Control and coordination

IN THIS LESSON YOU WILL LEARN ABOUT

Animal – nervous system

  • what is nervous system
  • structure and function of neurons
  • reflex arc: definition, component, location, function, examples

Human brain

  • difference between central nervous system and peripheral nervous system
  • brain: different parts, functions of different part of brain

Coordination in plants

  • introduction
  • Definition with examples of different terms used in plants movement
  • Plant hormones- types and functions
  • Hormones in animals

Nervous system-:

  • Coordination is the process through which two or more organs interact and complement the functions of one another.
  • The neural system of all the animals is composed of specialized cells called neurons which can detect, receive and transmit different kinds of stimuli through electrical impulses from one part of body to another.
  • A neuron is a microscopic structure composed of three major parts-

Cell body- it is the spherical part contain nucleus and connect to dendrites on upper side and to axon to the down side.

Dendrites- they receive the stimulus and generate the electrical impulse.

Axon- impulse travel through dendrite to the cell body then axon fragment to its end. At the end of axon, the electrical impulse releases some chemicals.

These chemicals cross the synapse, and start a similar electrical impulse in the dendrite of the next neuron.

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NOTE- SYNAPSE IS A JUNCTION BETWEEN TWO NERVE CELL, CONSISTING OF A MINUTE GAP ACROSS WHICH IMPULSES PASS BY DIFFUSION OF A NEUROTRANSMITTER.

REFLEX ACTIONS

  • The process of detecting the signals or the input and responding to it by an output action might be quickly. Such a connection is commonly called a reflex arc.
  • Reflex arc are formed in spinal cord .
  • Reflex arc evolved in animal because the thinking process of brain is not fast enough

Component of reflex pathway

  1. Receptor organ -which get the stimulus ex heat, pain, cold, electric current
  2. Sensory neurons- receives signal from receptor organ and transmit the impulse to spinal cord.
  3. Relay neuron-connecting neuron and it transmit the signal from sensory neuron to motor neuron.
  4. Motor neuron- carries the signal or response from spinal cord to the receptor organ.

EXAMPLES of reflex action-

  1. Pulled back of hand from the flame
  2. Watering of mouth by reflex when we are hungry
  3. Sudden close of eye when an abject reaches your eye.
  4. Removal of your hand from sharp object.
  5. Change in Size of pupil in reflex to light.

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HUMAN BRAIN

  • Brain is the main coordinating centre of the body.
  • The brain and spinal cord constitute the central nervous system.
  • They receive information from all parts of the body and integrate it.
Central nervous system(CNS) Peripheral nervous system(PNS)
It include brain and spinal cord It includes all the nerves associated with CNS
It is site of information processing and control They help in communication between CNS and other part of body

 

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PARTS OF BRAIN AND THEIR FUNCTIONS:-

FORE BRAIN-

  • it is main thinking part of brain
  • Fore brain consist of cerebrum, thalamus, and hypothalamus
  • It has regions which receive sensory impulses from various receptors.
  • Association area in the brain is responsible for complex functions like memory, communication and interpreting the sensory information with the information from other receptor as well as with information already stored in brain.
  • Fore brain control body temperature, urge of eating and drinking etc.

MID BRAIN-

  • Many involuntary actions are controlled by mid brain and hind brain.
  • Example-it control reflex movement of head, neck, and trunk in response to visual and auditory stimuli.
  • It controls the reflex movements of the eye muscles, changes in pupil size and shape of the eye lens.
  • Mid brain and hind brain form the brain stem.

HIND BRAIN-

  • it consists of Pons, cerebellum and medulla oblongata.
  • Hind brain control number of involuntary actions like-
  • Blood pressure, salivation, vomiting, respiration they are mainly regulated by medulla
  • Balance of body, speech and muscular activity are mainly regulated by cerebellum.

NOTE- BRAIN IS PROTECTED BY SKULL INSIDE OF SKULL IT CONTAIN CEREBRO SPINAL FLUID (CSF) WHICH PROTECT BRAIN FROM JERK AND SHOCK.WHILE SPINAL CORD IS PROTECTED BY VERTEBRALCOLUMN.

