Gas Exchange In Mammals/Humans

Question 1

Why do mammals need an increased rate of aerobic respiration

Answer 1

Mammals have a low surface area to volume ratio, however they are also very active and maintain a constant body temperature.

Question 2

What is a result of a high rate of aerobic respiration

Answer 2

Mammals have a very high oxygen demand

Question 3

How do mammals get oxygen

Answer 3

From the air by their lungs

Question 4

How many lungs do humans have and where are they found

Answer 4

They have two lungs which are found in the thorax or chest cavity.

Question 5

What are the lungs protected by

Answer 5

The lungs are protected by the ribs

Question 6

What are the different parts of the body that are involved in breathing/ventilation

Answer 6

Intercostal muscles, ribs, and the diaphragm

Question 7

What happens when humans breathe through their noses

Answer 7

Air passes through their nasal cavity

Question 8

What are some adaptations of the nasal cavity

Answer 8

It has a large surface area with a good blood supply that warms the air to body temperature

A hairy lining which separates the mucus to trap dust and pathogens protecting the lungs.

Moist surfaces which increase the humidity of the air, reducing evaporation from exchange surfaces

Question 9

Where does air go after passing through the nasal cavity

Answer 9

The trachea

Question 10

What are the 2 main adaptations of the trachea (1)

Answer 10

The walls of the trachea contain incomplete rings of cartilage, which is a firm but flexible material.
This prevents the walls of the trachea from collapsing when we inhale.

Question 11

Why are the cartilage rings in the trachea incomplete

Answer 11

The trachea is very close to the oesophagus (a tube which carries food to the stomach)
The cartilage in the trachea forms incomplete rungs and there is no cartilage near the oesophagus allowing food to pass down it easily.

Question 12

What are the 2 main adaptations of the trachea (2)

Answer 12

The walls of the trachea are lined with ciliated epithelia and goblet cells.
Goblet cells secrete mucus which traps dust particles and pathogens.
The ciliated epithelial cells have cilia extending from their cell membranes and the beating of the cilia moves the mucus to the throat.
The mucus is then swallowed and the dust and pathogens are digested by the stomach enzymes and HCL

Question 13

What does the trachea divide into

Answer 13

It divides into two bronchi

Question 14

Where does each bronchus carry air into and what do they contain

Answer 14

Each bronchus carries air into one of the lungs. And each bronchi contains cartilage, ciliated epithelial and goblet cells.

Question 15

What do the bronchus split into

Answer 15

Each bronchus then splits forming progressively narrower airways called bronchioles.

Question 16

What do the bronchioles contain and not contain

Answer 16

They contain no cartilage rings
The walls of the bronchioles contain smooth muscle

Question 17

What happens when the smooth muscle in the bronchioles contract

Answer 17

When the smooth muscle contracts they widen allowing more air to pass into the deeper parts of the lungs.

Question 18

What are the bronchioles lined with

Answer 18

They are lined with a thin layer of flat epithelium, making some gaseous exchange possible in the bronchioles.

Question 19

What do the bronchioles lead to

Answer 19

They lead into air sacs called alveoli

Question 20

What are the alveoli the site of

Answer 20

Gas exchange

Question 21

How many alveoli are in the lungs

Answer 21

There are hundreds of millions of alveoli in the lungs.

Question 22

What do the alveoli consist of

Answer 22

A layer of thin, flattened epithelial cells along with some collagen and elastic fibres (comprised of elastin)

Question 23

What are the internal walls of the alveoli covered in. And what does it make possible to do.

Answer 23

With a thin layer of solution of water, salts and lung surfactant. This surfactant makes it possible for the alveoli to stay inflated.

Question 24

What are the alveoli covered with (blood vessels)

Answer 24

They are covered with extensive blood capillaries.

Question 25

What does the oxygen in the air of the alveoli do

Answer 25

Dissolves n the moisture on the inside of the alveolar wall. And it then diffuses into the red blood cells where it combines with haemoglobin.

Question 26

What does the CO2 in the blood do

Answer 26

It diffuses from the blood into the alveolar airspace

Question 27

What is present between alveoli and what is the process that they do called

Answer 27

Elastic fibres which stretch when air is drawn in and when they return to their previous size are is squeezed out. And this is known as the elastic recoil of the lungs.

Question 28

What are the adaptations of the alveoli to maintain high rates of diffusion (1 and 2)

Answer 28

Because there area lots of alveoli it provides a very large surface area for the diffusion of gases. Both the wall of the alveoli and blood capillaries are 1 cell thick so there is a very short diffusion distance between the air in the alveoli and the red blood cells in the capillary.

