The mammalian gases exchange system 7.2

Question 1

why are gases exchange surfaces moist and what is the problem with this

Answer 1

so oxygen dissolves in the water before diffusing into the body tissues.

As a result for the conditions needed to take in oxygen successfully are also ideal for the evaporation of water

Question 2

where does the exchange of gases take place in human

Answer 2

in humans it takes place in the lungs

Question 2

What are the important features of the nasal cavity

Answer 2

• large surface area with good blood supply
• secretes mucus to trap debris and pathogens
• Moist surfaces

Question 3

what is the trachea

Answer 3

• main airway carrying clean, warm, moist air from the nose into the chest.

Question 4

what is the structure of the trachea

Answer 4

• wide tube supported by incomplete rings of strong, flexible cartilage
  ^stop trachea from collapsing
  ^rings incomplete so food can move easily down the oesophagus
• lined with ciliated epithelium and goblet cells

Question 5

what is the function goblet cells and cilia in the trachea

Answer 5

• goblet cells produce mucus to trap debris and pathogens
• cillia beat in rhythmic pattern to move away mucus

Question 6

how does cigarette smoke effect cilia

Answer 6

1 of the effects of cigarette smoke is that it stops cilia beating

Question 7

what path does the air involved in gaseous exchange in humans take through the human body

Answer 7

Nasal cavity
trachea
bronchus
bronchioles
alveoli

Question 8

• what is the bronchus structure
• what is the function
• where can you find it in the body

Answer 8

• trachea divide to form the bronchus
• found in the lungs
• tubes with supporting ring of cartilage but are smaller than trachea
• carry air from trachea to the bronchioles

Question 9

• what are bronchioles split from
• what is there structure and how does this aid there function

Answer 9

• bronchi divide to form small bronchioles.
• have no cartilage rings.
• there walls contain smooth muscle
  ^can contract and relax, so vol of air reaching lungs is influenced
• lined with thin layer of flattened epithelium which makes some gaseous exchange possible

Question 10

what is the alveoli structure and function and where can you find it in the body

Answer 10

• tiny air sacs
• main gas exchange surface
• Each alveolus consists of layer of thin, flattened epithelial cells, along with some collagen and elastic fibres

Question 11

what is meant by the elastic recoil of the lungs

Answer 11

The elastic tissues in the alveoli allow the alveoli to stretch as air is drawn in. When they return to their resting size, they help squeeze the air out.

Question 12

How is the surface area in the alveoli adapted for effective gaseous exchange

Answer 12

large surface area
there are 300-500 million alveoli per adult lung. The alveolar surface area for gaseous exchange in the 2 lungs combined is around 50-75 m^2 which is larger than the average floor area of a house at 67m^2

Question 13

How are the layer of cells in the alveolus adapted for effective gaseous exchange

Answer 13

they have thin layers
both the alveoli and the capillaries that surround them, have walls that are only a single epithelial cell thick, so the diffusion distance between the air in the alveolus and the blood in the capillaries are very short

Question 14

How is the blood supply for alveoli adapted for effective gaseous exchange

Answer 14

• Good blood supply
• supplied by network of capillaries.
• constant flow of blood maintains steep concentration gradient for both CO2 and O2

Question 15

How is ventilation adapted in the alveoli for effective gaseous exchange

Answer 15

Good ventilation
breathing moves air in and out of the alveoli, helping maintain steep diffusion gradients for oxygen and carbon dioxide between the blood and the air in the lungs

Question 16

How are the alveoli adapted for effective gaseous exchange

Answer 16

Large surface area
Thin layers
Good blood supply
Good ventilation

Question 17

what is the inner surface of alveoli covered in

Answer 17

The inner surface of the alveoli is covered in a thin layer of a solution of water, salt and lung surfactant

Question 18

what are the pros and cons of the solution lining the inner surface of the alveoli

Answer 18

the lung surfactant makes it possible for the alveoli to remain inflated.
Oxygen dissolves in the water before diffusing into the blood
Water can also evaporate into the air in the alveoli

Question 19

How are the lungs ventilated

Answer 19

changes in volume and pressure in the thorax drawws air into and out of the lungs

Question 20

what does inspiration mean

Answer 20

taking air in or inhalation is an energy using process

Question 21

Name all the sections of the thorax involved in ventilation and where are they found

Answer 21

The rib cage provides a semi-rigid case within which pressure can be lowered with respect to the air outside it.
The diaphragm is a broad, domed sheet of muscle which forms the floor of the thorax.
The external intercostal muscles and the internal intercostal muscles are found between the ribs.
The thorax is lined by the pleural membranes, which surround the lungs.
The space between them, the pleural cavity, is usually filled with a thin layer of lubricating fluid so the membranes slide easily over each other as you breathe

Question 22

how does the process of inspiration occur

Answer 22

diaphragm contracts, flattening and lowering.
external intercostal muscles contract, moving the ribs upwards and outwards.

this increases volume decreasing pressure compared to atmospheric air so air moves into lungs

Question 23

what is expiration

Answer 23

Breathing out or exhalation is a passive process

Question 24

How does the process of expiration work

Answer 24

passive
diaphrgam relaxes moving up, external intercostal muscles relax, rib cage moves down and in, elastic fibres in alveoli reuturn to normal shape

forcible expiration
internal intercostal muscles contract pulling ribcage in and down fast, abs contract forcing diaphragm up

all of these decrease volume and increase pressure so air is pushed out of lungs

Question 25

How much more force is needed for your first breathe

Answer 25

The first breathe of a newborn baby takes needs a force 15-20 times greater than any normal inhalation to inflate the lungs. The lungs are enormously stretched as the air flows in, and the elastic tissue never returns to its original length

Question 26

What does the lung surfactant important for the alveoli

Answer 26

Lung surfactants contain phospholipids and both hydrophilic and hydrophobic proteins. The surfactant stops the alveoli collapsing and sticking together as you take your first breathe, without it your second breath would be as hard as your first breathe and breathing would be impossible