New Senior School Biology Practical Activity & Work Book 3
Chapter
1
REGULATION OF THE INTERNAL ENVIRONMENT
Notable Concepts
Homeostasis Processes.
Organs of homeostasis.
Hormones.
Background Information
The internal environment of multicellular organisms are made up of body fluids such as tissue fluid, blood and lymph. Cell live in the internal environment. For efficient functioning of the cells, the components of the internal environment need to operate within and around certain optimal conditions. Such conditions include physical and chemical conditions such as pH level, osmotic pressure, temperature, concentration of ions and dissolved substances like urea, food substances, carbon(iv)oxide, oxygen etc. Any wide deviation of these conditions from the optimum level required for a given organism can harm the cells or even bring about their death. In multicellular organisms (especially the higher ones) these conditions have to be regulated within an allowable range for a given organisms so as to maintain a steady internal environmental condition. The maintenance of this internal steady environment is called HOMEOSTASIS. Homeostasis is achieved by homeostasis process, which involves:
The sensory detectors, which stimulates relevant body parts, for control on recognizing of a change in a given condition.
Relevant body parts which receive the signal from sensory detectors, interpret it and send out instruction to the effector organs. (example glands).
The effector organs, which restore the condition to normal.
Organs and Parts Involved in Homeostasis
The brain which has overall control of homeostasis.
The kidneys
The liver
The skin and
The hormones.
Organs of homeostatsis
fig1.1:
The Kidney Nephron
Kidney disease
Glomerular nephritis
Kidney stones
Duiresis
Oedema
Functions and Homeostasis role of the organ or (part of the body).
The Kidneys
The Kidneys carries out its homeostatic throughitsexcretoryandosmoregulatory functions. In performing these functions, the kidneys maintains water balance and constant osmotic pressure in the blood and tissue fluid. Osmoreceptors at the hypothalamus in the brain detects changes in osmotic pressure as blood circulates, they send nerve impulses to the pituitary gland which releases antidiuretic hormone from its posterior part. When osmotic pressure is high. This hormone increases the permeability of the distal tubules and collecting dusts thus causing increased reabsorption of water by the tubules into the blood stream, in order to bring down the osmotic pressure. When normal osmotic pressure is attained it is again detected by osmoreceptors, the pituitary gland is stimulated by the nerve impulse from the receptors to stop releasing the antiduiretic hormone. The kidney also helps to maintain normal pH level of the blood by controlling excretion of H+ and Hco3-ions.
fig1.1:
The Liver
Liver diseases
Jaundice
Gallstones
Viral hepatitis
Cirrhosis
Amobic liver Abscess.
Functions and Homeostasis role of the organ or (part of the body).
The liver through its numerous functions outlined below performs important roles in the homeostasis.
It controls blood glucose level and keeps it within normal limit by converting excess glucose to glycogen (a process stimulated by insulin) and also by converting glycogenintoglucosewhenthere is deficiency of glucose in the blood (a process stimulated by glucagon)
Releasing required amount of amino acid into general circulation and carrying out deamination.
Breaking down lipids to glucose and other substances to meet body needs, It can also convert glucose to fats for storage after its glycogen storage capacity is exceeded.
Bile production.
Storage of vitamins and minerals.
Storage of blood.
Inactivation of hormones.
Formation and breakdown of red blood cells.
Detoxication
Production of heat.
fig1.1:
The Skin
Two main layers are recognized in the skin.(1) The Epidermis and (2) The Dermis
(1) The epidermis consist of:
The inner malpighian layer
The middle gramular layer and
The outer cornified layer.
The Dermis consists of a layer of connective fissues, hair follicles, Sweat glands, Sebaceous gland, Fats cells and Sensory nerve endings.
Functions and Homeostasis role of the organ or (part of the body).
Apart from protection, production of vitamin D and sensitivity functions of the skin,the skin has a temperature regulatory function in warm blooded animals. It also functions as an excretory organ. These last two functions make the skin an organ of homeostasis. Whenever there is a distortion in the temperature balance of the body (either by intense physical activity or changes in environmental temperature), the skin together with the hypothalamus in the brain help to Restore the balance. The hypothalamus monitors the temperature of the blood that flows through it and detects changes there in. Also it receives information on the external environmental temperature changes through thermo receptors in the skin.A rise in temperature stimulates heat loss center of the hypothalamus to initiate a process that will reduce the heat while temperature decrease stimulates the heat gain center of the hypothalamus to initiate the process that will raise the heat.
Hormones
Hormones are secretions of the endocrine glands, which act as chemical messenger by evoking responses at target organs.
