CHAPTER 10 Respiration in Humans. 10.1Why Do Living Things Respire? 10.2Studying Respiration 10.3 Gas Exchange in Humans 10.4How Does Inspired Air Differ

CHAPTER 10Respiration in Humans

10.1 Why Do Living Things Respire?

10.2 Studying Respiration

10.3 Gas Exchange in Humans

10.4 How Does Inspired Air Differ from Expired Air?

10.5 Effects of Tobacco Smoke on Human Health

Chapter 10

Respiration in Humans

Learning Outcomes

After this section, you should be able to:

• define and state the equations in words for aerobic and anaerobic respiration in humans;

• describe the effect of lactic acid in muscles during exercise.

Why Do Living Things Respire?10.1

• Energy that is needed for organisms to move, grow, excrete and reproduce, is obtained through the consumption of food.

• To use the energy available in food, living organisms need to break down the food molecules through a process called oxidation.

• The oxidation of food molecules to produce energy is called respiration.


What is aerobic respiration?

• The oxidation of glucose in the presence of oxygen

• Results in the production of a large amount of energy by giving off carbon dioxide and water as waste products

• The word equation for aerobic respiration:

10.1

+glucose oxygen energycarbondioxide

+ water +

Why Do Living Things Respire?

10.1

Aerobic respiration occurs in the mitochondria of all cells.

mitochondria


What is anaerobic respiration?

• The oxidation of glucose in the absence of oxygen

• Releases less energy than aerobic respiration

• The word equation for anaerobic respiration in humans:

10.1

glucose + energylactic acid


What happens during exercise?

• Muscles contract vigorously to enable movement.

• Respiratory rate and heart rate increase to enable more oxygen to reach the muscles.

• If the increased oxygen intake is not able to meet the oxygen demand, anaerobic respiration will take place to provide the energy required.


• When anaerobic respiration occurs, lactic acid accumulates and the muscles incur an oxygen debt.

• Lactic acid accumulation causes the soreness and tiredness in muscles.

What happens during exercise?


Chapter 10





10.4 How Does Inspired Air Differ from Expired Air


Learning Outcome


• carry out simple experiments to determine the products of respiration.


• The potassium hydroxide solution in flask A removes carbon dioxide from the air.

• The air entering flask B and C does not contain carbon dioxide. Hence, any carbon dioxide detected in flask D would be due to respiration by the snails.

10.2

Carbon dioxide is a product of aerobic respiration

potassium hydroxide solution

limewater

A B

limewatersnails

C D

Studying Respiration

10.2

• The glucose solution is first boiled and cooled to:- remove dissolved oxygen

- kill microorganisms

• Due to limited oxygen availability, the yeast undergoes anaerobic respiration.

• If carbon dioxide is released during the anaerobic respiration of yeast, the limewater will turn chalky.

limewaterglucose and yeast

suspension

Carbon dioxide is a product of anaerobic respiration


10.2

vacuum flask

pea seeds in antiseptic solution

cotton wool plug

thermometer

• The vacuum flask insulates the experimental set-up.

• The cotton wool plug allows gaseous exchange between the seeds and the environment.

• The antiseptic solution prevents growth of microorganisms.

• If heat is produced during respiration, the thermometer would register a temperature higher than the surrounding temperature.

Heat is a product of respiration


Chapter 10







Learning Outcomes


• identify the organs involved in the human gaseous exchange system;

• describe the role of the alveoli in gaseous exchange.


10.3

• Humans are large organisms that are made up of millions of cells.

• We have a small surface area to volume ratio, unlike unicellular microorganisms.

• This mechanism of exchange is called external respiration and it involves a process called breathing.

Why the need for a respiratory system?

Gas Exchange in Humans

10.3

Gas exchange system in humans

nasal cavity

larynx

pharynxThe fringe of hair and the mucous layer on the walls of the nasal cavity trap dust and foreign particles.

The air is warmed and moistened as it passes through the nasal passages.


10.3


C-shaped ring of cartilage

Transverse section of a trachea

nasal cavity

larynx

pharynx

trachea

bronchus

C-shaped rings of cartilage support the trachea.

They keep the lumen of the trachea open.


10.3

gland cell

epithelial cellcilia

mucus produced by gland cell

On the inner walls of the trachea and bronchi are:

Epithelial cells have cilia that sweep trapped particles and bacteria up the bronchi and trachea, to the pharynx.