COORDINATION IN PLANTS-

  • Plants have neither nervous system nor muscles.
  • So plants hormones and electro-chemical communication play a major role in their coordination.
  • Plants show two different types of movements- one dependent on the growth and other independent of growth.
  • Growth independent type of movement (nastic movement) include electrical-chemical means of communication from cell to cell, in response to stimulus plant cells change shape by changing in the amount of water in them, resulting in swelling or shrinking.

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Example- shrinking of leaves when touching the sensitive plant like shame plant (mimosa pudica).

Note-

  • SEISMONASTIC MOVEMENTS- MOVEMENTS OR ORIENTATION IN RESPONSE TO TOUCH .
  • THESE MOVEMENTS ARE VERY QUICK AND BEST SEEN IN ‘TOUCH-ME-NOT’ PLANT.
  • Movement due to growth( tropic movement) includes various type of plant movement in response to environmental triggers such as light, gravity, water etc. These directional movements (tropic) can be either towards the stimulus, or away from it.
  1. POSITIVE GEOTROPIC– movement of plant part toward the gravity. Example – roots
  2. NEGATIVE GEOTROPIC– movement of plant part against the direction of gravity. Examples-stem

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  1. POSITIVE PHOTOTROPIC – movement of plant part towards the direction of light. Example-sunflower
  2. NEGATIVE PHOTOTROPIC– movement of plant part against the direction of light. Example-roots

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CHEMOTROPISM- movement of plant part navigated by chemical stimulus. Example- growth of pollen tubes towards ovules.

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HYDROTROPISM movement of plant part towards or away the moisture.

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If movement is towards the moisture it is known as positive hydrotropism and if movement is away the moisture it is known as negative hydrotropism.

PLANT HORMONES

  • HORMONES are the chemical compounds synthesized and released by plants all around the original cells.
  • If the surrounding cells have the means to detect this chemical compound, then they would be able to recognize information, and even transmit it.
  • This is slower method of coordination, but it can potentially reach all the cell of the body.
  • Plant hormones help to coordinate growth, development and responses to environment.

TYPES OF PLANT HORMONES

AUXIN

  • Sunlight stimulates the synthesis of auxin at the shoot tip.
  • Auxin helps in growth of stem.
  • Auxin concentrated at the shady part of shoot and stimulates cell growth in this region and cause bending of tip towards light.
  • Auxin promotes flowering ex in pineapple
  • Auxins are widely used as herbicides.

GIBERLLINS

  • It promotes stem growth.
  • It elongates and improves the shape of apple
  • It promotes early seed production
  • It delays senescence (plant aging).

CYTOKININS

  • IT promotes cell division.
  • They are present in greater concentration in areas of rapid cell division such as fruits and seeds.
  • It helps to produce new leaves.
  • It delays leaf senescence.

 ABSCISIC ACID

  • IT inhibits the plant growth.
  • It promotes wilting of leaves.
  • It is also known as stress hormone.
  • It stimulates the closure of stomata to increase the tolerance of plants in stress conditions.

EHTYLENE

  • It promotes ripening of and growth of fruits.
  • It promotes yellowing and senescence of leaves.
  • It helps in breaking the dormancy in buds and seeds.
  • It stimulates the formation of separation layer in leaves, flowers and fruits.

HORMONES IN HUMAN

  • HORMONES are chemical compound produced by endocrine gland and released into the blood and transported to different target organs.
  • The timing and amount of hormones released regulated by feedback mechanism of human body.
  • Release of hormones is regulated by hypothalamus.

HORMONE

FUNCTIONS ENDOCRINE GLAND
GROWTH HORMONE It is secreted by pituitary. Regulate growth of bones and all organs. PITUITARY GLAND
PROLACTIN Synthesizing milk during pregnancy. PITUITARY GLAND
GONADOTROPINS

  • FOLLICLE STIMULATING HORMONE(FSH)
  • LUTEINISING HORMONE(LH)
Gametes formation.

-It stimulates the follicle cells in the ovaries to develop into mature eggs.

PITUITARY GLAND
-In male it stimulates secretion of male hormone, TESTOSTERONE. In females, it stimulates the secretion of OESTROGEN and PROGESTERONE.
THYROID HORMONE

(THYROXINE)

(TRIIODOTHYRONONE)

It controls the growth and functioning of the THYROID GLAND.

