Chapter-1-Control & Cooridnation
CONTROL AND COORDDINATION
1. Stimuli: - These are the changes in the environment or its factors which tends the organisms to react or interact are called as stimuli (singular of stimuli is stimulus) it is done to prevent the body from injury or danger. The process which interact the stimuli is called as response.
2. The response to stimuli is a basic property of the living organisms.
3. Organism like plants show very little responses while the animals show lot of responses
4. Coordination: - It is relation of body to environment. The working of organs of an organism together to maintain steady state also to produce proper reaction to all situations is called as coordination. It is done by two components or system.(a)Chemical coordination by hormones (b) Nervous coordination by nervous system.
Control and Coordination
In plants the coordination is only done by hormones. They are produced from various parts of the plants and help in coordination.
In plants response to stimuli very slow or little mainly done to light, water concentration or requirement of gases mainly done to regulate growth or obtained reguarments (called as endocrine glands).
Hormones: These are the chemical produced by special glands. They help the body to coordinate with the environment. They show responses to stimuli not only this but also they help the organism at various phases of growth.
Plant Hormones (or Phytohormones)
Those hormones which are produced by plants and help in control and coordination of various life processes of plants called as phytohormones. They help in three stages – (a) Plant growth as well as promotion or breaking of dormancy (b) controlling of stomata, falling of leaves (C) Fruit growth, fruit ripening and ageing of plants.
(A) Auxins – It is a plant hormone which is similar as IBA (Indole Butric Acid) or NAA (Naphthalene Acetic Acid) or IAA (Indole Acetic Acid). Which was discovered by W.F.W went (1928).
Function of Auxins:-
(i). It helps in promoting vertical growth of plant (growth of stem, root, enlargement of root) Apical-dominance:- But it stops the lateral bud in growth of plant
(ii). It helps in cell division to increase vascular tissue.
(iii). It helps in growth of roots.
(iv).It helps in increase the metabolism of plant.
(v). It helps in tissue culture.
(vi).It helps in the development of seedless fruit (Parthenocrapy) or parthenocarpic fruits.
(vii). It helps in the growing of plants like pineapple and leeches.
(viii). It helps in controlling weeds.
(ix).It helps in the growth of fruit by controlling fruit fall.
(B) Gibberellins: - This plants hormone was discovered by E.Kurosawa (1926) as gibberellinic acid.
Functions
1. It helps in the growth of leaf, sheaths.
2. It helps in the elongation of stem. Where Auxin remains ineffective.
3. It helps in germination of seed by removing dormancy
4. It helps in parthenocarpic.
5. It remove the genetic dwarfism of plant.
6. It helps to inucid flowering.
7. It has no effect on apical dominance.
8. It does not cause coleoptiles curvature which is caused by Auxins.
9. It has little effect on root growth inhibits the adventitious roots.
10. It helps in the promoting of flowering process.
(C) Cytokinins: - These are plant hormones which helps in the breaking of dormancy of seeds and buds. It delays aging of leaves to control leaf fall. It helps in producing the lateral buds and reduced longitudinal growth & stomata. It helps in the growth of fruits.
(D) Abscisic Acid (ABA) – This hormone reduces the effect of Auxins and Gibberellins. Thus reduces apical dormancy. It promotes the dormancy of seeds and buds. It promotes the closing of stomata, falling of leaves & fruits.
(E)Ethylene or Ethene (C2H4):- It is another type of plant hormone which help in ripening of fruit and breaking the dormancy of fruit and buds.
(4) Plant movement – In plant various movements can be seen, they are growth (Increase in height of plant) (Increase in length of branches) dropping of leaves opening and closing of leaves stomata flowers. All the movements are controlled by hormones or light intensity etc.
(5)Tropism: - If the movement of a part of a plant in response to an external stimulus is called tropism. It is directional movement organs of plants.
(6) Geotropism – It is the response of plant towards the gravity or against the gravity called an geotropism. (a) Positive Geotropism – The geotropism in which plant shows the movement towards the gravity. Ex- growth of roots. (b) Negative Geotropism – The geotropism in which plant shows the movement against the gravity Ex-growth of shoots.
