Chapter 7: Control and coordination

Chapter 7

Control and coordination 

All living organisms respond to various stimuli like heat, light, cold, touch, Pressure etc. Example withdrawal of hand on touching hot object. 

Control and coordination in animals
1. Nervous system
2. Endocrine system

Nervous system

Nervous tissue - nervous tissue is made up of an organised network of Nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.
Nervous cell - The unit of nervous tissue is called neuron or nervous cell.

Parts of nervous cell 

1. Dendrite - when informations acquired at the end of the dendrite tips of a nervous cell.
2. From dendrite to cytoplasm - Here the impulse travels from the dendrite to cell body, and then along the axon to its end.
3. Axon - At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemical cross the gap, or synapse and start a similar electrical impulse in a dendrite of the next neuron.

Propagation of information through nerves 

All the information to our brain that delivers the information that are acquaired at one end of dendrites of the nerve cell and sets off a chemical reaction travel in body

Synapse

The gap bw two nerve cells.

Receptor

Receptors are specialised tips for some nerve cells that detect the information from the environment.

Reflex Action

Reflex action- Reflex action is quick, sudden and immediate response of the body to a stimulus.

eg- knee jerk, withdrawl of hand on touching hot object.

Stimulus- It is observable or detectable change in the external or internal envt. to which an org. reacts.

Reflex arc - The pathway through which nerve impluses pass during reflex action is called reflex arc.

Responese- It is the final reaction after the reflex action.

Types-

1. Voluntary- Controlled by fore brain eg- talking, walking

2. Involuntary- Controlled by mid & hind brain eg-digestion,, heart beat etc.

3. Reflex action- Controlled by spinal cord. eg- withdrawl of hand on touching a hot object.

 Qus 1 What is the need of reflex actions?

Ans. In some situations such as touching a hot object, pinching etc. we need to act quickly, otherwise our body would be harmed. Here  response is generated from spinal cord instead of brain. In this way, time for taking actions is reduced which save us from injury.

Human Brain

Brain is the main coordinating centre of the body. It works with the spinal cord.

It has three parts:-

1. Fore Brain

2. Mid Brain

3. Hind Brain

Functions

1. Fore Brain

- Thinking

- Listening, seeing, smelling

- Controlled coluntary actions

- Centre associated with hunger

- Store information (Memory)

- Receives sensory impulse from various parts of body

2. Mid Brain

- Controlled involuntary actions such as change in pupil size and reflex movements of head, neck and Trunk.

3. Hind Brain

- Controlled Involuntary actions such as blood Pressure, salivation, vomitting by medulla.

- Controlled Posture and balance through cerebellum. eg. Picking of pen, Bicycle. etc.

- Pons-  Involuntary actions, regulation of respiration.

Coordination b/w Nervous  and Muscular Tissue