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Biology AS > 7.2 Mammalian Gaseous Exchange System > Flashcards

7.2 Mammalian Gaseous Exchange System Flashcards

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1
Q

Why do mammals need effective gas exchange systems?

A

Small SA:V ratio, large volume of cells

Higher metabolic rate because:

  • Active
  • Maintain body temperature
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2
Q

What’s the consequence of mammals having a small SA:V ratio and high metabolism?

A

They need lots of oxygen for cellular respiration and they produce CO2 (which needs to be removed.

This exchange of gases occurs in the lungs.

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3
Q

What are the 3 features of the nasal cavity?

A
  1. Large SA w/ GBS
  2. Hairy lining
  3. Moist surfaces
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4
Q

What is the function of a large SA w/ GBS in the nasal cavity?

A

Warms inhaled air to body temperature

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5
Q

What is the function of a hairy lining in the nasal cavity?

A

Secretes mucus.
Mucus traps dust and bacteria.
This protects lung tissue from irritation or infection.

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6
Q

What is the function of moist surfaces in the nasal cavity?

A

Humidity of incoming air is increased, reducing evaporation from exchange surfaces.

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7
Q

What is the state of the air entering the lungs as a result of the nasal cavity adaptations?

A

The air entering the lungs is a similar temperature + humidity to air already there.

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8
Q

What is the trachea and what does it do?

A

Main airway carrying clean + warm + moist air from the nose to the chest

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9
Q

Describe the structure of the trachea

A

Wide tube supported by incomplete rings made up of strong, flexible cartilage - stops trachea collapsing

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10
Q

Why are the rings supporting the trachea incomplete?

A

So food can move down the oesophagus behind the trachea

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11
Q

What is the trachea and its branches lined with?

A

A ciliated epithelium w/ goblet cells between and below the epithelial cells

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12
Q

What is the function of goblet cells?

A

To secrete mucus onto the lining of the trachea.

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13
Q

What is the function of mucus released from goblet cells?

A

To trap dust and microorganisms that escaped the nose lining

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14
Q

What do cilia do?

A

Beat and move mucus along w/ any trapped dirt and microorganisms away from the lungs - most goes into throat = swallowed + digested

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15
Q

What is one effect of smoking?

A

Cigarette smoke stop cilia beating

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16
Q

What is the bronchus?

A

Where the trachea divides to form the left bronchus leading to left lung, and right bronchus leading to right lung.

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17
Q

What is the structure of the bronchi?

A

Similar to trachea, w/ supporting rings of cartilage, but smaller

18
Q

What does 1 bronchi divide into?

A

Many small bronchioles

19
Q

What is the structure of the bronchioles?

A

No cartilage rings ( Diameter 1mm< )

Walls contain smooth muscle

Lined with thin layer of flattened epithelium, making some gas exch. possible

20
Q

What is the function of the smooth muscle in the walls of bronchioles?

A

Muscle contracts = bronchioles constrict (close)

Muscle relaxes = bronchioles relax (open
Changes how much air reaches lungs)

21
Q

What are alveoli?

A

Tiny air sacs which are the main gas exchange surfaces of the body

22
Q

Describe the structure of alveoli and the function of its structure

A
  • Consist of thin, flattened epithelial cells + collagen + elastic fibres (composed of elastin)

These elastic tissue enable alveoli to stretch as air comes in. When they return to normal size, air is pushed out. This is known as elastic recoil of the lungs.

23
Q

What are the 4 adaptations of the alveoli?

A
  1. Large SA
  2. Thin layers
  3. GBS
  4. Good ventilation
24
Q

Explain how thin layers are an adaptation in alveoli

A

Alveoli are one cell thick - short diffusion distance

25
Q

Explain how a good blood supply is an adaptation in alveoli

A

Constant blood flow maintains a steep concentration gradient

26
Q

Explain how good ventilation is an adaptation in alveoli

A

Breathing moves air in + out of alveoli, maintaining steep diffusion gradients for O2 + CO2 between blood + air in lungs

27
Q

What is the inner surface of the alveoli covered in?

A

Thin layer of water, salts and lung surfactant

28
Q

Where are lung surfactants? What is their function?

A
  1. Inner surface of alveoli

2. Enables alveoli to remain inflated

29
Q

What happens to oxygen as a result of the solution of water on the inner surface of the alveoli?

A

Oxygen dissolves into the water before diffusing into the blood, but water can also evaporate into the air in the alveoli

30
Q

What is ventilation?

A

Movement of air in + out of lungs as a result of pressure changes in the thorax (chest cavity) as a result of breathing movements.

31
Q

What does the shape of the ribcage provide?

A

A semi-rigid case, in which pressure can be lowered in comparison to the air outside of it

32
Q

What is the diaphragm?

A

Broad, domed sheet of muscle which forms the floor of the thorax

33
Q

What types of muscle can be found between the ribs?

A

External intercostal muscles

Internal inercostal muscles

34
Q

What is the thorax lines lined by?

A

Pleural membranes which surround the lungs

35
Q

What do you call the space between the pleural membranes which line the thorax and what is their function?

A

Pleural cavity - Filled w/ thin layer of lubricating fluid so membranes easily slide over each other as you breathe

36
Q

What is inspiration?

A

Taking in air (inhalation)

Energy-using process

37
Q

What happens during inspiration?

A
  • Diaphragm contracts + lowers
  • External intercostal muscles contract, moving ribs upwards + outwards
  • Vol. of thorax increases so pressure in thorax decreases - now lower than pressure of air so air is drawn through airway - this equalises pressure inside +
    outside chest
38
Q

What is expiration?

A

Exhalation (breathing air out)

Passive process

39
Q

What happens during expiration?

A
  • Diaphragm relaxes; moves up into its resting domed shape
  • External intercostal muscles relax = ribs move downwards + inwards due to gravity
  • Elastic fibres in alveoli return to normal length

The effect of this is that the vol. of thorax decreases

  • Pressure in thorax is now greater than normal air pressure, so air moves out of lungs until pressure inside and outside of lungs is equal
40
Q

What happens when you exhale forcibly?

A
  • Internal intercostal muscles contract, pulling ribs down hard + fast
  • Abs contract, forcing diaphragm up to rapidly increase pressure in lungs

Biology AS (148 decks)

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