1.1 The Human Respiratory SystemBy the end of this section, you will be able to:

(a)Identify the structure of the human respiratory system

(b)Identify the structure of the lung

(c)Describe the process of inhalation and exhalation

(d)Relate the changes of air pressure in the thoracic cavity to inhalation and exhalation

(e)Describe the breathing mechanism

The Human Respiratory SystemThe Human Respiratory System1) The human respiratory system provides an area for

gas exchange between the blood and the environment.

2) The gas exchange in lungs is called breathing.This exchange involves the taking in and letting out of air.

3) The human respiratory system consists of:

a) Breathing organ (nose and trachea)b) Intercostal musclesc) Ribsd) diaphragm

Air enter the respiratory system through the nasal cavity.

As air passes the nasal cavity, it is warmed and moistened. Dust is trapped by the hairs.

After the air leaves the nasal cavity, it enters the trachea.

The trachea branches into two bronchi (singular:bronchus)

Each bronchus branches into smaller tubes called bronchioles.

The bronchioles end in millions of tiny air sacs called alveoli (singular:alveolus)

4) How does it occur???

*** Each alveolus has a very thin wall which is moist and contains a network of blood capillaries.

Pathways of the inhale air:

Nose trachea bronchus bronchiole alveolus

5) The lungs are made up of alveoli, bronchioles and blood capillaries, bronchus.

6) The lungs are located in a space called the thoracic cavity.

7) The lungs are protected by the rib cage which consists of ribs and intercostal muscles.

8) A sheet of muscle called the diaphragm separates the thoracic cavity from the abdomen.

Inhalation Differences Exhalation

Move upwards and outwards

Rib cage Move downwards and inwards

Move downwards,contract, flatten

Diaphragm Upwards, relaxes, curve

bigger Volume of thoracic cavity

smaller

Decrease/lower Air pressure in the lungs

Increase/higher

Comparison between inhalation and exhalation mechanism.

PARTS OF THE MODEL

PARTS OF THE RESPIRATORY SYSTEM

Bell jar

Y-shaped glass tube

Balloons

Rubber sheets

Rubber sheet

Changes in the balloons

Breathing process

Pulled down

Pushed up

1.2 Transport of Oxygen in the Human BodyBy the end of this section, you will be able

to:(a) Describe the diffusion of oxygen from the

alveoli into the blood capillaries(b) Describe the transport of oxygen by

blood(c) Describe the diffusion of oxygen from

blood capillaries into the cells.

1) The movement of oxygen from the alveolus into the blood capillaries is diffusion.

2) Diffusion is the movement of molecules from a region of higher concentration of the molecules to a region of lower concentration of the molecules.

Higher concentration lower concentration3) In the blood, the oxygen will combine with

haemoglobin in the red blood cells to form oxyhaemoglobin.

Oxygen + Haemoglobin oxyhaemoglobin

4) The blood containing oxyhaemoglobin is transported from the lungs to other parts of our body.

5) The oxyhaemoglobin breaks down and releases its oxygen at places where the oxygen concentartion is lower.

6) The oxygen then diffuses through the blood capillaries into the cells.

7) Then the oxygen is used by the cell for respiration.

Glucose + oxygencarbon dioxide + water+ energy

8) The carbon dioxide produced is carried by deoxygenated blood (blood without oxygen) to the lungs to be eliminated.

9) Adaptation of the alveoli for efficient gas exchange

a) Large surface area #The lungs have millions of alveoli to provide

a large surface area for gas exchange.

b) Very thin walls#The wall of each alveolus is one-cell thick to provide a very short distance for the diffusion of gases.

c) Moist inner surface#The inner surface of each alveolus is moist so that oxygen can dissolve in the moisture before diffusing across the alveolar wall.

d) Surrounded by numerous blood capillaries#The blood capillaries help to transport gases to and from the alveoli quickly.