Regulate metabolism of fat, protein and carbohydrate.

Maintain balanced growth of body.

PITUITATRY GLAND
INSULIN Reduce blood glucose level. PANCREAS
GLUCAGON Increases the blood glucose level. PANCREAS
ANDROGEN Regulate changes during puberty in males like facial hair growth, low pitch voice, TESTES
ESTROGEN AND PROGESTEREON Regulate changes during puberty in females such as growth of uterus, fallopian tube, growth of breasts etc. OVARIES
ADRENALINE

NORADRENALINE

Both these hormones together control emotions, fear, anger, blood pressure, heart beat, respiration and relaxation of smooth muscles. ADRENAL MEDULLA
GLUCOCORTICOIDS Regulate the metabolism of protein, fat and carbohydrates in the body. ADRENAL CORTEX(KIDNEY)
MINERALOCORTICOIDS

(ALDOSTERONE)

Regulate minerals and water balance in the body ADRENAL CORTEX(KIDNEY)
MELANOTONIN Regulate sleep cycle( circadian rhythm) PINEAL GLAND

 

PREVIOUS YEAR QUESTION FROM NCERT

QUE 1- NAME THE HORMONES SECRETED BY THE FOLLOWING ENDOCRINE GLANDS AND SPECIFY ONE FUNCTION OF EACH:

  1. Thyroid C) Pancreas
  2. Pituitary

ANSWER- A) thyroid gland releases thyroxin hormone. It regulates the metabolism and blood pressure of body.

B) Pituitary gland releases growth hormone. It helps the bones and all other body organs to grow properly.

C) Pancreas secreted insulin. It helps in maintaining blood glucose level.

QUE 2- NAME THE ORGAN THAT PRODUCE SPERMS AS WELL AS SECRET A HORMONE IN HUMAN MALES. NAME THE HORMONE AND WRITE ITS FUNCTIONS?

ANSWER- Testis produces sperm and secreted testosterone hormone. Their important functions are as follows:

I) it stimulates sperm production

ii) It stimulate to develop secondary sexual characters in males like growth of facial hairs, low pitch voice etc.

iii) It stimulate the development, maturation and functioning of male accessory sex organs like vas deferens and seminal vesicles.

QUE 3- NAME THE PLANT HORMONES RESPONSIBLE FOR FOLLOWING ACTION:

I) GROWTH OF STEM

II) PROMOTES CELL DEVISION

III) WILTING OF LEAVES

IV) INHIBIT GROWTH

ANSWER- I) auxin and gibberellins

ii) Cytokinin

iii) abscisic acid

iv) abscisic acid

QUE 4- NAME ONE PLANT HORMONE WHICH INHIBITS GROWTH. WRITE IT’S ONE MORE FUNCTION.

ANSWER- abscisic acid is plant hormone which inhibits the plant growth. Its other functions include

I) it promotes the dormancy in seeds and buds.

ii) It promotes closing of stomata.

QUE5- MENTION THREE CHARACTERISTICS FEATURES OF HORMONAL SECRETION IN HUMAN BEINGS.

ANSWER- i) endocrine system releases the hormones in blood.

ii) Timing and quantity of hormone secretion is regulated by feedback mechanism of body.

iii) The working of endocrine gland is controlled by nervous system. The hormones produced by the endocrine system act as messengers between the nervous system and the organs of the body.

QUE 5- A) WRITE THREE MAIN FUNCTIONS OF THE NERVOUS SYSTEM.

B) IN THE ABSENCE OF MUSCLE CELLS, HOW DO PLANT CELLS SHOWS MOVEMENT?

ANSWER- a) main function of nervous system are-

  • Coordinates the different activities of the body
  • Help all other system of body to work together.
  • The nervous system of all the animals is composed of specialized cells called neurons which can detect, receive and transmit different kind of stimulus.

b) The movement of any part of plant body is due to change in shape of plant cells.

Plant maintains their coordination by electro-chemical communication and by plant hormones.

Plant hormones help in growth, development and response to environment stimuli.

 

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