(i). Phototropism- It is response of plants against light called as phototropism. It is done by the reaction of auxins. Ex- bending of stem towards light because auxins tend to remain in shade. The phototropism depend upon day length in summer days length is mere, in winter days length is less. The day length effects on the plant for attaining the requirement of raw material maintain its processes which is also called phototropism. This day length effects on the germination of seeds of flowering so this response is called as phototropism. The pigments in plants which are sensitive to day length are called as phototropism. The pigments in plants which are sensitive to day length are called as phytochrome.
(ii). Hydrotropism: It is response of the plants mainly roots towards water called as hydrotropism.
(iii). Nastic movement of plants – These movement of plants which are done in the response of various stimuli and take place in any direction (neither towards the stimulus nor away from the stimulus) called as nastic movement of plants or Nastic. In plants drooping of leaves (mimosa or touch me not plant), opening & closing of flower and stomata. The movement of a plant part is response to an external stimulus in which the direction of response is not determined by the direction of stimulus is called nastic movement. Nastic movements of plants are also called nasties. The nastic movements of plants are induced by stimuli such as heat, light, touch (or contact) etc. The main difference between tropic and nastic movements is not a directional movement of a plant part but nastic movement is not a directional movement of the plant part with respect to the stimulus
(a) Thigmonasty:- The non-directional movement of a plant part in response to the touch of an object is called thigmonasty. The sensitive plant has pad-like swellings called ‘pulvini’ at the base of each leaf. The folding up of the leaves of a sensitive plant on touching is due to the sudden loss of water from pad-like swelling called ‘pulvini’ present at the base of all leaves of the sensitive plant which make the pulvini lose their firmness causing the leaves to droop and fall. All the pulvini lose firmness and become limp due to which all the leaves above them collapse and fold-up.
(b) Photonasty:- The non-directional movement of a plant part (usually petals of flowers) in response to light is called photonasty. Please note that the opening and closing of flowers to response to light (or photonasty) are growth movements. Petals open when their inner surfaces grow more than their outer surfaces. On the other hand, petals close when their outer surfaces grow more than their inner surfaces. Before we end this discussion, we would like to give the functions of plants hormones.
(iv). Give various functions of plants hormones?
Ans
a. Germination of seeds or breaking the dormancy of seeds.
b. Growth of roots, stem and leaves.
c. Movement of stomata and controlling the part by guard cells.
d. Flowering process.
e. Ripening of fruits
f. Phototropism, geotropism, chemotropism and nastic movement.
(v). Response of plant to Chemicals is Chemotropism:- Chemical tropism- That tropism which is shown by influence of various chemicals like hormones is called as chemical tropism. Ex-Use of Auxins increases the flowering and height. The growth of the pollen tube in response to a chemical substance secreted by the stigma of a flower is an example of chemotropism.
(vi). Directional Response of plants to the touch of an object : Thigmotropism:- There are some plants ‘climbing plants’ which have weak stems and hence cannot stand upright (or erect) on their own. The climbing plants have climbing organs called tendrils. Tendrils are thin, thread like growths on the stems or leaves of climbing plants. Thus, there are two types of tendrils : stem tendrils and leaf tendrils. Tendrils are sensitive to the touch (or contact) of other objects. Thigmotropic is often seen in plants having tendrils. Tendrils are positively thigmotropic which means that they happen to touch. For example Pea plants & other vanes, bittergourd, bottlegourd, grapevine
Q- How is the movement of the leaves of the sensitive plant different from the movement of a shoot towards light?
Movement of leaves of sensitive plant
1. It is a nastic movement which does not depend on the direction of stimulus applied.
2. The stimulus is ‘touch’.
3. It is caused by the sudden loss of water from the swellings at the base of leaves.
4. It is not growth movement.
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Movement of a shoot towards light
1. It is a tropic movement which depends on the direction of stimulus applied.
2. The stimulus is ‘light’.
3. It is caused by the unequal growth on the two sides of the shoot.
4. It is a growth movement.
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Control and Coordination in Animals
Control and Coordination in Animals is done by two system; one is hormonal system or other is nervous system.
Homeostasis:- It is a capacity of an organism to maintain a steady state is termed as homeostasis, a term coined by Walter B. Cannon in 1920. The Latin word “hameo” means the same or similar and ‘stasis’ refers to standing still, i.e., in the same state. Thus, like coordination, the control of various physiological functions is an important property of higher organism.
