NUTRITION IN ANIMALS

NUTRITION IN ANIMALS

Nutrition is the process by which organisms take in and use nutrients.

Nutrients are any substances that nourish an organism or are substances which

organisms use for the body processes.

Food is any material when taken in absorbed and utilized meet requirement of plant

and animal body.

Function of food

1. Oxidized to release energy

2. 3. Used in growth of cells

Used to repair lost cells and tissue

Types of nutrition

There are two main types of nutrition:

 Autotrophic nutrition and

 Heterotrophic nutrition.

Autotrophic Nutrition

Is the process by which organisms manufacture their own food from simple

inorganic substances like carbon and hydrogen using either light energy

(photosynthesis) or chemical energy (chemosynthesis). Organisms which feed by

this way are known as autotrophs; Example green plants, iron bacteria and sulphur

bacteria

Heterotrophic Nutrition

Is the process in which organisms get nutrients from other organisms, they feed on

already manufactured/made food. Organisms which feed on this way are known as

heterotrophs. There are three types of heterotrophic nutrition.

 Saprophytic nutrition

This is the mode of nutrition where by organisms feed on dead decaying

bodies parts of animals or their excrete; organisms feeding by this way are

known as saprophytes.

 Symbiotic nutrition

This mode of nutrition where there is a close relationship or association between

organisms this association could take various forms like mutualism, commensalism,

and parasitism

 Mutualism

Is a relationship where two organisms benefit each other for example the rhizobium

bacteria in the root nodules of legumes fix nitrogen into nitrate to be used by the

plant. The bacteria get protection and nutrients from the plant.

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 Commensalism

Is the interaction that is beneficial to one organism and is neutral to the other

organism. For example when a bird builds a hole or a nesting a tree, epiphytes

(plants that grow on other plants) eg mosses and algae which on upper parts of big

trees to get sunlight easily.

 Parasitism

Is the association where one organism benefits while the other is harmed. E.g

plasmodium that cause malaria to human being

Endoparasites: They live inside the body of the host e.g. tapeworm, roundworm and

plasmodia.

Ectoparasites: Parasite that lives on host’s surface [outside the body] examples

includes some mites, flea and body lice.

 Holozoic nutrition

This is mode of nutrition where by organism take food by mouth. It passes

through a digestive system and broken down, finally absorbed into body

tissue.

Forms of Holozoic nutrition

1. Herbivores-are animals which feed on plants only eg cow, goat and

zebra

2. Carnivores-area animals which feed on flesh only eg lion, tiger and etc

3. Omnivores-are animals which feed on varieties of food (flesh, plants,

insects etc) eg man, monkey, pigs

4. Insectivores- are animals that feed on insects eg shrew and ant

The Importance of Nutrition in Living Things

1. 2. 3. Helps growth and development of cells, tissue and organs

It helps to repair damaged parts

It helps to protect the body against infection and diseases

Nutrition in Mammals

Human Nutrition

Human Nutrition is the provision to obtain the essential nutrients necessary to

support life and health.

OR

Are several types of food substances that are needed by the human body for its

proper functioning.

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The Digestion Process in Human Being

Digestion is the process by which food is broken down into a form that can be

absorbed and used by the body.

Types of Digestion.

 Mechanical digestion/physical digestion

It involves breaking down large pieces of food into smaller ones using the teeth.

 Chemical digestion

Digestive enzymes achieve chemical break down of food. The digested food is

absorbed and assimilated in the body.

Digestion in the mouth

In the mouth, food is chewed by teeth and mixed with saliva to form a ball like. Food

is broken into small particles thus increase the surface area for enzymatic activities.

Saliva is secreted by salivary glands and it is alkaline in nature, so it makes the food

alkaline when in the mouth,

Secretion of saliva is controlled by the nervous system. These smell, taste, sight or

thoughts of food cause saliva to flow from the gland.

Components of saliva

 Mucin – lubricates the food for easy swallowing.

 Water – Acts as a solvent for dissolving food substances ( 95%)

 Salts eg bicarbonates, chloride, calcium, potassium, sodium and magnesium

 Enzymes eg salivary amylase and lingual lipase

 Antibacterial compounds eg thiocyanate, hydrogen peroxide

 Antimicrobial enzymes i.e enzymes that kill bacteria eg lysozyme

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Functions of hydrochloric acid

o Provides suitable acidic medium foe enzymes to work best

o Kills bacteria present in food

o Hydrolyses or breaks down food to simple particles

o Activates pepsinogen to pepsin.

Pepsin.

