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Biology > Unit 3- Gas exchange in humans > Flashcards

Unit 3- Gas exchange in humans Flashcards

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1
Q

Why do we need a gas exchange system?

A

-getting oxygen into the blood for respiration
-Get rid of carbon dioxide made from respiring cells

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2
Q

What are the two types of intercostal muscles?

A

-Internal
-External

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3
Q

What does ventilation consist of?

A

-Inspiration (breathing in)
-Expiration (breathing out)

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4
Q

What is ventilation controlled by?

A

Movement of the diaphragm, i external and internal intercostal muscles and the ribcage

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5
Q

Explain what happens during inspiration

A

-External intercostal muscles and diaphragm contract
-Ribcage moves upwards+ outwards
-Diaphragm flattens, increases volume of the thoracic cavity
-Lung pressure decreases to below atmospheric pressure
-air flows down the trachea and into the lungs

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6
Q

Is inspiration an active process?

A

-Yes- it requires energy

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7
Q

Explain what happens during the expiration

A

-External intercostal and diaphragm muscles relax
-Ribcage moves downwards+ inwards
-Diaphragm curves again
-Volume of thoracic cavity decreases
-Air pressure increases to above atmospheric level
-Air is forced won the pressure gradient and out of the lungs

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8
Q

Is normal expiration active or passive?

A

Passive-Does not require energy

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9
Q

What happens when the intercostal muscles are antagonistic?

A

-External relax
-Internal contract pulling the ribcage down and in

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10
Q

Where does the gas exchange occur

A

The alveoli

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11
Q

What are the alveoli surrounded by?

A

A network of capillaries

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12
Q

What is the structure of an alveolus?

A

-Wall is made up of a single thin layer of flat cells called alveolar epithelium
-These walls contain a protein called elastin
-The wall of each capillary is made up of capillary endothelium

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13
Q

What is the purpose of elastin in an alveolus wall?

A

-Helps the alveoli to recoil to their normal shape after inhaling and exhaling

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14
Q

How does air (containing oxygen) reach the alveoli?

A

-Trachea
-Bronchi
-Bronchioles
-Alveoli
-Down a pressure gradient

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15
Q

Why does carbon dioxide move down its own diffusion + pressure gradient?

A

-Moves in an opposite direction to O2 so it can be breathed out

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16
Q

How does oxygen move across the gas exchange system?

A

-Trachea =pressure gradient
-Bronchi =pressure gradient
-Bronchioles =pressure gradient
-Alveoli =pressure gradient
-Alveolar epithelium =Diffussion gradient
-Capillary endothelium =Diffussion gradient
-Blood (into haemoglobin)=Diffussion gradient

Carbon dioxide moves in the opposite direction

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17
Q

What features of the alveoli speed up the rate of diffusion?

A

-Thin exchange surface- Alveolar epithelium is only one cell thick, short diffusion pathway
-Large SA- millions of alveolili
-Steep concentration gradient of oxygen and carbon dioxide between alveoli and capillaries (maintained by flow of blood and ventilation
-Extensive capillary network-diffusion distance for gases short, steep concentration gradient

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18
Q

Do lung diseases affect ventilation or gas exchange?

A

Both

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19
Q

What is tidal volume?

A

The volume of air in each breath (usually between 0.4dm3 and 0.5dm3)

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20
Q

Define ventilation rate.

A

The number of breaths per minute (about 15)

21
Q

What is the forced expiratory volume?

A

The maximum volume of air that can be breathed out in 1 second

22
Q

What is forced vital capacity?

A

The maximum volume of air possible to breathe out of the lungs after a deep breath in

23
Q

Tuberculosis is a disease caused by bacteria, immune system cells build a wall around the bacteria in the lungs which form turbcles, infected tissue within these dies and the gas exchange surface is damaged what effect does this disease have on the gas exchange?

A

-Reduced tidal volume
-TB also causes fibrosis which further decreases it
-As a result, they have an increased ventilation rate

24
Q

Fibrosis is the formation of scar tissue in the lungs which can form after an infection. Scar tissue is thicker and less elastic than regular tissue which means the lungs cannot expand as much, what effect does this have?