Coordination in Hydra – In Hydra the nervous system is a simple network of nerves. A mass of nerves connected in a net to form ganglia. The ganglia or the nerve cord moves in the nervous system of higher animals.
It produces few hormones or its has photoreserptors cell to receive light Reflections.
Coordination in Insects – In Insects the brain is present at the top of head from where the main nerves cord starts at lower position of abdomal or run towards the tail end. The nerve cord has various segments from were nerves images out. These points are called as ganglia. The nerves starting from the abdomal and moves towards the brain by sideward positions. The grasshopper and cockroach can respond to light, sound, smell or chemicals. The brain control all the voluntary functions of muscles. It has compound eye which can see in many direction. The nervous system of the cockroach is highly developed. The central portion contain brain or nerve cord or the peripheral system contain only nerves. The cockroach and grasshopper also have chemical coordination by hormones.
A neuron:-Basic unit of nerve cell is neuron:- A neuron is specialised cell and is quite different from typical animals cell. It is specialised for the reception of stimuli and transmission of impulses to the organ concerned. A neuron is of three types (a) the sensory or unipolar neuron,(b) the motor or bipolar neuron and the (3) multipolar neuron.
A neuron typically has three parts:1 An enlarged cell body, the cyton or some having nucleus and Nissl’s granules (clumps of ribosomes). 2 The dendrites which are two or more highly branched cytoplasmic processes of soma. 3. The axon which is a long and thin extension of the soma. At one end the neuron is connected to a sensory receptor. This receives the sensation and converts it into an electric signal which is carried by neuron. At the other end, it goes to brain by the sensory neuron, where the message is received and acted upon. Motor neurons carry message between the nerve centre(or integrating center) and the effector such as muscle or gland. Often a message has to be passed from one neuron to another. This is done through junction points called synapses which is a junction between the axon of one neuron and the dendrite of next neuron in the chain. At the synapse the axon and the dendrite do not actually touch; there is small gap between the two. Transmission of impulse across the synapse involves the release of neurotransmitter acetylcholine from the axon’s bouton (synaptic knob). An impulse can travel across the synapse only from axon to a dendrite, thus, the synapse serve as a valve to prevent the backflow of impulses. When you feel pain in your toe, the sensation (the stimulus) is first received by the dendrites of a neuron and transported through the axon of the neuron as an electric impulse. The signal (i.e., impulse) is passed on to other neurons through synaptic junctions and eventually reaches a nerve centre. From here the response is transmitted through a motor neuron to the muscle of the foot which react appropriately.
Synapse:- The junction or region of union of axon of one neuron with the dendrite of another through which nerve impulses are transferred.
Coordination in Human body
Human body has highly developed chemical coordination or nerves coordination.
Human Nervous System – Human nerves system is divided into three sub-systems: -
(a) Central Nerves System (CNS) - It has brain medulla oblongata or spinal cord with spinal nerves.
(b) Peripheral Nerves System (PNS) – It includes all type of nerves-(i)The nerves starting from brain called as cranial nerves, (ii)The nerves starting from spinal cord called as spinal nerves-(iii) The nerves starting from viscera called as visceral nerves.
(c) Autonomic Nervous System (ANS) – It includes all nerves which are connected to peripheral nerves or further divided into two sub-system they are sympathetic or parasym pathetic system.
Central Nervous System
(i) Brain: - It is present in cranium (protect brain from injury) at the top of head. It has inner layer called as meninges (prevent brain and spinal cord from physical jerks) and fluid present b/w both cranium (brain case) called as cerebro spinal fluid. The brain is divided into three sub-parts:-
(a)Fore Brain (b) Mid Brain (c) Hind Brain
(A) Fore Brain is about of two-third in size. It has grey matter outside and white inside. The gray matter has lot of nerves endings while matter contains nerves fibers or nerves tissue. It is also called as cerebrum. It has various lobs. The occipital lobes is responsible for visual perception, temporal lobe is for auditory perception, parental lobs or small or touch, while frontal lobe for muscular activities.