Question 29

What are the adaptations of the alveoli to maintain high rates of diffusion (3)

Answer 29

Because of the extensive capillary network once oxygen diffuses into the blood it is rapidly carried away from the alveoli meaning that a steep concentration gradient of oxygen is maintained.

Question 30

What are the adaptations of the alveoli to maintain high rates of diffusion (4)

Answer 30

Good ventilation - breathing moves air in and out of the alveoli helping maintain step diffusion gradients for oxygen and carbon dioxide between the blood and air in the lungs, increasing the rate of diffusion.

Question 31

What muscles are involved in ventilation

Answer 31

The diaphragm which separates the thorax from the abdomen and the intercostal muscles.

Question 32

What do the muscles work together to do

Answer 32

Change the volume of the thorax, which changes the pressure of the air in the lungs, allowing air to be drawn into the lungs during inspiration and to expel air from the lungs in expiration.

Question 33

How many types of intercostal muscles are present

Answer 33

There are two sets of intercostal muscles, the external and the internal intercostal muscles.

Question 34

What occurs during inspiration (1)

Answer 34

The external intercostal muscles contract, pulling the ribs upwards and outwards, the diaphragm also contracts causing it to flatten. The effect of these is to increase the volume of the thorax and lungs. Reducing the air pressure in the lungs.

Question 35

What occurs during inspiration (2)

Answer 35

Because the air pressure in the lungs is less than atmospheric pressure, air is drawn into the lungs. Air moves into the alveoli and the elastic fibres between the alveoli stretch.

Question 36

What is a feature of inspiration

Answer 36

Because it involves muscle contraction inspiration is an active process, energy is required.

Question 37

What is a feature of expiration

Answer 37

It is a passive process as the muscles relax.

Question 38

what occurs during expiration (1)

Answer 38

The external intercostal muscles relax and return to their original length. The diaphragm also relaxes returning to the original domed shape. The elastic fibres of the alveoli also return to their previous shape. Reducing the volume of the thorax and the lungs.

Question 39

what occurs during expiration (2)

Answer 39

So the air pressure in the lungs is greater than atmospheric pressure and air is pushed out of the lungs. The elastic fibres between the alveoli also recoil, pushing air out.

Question 40

What are the lungs surrounded by, what is between them and what does it act as

Answer 40

The lungs are surrounded by the pleural membranes, between them is the pleural fluid, which acts as a lubricant when the lung volume changes.

Question 41

What happens when we exhale strongly

Answer 41

The internal intercostal muscles contract pulling the ribs down and inwards forcing air out of the lungs. At the same times the external intercostal muscles relax. The abdominal muscles also contract.

Question 42

What can we use to measure things that occur when breathing

Answer 42

Spirometers

Question 43

What is a float spirometer

Answer 43

It consists of a large plastic tub which sits in a tank of water.

Question 44

What are some things that should be done when using a float spirometer

Answer 44

The subject should wear a nose clip so that they only breathe through their mouth. Each subject should use a fresh sterilised mouthpiece to avoid passing on any infections.

Question 45

What do spirometers contain and what does it absorb

Answer 45

It usually contains soda lime absorbing any CO2

Question 46

What is the breathing rate and how can it be interpreted on a Spirogram

Answer 46

Breathing rate is the number of complete breaths per minute Where the distance from one peak to the next or one trough to the next is one breath. The number of peaks or troughs in one minute = breathing rate.

Question 47

What is the tidal volume and how can it be interpreted on a spirogram

Answer 47

Is the volume of air passing into and of of the lungs during a breath. This is the volume of air from a trough to a peak.

Question 48

What is the inspiration reserve volume

Answer 48

When a person inhales as much as they possibly can then this volume of air is the inspiratory reserve volume.

Question 49

What is the expiratory reserve volume

Answer 49

When a person exhales as much as they possibly can then this volume of air is the expiratory reserve volume.

Question 50

What is vital capacity

Answer 50

Expiratory reserve volume + inspiration reserve volume

Question 51

Why does the total volume of air in the spirometer decrease over time

Answer 51

Because the carbon dioxide is absorbed by the soda lime absorbing

Question 52

What is the oxygen uptake equal to

Answer 52

The volume decrease in a minute.

Question 53

What is the residual volume

Answer 53

The volume of air left in your lungs when you have exhaled as hard as possible

Question 54

What is the total lung capacity equivalent to

Answer 54

The vital capacity + residual volume

Question 55

What is the ventilation rate = to

Answer 55

Tidal volume x breathing rate

Question 56

What happens when the oxygen demand of the body increases

Answer 56

The tidal volume of air moved in and out of the lungs can increase. The breathing rate also increases. The ventilation of the lungs and so the oxygen uptake during gaseous exchange can increase to meet the demand of the tissue.