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Biology Unit 1 > 3.1.4 Lungs > Flashcards

3.1.4 Lungs Flashcards

1
Q

What characteristics must an exchange surface have in order to support fast diffusion?

A

Large surface area, short diffusion path, steep concentration gradient.

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2
Q

What is Epithelial tissue?

A

The name given to layers of cells which cover all external and internal surfaces of the body

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3
Q

Where is Squamos Epithelium found?

A

Surrounding the alveoli

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4
Q

What is ciliated epithelium?

A

Tissue that is found on the trachea and bronchi, which is not adapted for exchange, but lubrication and protection.

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5
Q

How do alveoli meet the three requirement of Fick’s Law?

A
  • Have huge surface area
  • They are composed of flattened epithelial cells to give short diffusion path
  • blood flow and ventilation maintain steep concentration gradient.
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6
Q

What is Fick’s Law?

A

The rate at which a substance can diffuse, calculated by

(Surface Area x Concentration Difference)/Distance

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7
Q

How does water loss occur in the gas exchange system?

A

Water diffuses down the concentration gradient from tissue cells into the air in the alveoli

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8
Q

How is water loss minimised in the gas exchange system?

A

By having the gas exchange surface deep in the body.

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9
Q

Why do epithelial cells in the bronchioles secrete mucus?

A

To trap bacteria and other microscopic particles that enter the lungs.

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10
Q

What happens to the mucus in the bronchioles?

A

It is swept up by the cilia of the ciliated epithelial cells to the throat, then swallowed so all bacteria in the mucus is killed by stomach acid.

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11
Q

What is Ventilation?

A

The movement of air over the gas exchange surface.

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12
Q

Through what muscles does ventilation work?

A

The whole thorax moves and changes size due to the action of the diaphragm and the intercostal muscles

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13
Q

How are the movements from the diaphragm and intercostal muscles transmitted to the lungs?

A

Via the pleural sac surrounding each lung

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14
Q

How is the pleural sac involved in ventilation?

A

The outer membrane is attached to the thorax and the inner membrane is attached to the lungs. Between them is incompressible pleural fluid, so when the thorax moves, so do the lungs

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15
Q

How do muscle contractions in the thorax cause air to move in and out of the lungs?

A

They cause the volume of the hora. To change which changes the pressure in the lungs causing air to flow in or out

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16
Q

Ventilation in humans is tidal. What does this mean?

A

Air flows in and out by the same route

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17
Q

What is the relationship between air flows and pressure?

A

Air always flows from high pressure to low pressure

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18
Q

Describe Inspiration as a part of ventilation

A

The diaphragm contracts and flattens, external intercostal muscles contract, pulling the ribs up and out, increasing the volume of the thorax and stretching the alveoli, decreasing the pressure below atmospheric levels so air flows in.

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19
Q

Describe normal expiration in ventilation

A

Diaphragm and intercostals relax, so ribs fall. This decreases the volume of the thorax and lungs and alveoli shrink by elastic recoil. Pressure increases above atmospheric level and air flows out

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20
Q

Explain forced expiration in ventilation

A

Abdominal a contract pushing the diaphragm up, intercostals contract pulling ribs down. Expiration is much faster

21
Q

What is pulmonary ventilation?

A

The volume of air ventilating the lungs each minute. Ventilation rate * Tidal Volume.

22
Q

What is the ventilation rate?

A

Can be measured using pressure graph by measuring time taken for one ventilation cycle. Ventilation rate = 60/cycle time

23
Q

What is tidal volume?

A

The normal volume of air breathed in each breath. Can be measured from the volume graph

24
Q

What is the difference between gas exchange and ventilation?

A

V is active and uses ATP. GE does not. V is quick, GE is slow. Gases in GE can move in different directions at once, in V all gases flow in one direction.

25
Q

What is Asthma?

A

An allergic response that causes difficulty breathing, wheezing, tight chest and coughing.

26
Q

What allergens cause Asthma

A

Pollen, dust mite faeces and fur.