• gland cells

• epithelial cells

Gland cells secrete mucus that trap dust particles and bacteria in the air that is channelled to the lungs.



10.3


nasal cavity

larynx

pharynx

trachea

lung

The lungs lie in the thoracic cavity.

Within the lungs, the bronchial tubes divide repeatedly to form bronchioles.

Bronchioles end in clusters of air sacs called alveoli.

bronchiole

a cluster of alveoli

bronchus

URL


http://www.youtube.com/watch?v=sU_8juD3YzQ&feature=player_embedded

10.3

How are the alveoli adapted for efficient gaseous exchange?

• The numerous alveoli in the lungs increase the surface area for gaseous exchange.

• The alveoli are well-supplied with blood capillaries to maintain a steep concentration gradient of gases.

capillary network


10.3

• The alveolar surface is coated with a thin film of moisture to allow oxygen to dissolve.

• The wall of each alveolus and its surrounding capillaries are one-cell thick, ensuring faster rate of diffusion.

alveolar wall

capillary wall thin film

of water

How are the alveoli adapted for efficient gaseous exchange?


10.3

CO2

O2

inhaled oxygen

carbon dioxide to be exhaled

capillary

alveolus

Gaseous exchange in the alveolus

deoxygenated blood (carbon dioxide rich)

oxygenated blood (transported to the heart)

URL


http://www.youtube.com/watch?v=DoSTehS7iq8&feature=player_embedded

How is oxygen transported?

10.3

Oxygen molecules bind to haemoglobin in red blood cells to form oxyhaemoglobin.

This process is reversible.

+ oxygen molecules

- oxygen molecules

haemoglobin oxyhaemoglobin


How is carbon dioxide transported?

10.3

Carbon dioxide molecules produced by tissue cells are converted to hydrogen carbonate ions which diffuse into the blood plasma.

In the lungs, the hydrogen carbonate ions are converted back into carbon dioxide.

In blood, converted to

In the lungs, converted toCarbon dioxide

Hydrogen carbonate ions


Chapter 10





10.4 How Does Inspired Air Differ from Expired Air?


How Does Inspired Air Differ from Expired Air?

Learning OutcomeAfter this section, you should be able to:

•state the difference in composition between inspired air and expired air.

10.4

10.4

• Breathing is the muscular contractions and movements

of the ribs, which result in air moving in and out of the lungs.

• The taking in of air is called inspiration (or inhalation).

• The giving out of air is called expiration (or exhalation).

How Does Inspired Air Differ from Expired Air?

10.4How Does Inspired Air Differ from

Expired Air?

Chapter 10







Learning Outcome


• describe the effects of the major toxic components of tobacco smoke on human health.

10.5Effects of Tobacco Smoke on

Human Health

10.5

Nicotine• addictive

• increases risk of blood clot in blood vessels

• increases the risk of heart diseases

Carbon monoxide• decreases the ability of

red blood cells to transport oxygen

• increases the rate at which fats are deposited on the inner arterial walls (leads to artherosclerosis)

Tar• carcinogenic

• paralyses the cilia lining in air passages

• reduces the efficiency of gaseous exchange

Irritants(e.g. formaldehyde,

hydrogen cyanide)

• paralyse the cilia lining in air passages

• increase the risk of chronic bronchitis and emphysema

Effects of Tobacco Smoke on Human Health

10.5

Chronic bronchitis

In chronic bronchitis,• the epithelium lining the airways is

inflamed• there is excessive mucus

secretion• the cilia lining the airways are

paralysed

Symptoms:• Breathing difficulties due to

blocked airways• Persistent cough (body’s

response to clear the blocked airways)

over secretion of mucus

cilia paralysed and unable to remove mucus


10.5

In emphysema,• the partition walls between

alveoli break down due to violent coughs. (This reduces the surface area available for gaseous exchange.)

• the lungs lose their elasticity and become inflated with air

Symptoms• Breathing difficulties• Wheezing diseased

lungs

damaged partition walls

healthy lungs

partition walls between alveoli

Emphysema


Chapter 10


Documents

CHAPTER 10 Respiration in Humans. 10.1Why Do Living Things Respire? 10.2Studying Respiration 10.3 Gas Exchange in Humans 10.4How Does Inspired Air Differ