Human Physiology - 6.4 Gas Exchange

Question 1

processes involved in physiological respiration

Answer 1

1. Ventilation
2. Gas Exchange
3. Cell Respiration

Question 2

Ventilation

Answer 2

maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing flowing in adjacent capillaries

The exchange of air between the atmosphere and the lungs – achieved by the physical act of breathing

Question 3

Gas Exchange

Answer 3

The exchange of oxygen and carbon dioxide between the alveoli and bloodstream (via passive diffusion)

process of swapping carbon dioxide for oxygen

occurs in the alveoli of the lungs but the process of diffusion down concentration gradients between to blood and the air

Question 4

Cell Respiration

Answer 4

The release of energy (ATP) from organic molecules – it is enhanced by the presence of oxygen (aerobic)

oxygen is used and carbon dioxide is produced

Question 5

Physiological respiration involves

Answer 5

the transport of oxygen to cells within the tissues, where energy production occurs

It is comprised of three distinct processes and is not to be confused with cellular respiration (a single component of the activity)

Question 6

Purpose of Ventilation

Answer 6

Because gas exchange is a passive process, a ventilation system is needed to maintain a concentration gradient in alveoli

the exchange of air between the atmosphere and the lungs (ie the physical act of breathing)

Question 7

to maintain the concentration gradients the air must…

Answer 7

be refreshed frequently

Question 8

Function of the lungs

Answer 8

it is a ventilation system by continually cycling fresh air into the alveoli from the atmosphere - O2 levels stay in the alveoli (and diffuse INTO the blood) and CO2 levels stay low (and diffuse FROM the blood)

Question 9

why do you need a concentration gradient

Answer 9

so oxygen and carbon dioxide and flow down the concentration gradient without the use of energy - if used energy = taking away from other things (eg managing body tempreture)

Question 10

benefits to the lungs

Answer 10

The lungs are also structured to have a very large surface area, so as to increase the overall rate of gas exchange

Question 11

Lung structure

Answer 11

Air enters the respirator system through the NOSE or MOUTH and passes through the PHARYNX to the TRACHEA. The air travels down the trachea until it divides into two BRONCHI

The right lung is composed of three lobes, while the left lung is only comprised of two (smaller due to position of heart)

Inside each lung, the bronchi divide into many smaller airways called BRONCHIOLES (increasing in surface area). each bronchiole terminates with a closer of air sacs called ALVEOLI where gas exchange with the bloodstream occours

Question 12

Alveoli

Answer 12

= give the long a huge area for gas exchange (the longs contains about 700 millions of them) –> the wall of the alveoli consists of a singular layer of very thin cells so the gases only have to diffuse a short distense

it is covered by a dense network of BLOOD CAPILLARIES with low oxygen and high CO2 concentrations –> they diffuse out down the concentration gradients

Question 13

cells in the alveolus…

Answer 13

secrete a flud which keeps the inner surface of the alveolus moist allowing gases to dissolve

Question 14

purpose of concentration gradients

Answer 14

ventilation maintains concentration gradients of oxygen and CO2 between air in alveoli and blood flowing in adjacent capillaries

Question 15

How does ventilation work (2)

Answer 15

1) muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them

2) different muscles are required for inspiration and expiration because the muscles only do work when they contract

Question 16

examples of antagonistic muscle action

Answer 16

external and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action

Question 17

Inhaling - info.

Answer 17

1) external intercostals muscles contract, ribcage moves up and out
2) diaphragm contacts, flattens, moves down
3) volume of thorax increases
4) pressure inside thorax drops below atmospheric pressure
5) Air flows into the lungs until pressure evens out

Question 18

Exhaling - info.

