Cbse class-10th notes science||control and coordination

Chapter-7 biology Control and Coordination

●All the living organisms respond and react to changes in the environment around them.

●The changes in the environment to which the organisms respond and react are called stimuli such as light,heat,cold,sound,smell,touch etc.

●Both plants and animals are respond to stimuli but in a different manner.

Control and Coordination in Animals

It is brought about in all animals with the help of two main systems:

(a)Nervous system

(b)Endocine system

Nervous system

◆Control and coordination are provided by nervous and muscular tissues.

◆Nervous tissue is made up of an organized network of nerve cells or neurons ,and is specialized for Conducting information via electrical impulses from one part to the body to another.

Receptor:Are specialized tips of some nerve cells that detect the information from the environment .These receptors are located in our sense organs .

◆Ear:   •Photoreceptors

              •Hearing 

              •Balance of the body

◆Eyes:  •Photoreceptors

              •Seeing

◆Skin:  •Thermoreceptors

              •Heat or Cold

              •Touch

◆Nose: •Olfactory receptors

              •Smell detection

◆Tongue :  •Gustatory receptors

                     •Taste detection

Neuron:It is the structural and functional unit of nervous system.

Parts of Neuron:

(a)Dendrite:Acquired information.

(b)Cell body:Acquired information travels as an electrical impulse.

(c)Axon:Longest fibre on the cell body is called axon.It transmits electrical impulse from cell body to dendrite of next neuron.

Synapse:It is the gap between the nerve ending of one neuron and dendrite of the other neuron

 Here electrical signal is Converted into chemical signal for onward transmission.

Reflex Action

Reflex action is quick ,sudden and immediate response of the body to a stimulus ,Eg,:knee jerk,withdrawal of hand on touching hot object.

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

Respone : Responses are of three main types:

(a) voluntary:Controlled by forebrain

Eg;talking, writing.

(b) Involuntary:Controlled by mind and hind brain;Eg ,heart beat, Vomiting,respiration.

(c)Reflex action: Controlled by spinal cord E.g,withdrawal of hand on touching a hot object.

Need of reflex Action: 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.

Human Brain

Brain is the main coordinating centre of the body.It has three major Parts:

(a)Fore-Brain   (b)Mid-Brain   (c)Hind-Brain

(a)Fore-Brain:It is the most complex or specialized part of the brain.It consists of cerebrum.

Functions:-

◆Thinking part of the brain.

◆Control the voluntary actions.

◆Store information (memory)

◆Receives sensory impulses from various parts of the body and integrate it.

◆Centre associated with hunger.

(b)Mid-Brain:Controls involuntary actions such as:

•Change in Pupil size.

•Reflex movements of head,neck and trunk.

 (c)Hind-Brain:- It has three parts:

(i)Cerebellum:Controls posture and balance.Precision of voluntary actions e.g;Picking pen.

(ii)Medulla:Controls involuntary actions e.g;Blood Pressure,Salivation,vomiting .

(iii)Pons: Involuntary actions, regulation of respiration.

Protection of Brain and Spinal cord

(a)Brain:Brain is protected by a fluid filled ballon which acts as shock absorber and is enclosed in cranium(skull or brain box).

(b)Spinal Cord:Spinal cord is enclosed in vertebral coloumn.

Coordination between Nervous and Muscular Tissue.

Limitations of Electric Communication/nervous system:

(a)Electric impulse will reach only to those cells that are connected by nervous tissue.

(b)After generation and transmission of an electrical impulse,the cell takes some time to reset its mechanism before transmitting another impulse.So cells cannot continually create and transmit impulse.

(c)Plants do not have any nervous system.

Chemical Communication:To overcome the limitations of electric Communication.

Coordination in Plants

Movements in Plants:

(i) Independent of growth

(ii)Dependent of growth

  

(I) Independent of growth:Immediate respone to stimulus.

◆Plants use electrical -chemical means to convey information from cell to cell.

◆For movement to happen ,cells change their shape by changing the amount of water in them, resulting in swelling or shrinking of cells.

E.g,Dropping of leaves 'Touch-me-not' plant on touching it.

(ii)Dependent on growth:These movements are tropic movements I.e.., directional movements in response to stimulus.

◆Tendrils:The part of tendril away from the object grows more rapidly as Compared to the part near the object.This Causes Circulating of tendril around the object.

◆Phototropism:Movement towards light.

◆Geotropism:Movement towards/away from gravity.

◆Chemotropism:Growth of Pollen tube towards ovule.

◆Hydrotropism:Movement towards water.

Plant Hormones:Are chemical compounds which help to coordinate growth , development and respones to the environment..

Main plant Hormones are:

(a)Auron:     ●Synthesized at shoot tip.

                       ●Helps the cells to grow                             longer.

                       ●Involved in                       phototropism

(b)Gibberellin:Help in the growth of the stem.

(c) Cytokinins:    ●Promotes cells        division.

                               ●Present in greater Concentration in fruits and seeds.

(d)Abscisic Acid : ●Inhibits growth

                                  ●Cause wilting of leaves.

                                  ●Stress hormone

Hormones in animals:

Hormones:Hormones are the chemical substance which coordinate the activities of living organisms and also their growth.

Endocrine glands:These glands secrete their product (hormone)into the blood.

Endocrime  Gland Hormones and their Functions

(1)Hormone:- Thyroxine

Endocrine gland :- Thyroid

Location:- Neck /throat region

Function:- Regulation of metabolism of carbohydrates,fats and proteins.

(2)Hormone:- Growth hormone

Endocrine gland :- Pituitary (master gland)

Location:- Mid brain

Function:- Regulates growth and development.

