Control and Coordination- Notes

Class – X Subject: Biology

Teacher: Ms Arpita

Control and Coordination: -The working together of various organs of an organisms in a systematic manner to produce a proper response of a stimulus is called Coordination.

Stimulus: -The changes in the environment to which an organism respond or react.

Response: -The reaction of the body to the change or stimulus.

Effectors: - are the muscles and glands which respond to the information from the brain and spinal cord through the motor nerves.

Receptors:- are the sense organs which receive the stimuli and pass the message to the brain or spinal cord through the sensory nerves.

Photoreceptors in the eyes to detect light.

Phono receptors in the ears to detect sound.

Olfactory receptors in the nose to detect smell.

Gustatory receptors in the tongue to detect taste.

Tango receptor or Thermoreceptor in the skin to detect touch.

Neuron: -

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

It has a cell body called cyton containing a nucleus and cytoplasm.

It has several branched structures called dendrites.

It has a long nerve fiber called axon which is covered by a protective covering called Myelin sheath.

The junction between two neurons is called synapse.

Nerve Impulse: -Messages pass through the nerve cell in the form of chemical and electrical signals called nerve impulse.

The dendrites receive the information and starts a chemical reaction which produce electrical impulse which passes through the axon.

Parts of the Nervous System: -

1- Central Nervous System(CNS): Brain and Spinal Cord2- Peripheral Nervous System (PNS): Nerves originating from CNS.

Spinal Cord:-

Spinal cord is a soft bundle of nerves which is an extension of the Medulla Oblangata region of the brain which is cushioned by three layers of meninges and present inside the neural canal of vertebral column.

Spinal cord connects brain to rest of the body.

Internally Spinal cord has inner H shaped structure called gray matter which is dark in color.

It is 45 cm in man and 43 cm in female and slightly thicker than a pencil.

There are 31 pairs of spinal nerves originates from spinal cord.

They are named according to their associated vertebrae.

Sensory nerves bring the messages to the spinal cord and motor nerves carries information back to the body parts.

Spinal cord is a center of reflex action.

Reflex Action: -Rapid automatic, involuntary response to the stimulus by the nervous system.

Name the missing part of the following Reflex Arc

Mechanism of Reflex Arc

Receptor organ like skin receives the stimulus and activates nerve impulse.

Sensory impulse is carried to Spinal Cord via Sensory Neuron.

The Spinal cord acts as a moderator and sends its processed information to effector organ through motor neuron.

Advantages of Reflex Action

It enables our body to give quick response.

It minimizes overloading of brain

Parts of Brain: -

i) Fore brain: - It is the main and largest part of the brain.

It is divided into two cerebral hemispheres.

Both Cerebral hemisphere are joined together by Nerve fiber called Corpus Collasum.

Each Cerebral hemisphere is divided into 4 parts

1) Frontal 2) Parietal 3) Occipital and 4) Temporal

It consists of the cerebrum and olfactory lobes.

It is the thinking part of the brain and controls voluntary actions. It controls touch, smell, hearing, taste, sight, mental activities like thinking, learning, memory, emotions etc.

ii) Mid brain: - It contains Endocrine Glands like Hypothalamus and Pituitary Gland.

It controls many involuntary actions and reflex movements of ears, head, neck, eyes etc.

iii) Hind brain: - consists of cerebellum, pons and medulla oblangata.

Cerebellum: - controls body movements, balance and posture.

Pons: - controls respiration.

Medulla: - controls heartbeat, blood pressure, swallowing, coughing, sneezing, vomiting etc.

Endocrine Glands: -These are ductless gland which pour their secretion i.e. hormones directly into the blood. Hormones help in coordinating activities in the body.

Endocrine System: - A group of Endocrine gland s which produces various hormones.

Hormones: -These are the chemical substances which enhances growth, metabolism of the living organisms.

Target organ- Organ that a hormone affects. Hormone reaches target organ through blood stream.

Characteristics of Hormones

Hormones are the secretion of Endocrine Glands.

They are poured directly into the blood and carried throughout the body by blood circulatory system.

They act on specific organ called target organ.

They are secreted in minute quantities.

Chemically hormones are proteins or steroids.

Types of Endocrine Glands

1. Hypothalamus: - It is present in the brain which releases Releasing Hormones and Inhibitory hormones. It regulates the secretion of hormones from Pituitary gland.

2. Pituitary Gland: - It is present below Hypothalamus in the brain. It secretes many hormones. One of the hormone secreted by Pituitary gland is Growth Hormone. Growth hormone controls growth of body by growing bones and muscles.

Too much growth hormone can cause Gigantism and less secretion causes dwarfism.

3.Pineal Gland: - It is found deep in the brain.

It secretes melatonin hormone which gives the feeling of sleepiness in the absence of light

It maintains an internal clock and we feel sleepy at a time every day.

4.Thyroid Gland:-It is attached with trachea.

It makes a hormone called thyroxine. Thyroxine controls the rate of metabolism of carbohydrate, protein and fat in the body.

