TOPIC 1:CLASSIFICATION KINGDOM FUNGI

Structure of a tooth

PART	FUNCTION
Enamel	-Protects inner part from mechanical damage and infection -Provide surface for bitting and grinding
Dentine	- make up bulk of tooth -replaces dead cells of enamel.
Pulpy cavity	-contain blood capillaries, which functions as ·         supplying oxygen and nutrients ·         remove metabolic wastes. ·         make tooth sensitive to temperature and pain.
Cement	-it holds the tooth firmly

DENTAL FORMULAE

This shows the type, number and position of teeth in each half of the jaw.

1. Saliva is alkaline in nature, so it makes the food alkaline when in the mouth.

Saliva is secreted from three pairs of gland such as

(a) Parotid salivary gland

(b) Sub mandibular salivary gland

(c) Sub lingual salivary gland

These glands are collectively known as salivary gland

2.Secretion of saliva is controlled by the nervous system. These smell, taste, sight or thoughts of food cause saliva to flow from the gland.

3.Saliva is a mixture of mucus water, a variety of salts and the enzymes known as salivary amylase

FUNCTION OF SALIVA

1. Water acts as solvent for dissolving food substance

2. Mucus lubricants thus food for easy swallowing.

3. Salivary amylase turns starch to maltose.

                

NOTE: The tongue rolls the food in the round mass known as houses, the boluses are pushed down the esophagus by the tongue, by the process known as peristalsis.

  THE PHARYNX

• The region where crosses the air passage known as glottis, There is a structure known as epiglottis which prevent food from entering the wind pipe or trachea. There is no digestive function

         

 THE OESOPHAGUS (GULLET)

This is the tube which connects the pharynx and the stomach. The food passes the gullet rapidly by contraction and relaxation of the gullet muscles, this is known as peristalsis

Peristalsis is the process by which food substances move down the alimentary canal in the form of boluses through muscle valve known as sphincter. OR  is the wave like contraction of the gut muscles that pushes the boluses down the alimentary canal. There is no digestive function.

DIGESTION IN THE STOMACH

• The food is mixed with hydrochloric acid and gastric juice to produce a semi – solid mass known as chymes.
• The wall of the stomach contains gastric glands which secretes gastric juices.
• The gastric juices contain water, hydrochloric glands which secrete gastric juices.

FUNCTION OF THE HYDROCHLORIC ACID

1) Provides suitable acidic medium for enzymes to work best

2) Hydrolyses or breaks down food to simple particles

3) Kills bacteria present in food

- The function of pepsin is to breakdown proteins into peptides.

- The function of rennin is to coagulate (solidifies) soluble milk protein (casein) into an insoluble cord which is then acted on by the enzymes pepsin. This enzyme is mostly found in young mammals during sucking period.

The function of mucus is to protect the stomach against corrosion by the hydrochloric acid.

GENERAL FUNCTIONS OF THE STOMACH

• It is a temporary storage of food
• Digestion of proteins starts in the stomach
• Helps in mixing food during charming, also absorb water alcohol and some vitamins.

There is a muscle value between the stomach and the duodenum known as pyloric sphincter

The chyme (liquid food) passes periodically from the stomach through the pyloric sphincter to the duodenum.

DIGESTION IN THE DUODENUM

• Duodenum is the first part of the small intestine
• It is associated with the liver and pancreas.

THE LIVER

• The liver has cell which secrete bile
• Bile is stored in the gall bladder and is released through the bile duct. It is greenish yellow in colour and contains bile salts.

FUNCTION OF THE BILE

i) It emulsifies fats (lipids) i.e. break down fats into tiny fat droplets to increase the surface area for enzymatic activities.

ii) Provides an alkaline medium for enzymes to work best.

iii) It neutralizes the acidic food from the stomach.                                      

THE PANCREASE

The pancreas secretes digestive juices known as pancreatic juice. The juice contains the following.

1. Pancreatic amylase – it breaks down the starch into fatty acids and glycerol

2. Pancreatic lipase – digest the fat droplets into fatty acids and glycerol

3. Sodium hydrogen carbonates (NaHCo₃) provides alcoholic medium for pancreatic enzymatic work best i.e. neutralize the acidic chyme from the stomach. The resulting food mixture in the duodenum is known as chyme.

4. Trypsin – break down proteins into peptide. 

DIGESTION IN THE ILEUM (SMALL INTESTINE)

• The ileum is the largest section in the alimentary canal.
• The intestine contains secretory cells which secrete mucus and digestive juice known as intestinal juice or succusentericus.
• The juice has 4 enzymes

1. Erepsin or peptidase digests peptides to amino acids.

2. Maltose – breaks down maltose to glucose.

3. Lipase – breaks down fat droplets to fatty acids and glycerol.

4. Sucrase – breaks down sucrose (cane sugar) to glucose.

• The ileum has two main function

a) Digests all types of food.

b) Absorption of end products of digestion into the blood stream

NOTES: The walls of the alimentary canal secrete mucus which performs two major functions.

a) Allows smooth movement of food materials along the alimentary, absorption of the end product of digestion into the blood of stream

b) Protect the wall of the alimentary canal against corrosive (digestion) by digestive enzymes.

-End products are:

• Amino acids – simple form of proteins.
• Glucose – simple form of carbohydrates.
• Fatty acids and glycogen – simplest form of lipids.

ABSORPTION

Absorption is the process by which the soluble end products e.g. digestion diffuses into the blood stream.

