Control and Coordination

   

 

Summary

While the nervous system and endocrine system have their own features, they have a common

method of communication. Both the systems release chemicals to communicate between cells.

Together these two systems carry out a very complex process of maintaining a homeostatic

(balanced) internal environment of an organism.

With increasing complexity, the organisms have had to develop means of control and

coordination between the different parts of the body.

Coordination is necessary for acting as one unit and also maintain the homeostasis or

steady state within the body.

The growth of the plants, their development and their responses to the environment are

controlled or coordinated with the help of chemicals called the growth regulators. They are

different from the hormones as they either promote or inhibit the growth of the plants.

Auxins are phytohormones and are mainly concerned with cell enlargement.

The chief functions of auxins are shoot and root development, apical dominance and

delay in abscission.

Commercially, one of the major roles of auxins is in parthenocarpy, that involves

production of seedless fruits.

Gibberellins are concerned with cell elongation and cause bolting in rossette plants like

cabbage.

GA-3 (gibberellic acid), a gibberellin that has been most studied, is used in the brewing

industry for malting.

Cytokinins are phytohormones that enable cell divisions even in mature tissues.

Commercially, cytokinins are mainly used in tissue culture to induce cell division and to

keep the cut flowers fresh.

Ethylene is a gaseous growth regulator that speeds up the ripening process. It is

commercially used for artificial ripening of fruits.

It is a growth inhibitor that results in dormancy and abscission.

It conserves energy during drought by suppressing growth and conserves water by

closing the stomata.

Control and coordination in animals is done with the help of nerves and chemicals called

the hormones.

The nervous system has three parts - central nervous system (CNS), peripheral nervous

system (PNS) and autonomic nervous system (ANS).

The CNS is made up of brain and spinal cord. Brain has different areas that are

responsible for specific functions. The areas are divided into:

- sensory nerves that receives messages from the body

- motor nerves that sends messages to the body and association areas that relate the message to

previous experiences.

Spinal cord is protected by the vertebral column and gives out nerves.

The nervous system is composed of three types of nerve cells or neurons - sensory

neurons that receive messages and carry it to the CNS, the motor neuron that carries

messages from the CNS to the muscle or gland and the interneuron that runs between

sensory and motor neurons.

A bunch of neurons together make up a nerve.

Based on the types of neurons present, the nerve is called sensory, motor and mixed.

The messages are transmitted along the nerves in the form of electrical impulses. These

are maintained by the changing concentrations of potassium and sodium ions across the cell

membrane of the neurons.

When the body instantly responds to an external stimulus, it is called reflex action.

Reflex may be natural or conditioned. Natural reflex does not involve the brain whereas

conditioned reflex involves the brain. The path along which the impulses travel in a reflex are

called the reflex arc.

Chemical coordination and control is done with the help of hormones. Hormones are

secreted by endocrine glands.

Human body has eight types of endocrine glands that pour their secretions into the blood.

In addition, it also has the gastrointestinal glands.

The endocrine glands are pituitary, pineal, thyroid, parathyroid, thymus, pancreas, adrenal

and the gonads (ovaries and testes).

Some of the important hormones are growth hormone, thyroxine and insulin.

Though both nervous and endocrine systems are different, they both basically function by

the release of chemicals. Together they bring about a balance or homeostatic state in the

body.

Question (1): Why is control and coordination system necessary in organisms?

Answer:  All organisms have mechanisms to control their functions. However, in higher organisms the system

required is more complex as the individual is a complex multicellular organism with the parts separated by

greater distances.

Question (2): What is homeostasis?

Answer:  Homeostasis comes from two words - 'homeo' meaning same and 'stasis' meaning steady state within

the body.

Question (3): Give examples of some of the movements shown by plants.

Answer:  Movements as in animals is absent in plants except in cases of sperm cells of ferns and mosses

swimming towards the egg. In plants, movement is associated with the growth of the plants. For example, the

shoot system moves towards sunlight and the root system towards earth.

Question (4): What are growth regulators?

Answer:  Growth regulators are the chemicals that either promote or inhibit growth of the plants, their

development and their responses to the environment. They are also called the phytohormones.

Question (5): What are the stages of growth in plants?

Answer:  Growth in plants has three stages: Cell division Cell enlargement Cell differentiation

Question (6): Name the different phytohormones.

Answer:  The different phytohormones are auxins, gibberellins, cytokinins, ethylene and abscissic acid.

Question (7): What are auxins?

Answer:  Auxins are phytohormones that are concerned with shoot and root elongation, maintaining dormancy

and apical dominance.

Question (8): Give four major functions of auxins.

Answer:  Four major functions of auxins are:

1) Elongation of stem and root: In high concentrations it causes stem elongation and in low concentration, it

causes root elongation.