Iodine is an important constituent of Thyroxine.

Its deficiency causes swelling of Thyroid gland called Goiter.

5.Parathyroid Gland: - There are four Parathyroid glands which are embedded in the thyroid gland.

It releases hormone called Parathormone which regulate calcium and Phosphate level in the blood.

6. Thymus Gland: -It is located behind sternum and between lungs.

Thymosine is the hormone secreted by Thymus gland.

It is active until puberty only and provide disease fighting T cells and hence provide immunity to the body.

7.Adrenal Glands: - There are two adrenal glands located on the top of each kidneys.

It secretes hormone called Adrenalin hormone.

It prepares the body for action during stressful condition by increasing temperature, heart beat and blood pressure.

Breathing rate and allows more glucose into the blood to give us a lot of energy.

8. Pancreas:-It is located just below the stomach in the body.

It releases Insulin Hormone. It converts Glucose to glycogen and stores in liver and muscles as Glycogen.

9.Testes: -They are the part of Male Reproductive system

It secretes male sex hormones testosterone.

It controls the development of male sex organs and features such as deepening of voice, moustache, beard, more body hairs.

It brings puberty at the age of 13 to 14 years in male.

It also makes male gametes called sperms.

10. Ovaries: -Ovaries are the part of female reproductive system.

Ovaries make two sex hormones called Oestrogen and progesterone.

Oestrogen is associated with changes in female puberty at the age of 10 to 12 years like soft skin, mammary glands, feminine voice and menstrual cycle.

Progesterone controls the changes of uterus during menstrual cycle and maintains pregnancy.

Ovaries releases female gametes called ova.

Feedback Mechanism: It is a method of controlling the hormone production. In some cases, the production of hormones is controlled by the nervous system. In other cases hormone, itself acts as control.

If the sugar level rises too much they are detected by pancreas which responded by producing and secreting more insulin into the blood.

And as the blood sugar falls to a certain limit the secretion of insulin is automatically reduced.

Coordination in Plants: In plants control and coordination is done by chemical substances called plant hormones or phytohormones.

There are five types of plant hormones.

1- Auxins 2- Gibberellins 3- Cytokinins 4-Abscisic Acid 5- Ethylene

i) Auxins :-It is synthesized in shoot tip or root tip which help in cell division, cell elongation and growth.

ii) Gibberellins :-It helps in growth of stem and branches by promoting cell enlargement and differentiation. It helps in breaking the dormancy in seeds and buds and promotes growth in fruits and flowering.

iii) Cytokinins:- It helps in cell division. It helps in breaking dormancy of seeds and buds. They delay the ageing in leaves. It promotes opening of stomata and fruit growth.

iv) Abscisic acid:- It is a growth inhibitor. It inhibits growth, maintains dormancy in seeds and buds, promotes closing of stomata and falling of leaves. It also causes falling of fruits and leaves from the plant.

vi) Ethylene :-It helps in flowering and ripening of fruits.

Movement in Plants: Plant do not show locomotion. However, movement of the individual parts are possible when they are subjected to any external stimuli like light, gravity water or chemical substances.

Movements in plants are of two main types.

1-Tropic movements

2- Nastic movements.

a) Tropic movements: - Slow response of a plant to a stimulus by growing in a direction or away from it is called tropism. They are of diverse types like Phototropism, Geotropism, Chemotropism, Hydrotropism and thigmotropism.

i) Phototropism: The response of plant towards sunlight.

Ex:- Shoot of a plant is positive phototropic and root of the plant is negative phototropic.

When light is coming from one side of the plant auxins diffuses towards shady side of the shoot and helps in phototropism by bending shoot towards light.

ii) Geotropism :- The response of the plant towards gravity. The root of the plant is positive eotropic whereas shoot of the plant is negative geotropic.

iii) Chemotropism :-It is the movement of plant in response to chemical stimuli. Eg: - Growth of pollen tube towards the sugar of the ovary.

iv)Thigmotropism:-It is the directional movement shown by parts of the plants in response to touch or physical contact with another object.

Ex:- it is shown by tendrils of plants

v) Hydrotropism: -The response of the plant towards water.

Ex: - Roots gets attracted towards water reservoir.

Hydrotropism is a stronger force than geotropism.

Nastic Movement: -The quick movement of a plant part in response to an external stimulus in which direction of the movement is not specified.

Ex:- Drooping of the leaves of the touch- me – not plant.

Home Work

1. What are the two systems which coordinate the activities in human?

2. Write the types of receptor?

3. Write the difference between a receptor and effector?

4. What are the two parts of Vertebrate Nervous system?

5. Why are the brain and spinal cord more protected than any other organs in the body.

6. What is a reflex action? Explain with the help of examples

7. Define Reflex arc. Give a flowchart of the spinal reflex arc.

8. Why brain is not involved in the process of reflex action?

9. What is spinal cord ?What is its main function?

10. How many types of Neurons are associated with Spinal Cord?