A

-Reduced tidal volume
-Reduced FVC
-Diffusion is slower across a thicker scarred membrane #
-Faster ventilation rate to get enough oxygen into the lungs to oxygenate the blood

25
Q

Asthma is a condition where the airways become inflamed and irritated. During an asthma attack, the smooth muscle lining and bronchioles contract and a large amount of mucus is produced which causes constriction of the airway. Airflow out of the lungs is also severely reduced. What effect would this have?

A

-Less oxygen enters the alveoli and moves into the blood
-The FEV is severely reduced

26
Q

Emphysema is when foreign particles become trapped in the alveoli which causes inflammation and attracts phagocytes which break down elastin (the protein found in the walls of the alveoli) . What effect does this have on the gas exchnage?

A

-Elastin helps alveoli to return to their normal shape after inhaling and exhaling
-Loss of this causes the alveoli to not be able to recoil to expel air as well
-Leads to destruction of the alveoli walls so the gaseous exchange rate is reduced
-Have an increased ventilation rate

27
Q

What do all 4 of the diseases reduce?

A

The rate of gas exchnage in the alveoli

28
Q

What effect does this have on the person?

A

-Less oxygen can diffuse into the bloodstream
-The body cells receive less oxygen
-Rate of aerobic respiration is reduced
-Less energy is released causing the person to feel tired and weak

29
Q
A

Percentage change final value -original value
———————————– x100
original value

30
Q

What are the structures involved with the human gas exchange system?

A

-Trachea
-Lungs
-Bronchi
-Bronchioles
-Alveoli
-Capillary network

31
Q

What is the function of the trachea?

A

-Airway that leads from the mouth and nose to the brobnchi
-Is lined with mucus- secreting cells and cilia

32
Q

What is the function of cilia?

A

sweep mucus, dust and bacteria upwards and away from the lungs and the epithelium itself

33
Q

What is the function of the lungs and alveoli?

A

Where gas exchange takes place

34
Q

What are bronchioles?

A

-Narrow tubes which carry air from the bronchi to the alveoli

35
Q

Why do bronchioles collapse?

A

They have no supporting cartilage

36
Q

What is the function of the capillary network?

A

-An extensive network of capillaries surround the alveoli
-Act as an exchange surface between the lungs and blood
-Oxygen diffuses from the alveoli into the capillaries
-carbon dioxide diffuses the other way and is exhaled

37
Q

What are tracheal rings and what are their function?

A

-Rings of carilage
-help to support the trachea and ensure it stays open, while allowing it to move and flex while we breathe

38
Q

What is Ciliated epithelium?

A

a specialised tissue found along the trachea down to the bronchi

39
Q

Where are goblet cells found?

A

scattered throughout the ciliated epithelium in the trachea

40
Q

What is the function of goblet cells?

A

mucus-producing cells that secrete viscous mucus which traps dust, bacteria and other microorganisms and prevents them from reaching the lungs

41
Q

How is mucus destroyed?

A

-swept along by the cilia of the ciliated epithelium upwards and is swallowed
-mucus and any microorganisms will then be destroyed by the acid in the stomach

42
Q

What does the exchange of oxygen and carbon dioxide occur between?

A

alveoli and the capillaries

43
Q

How are oxygen and carbon dioxide exchanged?

A

simple diffusion; (passive movement from high to low concentration)

44
Q

Where is there a high concentration of oxygen?

A

The air in the alveoli

45
Q

What is the concentration of oxygen and carbon dioxide in the blood?

A

low concentration of oxygen and a high concentration of carbon dioxide

46
Q

Where does oxygen and carbon dioxide diffuse?

A

-The oxygen diffuses from the alveoli and into the blood capillaries, before being carried away to the rest of the body for aerobic respiration
- The carbon dioxide diffuses from the blood and into the alveoli and is then exhaled

47
Q

Where is there always a higher concentration of oxygen?

A

In the alveoli

48
Q

PVR (pulmonary ventilation rate)=

A

Tidal volume x breathing rate

Biology (50 decks)

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