2) Apical dominance: As long as the apical buds produce auxins, the lateral buds are not allowed to grow.

3) Prevention of abscission: As long as the leaves and fruits produce auxin, they remain attached to the plant. If

they stop producing auxins, they fall.

4) Parthenocarpy: Auxins induce the ovaries to produce fruits without fertilisation and this is called

parthenocarpy. It results in seedless fruits. For example, papaya, oranges, etc.

Question (9): What are gibberellins and where are they synthesised?

Answer:  Gibberellins are plant hormones that are mainly responsible for cell elongation. They are synthesized

in embryos, young leaves, root tips, buds and seeds.

Question (10): What is the most important commercial application of gibberellins?

Answer:  GA-3 (gibberellic acid), a gibberellin that has been studied the most, causes the barley seeds to

produce the starch-digesting enzymes like maltase, amylase. This process is called malting. It is used in the

brewing industry.

Question (11): What are cytokinins? Give an example.

Answer:  They are phytohormones that induce cell divisions even in mature tissues. They were named

'cytokinins' as the cell division is also called cytokinesis. For example: zeatin, a cytokinin present in maize grains

Question (12): Give one use of cytokinins in tissue culture.

Answer:  Cytokinins are used in tissue culture to induce cell division in mature tissues.

Question (13): Name the phytohormone that causes ripening of fruits. Give one more function of this

phytohormone.

Answer:  The growth regulator that causes ripening is ethylene. It also promotes flowering.

Question (14): Name a growth inhibitor. Give two of its functions.

Answer:  Abscissic acid is a growth inhibitor. Its functions are:

1) It causes bud and seed dormancy

2) It results in abscission of leaves and fruits

Question (15): What are the control and coordination mechanisms developed in animals?

Answer:  The two control and coordination mechanisms developed in animals are: Nervous system Endocrine

system

Question (16): How does the conduction of messages take place in 1) Nervous system 2) Endocrine system

Answer: 1) The conduction in nervous system takes place with the help of electrical impulses travelling along the

nerves

2) The conduction in endocrine system takes place by the hormones being circulated in blood

Question (17): What are the functions carried out by the nervous system in human beings?

Answer:  The functions carried out by the nervous system in human beings are:

1) It perceives the changes around us through our senses

2) It controls and coordinates all the activities of the muscles in response to the changes outside.

3) It also maintains the internal environment of the body by coordinating the functions of the various internal

organs and the involuntary muscles.

4) It stores the previous experiences as memory that helps us to think and analyse our reactions.

5) It conducts messages between different parts of the body.

Question (18): What are the units of nervous system?

Answer:  The units of nervous system are specialised cells called the neurons.

Question (19): What is an impulse?

Answer:  An impulse is an electrical disturbance.

Question (20): What are the two potentials that are generated while transmission of an impulse?

Answer:  The two potentials are resting potential and action potential.

Question (21): What is a synapse?

Answer:  The junction between the axon and the dendrites of the next neuron is called the synapse.

Question (22): What are nerve fibres?

Answer:  The long axons of neurons along with the associated structures are called the nerve fibres.

Question (23): What are nodes of Ranvier?

Answer:  The nerve fibres may be enclosed within sheaths called as myelin sheath. Along the fibres there are

regions where the myelin sheath is absent. These regions are called the nodes of Ranvier.

Question (24): What are the three types of nerves?

Answer:  The three types of nerves are:

1) Sensory nerves or the receptor nerves - They are made up of only sensory neurons. For example, the cranial

nerves that conduct impulses from the organs to the central nervous system.

2) Motor nerves or the effector nerves - They are made up of only motor neurons. For example, the cranial

nerves that conduct impulses from the central nervous system to the motor nerves.

3) Mixed nerves - the nerves that are made up of both sensory and motor neurons. For example, all spinal

nerves.

Question (25): What are receptors?

Answer:  Receptors are structures at the ends of the nerve fibres that collect the information to be conducted by

the nerves.

Question (26): What are effectors?

Answer:  Effectors are muscles or glands which work in response to the stimulus received from the motor

nerves.

Question (27): What are the three divisions of the human nervous system?

Answer:  Human Nervous system can be divided into:

1) Central nervous system

2) Peripheral nervous system

3) Autonomic nervous system

Question (28): What is the central nervous system composed of?

Answer:  The central nervous system is made up of the brain and the spinal cord.

Question (29): How are organs of the central nervous system protected?

Answer:  The organs of the central nervous system are protected by three membranes called the meninges and

a fluid within these membranes called the cerebrospinal fluid. The latter acts like a shock absorber of the brain.

The brain is protected by the hard skull and the spinal cord is enclosed inside the bony vertebral column.

Question (30): What is meningitis?

Answer:  The brain and the spinal cord are protected by membranes called the meninges. An infection of the

meninges is called meningitis.

