JAUNDICE (SKIN AND EYES)
This is a yellow colouration of the skin and eyes.
Cause:
Presence of excess bile pigments.
This happens due to blockage of bile duct or destruction of liver.
Symptoms: Yellow pigmentation of skin and eyes, nausea, vomiting and lack of appetite. Itching of skin.
Treatment
Removal of stones from the gall bladder by surgery.
Give patient fat-free diet, reduced amount of proteins.
Give antihistamines to reduce itching.
LIVER EXCRETION
Role of Liver in Excretion
The liver lies below the diaphragm and it receives blood from hepatic artery and hepatic portal vein.
Blood flows out of the liver through hepatic vein.
Excretion of Nitrogenous Wastes
Excess amino acids cannot be stored in the body; they are deaminated in the liver.
Hydrogen is added to amino group to form ammonia which combines with carbon (IV) oxide to form urea.
STRUCTURE AND FUNCTIONS OF THE KIDNEYS
The kidneys are organs whose functions are excretion, osmoregulation and regulation of pH.
Kidneys are located at the back of the abdominal cavity.
Each kidney receives oxygenated blood from renal artery, while deoxygenated blood leaves through the renal vein.
Urine is carried by the ureter from the kidney to the bladder, which temporarily stores it.
From the bladder, the urine is released to the outside via the urethra.
The opening from the urethra is controlled by a ring-like sphincter muscle.
EXCRETION AND HOMEOSTASIS (PLANT AND ANIMAL)
Introduction
Excretion is the process by which living organisms separate and eliminate waste products of metabolism from body cells.
If these substances were left to accumulate, they would be toxic to the cells.
Egestion is the removal of undigested materials from the alimentary canals of animals.
Secretion is the production and release of certain useful substances such as hormones, sebum and mucus produced by glandular cells.
Homeostasis is a self-adjusting mechanism to maintain a steady state in the internal environment
DISEASES OF THE RESPIRATORY SYSTEM
Asthma
Asthma is a chronic disease characterized by narrowing of air passages.
Causes:
Allergy
Due to pollen, dust, fur, animal hair, spores among others.
If these substances are inhaled, they trigger release of chemical substances and they may cause swelling of the bronchioles and bring about an asthma attack. Heredity
Asthma is usually associated with certain disorders which tend to occur in more than one member of a given family, thus suggesting’ a hereditary tendency.
FACTORS AFFECTING RATE OF BREATHING IN HUMANS
Factors that cause a decrease or increase in energy demand directly affect rate of breathing.
Exercise, any muscular activity like digging.
Sickness
Emotions like anger, flight
Effects of Exercise on Rate of Breathing
Students to work in pairs.
One student stands still while the other counts (his/her) the number of breaths per minute.
The student whose breath has been taken runs on the sport vigorously for 10 minutes.
At the end of 10 minutes the number of breaths per minute is immediately counted and recorded.
It is noticed that the rate of breathing is much higher after exercise than at rest.
GASEOUS EXCHANGE IN A MAMMAL – HUMAN
The breathing system of a mammal consists of a pair of lungs which are thin-walled elastic sacs lying in the thoracic cavity.
The thoracic cavity consists of vertebrae, sternum, ribs and intercostal muscles.
The thoracic cavity is separated from the abdominal cavity by the diaphragm.
The lungs lie within the thoracic cavity.
They are enclosed and protected by the ribs which are attached to the sternum and the thoracic vertebrae.
GASEOUS EXCHANGE IN AN AMPHIBIAN – FROG
An adult frog lives on land but goes back into the water during the breeding season.
A frog uses three different respiratory surfaces.
These are the skin, buccal cavity and lungs.
GASEOUS EXCHANGE IN BONY FISH (E.G. TILAPIA)
Gaseous exchange in fish takes place between the gills and the surrounding water.
The gills are located in an opercular cavity covered by a flap of skin called the operculum.
Each _gill consists of a number of thin leaf-like lamellae projecting from a skeletal base branchial arch (gill bar) situated in the wall of the pharynx.
There are four gills within the opercular cavity on each side of the head.
Each gill is made up of a bony gill arch which has a concave surface facing the mouth cavity (anterior) and a convex posterior surface.
GASEOUS EXCHANGE IN INSECTS
Gaseous exchange in insects e.g., grasshopper takes place across a system of tubes penetrating into the body known as the tracheal system.
The main trachea communicate with atmosphere through tiny pores called spiracles.
Spiracles are located at the sides of body segments;
Two pairs on the thoracic segments and eight pairs on the sides of abdominal segments.
Each spiracle lies in a cavity from which the trachea arises.
Spiracles are guarded with valves that close and thus prevent excessive loss of water vapour.
A filtering apparatus i.e. hairs also traps dust and parasites which would clog the trachea if they gained entry.