Hormones effects at target organs can be to excite, inhibit, it can also be to alter. Such effects can be achieved by affecting cell permeability to certain substance, promoting protein synthesis or by increasing the activity of certain enzymes.
fig1.4:
Important hormones in animals and their Functions
Hormones
Functions/Production
1. Pituitary gland hormones (Anterior)
Produced by the pituitary gland through stimulation by hypothalamus
(i) Adreno corticotropic hormone (ACTH)
Stimulates adrenal cortex to produce its hormones
(ii) Thyroid stimulating hormone (TSH)
Stimulates thyroid gland to produce its hormones.
(iii) Follicle stimulating hormone (FSH)
Stimulates follicle to ripe
(iv) Growth hornmones
(GH) stimulates growth of long bones
(v) Prolactin
Induces milk production in pregnant women
(vi) luteinizing hormone (LH)
Causes ovulation in women and stimulates secretion of testosterone in testis.
(Posterior)
(I) Anti-diuretic hormone (ADH)
Increases absorption of water at the kidney tubules. It also raises blood pressure by constricting the arterioles
(ii) Oxytocin
Inducces labour in childbirth and also induces milk secretion from nipples.
2i Thyroid hormone (thyroxine is the most important).
ii Calcitonin
Produced by the thyroid. Thyroxin regulates growth and development of all body cells. It also increases basal metabolic rate.
3. Parathyroid hormone
Produced by the parathyroid gland (it regulates blood calcium level in conjunction with calcitonin a thyroid hormone it raise blood calcium level.
4. Pancreatic hormone i. Insulin ii. Glucagon
Produced by islet of langerhans at the pancreas. Insulin promotes uptake of glucose by cells and its conversion to glycogen while glucagon converts glycogen to glucose when there is low glucose content in blood.
5. Oestrogen
Produced by the ovaries. It produces female secondary sexual characteristics.
6 Progesterone
Also produced by the ovaries, it inhibits ovulation during pregnancy, brings about development of placenta and prevents the uterus from contracting.
7 Male testosterone
Produced by the testes, it gives rise to male secondary sexual characteristics
Adrenal hormones
(i) Glucocorticoids (ii) Mineralocorticoids (iii) Adrenaline (iv) Noraldrenaline
Adrenal hormones are produced by the adrenal glandsThe Adrenal cortex produces (i) and (ii).Glucocorticoids raise blood glucose level by promoting the convertion of non carbohydrate e.g amino acid to glucose. Mineralocorticoids regulates levels of Calcium and Potassium in body fluids. (iii) and (iv) are produced by the adrenal medulla. They are emergency hormones.
Undersecretion
Oversecretion
(i) Growth hormones
Dwarism
Gigantism
(ii) Thyroxin
Cretinism (before adulthood) Myxoedema(at adulthood) Hyperplasticgoitre (which occurs when thyroid gland comes under prolonged stimulation)
Exophthalmic giotre
(iii) Pancreatic hormones
Diabetes mellitus due to under secretion of insulin
Insulin shock results when too much insulin is taken
Plant Hormones
Plant Hormone
Function
i. Auxin
Produced in shoots apices.The most important natural auxin is indoleacitic acid
Influences growth and development.Stimulates cells division, elongation and differentiation. It inhibits growth of lateral buds (apical dominance ) it also inhibits abscission. Auxins can allow flowers develop into fruits without fertilization. This is called parthenocarpy
ii. Gibberellins Found in root and stem apices.
This stimulate stem growth by cell division and elongation inducing germination in seeds, growth of dormant auxiliary buds and increasing of fruit size.
iii. Cytokinins
They are produced in roots
They stimulate cell division that leads to normals roots and stem growth. They also stimulate lateral buds unlike auxins. They also delay aging in plant organs.
iv. Abscisic acid
Produced in mature green leaves, fluid and root caps
It acts as a growth inhibitor. Its effects are opposed to those of i, ii, and iii. Its effects enables plants to withstand adverse environmental conditions.
v. Ethene Produced in leaves, stems and in young fruits
It hinders lateral bud development and hastens the ripening of fruits.
General Questions
1. The
,
and
make up the internal environment of a higher multicellular organism.
2. For the maintainance of a steady internal environment human beings require a temperature condition that does not deviate much from
oc
3. PH (Hydrogen ion concentration ) of the blood is normal at a value of
4. In Homeotasis, a cycle of actions in which the final event inhibits the first event is referred to as
5. The
controls homeostasis.
6. The pitiutary gland depends on the
in the brain for information and stimulation .
7. High osmotic pressure in the blood can result to the release of
hormone from the pituitary gland.
8.
is the kidney disease which occurs due to streptococcal (a bacterial) infection.
