Реферат: Gas Exchange Essay Research Paper Describe four

Gas Exchange Essay, Research Paper

Describe four features of Alveoli that allow them to carry out

gas exchanges efficiently o


so that the respiratory surface is much larger and much

more gas can be exchanged, o

surrounded by capillaries?

so that cases are exchanged by diffusion as a

consequence of the different partial pressures of oxygen and carbon dioxide, o

the barrier between the air in an albeolus and the

blood in its capillaries is only about .5 micrometer; o

the alveoli have their own capillaries so that they can

carry away the oxygen and CO2. Explain the necessity of a ventilation system

ventilation lungs- the exchange of air with the

atmosphere takes place by bulk flow as a result of chagnes in lung volume. Draw a diagram of the gas exchange system including trachea,

bronchi, bronchioles and lungs State the difference between breathing and cell respiration

Breathing- inspiration. This is only taking in air into

the body

Respiration is the breakdown of glucose using oxygen.

Also, breathing is carried out by the body; respiration is carried out by

individual cells. Explain how exercise improves the functioning of the heart and

the lungs o


stroke volume o


tidal volume o

leading to a lowering of both rates Explain how and why breathing rate varies with exercise

Variation in breathing rate o

increase in co2 level o

lowering of pH o

detected by chemosensors (in aorta and carotid

arteries) o

send impulses to breathing centre of brain (brain stem) o

nerve impulses to diaphragm and intercostals muscles to

increase contraction/relaxation rate o

involuntary control, but to some extent controllable

voluntarily Outline a Health problem associated with gas exchange

?The lung is

normally protected by ciliated cells lining the trachea and bronchi. The cilia

sweep out particles in the respired air that are caught in the mucus secreted

by the goblet cells. These cilia are paralysed by chemicals in cigarette smoke.

Cancer cells arising in the bronchi generally do not have cilia. 5.5

Homeostasis Define Homeostasis the maintenance of a constant

internal environment which ensures that an organism?s cells always experience

those conditions which permit effective functioning. Explain the Concept of homeostasis with reference to body

temperature and levels of blood glucose a.



Monitoring – Thermoreceptors 1. Skin

temperature is monitored by thermoreceptors in the skin 2. Blood

temperature is monitored by thermoreceptors in heat centres in the hypothalamus


Heat Adjustment mechanisms 1. Warming

down a. Vasodilation b. Sweating 2. Warming

Up a. Vasoconstriction b. Increased

cell metabolism c. Shivering b.

Glucose Adjustment mechanisms


Glucose levels monitored by chemoreceptors in Pancreas 1. Levels

rise due to diet or release from liver and muscles by demand 2. Levels

fall due to respiration or conversion to other metabolites or for storage



Adjustment mechanisms 1. Levels

rise a. Pancreas

cells glucagons which stimulates liver cells to convert (enzymically) glycogen

directly to glucose. 2. Levels

high a. Other

pancreas cells secrete insulin that stimulate


Cell respiration


Increased absorption of glucose by muscle cells


Increased conversion of glucose 1. to

fat (in adipose tissue) 2. to

glycogen in a. liver

cells b. muscle

cells Explain the concept of Negative Feedback

ie. a house thermostat- when the temperature in your

house drops below the preset thermostat level, the thermostat turns the furnace


When the termperature rises above the preset

temperature the thermostat turns the heat off. A deviation from a ‘preset’

condition stimulates a response that reduces the deviation. State that The nerve (thermoregulation) and endocrine (glucose

regulation) systems are involved in homeostasis. Describe the components of the Nervous System

Central Nervous System

Peripheral Nerves?

Special cells called neurons?

Carry electrical impulses rapidly State that the endocrine system consists of glands which release

hormones that are transported in the blood Define Excretion

The removal from an organism of the toxic waste

products of an organism. Define Osmoregulation

The control of the osmotic and water potential in a

cell or inside a living organism State the Functions of the kidney



еще рефераты
Еще работы по на английском языке