CBSE Class 10 Science Chapter 7 Control And Coordination

Introduction 

In this chapter, we delve into the fundamental aspects of control and coordination in living organisms. Exploring the intricate mechanisms that enable organisms to maintain harmony and adapt to their environment. From nervous systems to hormonal regulation, we uncover the vital processes governing life's dynamic equilibrium.

Receptors: 

Receptors are the specialized tips of the nerve fibres that collect the information to be conducted by the nerves.Receptors are in the sense organs of the animals.

These are classified as follows :

Phono-receptors: These are present in inner ear for sound

Photo-receptors: These are present in the eye to respond to the light.

Thermo-receptors: These are present in skin for heat/cold.

Olfactory-receptors: These are present in nose for recieving smell

Gustatory-receptors: These are present in the tongue for teste detection.

Nervous System: 

The nervous system is composed of specialized tissues, called nervous tissue. The nerve cell or neuron is the functional unit of the nervous system. It is the nervous system which is mainly responsible for control and coordination in complex animals.

Functions of the nervous system ;-

-Nervous system receives information from the environment.

-To receive the information from the various body.

-To act according to through muscles and glands.

Neuron:—

A neuron is the structural and functional unit of the nervous system. Neuron is a highly specialized cell which is responsible for the transmission of nerve impulses. The neuron consists of the following parts:-

(i) Cyton or cell body: 

The cell body or cyton is somewhat star-shaped, with many hair like structures protruding out of the margin. These hair-like structures are called dendrites. Dendrites receive the nerve impulses.

(ii) Axon: 

This is the tail of the neuron. It ends in several hair-like structures, called axon terminals. The axon terminals relay nerve impulses.

(iii) Myelin sheath: 

There is an insulator cover around the axon. This is called myelin sheath. The myelin sheath insulates the axon against nerve impulse from the surroundings.

Types of neuron

Sensory neuron: 

These neurons receive signals from a sense organ.

Motor neuron:

 These neurons send signals to a muscle or a gland.

Association or relay neuron: 

These neurons relay the signals between sensory neuron and motor neuron.

Synapse: 

The point contact between the terminal branches of axon of one neuron with the dendrite of another neuron is called synapse.

Transmission of nerve impulse: 

Nerve impulses travel in the following manner from one neutron to the next :

Dendrites → cell body → axon → nerve endings at the tip of axon → synapse → dendrite of next neuron.

Human Nervous System: 

The nervous system in humans can be divided into three main parts

1. Central Nervous System: 

The central nervous system is composed of the brain and the spinal cord. The brain controls all the functions in the human body. The spinal cord works as the relay channel for signals between the brain and the peripheral nervous system.

2. Peripheral Nervous System: 

The peripheral nervous system is composed of the cranial nerves and spinal nerves. There are 12 pairs of cranial nerves. The cranial nerves come our of the brain and go to the organs in the head region. There are 31 pairs of spinal nerves. The spinal nerves come out of the spinal cord and go to the organs which are below the head region.

3. Autonomous Nervous System:

 The autonomous nervous system is composed of a chain of nerve ganglion which runs along the spinal cord. It controls all the involuntary actions in the human body. The autonomous nervous system can be divided into two parts :

Sympathetic nervous system.

Parasympathetic nervous system.

Sympathetic Nervous System: 

This part of the autonomous nervous system heightens the activity of an organ as per the need. For example, during running, there is an increased demand for oxygen by the body. This is fulfilled by an increased breathing rate and increased heart rate. The sympathetic nervous system works to increase the breathing rate the heart rate, in this case.

Parasympathetic Nervous System:

 This part of the autonomous nervous system slows the down the activity of an organ and thus has a calming effect. During sleep, the breathing rate slows down and so does the heart rate. This is facilitated by the parasympathetic nervous system. It can be said that the parasympathetic nervous system helps in the conservation of energy.

Human Brain: 

Human brain is a highly complex organ, which is mainly composed of nervous tissue. The tissues are highly folded to accommodate a large surface area in less space. The brain is covered by a three-layered system of membranes, called meninges. Cerebrospinal fluid is filled between the meninges. The CSF providers cushion the brain against mechanical shocks. Furthermore, protection. The human brain can be divided into three regions, viz. forebrain, midbrain and hindbrain.