Answer 18

1) Interal intercostals muscles contract, ribcage moves down and in
2) abdominal muscles contract, pushes diaphragm uo
3) volume of thorax decreases
4) pressure inside thorax rises above atmospheric pressure
5) air flow out of the lungs until pressure evens out

Question 19

Alveolar cell types =

Answer 19

consist of an epithelial layer and extracellular matrix surrounded by capillaries

the alveoli contain some elastic fibres –> allow the alveoli to stretch as they are filled with air during inhalation –> spring back during exhalation in order to expel the CO2 rich air

Question 20

Alveolar cell types =

Answer 20

consist of an epithelial layer and extracellular matrix surrounded by capillaries

the alveoli contain some elastic fibres –> allow the alveoli to stretch as they are filled with air during inhalation –> spring back during exhalation in order to expel the CO2 rich air

Question 21

Type 1 pneumocytes

Answer 21

extremely thin epidermal cells that make up the all of the laveolus

Question 22

Type 2 pneumocytes

Answer 22

Secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension

Question 23

Alveolar Macrophages (dust cells)

Answer 23

are wandering macrophages that destroy bacteria and remove particulate matter (dust)

Question 24

Structure of an Alveolus

Answer 24

Alveoli function as the site of gas exchange, and hence have specialised structural features to help fulfil this role:

1) They have a very thin epithelial layer (one cell thick) to minimise diffusion distances for respiratory gases
2) They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood
3) They are roughly spherical in shape, in order to maximise the available surface area for gas exchange
4) Their internal surface is covered with a layer of fluid, as dissolved gases are better able to diffuse into the bloodstream

Question 25

Two types of alveolar cells –

Answer 25

type I pneumocytes and type II pneumocyteS

Question 26

Type I pneumocytes (BIONINJA)

Answer 26

Type I pneumocytes are involved in the process of gas exchange between the alveoli and the capillaries

They are squamous (flattened) in shape and extremely thin (~ 0.15µm) – minimising diffusion distance for respiratory gases

Type I pneumocytes are connected by occluding junctions, which prevents the leakage of tissue fluid into the alveolar air space

Type I pneumocytes are amitotic and unable to replicate, however type II cells can differentiate into type I cells if required

Question 27

Type II pneumocytes (BIONINJA)

Answer 27

Type II pneumocytes are responsible for the secretion of pulmonary surfactant, which reduces surface tension in the alveoli

They are cuboidal in shape and possess many granules (for storing surfactant components)

Type II pneumocytes only comprise a fraction of the alveolar surface (~5%) but are relatively numerous (~60% of total cells)

Question 28

Type II pneumocytes secrete a liquid known as pulmonary surfactant which reduces the surface tension in alveoli

Answer 28

As an alveoli expands with gas intake, the surfactant becomes more spread out across the moist alveolar lining
This increases surface tension and slows the rate of expansion, ensuring all alveoli inflate at roughly the same rate

Question 29

MORE ON THE MECHS OF BREATHING - MAINLY MOVEMENT — DONT BE LASY ACTUALLY WATCH THE VIDEO AT THE END

Answer 29

https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/64-gas-exchange/mechanism-of-breathing.html

Question 30

BREATHING - MOVEMENT

Answer 30

When the pressure in the chest is less than the atmospheric pressure, air will move into the lungs (inspiration)

When the pressure in the chest is greater than the atmospheric pressure, air will move out of the lungs (expiration)

Question 31

Chronic Obstructive Pulmonary Disease (COPD)

Answer 31

–> it is characterized by progressive airflow limitation
–> it can be classified as: mild, moderate or severe (based on measurement of Forced Expiratory Volume

Question 32

Forced Expiratory Volume

Answer 32

= the max volume of air that can be exhaled in 1 second

Question 33

Emphysema

Answer 33

Emphysema is a lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls

The loss of elasticity results in the abnormal enlargement of the alveoli, leading to a lower total surface area for gas exchange
The degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae)

The major cause of emphysema is smoking, as the chemical irritants in cigarette smoke damage the alveolar walls

The damage to lung tissue leads to the recruitment of phagocytes to the region, which produce an enzyme called elastase
This elastase, released as part of an inflammatory response, breaks down the elastic fibres in the alveolar wall
Elastase activity can be blocked by an enzyme inhibitor (α-1-antitrypsin), but not when elastase concentrations are increased
A small proportion of emphysema cases are due to a hereditary deficiency in this enzyme inhibitor due to a gene mutation

