GASEOUS

EXCHANGES Grade 11

Term 2

Paper 1

Introduction

Paste fig 2.4.1 pg. 203

A. Oxygen is necessary

• Cellular respiration: O2 is needed in cells

: Energy is released

• Breathing: O2 is inhaled from atmosphere

: CO2 is exhaled to atmosphere

• Gas exchange: lungs blood cell

: cell blood lungs

B. Gas Exchange

• ATP is released to perform functions

• Released in the atmosphere is CO2 as a by-product

• CO2 can become toxic & enzymes can denature

C. Requirements of a gas exchange

system

• Paste pg.205

D. Adaptations of efficient Gaseous

exchange

• Past pg.207

E. Structure of gaseous exchange in

Humans

• Made up: air passages

: lungs

: breathing muscles

1. Air passages

• Nostrils & nasal passages: 2 nostrils separated by vertical

septum

: nasal passage with septum

: hairs that catch up dust (paste fig 2.4.3)

• Trachea: nasal passage air into pharynx

: leads into opening – glottis

: food swallowed, glottis close – epiglottis

: prevents food going down the trachea= choking

: larynx upper part = voice box

: long tube = strengthened by C- shaped cartilage

: rings keep it open

: Oesophagus moves trachea when you swallow

(fig2.4.4)

• Bronchi & bronchioles: trachea divides into 2 bronchi

: cartilages structure

: enters 1 lung

: subdivides into smaller bronchioles

: smallest bronchioles have no cartilages

: ends in air sacs = alveoli

2. Adaptations of the air passages &

functions

• Paste pg. 211

3. Human lungs

• External Structure

- 2 spongy lungs

- Touching diaphragm muscle

- Right – 3 lobes; Left – 2 lobes

- Hilum = part of lung next to heart

= Pulmonary Artery enters lungs & Pulmonary Veins

exits lungs @ the hilum

- Pleura = double membrane covers the outside

= contains fluid to prevent friction

• Internal Structure

- Trachea Bronchi Bronchioles Alveoli

- Ends up in air sacs = alveoli

- Squamous epithelial cells = walls of alveoli

- Pulmonary arteries breaks into smaller arterioles capillaries

Form venules pulmonary veins leaves lung heart

Paste fig 2.4.5 pg. 213

4. Adaptations of the alveolus/ capillary/

blood & functions

• Paste pg.214

5. Ventilation of the lungs

(Breathing mechanism)

• 2 stages : inhalation (O2 into lungs)

: exhalation (CO2 exits lungs)

Paste pg. 217

Act 2.4.5 pg. 218

1.1 diaphragm

1.2 intercostal muscles

2. diaphragm 1

3. diaphragm contracts and becomes flattened/arrow goes downward chest cavity pushed forward/upward

4.1 prevent food from going into the trachea during swallowing

4.2 the open part of the ring allows the oesophagus to stretch into it when large pieces of food are swallowed

5. - lobed and thus provides a large surface area for gas exchange

- thin, to allow rapid diffusion of gases

- moist, to prevent drying out of gas exchange surfaces

- richly supplied with blood capillaries to transport gases to and away from it

6. - The thoracic cavity will not be a closed system

-The pressure in the thoracic cavity & the atmosphere will be

the same

- Volume changes in the thoracic cavity will not result in

pressure changes

- As a result the lungs will not inflate or deflate

6. Breathing rate relation to needs of

the body

• Physical activities = more breathing

= more O2

• Muscles needs more O2

Paste fig 2.4.6 pg. 224

7. Gas exchange & gas Transport in

Humans

Gas exchange at the lungs

• Blood arriving in alveolus CO2

• In alveolus is a concentration of CO2

• Dissolved CO2 diffuses = endothelial walls of capillaries

= & squamous wall of alveolus

• Blood of O2

• Alveolus has O2

• O2 dissolves in film of water lining the alveolus & diffuses

through the alveolus walls wall of the blood capillary

enters the blood capillary

Paste 2.4.7

Oxygen Transport

• O2 diffuses from alveolus into capillary

• O2 combines with : haemoglobin (red blood corpuscles)

to form oxyhaemoglobin

• Small amount diffuses into blood capillary into the blood plasma

• 2 forms: oxyhaemoglobin O2 is transported to

: solution in blood plasma the heart & then tissues

Gas Exchange at the tissues

• Blood arriving at capillary branches of the arteries O2 in

form of oxyhaemoglobin

• Oxyhaemoglobin = O2 + haemoglobin

• O2 diffuses capillary wall tissue fluid cells

• CO2 in cells THAN tissue fluid & blood capillaries

• CO2 diffuses cells tissue fluid blood capillary

• Paste 2.4.8

Transport of CO2

• CO2 diffuses form tissues blood capillaries & reacts with H2O in blood plasma = CARBONIC ACID 1st

= and then BICARBONATE IONS

• CO2 dissolves in blood plasma

• CO2 + haemoglobin = CARBHAEMOGLOBIN

• 3 forms: Bicarbonate ions

: solution blood plasma CO2 transported to

: carbhaemoglobin lungs

Paste 2.4.9

8. Diseases

• Paste table on pg. 231

TB

• Causes: bacteria = Mycobacterium tuberculosis

• Spread: coughs / sneezes

• Symptoms: weakness, weight loss, chills, fever, sweating at

night

• Bacteria does to the body: attack the body & destroy tissue,

create a hole in the lung

• TB affects? – Infect anyone who breathes the bacteria in

• Test for TB: X-rays, TB skin test, Tissue Culture

• Vaccine against TB: BCG vaccine given to children

• Treatment: Cure patient of active TB, prevent spread of the disease

Summary:

• TRACHEA – passage for air to lungs

• BRONCHUS – bronchi's of trachea

• BRONCHI – 2 smaller subdivisions of bronchus

• BRONCHIOLE – even smaller subdivisions of bronchi

• ALVEOLI – gas exchange units