9. Drugs that increase urine output can be referred to as
10. A patient suffering from kidney failure can be kept alive by
11. What will happen if blood glucose level falls below 40g/100cm3
12. During deamination by the liver, nitrogen containing amino part is converted to
while the keto acids (which is a carbon compound) is converted to
13. The parasite which causes Amoebic liver abscess is called
14. Jaundice is caused by
an increase in the blood fluid
an increase in level of urea in the blood
an increase in the blood bilirubin level
15. The layer of the skin which contain melanin pigment is the
fig1.5:
Use the diagram above to answer question numbers 17 to 20.
Properly and clearly label the parts numbered 17 – 20 and write their functions.
Write their functions.
21. Over secretion of thyroxine results to
dwarfism or lack of growth
non secretion of growth hormones
enlarged thyroid gland. A condition known as exophthalmic goitre
22. Apart from thyroxine another hormone secreted by thyroid gland is
calcitonin
Di-iodothyronine
Adreneline
23. Write down the plant hormone that is a growth inhibitor
24.Write down two emergency hormones
and
25. Two hormones that can be produced by the ovary are
and
Expression Excercise
1. What is the name of the diagram below?
fig1.6:
2. How often should the machine be used for purifying the blood of a kidney failure patient
3. Briefly explain how the machine works as a remedy for kidney failure
3a. What is feed back mechanism?
(b) In a negative feed back illustrated below, what effect does the final action have on the first event.
fig1.7
4. Write down five functions of the liver
5a. Write down four liver diseases
(b) Write five effects of liver diseases
6 The diagram below illustrates one form of heat regulation by the skin. Use it to answer the questions that follow
Identify and write down the part that is involved in vasoconstriction
What happens to the hair and the errector muscles during Vasoconstriction?
fig1.8:
Practical Activities
Your teacher wil help you to cut and open a rat or rabbit or guinea pig and expose the abdomenal internal structures which includes the liver, intestine pancreas etc.
Procedure/Method
First locate the position of the liver and pancreas
Also try to locate the position of the kidneys.
Observe those organs carefully
Questions
(i) What is the colour of the liver
(ii) What is the shape and manner of positioning of the liver in respect to the stomach
(iii) What structure connects the liver to the pancrease
(iv) What hormone does the pancreas produce?
(v) State three liver diseases
2. Compare the way you feel thirsty on a sunny dry day and the way you feel thirsty on a rainy cold day. Also compare the way you urinate on a cold rainy day and the way you do not do the same on a bright sunny day when you are actively engaged in moving up and down
Explain your observations using your knowledge of homeostasis and osmoregulatory functions of the kidneys
Test of Practical Work / Alternative to Practical
fig1.9: A
fig1.9: B
Diagram A and B shown in fig. 1.9 represents the reaction of some structure of the mammalian skin in different environmental conditions. Use them to answer the questions that follow.
(i) Which diagram represents the reactions of the skin to cold conditions?
(ii) List four observations from the diagrams to support your answer.
(iii) What is vasodilation?
(iv) What is the difference between homeothermic animals and poikilothermic animals?
(v) Apart from temperature controls, state four other functions of the skin.
fig1.95:
(i) At what part of the diagram does ultrafilteration take place?
(ii) Explain the role of ADH (antidiuretic hormone) and osmoreceptors in water re-absorption by the kidney tubules
Regulation of the internal environment
(Past SSCE Questions)
1979 Q3
1. Why is sugar contained in the urine of a person with diabetes mellitus?
2. Which hormone controls water re-absorption in the kidney?
3. Specimen B among group I is a fresh liver of a small mammalExamine the specimen carefully.
(i) Describe the specimen
(ii) Mention the name of the structure you can see apart from liver lobe
Pierce the structure with a clean sharp dissecting pin or office pin
(iii) Test the oozing content with a red litmus paper. Record your observation and state the pH of the content.
(iv) Name the oozing substance and where it is manufactured.
(v) State three functions of the substance named in 3 (ii) and (iv) above
(vi) List three functions and two diseases of the liver
Liver Diseases:
(vii) Suggest the system in the mammalian body associated with specimen B.
Regulation of the internal environment
(Past SSCE Questions)
2. A farmer applied different concentrations of cytokinins to his pineapple plants and observed the development of new shoots over a period of time. The result of his observation shown below.
S/No.
Concentration of cytokinin in mg/litre
Number of new shoots
1
0
2
2
1
5
3
2
8
4
3.5
12
5
4
18
6
4.5
25
7
5
20
8
6
10
9
7.5
8
10
8
6
11
9
5
12
10
5
(a) Plot a graph to show the relationship between cytokinin concentration and shoot development. [15marks]
(b) Use the graph to describe the effect of cytokinin concentration on shoot development.[4marks]
(c) What advice should be given to the farmer based on the results from the graph?[2marks]
(d) List (i) two substances in plants, (ii) two substances in animals which have similar effect as cytokinins.[4marks]
