Animal Survival

The need for food

• Required to provide the body with the necessary energy for living.

• The elements Carbon (C), Hydrogen (H) and Oxygen (O) are present in both Carbohydrates and Fats. The extra element Nitrogen (N) is found along with these in Proteins.

• Carbohydrates: - provide the body with energy.

• Proteins: - repair any damaged tissues or cells.

• Fats: - provides the body with energy.

• Vitamins & Minerals: - protects the body against diseases.

• Carbohydrates are long chain molecules made up of many simple sugars. In plants excess glucose (soluble) is stored as insoluble starch. In animals excess glucose is stored as insoluble glycogen in the liver. Cellulose is a long chained complex carbohydrate and makes up the basic framework for the cell wall of a plant cell.

• Fats are made up of a glycerol backbone and three fatty acids.

• Proteins are made up of many, many subunits called amino acids. If there is any excess dietary protein the body will use this for energy. Structural proteins make up the basic framework for the body¡¯s internal organs.

• Digestion is the process by which large insoluble molecules are broken down into smaller soluble molecules. This process begins in the mouth.

• Teeth are responsible for mechanically breaking down food into smaller manageable pieces.

• There are 3 different types of diets that animals can follow:-
  1. Omnivore (e.g. humans) eats both plants & animal tissue.
  2. Carnivore (e.g. lions) eats animal tissue.
  3. Herbivore (e.g. sheep) eats plant tissue.

• Omnivores have 4 different types of teeth:-
  1. Incisors - for biting
  2. Canines - for tearing
  3. Pre-molars - for crushing and grinding
  4. Molars }

• Carnivores have 5 different types of teeth:-
  1. Incisors - for biting
  2. Backward curved canines - for stabbing & holding prey
  3. Pre-molars - have sharp cutting edges
  4. Molars
  5. Carnassial teeth - work like shears & can cut through bone & tendons

• Herbivores have 3 different types of teeth:-
  1. Incisors - incisors help cut the grass by biting against
  the horny pad
  2. Horny Pad
  3. Molars - have sharp enamel ridges that help grind the grass

• The Human Digestive System is made up of the
  1. Alimentary canal - this is a long muscular tube running from the mouth to the anus.
  2. The salivary glands, liver and pancreas (known as the associated organs). These are connected to the alimentary canal by tubes called DUCTS.
• Digestive juices these aid in the digestion of food and these are made at various stages along the digestive system.

SITE OF PRODUCTION
Salivary glands
DIGESTIVE JUICE PRODUCED
Saliva

SITE OF PRODUCTION Gastric glands in stomach
DIGESTIVE JUICE PRODUCED Gastric juice

SITE OF PRODUCTION Pancreas
DIGESTIVE JUICE PRODUCED Pancreatic juice

SITE OF PRODUCTION Glands in the wall of the small intestine
DIGESTIVE JUICE PRODUCED Intestinal juice

• Peristalsis this is the muscular action along the alimentary canal that moves food down into the stomach.

• Stomach contains layers of muscles that contract and relax causing churning of the stomach contents. The food is held within the stomach by the closure of the stomach valves called the sphincters. The vigorous churning of the stomach allows the food to come into contact with the digestive juices and aid in digestion.

• Digestive enzymes these promote the breakdown of food and help speed up the digestive process. Different enzymes are responsible for the breakdown of fats, proteins and carbohydrates.

• Enzymes are a biological catalyst and are made of proteins. They have the ability to speed up a chemical reaction e.g. digestion but are able to remain unchanged at the end of the reaction.

• Amylase this enzyme is present in saliva and pancreatic juices. It is responsible for the breakdown of starch (a large complex carbohydrate) into simple sugars.

• Pepsin this enzyme is present in the glands found in the lining of the stomach wall. It is responsible for the breakdown of proteins into amino acids and peptides.

• Lipase is made in the pancreas but is active in the small intestine. It is responsible for the breakdown of fat into 3 fatty acids and glycerol.

• Bile is not an enzyme but it does help in the digestion of fat. On mixing with fat it can convert large drops of fat into small droplets therefore increasing the surface area for the lipase to work on.

TYPE OF ENZYME
amylase
EXAMPLES
salivary amylase
TYPE OF FOOD DIGESTED
pancreatic amylase
END PRODUCTS
starch

TYPE OF ENZYME
protease
EXAMPLES
pepsin (gastric juice)
TYPE OF FOOD DIGESTED
pepsin (gastric juice) trypsin (pancreatic juice)
END PRODUCTS
protein peptides

TYPE OF ENZYME
lipase
EXAMPLES
pancreatic lipase
TYPE OF FOOD DIGESTED
fat
END PRODUCTS
fatty acids and glycerol

• All enzymes are specific, that is that are only able to work on a certain food group (called the substrate).

• This specificity allows the enzyme and the substrate to join together like a lock and key.
  e.g. ENZYME + SUBSTRATE - ENZYME-SUBSTRATE COMPLEX - ENZYME + END PRODUCT
  

• The Small Intestine's main function is the absorption of the end products of digestion. These products are absorbed through its very thin wall and then passed into the bloodstream. The efficiency of this function is aided by the small intestine¡¯s structure.

