Class 10 Control and Coordination Notes

Notes Previous Years Questions Important Questions

Control and Coordination Notes

Stimulus:-

The change in the environment to which an organism respond and react is called stimulus.

Receptors:-

The group of cells present in sense organs which are sensitive to change in environment are called receptors.

There are five types of receptors:-

• Gustatory receptor
• Olfactory receptor
• Photo receptor
• Phono receptor
• Thermo receptor

Gustatory receptor:-

• Present in tongue.
• Responsible for taste detection.

Olfactory receptor:-

• Present in nose.
• Responsible for smell detection.

Photo receptor:-

• Present in eyes .
• Responsible for light detection.

Phono receptor:-

• Present in ears.
• Responsible for hearing.

Thermo receptor:-

• Present in skin.
• Responsible for feeling the touch of external stimuli.

Neuron (nerve cell):-

The structural and functional unit of nervous system is called neuron.

Synapse:- The gap between nerve ending of a neuron and dendrites of other neuron is called synapse.

• Information is passed through synapse in the form of chemical signal (not in the form of electrical impulse).

Types of neuron:-

• Sensory neuron:- The neuron that transmits the information from body to central neurons system is called sensory neuron.
• Motor neuron:- The neuron that transmits the information from central nervous system to different body parts is called motor neuron.
• Relay neuron:- The neuron that transmits the signal within the central nervous system is called relay neuron.

Reflex action:-

A quick, sudden and immediate response of the body to a stimulus is called reflex action.

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

Nervous system:-

• Peripheral nervous system (PNS)
• Central nervous system (CNS)

Peripheral nervous system (PNS):-

• Cranial nerves
• Spinal nerves

Central nervous system (CNS):-

• Brain
• Spinal cord

Cranial nerves:- The nerves arising from the brain are called cranial nerves.

Spinal nerves:- The nerves arising from spinal cord are called spinal nerves.

Voluntary actions:- The actions which are controlled by our conscious will are called voluntary actions. Ex:- walking, talking etc.

Involuntary actions:- The actions which are not controlled by our conscious will are called involuntary actions. Ex:- digestion, sweating, blinking of eyes etc.

Brain:-

It is the main coordinating part of the body.

It has three major parts:-

• Fore brain
• Mid brain
• Hind brain

Fore brain:-

• It is the main thinking part of the brain.
• It controls voluntary actions like movement of legs, writing, walking etc.
• It is responsible for memory.
• Feeling associated with hunger is controlled by fore brain.
• It receives sensory impulses from the body and interprets it.

Mid brain:-

• It controls involuntary actions such as change in the size of pupil, blinking of eyes.

Hind brain:-

• It controls involuntary actions such as salivation, BP, vomiting, sweating, heart beat etc.

Hind brain has three parts:-

• Pons
• Cerebellum
• Medulla

Pons:-

• It controls respiratory system.
• It acts as a bridge between brain and spinal cord.

Cerebellum:-

• It controls the activities like walking in a straight line, ridding a bicycle, piking up a pencil etc.
• It is responsible for precision of voluntary action and maintaining the posture and balance of the body.

Medulla:-

• It controls the involuntary actions like BP, salivation, vomiting etc.

➢ Brain is protected by skull and spinal cord is protected by vertebral column/ backbone.

Limitations of electrical impulses:-

• Electrical impulse reaches only to those cells that are connected by nervous tissue.
• Cells can’t continuously create and transmit electrical impulses.
• Plants do not have any nervous system.

Coordination in plants:-

There are two types of movements in plants:-

• Independent of growth
• Dependent of growth

Independent of growth:-

• It has immediate response to the stimulus.
• Plants use chemical means to convey the information.
• In plants, cells change shape and show the movement by changing the amount of water.

➢ In animals, cells change their shape and show movement with the help of specialized proteins found in them.

Dependent of growth:-

• These movements are tropic i.e, directional in response to stimulus.

➢ The tropic or directional movement can be either towards the stimulus or away from it.

Some tropic movements are:-

• Phototropism:- Movement towards light or away from it is called phototropism.
  Ex:- Shoots respond by bending towards light while roots respond by bending away from it.
• Geotropism:- Movement towards or away from gravity is called geotropism.
  Ex:- Roots grow towards gravity i.e., in downward direction while shoots grow away from it i.e., in upward direction.
• Chemotropism:- Movement towards chemicals or away from it. Ex:- Growth of pollen tube towards ovule.
• Hydrotropism:- Movement towards water or away from it is called hydrotropism. Ex:- Roots respond by bending towards water while shoots respond by bending away from it.

Plant hormones:-

These are chemical compounds which help to coordinate growth, development and respond to the environment.

Some plant hormones are:-

• Auxins
• Gibberlins
• Cytokinins
• Abscisic acid

Auxins:-

• These hormones are synthesized at shoot tip.
• They help the cells to grow longer.
• When light is coming from one side of plant auxin diffuses towards the shady side of the shoot and helps the plants to bend towards the light.

Gibberlins:-

• They help in the growth of stem.

Cytokinins:-

• They promote cell division.
• They are present in greater concentration in fruits and seeds.

Abscisic acid:-

• It inhibits growth.
• It helps in wilting of leaves.
• It is called stress hormone.

Animal hormones:-

• Endocrine System helps in control and coordination through chemical compounds called hormones

Endocrine glands:-

These are ductless glands which secrete hormones directly into bloodstream.

Adrenal gland:-

• Hormone:- Adrenaline
• Functions:-
  • It works in stressful situations.
  • It makes heart beat faster to supply more oxygen.
  • It increases the breathing rate.
  • It diverts the blood to skeletal muscles from digestive system and skin.

Thyroid gland:-

• Hormone:- Thyroxin
• Function:- It regulates carbohydrates, proteins and fat metabolism to provide best balance for growth.

➢ Iodine is essential for the synthesis of thyroxin.
➢ Goitre is caused due to the deficiency of iodine whose symptom is swollen neck.

Pituitary gland:-

• Hormone:- Growth hormone
• Function:- It regulates growth development of the body.

Testis:-

• Hormone:- Testosterone (Male sex hormone)
• Functions:- It controls the changes at the time of puberty in males.

Ovary:-

• Hormone:- Oestrogen (Female sex hormone)
• Function:- It controls the changes at the time of puberty females.

Pancreas:-

• Hormone:- Insulin
• Function:- It regulates blood sugar level.