CBSE Class 10 Science Control And Coordination Notes Set 06

CHAPTER 7 – CONTROL & COORDINATION

KEY CONCEPTS & GIST OF THE LESSON

Coordination-The working together of various organs of the body of an organism in a proper manner to produce appropriate reaction to a stimulus is called coordination.

♦ Stimulus- The changes in the environment to which an organism responds and reacts is called Stimulus

♦ Control & coordination in animals- takes place by (i) Nervous system & (ii) Endocrine system

♦ Nervous system

Stimulus → Receptor organ → Sensory nerve → Brain/Spinal cord
↓
Response ← Effector organ ← Motor nerve

♦ Endocrine system

Stimulus → Endocrine organ → Secrete hormone → Hormone in blood
↓
Response ← Target organ

♦ Parts of the Nervous system – (i) Brain (ii) Spinal cord (iii) Nerves (Neurons)

♦ A Neuron is the structural & functional unit of Nervous system

♦ Parts of a neuron- (i) Dendrites (ii) Cell body (iii) Axon

♦ Synapse- Space/junction between two adjacent nerves is called Synapse.

♦ Passing of information takes place –(i) By Electric impulse (inside the neuron) and (ii) In the form of chemicals (At synapse)

♦ Reflex action- Spontaneous, involuntary and automatic response to a stimulus to protect us from harmful situations. Eg. On touching a hot object unknowingly we instantly withdraw our hand.

♦ Reflex arc- The pathway of the reflex action is called Reflex arc.

Stimulus → Receptor organ → Sensory nerve → Spinal cord →→Effector organ→ Response Refer to figure 7.2 page no. 117 of N.C.E.R.T Text book)

♦ Nervous system- (1) Central Nervous system (CNS)

(2) Peripheral Nervous system (PNS)

(i) Brain (i) Autonomic Nervous system

(ii) Spinal cord (ii) Voluntary Nervous system

v Brain (i) Centre of coordination of all activities (ii) Thinking is involved (iii) Complex process

♦ Parts of brain- Refer to figure 7.3 page no. 118 of N.C.E.R.T Text book 

♦ Fore brain Cerebrum- (i) Main thinking and largest part of the brain.

(ii) It has 3 main areasa.

Sensory area- to receive impulses from sense organs via Receptors

b. Motor area- control voluntary movements.

c. Association areas- Reasoning, learning & intelligence.

Thalamus – It relays sensory information to the Cerebrum Hypothallamus- It forms the link between Nervous system & Endocrine system

♦ Mid brain- It connects Fore brain and Hind brain. Controls reflex of eyes & ears

♦ Hind brain- Connects the Fore brain & Hind brain

Cerebellum – Controls & coordinates muscular movements, maintaining body posture and equilibrium.

Pons- Acts as a bridge between brain & spinal cord Medulla oblongata- Controls involuntary actions like blood pressure, salivation, vomiting, etc.

♦ Spinal cord- Cylindrical or tubular structure extending downwards from the Medulla oblongata.

♦ Protection of the brain & the spinal cord-

(i) Bony outer covering: skull for the brain & vertebral column for the spinal cord.

(ii) Cerebrospinal fluid present in between the three membranes.

♦ Action caused by Nervous tissue

Information → Nervous tissue → Brain Muscles → Causes action

♦ Path or action-

Nerve impulse → Muscle cell → Changes shape due to special proteins↓

Action caused ← Shorter form of muscles ← Change shape & arrangement of cell

♦ Chemical communication by hormones- (advantages)

(i) Electrical impulses have their limitations because they reach only those cells connected to the nervous tissue.

(ii) Also the nerve cells cannot generate & transmit impulses continuously.

(iii) Electrical communication is slower.

♦ Hormones- (i) are chemical messengers secreted by endocrine glands

(ii) Are secreted in small amounts & may act in nearby places or distant places.

(iii) Do not take part in the reaction & are destroyed immediately.

◊ Coordination in plants- Only chemical coordination is present in plants.
◊ Tropic movements- The movements of plants in the direction of stimulus (positive) or away from it (negative) are called tropic movements. E.g. Phototropism, Geotropism.
Chemotropism.
Refer to figure 7.4 & 7.5 page no. 121 of N.C.E.R.T Text book)
◊ Nastic movements -The movements of plants independent of stimuli are called nastic movements. E.g.- Touch me not plant leaves close when touched.

◊ Plant hormones (Phytohormones)
Examples- 1. Auxins- Help in growth of root & shoot tips.
2. Gibberellins- Help in vegetative growth
3. Cytokinins- Promote cell division
4. Abscissic acid - Inhibits growth & causes wilting (falling) of leaves

◊ Important diagrams-
1. Structure of neuron (nerve cell)2.Reflex arc 3.Human brain4.Endocrine glands .

◊ Important activities-
1. To compare taste of sugar and food with open & blocked nostrils.
2. To demonstrate the response of a plant to the direction of light.
3. To demonstrate hydrotropism.

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