(B) Mid Brain has cerebral pons, cerebellum and medulla oblongata. It has various walls for cerebral cortex, which connects brain or spinal cord or other nerve to cerebellum. It includes three parts tectum (or colliculi), cerebral peduncle and pineal body (the endocrine gland). Mid-brain serves (i) as a minor center for some visual analysis; (ii) as a relay center for auditory information which is being sent from the hind-brain to the hypothalamus and cortex of fore-brain; and (iii) as a pathway for several ascending and descending neuron tracts connecting cerebrum with brain stem.
(c) Hind Brain consist of stem, pons and medulla or cerebellum (dorsal). Cerebellum is responsible for control centers for the heart-beat, circulation, breathing movements, salivary secretion and swallowing food, working of heart or coordination of muscle contraction. The pone is the bundle of nerve fiber, while medulla (Control involuntary function along with the help of cerebellum.) is a connecting cord b/w spinal cord or pons.
Function of Brain
i. It receives all impulses from sensory organ of the body.
ii. It helps in the respond the external stimuli or show motions.
iii. It controls various functions of glands secreating hormones.
iv. It helps to see, to hear, to process, to remember, move consciousness.
v. It control and coordinate function of internal organs.
vi. It helps to feet the sensation of fear, power to fight and remain constant emergency conditions.
Functions of different parts of Brain.
1. Cerebral Hemisphere - It is a principle site for memory and learning.
2. Cerebellum – It helps to operate muscular action or motor function.
3. Medulla oblongata – It helps to control involuntary function like heart beat, respiration, swallowing, blinking of eyes, and movement of food pipe. It also transfer the message of spinal cord to brain.
4. Olfactory lobes – It helps to recognizes smells.
5. Occipital lobes – It helps in vision or sight.
6. Spinal cord-It is main nerve cord Starting from midbrain running through downward till end of disk. It is extension of medulla oblongata. It controls all the reflex action and carries the impulses to and fro lower organs and other organs to CNS.
7. Reflex action – All the action which is controlled at the level of spinal cord called as reflex action. They are spontaneous and automatic respond to stimuli.
8. The path of reflex action is form receptor organ to sensory nerve then it travel in neurons up to the spinal cord. In spinal cord it travel from grey matter to while matter, and returned back by motor nerve to motor organ for muscular actions.
9. Reflex arc is the path through which the Reflex action is travelled (Stimuli ------- Receptor Organ Sensory nerve -----Spinal cord----- Motor Nerve-----Muscular action).Example- Blinking of eyes, sneezing.
Autonomic Nervous System (ANS) – It includes all nerves which are connected to peripheral nerves or further divided into two sub-system they are sympathetic or parasym pathetic system.
PARASYMPATHETIC NERVOUS SYSTEM (PNS)
It includes spinal nerves, sexbory nerves and cranial nerves. It acts as main receiving zone for all stimuli. They one made up of white matter and unipalay neuromas. They have many fibers. They control all voluntary activity of the body.
AUTONOMIC NERVOUS SYSTEM. (ANS)
This system used to regulate activities of muscular organs. They have mainly smooth or involuntary muscles. They also control the function of associate glands. This system has to sub system.
S.No
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Sympathetic system
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Parasympathetic system
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(i)
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It controls working speed of organ
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It control the speed to slow down
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(ii)
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It increases the strength of heart beat.
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It control down the speed of heart beat.
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(iii)
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It increases the blood pressure in arteries by construction in lumens.
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It widens the lumens to reduce the blood pressure.
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(iv)
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It decreases the speed of food movement in food pipe and reduces juices.
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It increases the speed of food movement in food pipe and increases juices or enzymes.
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(v)
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It has double chain of ganglia. Each has function 18 ganglia distribution.
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It has only paired ganglia.
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(vi)
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It is controlled by CNS.
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IT is controlled by spinal cord
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FUNCTIONOF DIFFERENT PARTS OF BRAIN-
v Fore Brain – It helps to regulate functions of glands, water balance, hungerness, thirst, temper, or behaves pattern, sleep, stress or sex.
v Mid Brain-It helps to analyze visual material, center to relay, auditory information. Also give the path for ascending or descending information.
v Cerebrum – It helps all major functions like mental activities (instinct, thinking, memory, consciousness. Sensory perception- (It includes pain, temper, touch, sight, hearing, taste or smell identification). The initiation of control or coordination of voluntary muscle for movement, motivation or attention.
v Cerebellum – It helps the person for equilibrium of the body sense of injury when intoxicated. It also connect pons or medulla oblongatal.
