Skin and temperature regulation – Upper primary science
Temperature regulation
The body temperature must be kept constant because enzymes work best within narrow temperature range. At very low temperature enzymes are inactive whereas at very high temperature enzymes are denatured both two condition are harmful life.
There are two types of animals based on temperature regulation
(a) Cold blooded animals have their temperatures varying with environmental temperatures. These maintain their body temperatures by moving to cold area when it is hot or to hot areas when it is cold. Examples are fish, amphibians e.g. frog, and reptiles e.g. lizard
(b) Warm blooded animals maintain constant body temperatures irrespective of environmental temperatures. They do so by lowering or increasing heat production regulating their metabolic rates
The figure below shows the relationship between body temperature and environmental temperature for a cat (warm blooded) and a lizard (cold blooded).
The skin
Functions of the skin
- Protects the inner parts of the body
- It excretes sweat (water, salts, ammonia, and urea). Evaporation of sweat cold the body.
- It keeps body temperature constant
- Provides a sense of feeling heat, cold, cold, rough, smooth, sharp and blunt.
- Produces vitamin D in presence of sunlight
Parts of the skin
The skin has two layer which consist of many connective tissues, elastic fibres and pigments.
Epidermis
This is the first layer of the skin which consist of the following
(a) Cornified layer
It the outer most layer.
It consists of dead cells,
It protects the body against bacteria and injuries
It reduces water loss by evaporation
(b) Granular layer
It a layer of living cells which replaces the dead cells of cornfied cells that wear away.
(c) Malpighian layer
This is the last layer of epidermis. It contains pigments called melanin and carotene that determine the skin color
Melanin protect the skin from ultra violet ray from the sun.
Dermis
This a layer of connective tissues with many elastic fibres. It consist of the following
(i) Capillaries that supply blood and oxygen to the skin
(ii) Sweat gland produces sweat a waste product of water, salts, ammonia, and urea. Evaporation of sweat cools the body.
(iii) Sebaceous glands produce oil that kills bacteria in the skin.
(iv) Fat layer stores fats and insulate the body against heat loss
(v) Nerve ending and sensory nerves provide sense of coldness, hotness of the skin, and pressure.
(vi) Hair follicle forms hair
(vii) Sweat duct is a tube that excretes sweat out of the body
Regulation of body temperature by the skin
Response to cold
- Rector pili muscle contract raising the hair. Air gets trapped in the spaces between the hairs and insulates the body
- The arterioles leading to the superficial capillaries contract. As a result, the blood flow is diverted from the surface cutting down the heat loss.
- Metabolic rate increases, heating up the body.
Responses to hot conditions
- The hair is lowers by relaxation of the erector pili muscle and removing air insulation
- The arterioles leading to superficial capillaries dilate and as a result of blood flow to the surface is increases leading increased heat loss
- Sweating (panting in dogs) occurs and evaporation of water cools the body
- Metabolic rate decreases reducing heat production.
Causes of overheating of the body
- Vigorous exercises
- Diseases
- Taking hot foods and drinks
The first aid for fever is applying a wet warm cloth (Tepid sponging)
Overheating of the body
Causes
- Diseases
- Cold weather
- Frustration
- Shocking news
First aid for lower fever is to cover the victim with thick blanket
Skin diseases
- Scurvy
It is a non-communicable disease caused by lack of vitamin C in the diet.
A person with scurvy develops slow healing wound, swollen and bleeding gums
Prevented by eating fruits
- Leprosy
It is caused by a bacteria
Spread by contact
It causes paralysis or inability of body parts to move, feel or function well. Fingers and toes may break off.
- Scabies
It is caused by itchy mites that cause itching and watery sores on the skin.
Spread by shearing clothes and beddings and by contact.
It is controlled by antiseptics, isolation of the victim and not sharing clothes
- Ring worms
It is caused by a fungi
It is spread by contact, sharing clothes, washing sponges
Causes development of white and round patches on the skin and head
Treated with antifungal drugs
Prevented by keeping personal hygiene
- Athlete’s foot
- German measles
Skin disorders
- Cuts and wounds
Treated by dressing and antibiotics to prevent pus
- Burn and scalds
A burn is an injury on the skin caused by dry heat while a scald is caused by hot liquid
First Aid for burn and scald
Pouring cold water on an affected part to cool the part and minimize further damage to the skin
Caring for the skin
- Regular bathing with soap and water
- Eat well balanced food with fruits
- Avoid strong chemicals on the skin
- Treat diseases
Revision Questions
- State the sense organ for feeling in the human body.
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- Which communicable disease in human affects both the skins and the skeletal system?
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- Why should cold water be poured on the part of the body which has been scalded or burnt?
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- Name the human body system to which the lungs, kidney and skin belong.
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- Betty’s home is near a pond.
(a) State any two diseases members of Betty’s family are likely to suffer from.
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(b) Suggest one thing that Betty can do to avoid one of the disease mentioned.
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(c) How is scabies spread?
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- How does leprosy spread?
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- In which way is the function of kidneys similar to that of the skins in a human body?