Breaks down proteins into peptides. It is produced in an inactive form called

pepsinogen. Hydrochloric acid (HCl) activates pepsinogen into pepsin. Pepsin is

produced in inactive form to prevent it from digesting the cells that produce it in the

gastric glands, and the wall of alimentary canal.

Rennin

It coagulates soluble milk protein (casein) into an insoluble curd which is then acted

by the enzyme pepsin. This enzyme is mostly found in young mammals during the

suckling period.

Functions of the stomach

 It act as a temporary storage of food

 Digestion of proteins starts in the stomach

 Helps in mixing food during churning, also absorbs water, and some vitamins

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

sphincter, the chyme (liquid food) passes periodically from the stomach through the

sphincter to the duodenum

Adaptations of stomach

1. Stomach has sphincter muscles to prevent food from flowing back into the

oesophagus

2. Stomach has gastric glands, which produce gastric juice for the digestive

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other parts of the plant by diffusion.

 Excretion of nitrogenous waste–nitrogenous waste such as urea and

ammonia leave the cells by diffusion.

 Gaseous exchange– In plants and animals gases are exchanged through

diffusion process.

Diagram showing diffusion

Factors affecting the rate of diffusion

 Size of the molecules—small and light molecules diffuse faster than large and

heavy molecules.

 Temperature- Increase in temperature increases the rate of diffusion and vice

versa

 Concentration gradient/diffusion gradient– The greater the difference of the

two concentration gradient the greater the rate of diffusion and vice versa

 Surface area to volume ratio – The higher it faster the diffusion rate.

 Distance over which diffusion takes place – example a thin layer of cells

increase diffusion rate and vice versa.

Osmosis

This is the movement of water molecules from a region of higher concentration to a

region of lower concentration through a semi-permeable membrane.

A partially-permeable membrane is a membrane that allows small particles such as

water molecules to pass through it, but not larger particles such as sugar molecules

and ions from salts.

Examples of semi-permeable membranes are cell membranes and a pig’s bladder.

These membranes allow transportation of water through them. In spite of the fact

that they allow transportation of water through them, they do not permit the passage

of sugar or salt molecules because they are solutes. Osmosis occurs when water

moves down its concentration gradient across the semi-permeable membrane.

Therefore, for osmosis to take place there must be:

1. 2. Two solutions with different concentrations; and

A partially permeable membrane to separate them.

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Diagram of osmosis

A dilute solution has a high water concentration, while a concentrated solution has a

low water concentration. For example, when salt is dissolved in water:

1. A little dissolved salt produces a dilute solution with a high water

concentration

2. A lot of dissolved salt produces a concentrated solution with a low water

concentration.

Effects of osmosis in living organisms

 Osmosis and animal cells

When an animal cell is placed in hypotonic solution, it absorbs water, if it

remains in the solution for long time, it absorbs excess amounts of water. A

cell that does not have a mechanism for removing the excess water bursts

due to excessive internal pressure.

When an animal cell is placed in hypertonic solution, it loses water, if it

remains in the solution for a long time, it loses a lot of water, shrinks and

shrives.

These effects of osmosis on animal cells can be observed in red blood cells.

Under normal conditions, the osmotic pressure of red blood cells is equal to

that of blood plasma i.e they are isotonic. Thus there is equal movement of

water in and out of the cells. This helps to maintain the disc shape of these

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cells.

When red blood cells is placed in hypotonic solution,(where solute

concentration is lower outside compared to inside of the RBC) they absorb

water, causing the cell volume to increase, excessive amounts of water cause

haemolysis (bursting).

When red blood cells are put in hypertonic solution,(Where the solute

concentration is higher outside compared to inside of the RBC) they lose

water, leading to shrivelling of the cell, this is referred as crenation.

When the RBC is placed in isotonic solution (where the solute concentration

outside and the inside the cell is the same or at equilibrium), water does not

move across the cell membrane and the RBC retains it normal disc like shape.

Illustration of the red blood cells in different solutions

 Osmosis and plant cells

In an isotonic solution, plant cells neither lose nor gain water. In hypotonic

solution cells absorb water, causing the cell membrane to push against the

cell wall, the cell become turgid, it does not burst because the membrane

exert pressure on the cell wall restrict additional intake of water.

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In dicot stems, the vascular bundles are arranged in a ring around the pith.

The arrangement of vascular bundles in the leaves of dicots and monocots differs. The

diagrams below show the differences in arrangement of the bundles. Can you notice the

differences? The xylem and phloem vessels are enclosed in a bundle sheath.

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