CHEMICAL COORDINATION IN ANIMALS AND TYPE OF GLANDS.
The chemical coordination in animals is done by hormones. These hormones are produced by duct less gland (endocrine glands). The hormones are produced in these glands are used at various places in different organs. So they are supplied through blood. These glands has no part or pipe. So hormones directly enter in blood vessels. It is also called as chemical coordination.
Second system is nervous system. It is done by brain nerve cods or related nerves.
S no
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Endocrine Gland
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Exocrine Gland
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(I)
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These glands have no duct.
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These glands have duct.
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(II)
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These glands produce hormones
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These glands produce enzymes.
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(iii)
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The secretions of these glands help in coordination
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These secretion of these glands help in metabolism
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(iv)
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These glands are present away from the organs.
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These glands are present near the target organ
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(v)
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These produce less secretion. E.g. Thyroid gland, pituitary gland.
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They produce more secretions. E.g. Liver, Gastric gland.
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S.no
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Vitamin
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Hormones
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Enzymes
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(i)
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These are organic food material carried.
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These are organic messenger of the body from inside.
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These are biocatalyst produced by various glands.
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(ii)
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They are used up during metabolism process.
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They are used up during chemical coordination.
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They remain unchanged during metabolism.
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(iii)
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They are obtained from food items.
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They produced by endocrine glands.
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They are produced exocrine glands.
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(iv)
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They are raw material.
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They are stimulants.
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They are catalyst.
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(v)
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Deficiency produced diseases E.g. vitamin A & B.
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They produced hormonal diseases (more dangerous) E.g. Thyrosin, Insulin.
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They don’t cause nay diseases. E.g. Amylase or pepsin.
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CHEMICAL COORDINATION IN HUMAN BODY
Hormone:-1 Chemical synthesized by endocrine gland cells and secreted into the body fluids (blood) where it travels to distant sites and affects the metabolism, growth or function of other cells. 2 An organic compound that is synthesized in minute quantities in one part of a plant and translocated to another part, where it influences a specific physiological process
In Human body the chemical coordination is done by hormones which are secreted by a gland one is male or one in female total eight.
PITUTARY GLAND:- This gland secrets most of the triggering hormones ( by the order of RH released from hypothamulus ) which controls the function of all other glands therefore it is called as master gland. It is present at base of Fore Brain.
It has 3 lobs (a) Anterior lob (b) Posterior lob (c) Middle lob.
(a) Anterior lob- It secrets most of the hormones needed for functioning of the body.
1. TSH (thyroid stimulating hormones) - This hormones activate the thyroid gland to produce thyroxine.
2. GH (Growth Hormones) - This hormones help in the growth of bones. Muscles or viscera resulting the growth of the body in height. The hormone start forming more by the gland than the person become giant like (gig antism) or the activities the GH become less than the person become dwarf dwarfness.
3. ACTH (A dreno- corticoter ophic hormones) - This hormones activate adrenal cortex to secretes its hormone (Corticosteroids) or the person defend against physiological stresses or exposes to prolong cold.
4. FSH (Follical Stimulating hormone) - This hormone helps the ovary to produce graafi a follicles or female sex hormones oestrogen or control the maturation of sperms in males.
5. LH (Luteinizing Hormones)- This hormone helps the male intersectional cells to produce male hormones testotrome which control secondary sexual character of males or in females it helps to release oestrogen or formation of corpusluteum.
6. Prolactin (LTH) luteotrophic hormone – This hormone control or maintained pregnancy or stimulate memory glands to secrete milk.
(b) Posterior lobe – The lobe secrets mainly the hormones it is connected to hypotheronous.
(i)ADH (Anti Diueretic Hormone) - This hormone helps the kidney to control the amount of water or reabsorbing of water. So it helps the memory gland to store milk.
(c) Middle lob – This lob secrets only one hormone that is MSH (Melanophore stimulating hormone). This hormone helps in the growth of melanocytes by which of skin or hair caused.