(3)Hormone:- Adrenaline

Endocrine gland:- Adrenal

Location:- Above both kidneys

Function:- Regulation (increasing) of blood pressure,heart beat, carbohydrate metabolism (during emergency)

(4)Hormone:- Insulin

Endocrine gland:- Pancres

Location:- Below stomach

Function:- Reduces and regulates blood sugar level.

(5)Hormone:- (a) Testosterone

                                   (in males)

                          (b) Estrogen 

                                (in females)

Endocrine gland :- (a)Testis

                                   (b)Ovaries

Location:- genital/lower abdomen area

Function:- changes associatated with puberty (sexual maturity)

Iodised salt is necessary because

Iodine mineral is essential part of thyroxine hormone secreted by thyroid gland .Tyrosine regulates metabolism of carbohydrates,fats and proteins.So,we must consume iodised salt which is necessary for proper working of thyroid gland ,it's deficient causes a disease called goiter(swollen neck).

Diabetes

Disease in which blood sugar level increase .

Cause:Due to the deficiency of insulin hormone secreted by pancreas that is responsible to control blood sugar level.

Feedback Mechanism 

The excess or deficiency of hormones has a harmful effect on our body.Feedback mechanism makes sure that hormones should be secreted in precise quantity and at right time.

NCERT Solutions for Class 10 Science Chapter 7 - Control and Coordination

In-text Questions (NCERT Questions)

Page 119:

Q1: What is the difference between a reflex action and walking?

Answer:

• Reflex Action: Reflex actions are automatic, rapid responses to a stimulus that do not involve conscious thought. They are controlled by the spinal cord.
• Walking: Walking is a voluntary action that requires conscious control by the brain. It involves coordination between different muscles and is a learned response.

Q2: What happens at the synapse between two neurons?

Answer:
At the synapse, a small gap between two neurons, chemical signals (neurotransmitters) are released by the axon terminal of one neuron, which then travel across the gap and bind to receptors on the dendrite of the next neuron. This triggers an electrical impulse in the next neuron.

Q3: Which part of the brain maintains posture and equilibrium of the body?

Answer:
The cerebellum is the part of the brain responsible for maintaining posture and equilibrium of the body.

Q4: How do we detect the smell of an agarbatti (incense stick)?

Answer:
When an agarbatti burns, it releases aromatic compounds into the air. These compounds are detected by olfactory receptors in the nose, which send signals to the brain, allowing us to perceive the smell.

Q5: What is the role of the brain in reflex action?

Answer:
The brain is generally not involved in reflex actions; instead, reflexes are managed by the spinal cord. The brain, however, may become aware of the reflex action after it has occurred.

Exercise Questions

Page 122:

Q1: Explain how auxins help in the bending of the plant stem towards light.

Answer:
Auxins are plant hormones that promote cell elongation. When light falls on one side of a plant stem, auxins accumulate on the shaded side, causing cells on that side to elongate more than the cells on the lighted side. This uneven growth causes the stem to bend towards the light.

Q2: How does chemical coordination occur in plants?

Answer:
In plants, chemical coordination occurs through plant hormones such as auxins, gibberellins, cytokinins, abscisic acid, and ethylene. These hormones regulate various functions like growth, flowering, fruit ripening, and response to environmental stimuli.

Q3: Why is the use of iodised salt advisable?

Answer:
Iodised salt provides iodine, which is essential for the production of thyroid hormones. These hormones are necessary for regulating metabolism and development. A deficiency of iodine can lead to goitre and other thyroid-related disorders.

Q4: How does our body respond when adrenaline is secreted into the blood?

Answer:
When adrenaline is secreted into the blood, it triggers the "fight-or-flight" response. This includes increased heart rate, dilation of pupils, faster breathing, and a redirection of blood flow towards muscles. These changes prepare the body to respond quickly to stress or danger.

Q5: Why are some patients of diabetes treated by giving injections of insulin?

Answer:
Diabetes patients are sometimes treated with insulin injections because their bodies are either not producing enough insulin or are unable to use it effectively. Insulin injections help regulate blood glucose levels by allowing cells to absorb glucose from the blood.

Q6: What are the differences between the nervous system and the endocrine system?

Answer:

Nervous System	Endocrine System
Works through electrical impulses	Works through chemical hormones
Response is fast and short-lived	Response is slower and long-lasting
Controls voluntary and reflex actions	Controls involuntary actions
Messages travel along neurons	Hormones travel through the bloodstream

Q7: Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.

Answer:

• Nervous Mechanism: Involves the transmission of electrical impulses through neurons, providing quick and targeted responses to stimuli.
• Hormonal Mechanism: Involves the release of hormones into the bloodstream, which act more slowly but provide a longer-lasting effect, often affecting multiple organs simultaneously.

Q8: What is the difference between the reflex action and walking?

Answer:
Reflex action is an automatic, involuntary response to a stimulus controlled by the spinal cord, whereas walking is a voluntary action controlled by the brain and requires conscious effort.

Q9: How do neurons transmit signals in the body?

Answer:
Neurons transmit signals by generating an electrical impulse that travels along the axon. When it reaches the end of the neuron, it triggers the release of neurotransmitters, which cross the synapse and initiate an electrical impulse in the next neuron.

Q10: Describe the structure and function of the human brain.

Answer:
The human brain consists of three major parts:

1. Forebrain: Responsible for complex functions like thinking, memory, emotions, and voluntary actions.
2. Midbrain: Acts as a relay station for auditory and visual signals.
3. Hindbrain: Includes the cerebellum (balance and coordination) and medulla (control of involuntary actions like breathing and heartbeat).