GASEOUS EXCHANGE IN ANIMALS
All animals take in oxygen for oxidation of organic compounds to provide energy for cellular activities.
The carbon (IV) oxide produced as a by-product is harmful to cells and has to be constantly removed from the body.
Most animals have structures that are adapted for taking in oxygen and for removal of carbon (IV) oxide from the body.
These are called “respiratory organs”.
GASEOUS EXCHANGE IN LEAVES OF TERRESTRIAL PLANTS
Gaseous exchange takes place by diffusion.
The structure of the leaf is adapted for gaseous exchange by having intercellular spaces that are filled.
These are many and large in the spongy mesophyll.
When stomata are open, carbon(IV)oxide from the atmosphere diffuses into the substomatal air chambers.
From here, it moves into the intercellular space in the spongy mesophyll layer.
The CO2 goes into solution when it comes into contact with the cell surface and diffuses into the cytoplasm.
AQUATIC PLANT STEMS
The water lily, Salvia and Wolfia whose stems remain in water are permeable to air and water.
Oxygen dissolved in the water diffuses through the stem into the cells and carbon (IV) oxide diffuses out into the water.
Gaseous Exchange in Roots
Terrestrial Plants
Gaseous exchange occurs in the root hair of young terrestrial plants.
Oxygen in the air spaces in the soil dissolves in the film of moisture surrounding soil particles and diffuses into the root hair along a concentration gradient.
It diffuses from root hair cells into the cortex where it is used for respiration.
GASEOUS EXCHANGE IN PLANTS AND ANIMALS
Necessity for Gaseous Exchange in Living Organisms
Living organisms require energy to perform cellular activities.
The energy comes from breakdown of food in respiration.
Carbon (IV) oxide is a by-product of respiration and its accumulation in cells is harmful which has to be removed.
Most organisms use oxygen for respiration which is obtained from the environment.
Photosynthetic cells of green plants use carbon (Iv) oxide as a raw material for photosynthesis and produce oxygen as a byproduct.
GASEOUS EXCHANGE IN PLANTS
Oxygen is required by plants for the production of energy for cellular activities.
Carbon (IV) oxide is required as a raw material for the synthesis of complex organic substances.
Oxygen and carbon (IV) oxide are obtained from the atmosphere in the case of terrestrial plants and from the surrounding water in the case of aquatic plants.
Gaseous exchange takes place mainly through the stomata.
APPLICATION OF ANAEROBIC RESPIRATION IN INDUSTRY AND AT HOME INDUSTRY
Making of beer and wines.
Ethanol in beer comes from fermentation of sugar (maltose) in germinating barley seeds.
Sugar in fruits is broken down anaerobically to produce ethanol in wines.
In the dairy industry, bacterial fermentation occurs in the production of several dairy products such as cheese, butter and yoghurt.
SUBSTRATES FOR RESPIRATION
Carbohydrate, mainly glucose is the main substrate inside cells.
Lipids i.e. fatty acids and glycerol are also used.
Fatty acids are used when the carbohydrates are exhausted.
A molecule of lipid yields much more energy than a molecule of glucose.
Proteins are not normally used for respiration.
However during starvation they are hydrolysed to amino acids, dearnination follows and the products enter Kreb’s cycle as urea is formed.
COMPARISON BETWEEN ENERGY OUTPUT IN AEROBIC AND ANAEROBIC RESPIRATION
Aerobic respiration results in the formation of simple inorganic molecules, water and carbon (Iv) oxide as the by¬products.
These cannot be broken down further. A lot of energy is produced.
When a molecule of glucose is broken down in the presence of oxygen, 2880 KJ of energy are produced (38 molecules of ATP).
In anaerobic respiration the by products are organic compounds.
These can be broken down further in the presence of oxygen to give more energy.
Far less energy is thus produced.
BIOLOGY PRACTICAL ACTIVITIES
To Show the Gas Produced When the Food is burned
A little food substance e.g., maize flour or meat is placed inside a boiling tube.
The boiling tube is stoppered using a rubber bung connected to a delivery tube inserted into a test-tube with limewater.
The food is heated strongly to bum.
Observations are made on the changes in lime water (calcium hydroxide) as gas is produced.
The clear lime water turns white due to formation of calcium carbonate precipitate proving that carbon (Iv) oxide is produced.
MEANING AND SIGNIFICANCE OF RESPIRATION
Respiration is the process by which energy is liberated from organic compounds such as glucose.
It is one of the most important characteristics of living organisms.
Energy is expended (used) whenever an organism exhibits characteristics of life, such as feeding, excretion and movement.
Respiration occurs all the time and if it stops, cellular activities are disrupted due to lack of energy.
This may result in death e.g., if cells in brain lack oxygen that is needed for respiration for a short time, death may occur.