Control and Coordination {Class 10th Biology}

Chapter: Control and Coordination

Class: 10th Biology

Presented By: Dr. Priyanka Patade

Control and Co-ordination in Animals

In animals, the nervous system and hormonal system (endocrine system) are responsible for control and co-ordination.

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.

Classification of receptors

Receptors are classified as follows:

1) Phono-receptors: These are present in inner ear.

Functions: The main functions are hearing and balance of the body.

2) Photoreceptors: These are present in the eye.

Function: These are responsible for visual stimulus.

3) Thermoreceptors: These are present in the skin.

Function: These receptors are responsible for pain, touch and heat stimuli.

4) Olfactory-receptors: These are present in nose.

Functions: These receptors receive smell.

5) Gustatory-receptors: These are present in the tongue.

Functions: These helps in taste 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: Neuron is a highly specialized cell which is responsible for the transmission of nerve impulses.

The neuron consists of the following parts:

(i) Dendrites: These are hair-like structures protruding out of the margin of cell body. Dendrites receive the nerve impulses.

(ii) Cyton or cell body: The cell body or cyton is somewhat star-shaped, with many hair like structures protruding out of the margin. Cyton/soma processes the impulse.

(iii) Axon: Axon transmits the impulse, either to another neuron or to muscles/glands etc. It ends in several hair-like structures, called axon terminals. The axon terminals relay nerve impulses.

(iv) 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. The impulse transmission is faster in myelinated neurons.

Neuron

Types of neuron⏩ Sensory neuron ⏪
⏩ Motor neuron ⏪

⏩ Association or relay 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 is the gap between nerve ending of one neuron and dendrites of another.

Transmission of nerve impulse

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

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

A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber.

 It allow the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction.

Questions

1. What are receptors? Explain the types of receptors along with their functions.

2. With a neat, labelled diagram, explain the structure of neuron.

3. What are the types of neuron?

4. Define synapse? Write the path of transmission of nerve impulse.

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Human Nervous System

⏩ Central Nervous System ⏪

⏩ Peripheral nervous system ⏪

⏩ Autonomous Nervous System ⏪

⏩ Sympathetic Nervous System ⏪

⏩ Parasympathetic Nervous System ⏪

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 out 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 :

i)Sympathetic nervous system.

ii)Parasympathetic nervous system.

i) Sympathetic Nervous System:

This part of the autonomous nervous system increases 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  and the heart rate, in this case.

ii) 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.

Human Brain

Human brain is a highly complex organ, which is mainly composed of nervous tissue.

The brain is protected by 3 main layers –

⏩ The bony skull (cranium) ⏪

⏩ The cerebrospinal fluid ⏪

⏩ The meninges (Dura mater, Arachnoid and Pia mater) ⏪

The human brain can be divided into three regions, viz. forebrain, midbrain and hindbrain.

Parts of Human Brain

⏩ Fore-brain ⏪

⏩ Mid-brain ⏪

⏩ Hind-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.

Functions of different parts of the brain are

Cerebrum is responsible for reasoning, logic, emotions, speech, memory, visual processing, recognition of auditory and taste stimuli, etc.

Cerebellum regulates and coordinates body movements, posture and balance.

Pons relays signals from hindbrain to forebrain.

Medulla Oblongata controls all involuntary movements like vomiting, sneezing, yawning, heartbeat, breathing, blood pressure, etc.

Spinal Cord

Medulla oblongata continues as the spinal cord which runs through the vertebral column and it controls reflex actions.

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

The vertebral column, commonly called backbone, protects the spinal cord.

Questions

1. What is synapse? Write the path of transmission along with their functions.

2. Explain the different types of human nervous system.

3. How is human brain protected?

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Reflex action

Reflex action is a sudden, involuntary reaction of the body in response to stimuli.

For example, when your hand touches a very hot electric iron, you move away your hand in a jerk. All of this happens instantly and your hand is saved from the imminent injury. This is an example of reflex action.

Reflex Arc: The path through which nerves signals, involved in a reflex action, travel is called the reflex arc.

The following flow chart shows the flow of signal in a reflex arc:

Receptor → Sensory neuron → Relay neuron → Motor neuron → Effector (muscle)

The receptor is the organ which comes in the danger zone.

The sensory neurons pick signals from the receptor and send them to the relay neuron.

 The relay neuron is present in the spinal cord.

The spinal cord sends signals to the effector via the motor neuron.

The effector comes in action, moves the receptor away from the danger.

Types of responses

⏩ Voluntary ⏪

⏩ Involuntary ⏪

⏩ Reflex action ⏪

i) Voluntary: Controlled by fore brain. Example: talking, writing.

ii) Involuntary: Controlled by mid and hind brain. Example: heart beat, vomiting, respiration.

iii) Reflex action: Controlled by spinal cord. Example: withdrawal of hand on touching a hot object.

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

Limitations of Electric communication/Nervous system

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

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

iii) Plants do not have any nervous system.

Chemical communication- It helps in overcoming the limitations of electric communication.

Stimuli- The change in the environment to which the organism responds.

Co-ordination: Working together of various organs of an organism in a systematic manner to produce a proper response.

Neuron- Functional unit of the nervous system.

Synapse- A microscopic gap between a pair of adjacent neurons.

