

Forces promoting alveolar collapse?

A

Elasticity of stretched lung connective tissue

Alveolar surface tension