Question 34

Common symptoms of emphysema

Answer 34

include shortness of breath, phlegm production, expansion of the ribcage, cyanosis and an increased susceptibility to chest infections

Question 35

Asthma - causes

Answer 35

Airborne allergens, such as pollen, dust mites, mold spores, pet dander or particles of cockroach waste

Respiratory infections, such as the common cold

Physical activity

Cold air

Air pollutants and irritants, such as smoke

Certain medications, including beta blockers, aspirin, and nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve)

Strong emotions and stress

Sulfites and preservatives added to some types of foods and beverages, including shrimp, dried fruit, processed potatoes, beer and wine

Gastroesophageal reflux disease (GERD), a condition in which stomach acids back up into your throat

Question 36

Asthma - consequences (symptoms)

Answer 36

SYMPTOMS:
1) Shortness of breath
2) Chest tightness or pain
3) Wheezing when exhaling, which is a common sign of asthma in children
4) Trouble sleeping caused by shortness of breath, coughing or wheezing
5) Coughing or wheezing attacks that are worsened by a respiratory virus, such as a cold or the flu

EXTREME CONCEQUENCES:
- A permanent narrowing of the tubes that carry air to and from your lungs (bronchial tubes), which affects how well you can breathe

Question 37

Chronic Obstructive Pulmonary Disease (COPD) - causes

Answer 37

Main cause = smoking
Minor causes = exposure to industrial dusts or genetics

Question 38

Chronic Obstructive Pulmonary Disease (COPD) - Consequences

Answer 38

Respiratory infections. People with COPD are more likely to catch colds, the flu and pneumonia. …
Heart problems. …
Lung cancer. …
High blood pressure in lung arteries. …
Depression.

Question 39

Lung cancer - what is cancer

Answer 39

cancer is cause by a series of mutations in genes that control gell growth (oncogenes) and repair damaged DNA (tumour suppressor genes)

==> cells become abnormal by growing out of control and thus forming TUMOURS

cancer cells do not die, and no longer to the purpose of the original cell.

blood vessels grow around the tumours to supply food for cell growth

cancer cells detach and spread to other parts of the body

Question 40

Oncogenes =

Answer 40

genes that control cell growth

Question 41

Tumour =

Answer 41

large mass of cells that are growing out of control

Question 42

Apoptosis

Answer 42

when normal cells commit cell suicide because they are no longer needed

Question 43

cells that no longer do their job become =

Answer 43

undifferentiated

Question 44

angiogensis =

Answer 44

blood vessels growing around tumours to supply food for cell growth

Question 45

Metastasis =

Answer 45

when cancer cells detach and spread to other parts of the body

Question 46

benign tumours =

Answer 46

remain in one place

Question 47

malignant tumors =

Answer 47

spread to other parts of the body:
either via:
1) the bloodstream
or
2) the lymphatic system

Question 48

tumours in the lungs

Answer 48

as tumors become larger and more numerous they undermine the lung’s ability to provide the bloodstream with oxygen

Question 49

cancer represents 13% of all

Answer 49

global deaths

Question 50

consequences of lung cancer

• just bullet points - for info refer to pg 24 of bio booklet

Answer 50

1) shortness of breath
2) coughing up blood
3) pain
4) fluid in the chest (pleural effusion)
5) cancer that spread to other parts of the body (metastasis)
6) shortened lifespan

Question 51

causes of lung cancer (3)

Answer 51

1) carcinogens
2) genetic predispositions (develops from exposure from certain environmental factors + genetic mutations)
3) spontaneous mutations

Question 52

causes of lung cancer - carcinogens

Answer 52

• they damage DNA
• when our bodies are exposed to carcinogens, free radicals have formed that try to steal electrons from other molecules in the body. These free radicals damage cells and affect their ability to function ad divide normally.

eg. tobaccos, asbestos, etc

Question 53

Spirometry

Answer 53

https://ib.bioninja.com.au/standard-level/topic-6-human-physiology/64-gas-exchange/spirometry.html