27
Q

Explain the inflammatory response caused by allergens in Asthma

A

White bloods cells called mast cells release histamines which cause the smooth circular muscles of the bronchioles to contract, narrowing the airways. This contracting is called bronchoconstriction

28
Q

In an asthmatic reaction, what happens after bronchoconstriction?

A

The epithelial cells secrete more mucus which further blocks the airways. The constricted bronchioles stimulate wheezing and coughing to loosen the mucus.

29
Q

What effect does bronchoconstriction have on tidal volume?

A

It reduces tidal volume, so alveolar air is replaced slowly, which reduces the oxygen concentration gradient across the alveolar epithelium so less oxygen is diffused into the blood for respiration

30
Q

What is the risk factor for Asthma?

A

Exposure to allergens.

31
Q

How can asthma be treated?

A

By inhaling drugs that relax the smooth muscles and anti inflammatory drugs

32
Q

What is Emphysema?

A

Severe breathing difficulties resulting in an inability to do any exercise

33
Q

What is the course of the disease for Emphysema?

A

Tar in cigarettes stimulates W. Blood Cells to release protease enzymes which digests the elastin in the alveolar epithelium, so they can no longer expand and recoil. This reduces oxygen diffusion gradient so less oxygen diffuses into the blood

34
Q

What occurs in severe cases of Emphysema?

A

The alveolar epithelium is completely destroyed so the alveoli merge to form large air sacs with thicker walls and smaller surface area, reducing the rate of oxygen diffusion.

35
Q

What is the risk factor for Emphysema?

A

Smoking. (Side note: Emphysema is Incurable)

36
Q

What is Lung Cancer?

A

Uncontrolled growth of epithelial tissue in the lungs due to Mutagenic Agents. This growth forms a tumour which may constrict the bronchioles and alveoli, slowing gas exchange.

37
Q

What is the risk factor for lung cancer?

A

Exposure to mutagenic agents such as radon gas, asbestos gas and tobacco smoke.

38
Q

What is Pulmonary Tuberculosis and what are its symptoms?

A

An infectious lung disease caused by bacteria. Symptoms include chest pains, tiredness, weight loss due to appetite loss, coughing up blood and death.

39
Q

How is Tuberculosis transmitted to a host?

A

Through aerosol droplets from coughs and sneezes of an infected person

40
Q

What are tubercles?

A

Lumps of bacterial cells that form in the alveoli and bronchioles

41
Q

What responsein the immune system occurs in response to the presence of tubercles in the lungs?

A

Inflammation caused by the W Blood cells which results in the formation of fibrous scar tissue which reduces the elasticity of he alveoli and thickens their walls, reducing the rate of oxygen diffusion

42
Q

What is the effect of TB after months/years?

A

The bacteria emerge from the tubercles and reproduce inside lung epithelial cells and kill them, and reducing the alveolar surface area.

43
Q

Apart from affecting the lungs, what other adverse affects does TB have on the body?

A

The bacteria can spread to other organs through the blood like kidney, bone tissue, nervous tissue, etc. which are destroyed causing the body to waste away and die.

44
Q

What is the main risk factor for TB?

A

Overcrowding, as it allows TB to spread rapidly. Other factors include poor diet and AIDS.

45
Q

How can TB be treated?

A

Antibiotics and the BCG Vaccine (but rising resistance to vaccine)

46
Q

What is Pulmonary Fibrosis?

A

Severe shortness of breath caused by the inhalation of fine dust particles or chemicals

47
Q

What is the course of Pulmonary Fibrosis as a disease?

A

Dust particles stimulate an inflammatory response which causes fibrous scar tissue growth around the alveoli, which thickens the alveolar epithelium and decreases the surface area, lowering the rate of oxygen diffusion. It also reduces the elasticity of the alveoli which reduces passive exhalation, which means less oxygen reaches the blood

48
Q

What is are the risk factors for pulmonary fibrosis?

A

Pulmonary fibrosis is seen as an occupational disease. Coal dust, silica dust, mould spores, etc.

49
Q

Describe the path by which oxygen goes from the alveolus to the blood

A
  • Through the alveolar epithelium

- and through the capillary epithelium

Biology Unit 1 (7 decks)

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