HYPOTHALAMUS
This gland is connected with pituitary gland or controlled the activity of this gland control the function of releasing hormones of pituitary gland. This all gland or their function is controlled by RH (releasing hormone). When this RH is returned back from the related gland in the activity of stimulating hormone is controlled E.g. – TSH-RH control thyroid gland. Hypothalamus also control temperature
Feedback System :- Any control system should have a feedback system to prevent excessive reaction or overreaction. TSH stimulates the production of thyroxine. But if there is an overproduction of thyroxine, it acts on the pituitary and controls the production of TSH there. Thus, the production of thyroxine is kept at an optimum level.TSH and thyroxine regulate the levels of each other just like the pedal and the breaks do in a bicycle. Such a system of opposing effect leads to proper control and balance in a system. The two opposing interact and feed back the information permitting the body to adjust its output accordingly. The ultimate effect of such a feedback system is homeostasis (or a steady state of functioning of the body).
Pineal Gland
This a small round gland present at the surface of hypothermic or cerebral hemisphere. This gland secrets melatonin. Which controls the growth of ovary ovulation or reproductive cycle of mammals? It is light sensitive glands.
Thyroid Gland
This gland is situated in neck at the lower part is larynx it is soft it is like butterfly or it is produced thyroxine hormone by using iodine. This hormone controls the rate of metabolism respiration, thermoregulation, mental or physical development. It also control the absorption of glucose of small intestine.
Parathyroid gland
This gland is present in a neck as four in number. This gland is embedded in thyroid gland it secrets parathormone. This hormone control calcium level in blood, bones or teeth. This hormone control the formation of vitamin D. phosphate or bone strength.
Thymus Gland
This gland is present in chest at the front of heart. This gland remain active in new born babies but with age it become smaller or smaller. This gland secrets thymosin which stimulates the lymphocytes cells to balance immunological function. This hormone control the rejunction of skin gland or produce antibodies.
Adrenal Gland
This gland is present at the top of kidney so it is called as double endocrine gland its cortex part is outer and cortex secrets two hormones while inner part medulla secrets one hormone.
The cortex secrets corticoids hormones which control sex hormones (testrosterone, oestrogen, or progesteronb). This hormone mainly act in emergency. Condition like infections fatigue, starvation, fright, cold, injury or bums. The other hormone glucosteroids which regulate metabolism of carbohydrate, protein, fats blood glucose level or conversion of protein into glucose level or conversion of protein into glucose.
Medulla of adrenal gland secrets two hormones. It is adrenaline which control emotional stresses like anger, fear, depression, stress of cold. The other hormone is noradrenalines which control emergency or extremes dangers conditions. It helps to decide fight or flight. It controls blood pressure or blood glucose level
Pancreas
It is called double glad because it secrets enzymes for digestion as well as hormones for coordination. It is leaf line gland present in abdomen. It has round or oval patch called as islets or Langerhans. It secrets two type of hormone from two type of cells alpha and beta. Alfa secrets glucagon which control the glucose level when level become low (100 Mg/100ML). This hormone help to increase the blood glucose level to the required level. Beta cell secrets insulin which helps to when the blood glucose level
When insulin become insufficient then the glucose level rises then the diseases to called as diabetes mellitus. This disease when increases than the blood glucose level rises this stage to called as glucosauria.
Ovaries
It is female organ to produce egg cells along with two hormones oestrogen and progesterone. Both hormones are activated by FSH. These hormone helps to regulate development of follicle. Its maturation also change the body during puberty age. They control ovulation and pregnancy. During delivery time the muscular of uterus are activated by this hormone.
Testes
It is male sex organ which is activated LH. Testes is helps to produce sperms along with male hormone called as test osterone. This hormone help the boy during puberty age to course secondary sexual changes like enlargement of penis scrotum. Public hair, deeper of voice and other changes of adolescent.
(4) Plant movement – In plant various movements can be seen, they are growth (Increase in height of plant) (Increase in length of branches) dropping of leaves opening and closing of leaves stomata flowers. All the movements are controlled by hormones or light intensity etc.
(5)Tropism: - If the movement of a part of a plant in response to an external stimulus is called tropism. It is directional movement organs of plants.
