10 Sc Bio Control And Coordination

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Control and Coordination Have you ever wondered how various organs of our body function in perfect symphony. How do you manage to walk without falling. How do you manage to balance yourself when you tend to fall. Even when you are fast asleep, how your internal organs go on doing their job. All these activities are managed by the nervous system. Nervous System Nervous System can be divided into two parts: 1. Central Nervous System: Central Nervous System consists of the Brain and the Nerve cord. Nerve cord is an offshoot of brain and passes through spinal column up to the lower part of the body 2. Peripheral Nervous System: Peripheral Nervous System comprises of branches of nerve fibres which come out from different parts of the Nerve cord. These branches reach out to different parts of the body. Functions of Nervous System: Nervous System collects information and sends message to brain to stimulate proper reaction. It also sends signals from brain to different parts of the body to carry out various activities. It can be said that nervous system helps make two way communication between the body and the external environment. Nerve Cell or Neuron:

Nerve cell is having amoeba like structure, with a tail of nerve fibre. The tail is covered by an insulating material, which is called dendrite. Messages pass through this tail in the form of electrical impulses. The way optic fibre helps transmit data for telephone and internet, nerve fibres transmit message for the communication going inside the body. Reflex Action: Those actions which are a result of sudden reaction to an outside stimulus are called reflex actions. For example, when you accidentally touch a hot electric iron you suddenly move your hand away from the iron. As these actions are not under our control, they are also known as involuntary actions. Your subconscious mind dictates events during reflex actions. Type of Receptors Based on External Stimulants:

1. Photoreceptors or Eyes give visual inputs to brain. 2. Audioreceptors or Ears give audio inputs to brain. www.excellup.com © 2009 Send your queries and suggestions to [email protected]

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3. Tactile receptors or skin give touch or tactile inputs to brain.

Brain gets all these inputs and processes them the way a computer processes our commands and gives required results. Parts 1. 2. 3.

of Brain: Forebrain Midbrain Hindbrain

Brain is composed of jelly like soft tissues with hollow space in the middle. The hollow space of brain and the nerve cord is filled with a fluid which is known as cerebrospinal fluid(CSF). CSF helps in giving a cushion to the nerve tissue by acting like shock absorbers.

COORDINATION IN PLANTS Although plants don't move from one place to other, but they also carry out different functions everyday. Moreover, growth in plants is greatly affected by one external stimuli, that is light. Phototropism:All the green parts of a plant grow in the direction from which they receive light. All the underground part like roots grow in the opposite direction.

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Finish Line & Beyond Certain creeping plants like pea, grow in the direction of some firm support. The tendril or spring like structure near stem coils along the support and helps the plant to grow further. Hormones: Hormones are chemicals which are released in small quantity to send specific message to the receptor cells. Various cells, after receiving message in this way carry out their specific functions. Plant Hormones: Plant hormones affect growth of various parts in the plant. Auxin:When growing plants detect light, a hormone called auxin, synthesised at the shoot tip, helps the cells to grow longer. When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light. Gibberellins: Gibberellins help in the growth of the stem. Cytokinins: Cytokinins promote cell division, and it is natural then that they are present in greater concentration in areas of rapid cell division, such as in fruits and seeds. These are examples of plant hormones that help in promoting growth. Abscisic Acid: But plants also need signals to stop growing. Abscisic acid is one example of a hormone which inhibits growth. Its effects include wilting of leaves. It also inhibits growth of buds. This is necessary when environmental conditions are not favourable to plants. For example during summer wilting of leaves helps prevent excess water loss due to transpiration. During winters fruit buds may be killed because of freezing temperature, so their growth is inhibited. Important Hormones & Their Effects in Human: Hormone

Organ/Gland

Effect

pineal gland

antioxidant and causes drowsiness

Serotonin

enterochromaffin cell

Controls mood, appetite, and sleep

tyrosine Triiodothyronine (a thyroid hormone)

thyroid gland

increase the basal metabolic rate

Epinephrine (or adrenaline)

adrenal medulla

Fight-or-flight response: Boosts the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasodilation, increasing catalysis of glycogen in liver, breakdown of lipids in fat cells.

Melatonin

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Finish Line & Beyond dilate the pupils Suppress nonemergency bodily processes (e.g. digestion) Suppress immune system Norepinephrine

adrenal medulla

Fight-or-flight response: Boosts the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume, vasoconstriction and increased blood pressure, breakdown of lipids in fat cells. Increase skeletal muscle readiness.

Follicle-stimulating hormone FSH

Pituitary gland

stimulates maturation of Graafian follicles in ovary. In male: spermatogenesis

Gonadotropin-releasing hormone GnRH

hypothalamus

promote maintenance of corpus luteum during beginning of pregnancy

Oxytocin

Pituitary gland

release breast milk

Testosterone

testes

Anabolic: growth of muscle mass and strength, increased bone density, growth and strength, Virilizing: maturation of sex organs, formation of scrotum, deepening of voice, growth of beard and axillary hair.

Estradiol

females: ovary, males testes

promote formation of female secondary sex characteristics accelerate height growth accelerate metabolism (burn fat) reduce muscle mass stimulate endometrial growth increase uterine growth maintenance of blood vessels and skin reduce bone resorption, increase bone formation

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