Receptor- A cell in a sense organ which is sensitive to stimuli.

Motor nerves- It carries the message from the brain to body parts for action.

Sensory nerves- It carries the message from body to brain.

Brain- An organ present in the skull which controls and regulates the activity of the whole body and is known as president of the body.

Cerebrum- Main thinking part of brain present in the forebrain area which controls all voluntary actions.

Cerebellum- It is present in the hindbrain area and helps in maintaining posture and balance of the body.

Medulla- It is present in the hindbrain area and helps in controlling voluntary actions of the brain.

Spinal cord- It is a cylindrical structure of nerve fibres enclosed in the vertebral column which helps in the conduction of nerve impulses to and from the brain.

Endocrine System

The endocrine system is composed of several endocrine glands.

A ductless gland is called endocrine gland.

Endocrine gland secretes its product directly into the bloodstream. Hormones are produced in the endocrine glands.

Hormone is mainly composed of protein.

Moreover, unlike nervous control, hormonal control is somewhat slower.

The list of endocrine gland with the hormones names and their functions are given below:

i) Thyroxine: This hormone is secreted by Thyroid gland. The Thyroid gland is located in Neck/Throat region regulates the metabolism of carbohydrates, fats and proteins.

ii) Growth hormones: This is secreted by Pituitary (master gland). This gland is located in Mid  brain. It regulates growth and development.

iii) Adrenaline: This hormone is secreted by Adrenal gland. The adrenal gland is located above both kidneys. It regulates blood pressure (increasing), heart beat, carbohydrate metabolism (during emergency).

iv) Insulin: This hormone is secreted by Pancreas. The pancreas are located below stomach. It reduces and regulates blood sugar level.

v) Sex hormones: (a) Testosterone in males: This hormone is secreted by testis. The testis is located in genital area. Its changes are associated with puberty (Sexual maturity).

(b) Estrogen in females: This hormone is secreted by Ovaries. The ovaries are located in lower abdomen area. Its changes are associated with puberty (Sexual maturity).

Importance of iodine

Iodised salt is necessary because iodine mineral is essential part of thyroxine hormone secreted  by thyroid gland.

Thyroxine regulates metabolism of carbohydrates, fats and proteins.

So, we must consume iodised salt which is necessary for proper working of thyroid gland.

It’s deficiency causes disease called goiter (Swollen neck).

Diabetes

Diabetes is a disease in which blood sugar level increases.

Cause of Diabetes

The disease is caused due to the deficiency of insulin hormone secreted by pancreas that is responsible to control blood sugar levels.

Treatment of Diabetes

Injections of insulin hormone can help in the treatment of diabetes.

What is coordination in plants?

Coordination is the ability to use different parts of the plant together, smoothly and efficiently.

In plants, coordination is due to the result of a chemical system, wherein plant hormones or phytohormones have a major role.

Plants exhibit two types of movements.

1) Growth-dependent movements called the Tropic Movements. ( towards or away from a stimulus)

2) Non-growth dependent movements called the Nastic Movements. ( independent of stimulus)

Tropic movements

These can be classified again into 5 types.

⏩ Phototropism (light) ⏪

⏩ Geotropism (gravity) ⏪

⏩ Hydrotropism (water) ⏪

⏩ Chemotropism (chemicals) ⏪

⏩ Thigmotropism (touch) ⏪

 Phototropism– It is the movement of plants in response to light. The shoot system of a plant exhibits this characteristic. The shoot moves towards the light.

Geotropism– It is the movement of a plant part towards the soil. This is a characteristic of the root system. The roots always move in the direction of the earth’s gravity.

Hydrotropism– It is the movement of a plant towards the water. The stimulus here is water.

Chemotropism– It is the movement of plants in response to a chemical stimulus. A classic example of this type of movement is the growth of the pollen tube towards the ovule, during  fertilization, in a flower.

Thigmotropism– It is a directional movement in plants in response to touch. For e.g. the plant tendrils climb around any support which they touch.

Nastic Movements

Nastic movements in plants are not directional movements.

They are not dependent on stimulus and are growth independent.

For example, the leaves of a touch me not plant (Mimosa pudica), fold up immediately when touched. These kinds of changes occur due to the changes in the amount of water in the leaves. Depending on the quantity, they either swell up or shrink.

Plant hormones or Phytohormones

They are responsible for the control and coordination of plants.

There are different types of hormones, which affect the growth of a plant.

Phytohormones are chemical compounds which are released by stimulated cells. These hormones are diffused around the plant cells.

They have a role to play in the cell division, cell enlargement, cell differentiation, fruit growth, falling of leaves, ripening of fruits, ageing of plants etc.

The different types of phytohormones are

⏩ Auxins ⏪

⏩ Gibberellins ⏪

⏩ Cytokinins ⏪

⏩ Abscisic acid ⏪

Auxins– They help in the cell growth at the shoot tips. By elongating the cells,  they help in the growth process.

Gibberellins– These hormones are responsible for the cell growth in the stem, seed, germination and flowering.

Cytokinin– They promote cell division in plants. They also promote the opening of the stomata and delay ageing in leaves.

Abscisic acid– This hormone inhibits the growth of the plant. Therefore, it promotes dormancy in seeds and buds. The detachment of fruits, flowers, and falling of leaves etc. are promoted by this hormone.

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