(6) Geotropism – It is the response of plant towards the gravity or against the gravity called an geotropism. (a) Positive Geotropism – The geotropism in which plant shows the movement towards the gravity. Ex- growth of roots. (b) Negative Geotropism – The geotropism in which plant shows the movement against the gravity Ex-growth of shoots.
(vii). Phototropism- It is response of plants against light called as phototropism. It is done by the reaction of auxins. Ex- bending of stem towards light because auxins tend to remain in shade. The phototropism depend upon day length in summer days length is mere, in winter days length is less. The day length effects on the plant for attaining the requirement of raw material maintain its processes which is also called phototropism. This day length effects on the germination of seeds of flowering so this response is called as phototropism. The pigments in plants which are sensitive to day length are called as phototropism. The pigments in plants which are sensitive to day length are called as phytochrome.
(viii). Hydrotropism: It is response of the plants mainly roots towards water called as hydrotropism.
(ix). Nastic movement of plants – These movement of plants which are done in the response of various stimuli and take place in any direction (neither towards the stimulus nor away from the stimulus) called as nastic movement of plants or Nastic. In plants drooping of leaves (mimosa or touch me not plant), opening & closing of flower and stomata. The movement of a plant part is response to an external stimulus in which the direction of response is not determined by the direction of stimulus is called nastic movement. Nastic movements of plants are also called nasties. The nastic movements of plants are induced by stimuli such as heat, light, touch (or contact) etc. The main difference between tropic and nastic movements is not a directional movement of a plant part but nastic movement is not a directional movement of the plant part with respect to the stimulus
(a) Thigmonasty:- The non-directional movement of a plant part in response to the touch of an object is called thigmonasty. The sensitive plant has pad-like swellings called ‘pulvini’ at the base of each leaf. The folding up of the leaves of a sensitive plant on touching is due to the sudden loss of water from pad-like swelling called ‘pulvini’ present at the base of all leaves of the sensitive plant which make the pulvini lose their firmness causing the leaves to droop and fall. All the pulvini lose firmness and become limp due to which all the leaves above them collapse and fold-up.
(b) Photonasty:- The non-directional movement of a plant part (usually petals of flowers) in response to light is called photonasty. Please note that the opening and closing of flowers to response to light (or photonasty) are growth movements. Petals open when their inner surfaces grow more than their outer surfaces. On the other hand, petals close when their outer surfaces grow more than their inner surfaces. Before we end this discussion, we would like to give the functions of plants hormones.
(x). Give various functions of plants hormones?
Ans Germination of seeds or breaking the dormancy of seeds, Growth of roots, stem and leaves, Movement of stomata and controlling the part by guard cells, Flowering process, Ripening of fruits,Phototropism, geotropism, chemotropism and nastic movement.
(xi). Response of plant to Chemicals is Chemotropism:- Chemical tropism- That tropism which is shown by influence of various chemicals like hormones is called as chemical tropism. Ex-Use of Auxins increases the flowering and height. The growth of the pollen tube in response to a chemical substance secreted by the stigma of a flower is an example of chemotropism.
(xii). Directional Response of plants to the touch of an object :Thigmotropism:- There are some plants ‘climbing plants’ which have weak stems and hence cannot stand upright (or erect) on their own. The climbing plants have climbing organs called tendrils. Tendrils are thin, thread like growths on the stems or leaves of climbing plants. Thus, there are two types of tendrils : stem tendrils and leaf tendrils. Tendrils are sensitive to the touch (or contact) of other objects. Thigmotropic is often seen in plants having tendrils. Tendrils are positively thigmotropic which means that they happen to touch. For example Pea plants & other vanes, bittergourd, bottlegourd, grapevine
Q- How is the movement of the leaves of the sensitive plant different from the movement of a shoot towards light?
Movement of leaves of sensitive plant
5. It is a nastic movement which does not depend on the direction of stimulus applied.
6. The stimulus is ‘touch’.
7. It is caused by the sudden loss of water from the swellings at the base of leaves.
8. It is not growth movement.
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Movement of a shoot towards light
5. It is a tropic movement which depends on the direction of stimulus applied.
6. The stimulus is ‘light’.
7. It is caused by the unequal growth on the two sides of the shoot.
8. It is a growth movement.
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