Chapter 7.2

Question 1

Why do mammals need effective gas exchange systems?

Answer 1

• This is because as the size mammal increases, the bigger the SA:V ratio
• Furthermore this means a lower metabolic rate because they are not that active and need to maintain there body temperature independent to the environment
• As a result they need not much of oxygen for cellular respiration and they produce CO2 which needs to be removed……………… so effective gaseous exchange systems needed.

Question 2

What are important features of the nasal cavity?

Answer 2

• Large surface area with good supply which warms the air.
• Have moist surfaces which reduce the dryness of the incoming air, reducing evaporation from the exchange surfaces.
• Hairy lining which trap dust and bacteria, which helps protect the lung delicate tissue from irritation and infection

Question 3

What is the air like after it passes the nasal cavity?

Answer 3

it is similar temperature and humidity to the air

Question 4

What is trachea? What is function?

Answer 4

Is is the main airway - and is responsible for carrying clean air from the chest up to nose.

Question 5

What is the structure of the trachea like? How does the structure relate to its’ adaptation?

Answer 5

Narrow tube supported by uncompleted rings of strong and flexible cartilage - which stops the trachea from collapsing and allows food to pass down the esophagus behind the trachea

Trachea branches are lined with smooth epithelium with goblet cell between cell and below the epithelial - which allows for the trapping of dust and microorganisms

Question 6

What is the job of the goblet cells?

Answer 6

To secrete mucus into the lining of the trachea, to trap dust and microorganisms that have escaped the nose lining.

Question 7

How does ciliated epithelium and goblet cells work to trap and move dust/bacteria?

Answer 7

Goblet cells produce mucus into the lining of the trachea which kills the pathogens and dust

Cilia beat and move the mucus along with any trapped dirt and microorganisms away from the lungs

Question 8

What is the structure of the bronchus like?

Answer 8

• consists of 2 bronchus

- have supporting uncompleted ring cartilages that are big

Question 9

What is the structure of the bronchioles?

Answer 9

• small bronchioles
• Smaller bronchioles are 1nm or less in a diameter with very small cartilage rings
• Walls of the bronchioles contain smooth muscles - which can constrict the bronchioles (closing them) and relax (causing them to dilate). As a result this allows them to control the amount that gets to the lungs.
• Bronchioles are lined with flattened with a thick epithelium - which allows gaseous exchange to take place.

Question 10

What is expiration?

Answer 10

is breathing out and is a active process.

Question 11

What are the main adaptations of the alveoli?

Answer 11

Large surface area - to keep up with the demand of oxygen in the body and gives an area for exchange.

Thin layers - Few epithelial cell thick walls in both the capillaries and the alveoli walls. Therefore allows faster exchange of gas as diffusion distance between air in the alveolus and the blood in capillaries is very short

Good blood supply - constant flow of blood through the capillaries brings carbon dioxide and carries oxygen maintaining a steep concentration gradient. between air in the alveoli and blood in the capillaries

Good ventilation - constant breathing in and out of the alveoli helps maintain a steep concentration gradient for oxygen and carbon dioxide between blood and air in the lungs.

Question 12

What is ventilation?

Answer 12

is the movement of air

Question 13

What causes ventilation to occur?

Answer 13

When air is moved in and out of the lungs this cause pressure changes in the thorax (chest cavity) brought about by the breathing movements.

Question 14

What is inspiration?

Answer 14

Taking air in

Question 15

How does inspiration happen?

Answer 15

• The dome shaped diaphragm contracts, flattens and rises
• The external intercostal muscles relax, moving the ribs downwards and inwards and the volume of the thorax decreases so the pressure in the thorax is reduced.
• Once is lower than the pressure of the atmospheric air, so air is drawn through the nassal cavity –> trachea —-> bronchi —-> bronchioles into the lungs

(it the equalizes the pressure inside and outside of the chest)

Question 16

How does expiration happen?

Answer 16

• The muscles of the diaphragm relax so it moves up in the domed shape
• The external intercostal muscles relax so the ribs move up and outwards
• Elastic fibers in the alveoli of the lungs stretch
  As a result of all these changes = this causes the decrease in the volume of the thorax, which causes the air in the thorax to be greater than the atmospheric pressure. This cause air moves out of the lungs until the pressure inside and outside is equal.

Question 17

What happens during forcible expiration?

Answer 17

• The internal intercostal muscles will then contract pulling the ribs down hard and fast.
• Also abdominal muscles contract forcing the diaphragm up to increase the pressure in the lungs rapidly

Question 18

What is the structure of the lungs like?

Answer 18

Rib cage - provides a semi rigid case within which pressure can be lowered with respect to air outside it

Diaphragm = broad and domed sheet of muscle which forms the the floor of the thorax

The external and internal intercostal muscles = that found in between the ribs.

The thorax = surrounds the lungs