• Absorption takes place mainly in the small intestine however; absorption of alcohol, some water, soluble vitamins B and c and soluble salts take place into the stomach.

PROCESS OF ABSORPTION

1. Amino acids and glucose. These materials are absorbed into the blood stream through the process of active transport

- These materials diffuse into the blood with the dissolved materials to the HEPATIC PORTAL VEIN

- The hepatic portal vein takes the blood with the dissolved materials to the river and then joins the general body circulation.

2. Fatty acids and glycerol.

- They are absorbed into the location of the villi

- They can drain into lymphatic vessel and finally join the body circulation at the vena cava.

NOTE: The wall of the small intestine has numerous fingers – like structure called villi: (singular villus) which increase the surface area for digestion and absorption to take place.

Adaption of ileum to its functions

1) It is long to provide large surface area for digestion and absorption.

2) It is highly coiled to increase the surface area for digestion and absorption.

3) It has villi and micro – villi which increase the surface area for absorption.

) It has dense network of blood capillaries which facilitate easy diffusion of digested materials.

ASSIMILATION

• This is the process by which the end products of digestion are incorporated in the cell metabolism. Assimilation occurs as follows:

Glucose: some is oxidized during respiration to produce energy (ATP) some is stored as glycogen in muscle some is converted to facts and stored as tissue beneath the skin

AMINO ACIDS

Some is used in the synthesis (formation) of proteins some is used in growth and repair of worn out cell. In absence of glucose and fats they may be oxidized to release energy during respiration.

FATTY ACID AND GRYCELOR

• Are oxidized to release energy during respiration.
• Stored as a dispose tissue beneath the skin. This helps in insulating the body.

  

THE CAECIUM AND THE APPENDIX

• These have no function in man.
• In herbivores the caecum and appendix contain bacteria that secrete an enzyme known as cellulose.

          THE LARGE INTESTINE (COLON)

• The large intestine has four functions.

1. Absorb water from the undigested materials
2. Absorb small amount of digested food.
3. Glandular lining of the colon produces mucus which lubricant the passage of faeces
4. It is a temporary storage of faeces up to the time of defecation (egestion). 

            EGESTION: The undigested and indigested materials are known as faeces. The faeces are removed from the body through anus by the process of egestion.

+	Enzymes secreted	Substance digested	Product of digestion
Mouth	Salivary amylase	Carbohydrates	Maltose
Stomach	Pepsin	Protein	Peptides
	Rennin	Soluble milk protein (caseinogens)	Insoluble milk protein e
	Trypsin	Protein	Peptides
Duodenum	Pancreatic amylase	Starch	Maltose
Ileum	Pancreatic juice	Lipase	Fatty acids and glycerol
		Maltase	Glucose
		Sucrase	Glucose and fructose
		Lactase

1. Test for carbohydrates

	Procedure	Observation	Conclusion
	Test for reducing sugar
	Dissolve specimen in water	colour changes from blues to green to yellow then orange	Reducing sugar is present
	Add an equal amount of Benedict’s solution to the solution
	Boil the mixture
	Test for non reducing sugar
1.	Dissolved the specimen in water Put 2cm3 of the solution in a test tube. Add 1cm3 of(dilute hydrochloric acid neutralizers disaccharides to monosaccharide’s) Boil the mixture Allow the mixture to cool Add small amounts of sodium hydrogen carbonate at a time (sodium addition) Continue until fizzing stops. Add 2cm3 of Benedict’s solution, then boil the mixture	Colour changes from blue, green to yellow to orange.	Non – reducing sugar is present
3.
5.
	Test for starch
	Add a few drops of iodine solution to the specimen	Colour changes to blue - black	Starch is present

Test for Protein

	Procedure	observation	Conclusion
	Million’s Test
	The specimen should be in solution form	Pink coagulating mass	Proteins are present
	Pour 2cm3 of specimen in a test tube
	Add 1cm3 of the specimen of millon’s reagent to the specimen
	Boil the mixture
	Burette test
	The specimen should be in solution form	Color changes to purple	Proteins are present
	Pour 2cm3 of specimen in a test tube
	Add 1cm3 of sodium hydroxide solution then a drop of copper sulphate solution shaking the mixture after each addition

Test for lipids

	Procedure	observation	Conclusion
	Grease spottiest
	Rub the specimen on a piece of dry filter paper	a translucent mark is formed	Specimen contain lipids
	Hold the paper against the light
	Sudan III test
	The specimen should be in solution form	Droplets of oil turn red	Specimen contains lipids
	Add some drops of Sudan III test
	Emulsion test
	Ensure the specimen is in solution form	The clear mixture turns cloudy forming a milky suspension	Specimen contains lipids
	Put the specimen in a test tube along with an equal amount of acetone, benzene or ethyl alcohol.
	Shake the mixture utilities clear
	Add an equal volume of water

THE NATURAL ENVIRONMENT

• The natural environment is made up of all living and non – living thing that occur naturally on earth it includes; air, water, animals, plants, micro – organism, stones, cloud and rock soil.

IMPORTANCE OF THE NATURAL ENVIRONMENT

1) It is a source of food for organism

2) Provides shelter and security for organism

3) It provides an appropriate setting for organism to reproduce and increase in number

4) It allows living and non – living things to interact.

>>>>>>>>>>>>>>Inaendelea>>>>>>>>>>>>>>>>>>>