• It is a very long and thin tubular structure and internally bears thousands of finger-like projections called Villi. Because of this the small intestine represents a very large absorbing surface area to the digested food.

• The specialised internal structures of the villi allow them to carry out their job effectively.
  1. Each villus is by a thin epithelium (1 cell thick) this allows the soluble end products of digestion to pass through rapidly.
  2. Each villus contains a dense network of blood capillaries into which glucose and amino acids pass. These end products are then transferred to the liver via the hepatic portal vein.
  3. Each villus also contains a tiny lymphatic vessel (lacteal) which collects the end products of fat digestion and then passes them into the lymphatic system.
  
  

• Large Intestine receives material that consists of undigested matter, bacteria and dead cells. The large intestine is responsible for the absorption of water from this unwanted material leaving faeces.

• Faeces are eliminated by being passed into the rectum from where they are later expelled through the anus.

Reproduction

• This is the production of new members of a species. Reproduction allows a species to survive as new offspring replace those that have died.
  

• Most animals produce sexually (2 parents) and in order for them to do this their bodies have to produce sex cells (gametes).
  

• In humans the male gamete is the sperm.
  

• In humans the female gamete is the egg (ova).
  

• Fertilisation is the joining (fusing) of the male and female nucleus. In humans this is when the sperm and the ova join together. A single cell is formed, this is called the zygote.
  

• For fertilisation to occur mating has to take place.
  

• In Fish mating takes place during a particular period. Fertilisation takes place outside of the body (external fertilisation). For this to occur the male fish normally digs a nest with his tail, the female fish then swims over the nest and sheds her eggs. As the female sheds her eggs the male fish swims above her and he releases his sperm. The sperm then swim to the egg and fertilise it.

• In Humans the watery environment is replaced by the presence of semen. This fluid is produced by the male and is inserted into the female during copulation (sexual intercourse). Semen is necessary due to this being internal fertilisation.

Human Reproductive System

FEMALE SYSTEM
ORGAN FUNCTION
Oviduct site of fertilisation
ovary where ova (eggs) are stored
uterus (womb) where the baby grows and develops
vagina where the penis deposits the sperm


MALE SYSTEM
ORGAN FUNCTION
sperm duct where the sperm travel from the testes to the penis
penis responsible for depositing the sperm in the vagina
testes site of sperm production

• Pregnancy (gestation) in humans lasts for 9 months. It is divided into 3 trimesters.

• Embryos are protected in different ways
  
  1. Fish - very few species protect their fertilised eggs. Many of the embryos formed are eaten by predators. Some do survive thanks largely to their protective covering. Those fish embryos that do survive obtain their food from their yolk sac. Fish overcome the number of young that get destroyed by releasing many eggs and sperm.
  2. Mammals - protect their growing young within the uterus (womb) of the mother. The mother¡¯s hips, the strong uterine wall and the amniotic fluid protect the growing embryo from any damage. The placenta provides nourishment to the embryo via the umbilical cord. Nutrients, oxygen and antibodies pass from the mother to the embryo. Carbon dioxide and waste products pass from the embryo to the mother.
  The placenta bring the mother and the embryo¡¯s blood into close contact but they never mix. Alcohol, nicotine and drugs (including paracetomol) can pass through the placenta to the embryo. Due to the high level of care that mammals give their developing young on average only one ova (egg) is fertilised at a time.

Water and Waste

 
WATER GAIN WATER LOSS
drinking fluids sweat
food exhaled breath
chemical reactions e.g. digestion,urine,faeces

• The kidneys are responsible for regulating water balance in the body.
  

• The kidneys are controlled by a special chemical called a hormone. This hormone is called Anti-Diuretic Hormone (ADH).
  

• ADH is released by the pituitary gland (attached to the brain).
  

• ADH controls the volume of water reabsorbed by the body any excess water is transferred to the bladder and is removed in the urine.
  

• Nephrons are tiny filtering units found in the kidneys.

Kidney Failure

Kidney Dialysis

BENFITS It effectively purifies the patients blood and saves their life. It cannot be rejected If successful the patient can lead a full life.
LIMITATIONS It is too large a machine to be mobile and is expensive to run. The patient¡¯s life style is limited as about 12 hours a week they have to be connected to a machine, usually in a hospital. The body may reject the donor organ. Anti rejection drugs have to used following surgery this also reduces the normal immune system.

Responding to the Environment

Choice chambers are used to observe the behaviour of certain insects.

TYPE OF RHYTHM BEHAVIOUR PATTERN ANIMAL
Tidal Behaviour responds to the tidal movements of the sea. e.g. Green Flatworm This animal rises to the surface of the sand when it is covered with water but buries itself when the sand dries out.
Circadian Behaviour that occurs once every 24 hours. e.g. Human This animal produces less urine at night.
Annual Behaviour that occurs once a year. e,g. Hedgehog This animal hibernates in late autumn.