Parts of Human Brain :

Fore-brain: It is composed of the cerebrum.

Mid-brain: It is composed of the hypothalamus.

Hind-brain: It is composed of the cerebellum, pons, medulla, oblongata.

Some main structures of the human brain are explained below :

Cerebrum: 

The cerebrum is the largest part in the human brains. It is divided into two hemispheres called cerebral hemispheres.

Functions of cerebrum:-

-The cerebrum controls voluntary motor actions.

-It is the site of sensory perceptions, like tactile and auditory perceptions.

-It is the seat of learning and memory.

Medulla: 

Medulla forms the brain stem, along with the pons. It lies at the base of the brain and continues into the spinal cord. The medulla controls various involuntary functions, like hear beat respiration, etc.

It controls involuntary actions.

Example: Blood pressure, salivation, vomiting.

Pons: 

It relays impulses between the lower cerebellum and spinal cord, and higher parts of the brain like the cerebrum and midbrain, also regulates respiration.

Spinal cord: 

 Spinal cord controls the reflex actions and conducts massages between different parts of the body and brain.

Reflex Action: 

Reflex action is a special case of involuntary movement involuntary organs. When a voluntary organ is in the vicinity of sudden danger, it is immediately pulled away from the danger to save itself. For example, when your hand touches a very hot electric iron, you move away your hand in a jerk. All of this happens in flash and your hand is saved from the imminent injury. This is an example of reflex action.

Co-ordination in Plants:

Co-ordination in Plants: Unlike animals, plants do not have a nervous system. Plants use chemical means for control and co-ordination. Many plant hormones are responsible for various kinds of movements in plants. Movements in plants can be divided into two main types :

-Tropic movement 

-Nastic movement

1. Tropic movement :-

Tropic movement is the movement of a plant in response to environmental stimuli such as water, gravity, light, contact, chemical etc.

2. Nastic movement :-

It is the Non-directional , induced movement of plant in response to an external stimuli due to the turgor changes.

Turgor changes= loss of water from leave/ flowers resulting in it causes wilt of leaves or flowers.

Plant hormones / Phyto hormones :-

Plant hormones are chemical which help to co-ordinate growth, development and responses to the environment.

Type of plant hormones: Main plant hormones are-

Auxin: (Synthesized at shoot tip).
Function: Helps in growth.
Phototropism: more growth of cells towards the light.
Gibberellin: Helps in the growth of the stem.
Cytokinins: Promotes cell division.
Abscisic acid: Inhibits growth, cause wilting of leaves. (Stress hormone)

Chemical Co-ordination in humans:-

Endocrine system / Endocrine glands in humans:-

1. Pituitary Gland:

- A pea-sized gland at the base of the brain.

- Master gland controlling other endocrine glands.

- Secretes hormones influencing growth, reproduction, metabolism, and stress response.

- Consists of anterior and posterior lobes, each with distinct hormone production.

2. Thyroid Gland:

- Located in the neck, below the Adam's apple.

- Produces thyroid hormones (T3 and T4) regulating metabolism, energy levels, and body temperature.

- Essential for proper development and functioning of various organs and tissues.

3. Adrenal Glands:

- Sit atop the kidneys, one on each side.

- Comprised of adrenal cortex and adrenal medulla.

- Cortisol, aldosterone, and sex hormones produced in the cortex, while adrenaline and noradrenaline released by the medulla.

- Key role in stress response, blood pressure regulation, and electrolyte balance.

4. Pancreas:

- An organ in the abdomen, part of both digestive and endocrine systems.

- Secretes insulin and glucagon to regulate blood sugar levels.

- Crucial in maintaining glucose homeostasis, converting excess sugar into glycogen for storage.

5. Gonads (Testes and Ovaries):

- Testes found in the scrotum, ovaries in the pelvic region.

- Produce sex hormones (testosterone in males, estrogen and progesterone in females).

- Responsible for sexual development, fertility, and reproductive functions in males and females.

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