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- (a) Name one practice which increases the spread of bilharzia.
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(b) Which vector is important in the spread of bilharzia?
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(c) Give any two ways of preventing the spread of bilharzia.
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- (a) Why is it a bad practice to apply soil or cow dung on any burnt area of our skin?
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(b) Suggest any two reasons why the injured part with a born or scald is dipped into cold water.
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(c) Give any one way of a voiding burns while lifting hot objects.
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- The diagram below of a human skin. Use it to answer questions that follow
(a) Name the layers A and B
(i) A- ……………………………………………………………………………………
(ii)B- ……………………………………………………………………………………
(b) Give the function of the part labeled Y and Z
(i) Y- ……………………………………………………………………………………
(ii) Z – ………………………………………………………………………………….
- State any one way in which the spread of scabies can be prevented.
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- (a) Name the outermost layer of the skin
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(b) State any one waste product removed by the skin
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(c) Apart from removing wastes, mention two other functions of the human skin
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- ……………………………………………………………………………………………………..………………….
- How does the skin of a person maintain its body temperature on a hot day?
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- Which First Aid would you give to a person who has a burn by fire?
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- Name the main food you would eat to prevent scurvy?
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- Whenever Bbosa runs on a sunny day, he sweats. What is the importance of sweeting to his body?
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- A child suddenly removed the cover of a saucepan full of boiling water. One arm of the child was burnt with steam.
(a) What kind of burn did the child get?
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(b) What First AID would you give to the child
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(c) Give the possible ways by which such accidents could be avoided?
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Suggested answers
- State the sense organ for feeling in the human body.
Skin
- Which communicable disease in human affects both the skins and the skeletal system?
Leprosy
- Why should cold water be poured on the part of the body which has been scalded or burnt?
To cool the affected part and minimize further damage to the skin
- Name the human body system to which the lungs, kidney and skin belong.
Excretory system
- Betty’s home is near a pond.
- State any two diseases members of Betty’s family are likely to suffer from.
- Bilharzia
- Malaria
- Cholera
- Typhoid
- Yellow fever
- bilharzia
- Suggest one thing that Betty can do to avoid one of the disease mentioned.
- Avoid playing in dirty water
- Drink boiled water
- Sleep in mosquito net
- Pouring oil on the pond to reduce mosquito breeding
- Draining the pond to remove mosquito breed place
- To add small fish in the pond to eat mosquito larvae.
- How is scabies spread?
Through contact with infected person
By sharing clothes with infected person
- How does leprosy spread?
Through body contact with infected person
Through nasal secretion for infected person
- In which way is the function of kidneys similar to that of the skins in a human body?
They are both organs of excretions
- (a) Name one practice which increases the spread of bilharzia.
Swimming
Urinate in water
Defecate in water
(b) Which vector is important in the spread of bilharzia?
Snail
(c) Give any two ways of preventing the spread of bilharzia.
Avoid swimming in river and ponds
Proper disposal of wastes
Treatment of infected persons
Clearing stagnant water
- (a) Why is it a bad practice to apply soil or cow dung on any burnt area of our skin?
They may contain germs
They do not reduce the heat from the burn
(b) Suggest any two reasons why the injured part with a born or scald is dipped into cold water.
To cool the burnt place
To minimize the effect of the burn
(c) Give any one way of a voiding burns while lifting hot objects.
Use pieces of paper of cloth
- The diagram below of a human skin. Use it to answer questions that follow
(a) Name the layers A and B
(i) A- Epidermis
(ii)B- Dermis
(b) Give the function of the part labeled Y and Z
(i) Y- insulate the body
(ii) Z – secrete sweat
- State any one way in which the spread of scabies can be prevented.
- Avoid body contact with infected person
- Avoid sharing clothes and comb
- Early treatment with calamine or benzylbenzoate
- (a) Name the outermost layer of the skin
Conified layer
(b) State any one waste product removed by the skin
Urea, ammonia
(c) Apart from removing wastes, mention two other functions of the human skin
- Protects inner part of the body
- Produce vitamin A
- Regulates body temperature
- How does the skin of a person maintain its body temperature on a hot day?
- It forms sweat which when evaporates cools the body
- Hair lowers leading to increase heat loss
- Blood capillaries on the skin dilate, and increase blood supply to the skin leads to increased heat loss
- Which First Aid would you give to a person who has a burn by fire?
Pour cold water to burnt area to reduce the effect of burn
- Name the main food you would eat to prevent scurvy?
Fruits like oranges, lemon
- Whenever Bbosa runs on a sunny day, he sweats. What is the importance of sweeting to his body?
Evaporation of sweat cools the body
- A child suddenly removed the cover of a saucepan full of boiling water. One arm of the child was burnt with steam.
- What kind of burn did the child get?
Scald
- What First AID would you give to the child
Pour cold water on the scald
- Give the possible ways by which such accidents could be avoided?
Keep small children away from hot objects
Construct fire guard around fire places.
Children should be taught dangers of fire and hot objects.
