CONTROL AND COORDINATION SA:-1

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BIOLOGY

CLASS:-X

CHAPTER-2

CONTROL AND COORDINATION

Movement is response to a change in environment control and coordination.

Specialized nervous and muscular tissues perform the function of control and coordination.

All information from our environment is detected by specialized tips of some nerve cells.

The receptions are located in our sense organs like inner ear, nose, and tongue.

Gustory receptors sense taste.

Olfactory receptors sense smell.

The information at the dendrite tip at the end of nerve cell sets off chemical reaction that

creates electrical impulse.

The impulse travels from one neuron to the next neuron through axon and dendrites.

When the impulse reaches the end of axon some chemicals are released in the gap between

two neurons. This gap is called as synapse.

These chemicals start the impulse in next neuron.

A similar5 synapse is there in between nerves and muscle cells or glands.

Neurons are specialized for conducting information via electrical impulses from one part of

body to another.

REFLEX ACTION

This is a rapid, automatic response to a stimulus which is not under the voluntary control

of the brain.

Reflex action is a sudden action in response to something in the environment.

The pathway (or route) taken by nerve impulses in a reflex action is called as reflex arc.

Reflex arcs are formed in the spinal cord.

The reflex action is an automatic response to a stimulus.

E.g. if we touch a hot object, we very quickly pull away our hand without thinking.

The receptors are p[resent in skin which sense the heat and takes the signal to the spinal

cord through sensory neuron. The response is conveyed through the motor neuron. Relay

neuron in the spinal cord joins the two neurons.

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HUMAN BODY Brain is the main coordinating center of the body.

Brain and Spinal Cord constitute the central Nervous System.

The Central Nervous System receives information from all parts of body and integrates it.

The nerves communicate with the muscles for various actions like walking, talking etc.

The communication between the Central Nervous System and other parts of the body is facilitated

by the Peripheral Nervous System (PNS).

Peripheral Nervous System comprises of nerves arising from the brain i.e. cranial nerves and

nerves arising from spinal cord i.e. spinal nerves.

The Brain has three major parts. I.e. Fore brain, mid brain and Hind brain

o It is the main thinking part of Brain.

o It receives sensory impulses from various receptors.

o It has separate areas specialized for hearing, smell and sight.

o It has association areas where the sensory information is interpreted.

o The information is passed on to the motor areas which involve movement of muscles.

o The center part is associated with hunger is also present in fore brain.

o Fore Brain consists of Cerebrum, Thalamus and Hypothalamus.

o Pituitary gland which is an endocrine gland is attached to Hypothalamus.

o The mid brain does not have any divisions.

o The functions of midbrain are it controls the involuntary actions like watering of

mouth, heartbeat.

o The Hindbrain comprises of Pons, Medulla and Cerebrum.

o The Cerebellum helps in maintaining the posture and balance of body.

o Medulla controls blood pressure, salivation and vomiting.

o Pons regulates respiration.

HOW ARE THESE TISSUES PROTECTED?

Brain is protect5ed inside a bony box in the skull called cranium.

The brain is surrounded by 3 membranes called meninges. The space between

membranes is filled with fluids.

The Spinal Cord is protected by vertebral column.

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HOW DOES NERVOUS TISSUE CAUSES ACTION?

When a nerve impulse reaches the brain the muscle fibre moves. The muscle cell

moves by changing their shape so that they shorten.

Muscle cells have a special protein that changes their shape and arrangement in

response to nervous electrical impulse.

COORDINATION IN PLANTS The plants do not have nervous system and sense organs.

The plants can sense things like light, gravity, chemicals, water and touch etc. by the

actions of hormones in them.

Plants show two different kinds of movements. One dependent on growth. Other

independent of growth.

The leaves of sensitive plants move very quickly in response to touch.

When a seed grows, the root goes down and stem comes up in air.

IMMEDIAE RESPONSE TO STIMULUS The plants use electrochemical means to carry information from cell to cell but there is no

specialized tissue to convey the information.

Plants cells change shape by changing the amounts of water in them resulting in swelling

or shrinking and resulting in change of shape.

MOVEMENT DUE TO GROWTH Plants respond to stimuli slowly by growing in a particular direction. E.g. the plant tendrils

are sensitive to touch. When tendril comes in contact with support it circles around it.

The plant shows various kinds of phototropic movement.

Shoot respond by bending towards light and said to be positively phototropic. The root

grows towards the earth and called as positively geostrophic and negatively phototrophic.

The plant also shows response towards earth i.e. Geostrophic movement or Geotropism.

Chemotropism means response towards chemicals.

Hydrotropism means response towards water.

The hormones are the compounds that diffuse around the cell. The other cells detect this

chemical and able to recognize information and transmit it.

Plant hormones help to coordinate growth, development and response to environment.

1. Auxin helps cells to grow.

2. Gibberellins helps in growth of stem.

3. Cytokinins promote cell Division. E.g. in fruits and seed.

4. Abscisic Acid inhibits growth. It causes wilting of leaves.

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HORMONES IN ANIMALS The Hormones are chemicals which are released from endocrine gland which help in

coordination of various activities inside the body.

Endocrine glands are ductless glands. They pour their secretion directly into the blood.

The different endocrine glands are: -

Adrenal gland – present on top of 2 kidneys.

--Secrete Adrenaline.

-Increases heart rate, breathing rate, Blood Pressure and Carbohydrate Metabolism

- it prepares the body for emergency situations.

Thyroid Glands- attached to wind pipe.

- Secretes Thyroxin (contains iodine)

-It controls the carbohydrate, fat and protein metabolism in body.

-Deficiency of Iodine in diet leads to disease called as Goitre.

Pituitary Gland-present below the brain attached to hypothalamus.

-secretes growth hormones.

-If there is deficiency of growth hormones in children, person is a dwarf.

- If growth hormones is secreted in large quantity the person become very tall (or giant)

Pancreas present below the stomach.

Secretes insulin.

Insulin lowers the blood sugar level.

Deficiency of insulin leads to Diabetes.

Testosterone secreted by Testis in males.

Estrogen secreted by ovaries in females.

Pineal gland secretes Melatonin. Acts as Biological Clock to control sleep waste cycle.

Hypothalamus secretes stimulating and inhibiting hormone. Controls activity of

Pituitary gland.

Parathyroid glands secrete parathyroid hormone. Maintain Blood Calcium level.

Thymus gland (near Heart) secretes thynosin. Provide immunity during childhood.