Question (31): Name the different regions of the brain and their parts.

Answer:  There are three main regions of the brain. They are:

1) Fore brain - It is made up of cerebrum, hypothalamus and thalamus

2) Mid brain - It is a relay centre

3) Hind brain - It consists of cerebellum, pons and medulla oblongata

Question (32): What is cerebrum? What are its functions?

Answer:  Cerebrum is the largest part of the brain and is a part of the fore brain. It is made up of two

hemispheres called the cerebral hemispheres. Cerebrum is responsible for the intelligence, thinking, memory,

consciousness and will power.

Question (33): What is the importance of hypothalamus?

Answer:  Hypothalamus, a small region situated below the thalamus, is an important region of the brain. It

carries out the following important functions:

1) It receives the taste and smell impulses.

2) It coordinates messages from the autonomous nervous system.

3) Controls the heart rate, blood pressure, body temperature and peristalsis.

4) It also forms an axis with the pituitary which is the main link between the nervous and the endocrine systems.

5) It also has centres that control mood and emotions.

Question (34): What are the functions of mid brain?

Answer:  The functions of the mid brain are:

1) It serves as a relay centre for sensory information from the ears to the cerebrum.

2) It controls the reflex movements of the head, neck and eye muscles.

3) It provides a passage for the different neurons going in and coming out of the cerebrum.

Question (35): What is cerebellum? Where is it present? What are its functions?

Answer:  Cerebellum is a part of the hind brain.

1) It is responsible for maintaining the balance while walking, swimming, riding, etc.

2) It is also responsible for precision and fine control of the voluntary movements. For example, actions like

eating are possible while talking or listening

Question (36): What is the importance of medulla oblongata?

Answer:  Medulla oblongata has the following functions:

1) It has the cardiovascular centre - It controls the rate and force of heart beat, blood pressure, constriction and

dilation of blood vessels.

2) It has the breathing centre - it controls the involuntary breathing mechanism.

3) It also controls activites such as sneezing, coughing, swallowing, salivation and vomiting.

Question (37): What are the functions of spinal cord?

Answer:  The functions of the spinal cord are:

1) Coordinating simple spinal reflexes

2) Coordinating autonomic reflexes like the contraction of the bladder

3) Conducting messages from muscles and skin to the brain

4) Conducting messages from brain to the trunk and limbs

Question (38): What are ganglia? Give an example.

Answer:  Ganglia are centres of collection of nerve cell bodies.

For example: dorsal root ganglion of the spinal cord

Question (39): What is a reflex?

Answer:  When the stimulation of a receptor results in a spontaneous, involuntary reaction, it is called reflex

action or simply reflex.

Question (40): What are the two main types of reflexes? Give one example for each.

Answer: The two main types of reflexes are:

1) Unconditioned reflex For example: moving away the hand on touching a hot object

2) Conditioned reflex For example: salivation at the sight of favourite food

Question (41): What are exocrine and endocrine glands?

Answer:  Exocrine glands are those which pour their secretions into a duct.

For example, sweat glands, tear glands, etc.

Endocrine glands are those which are richly supplied with blood vessels and pour their secretions into the latter.

The secretions reach their target through blood. These glands are called the ductless glands as they donot have

ducts. For example, thyroid, adrenal, etc.

Question (42): What are hormones?

Answer:  Hormones can be defined as secretions that are poured into blood in order to reach a specifc target

organ.

Question (43): What are the characteristics of hormones?

Answer: Hormones have the following characteristics:

1) they may be proteinaceous or non-proteinaceous (amino acids or steroids)

2) they are secreted as per need and not stored, only excreted

3) their secretion may be regulated by nerves or by feedback effect

4) they are transported by blood

5) they mostly cause long-term effects like growth, change in behaviour, etc.

6) they do not catalyse any reactions

7) they function by stimulating or inhibiting the target organs.

Question (44): Name the various endocrine glands.

Answer:  The various endocrine glands are pituitary, pineal, thyroid, parathyroid, thymus, pancreas, adrenal and

the gonads (ovaries and testes).

Question (45): What is TSH? Where is it produced?

Answer:  TSH is thyroid stimulating hormone that stimulates thyroid to produce thyroxine. It is produced by the

anterior lobe of the pituitary.

Question (46): Which gland has both exocrine and endocrine parts?

Answer:  Pancreas has both exocrine and

Question (1): The cells in our body that can be over a foot long are _____. 

1. muscle cells

2. nerve cells

3. bone cells

4. blood cells

Ans:  2

Question (2): The substance that accelerates the growth in the stem is ____. 

1. auxin

2. cytokinin

3. enzyme

4. vitamin

Ans:  1

Question (3): Learning is related to ______________. 

1. hypothalamus

2. thalamus

3. cerebrum

4. cerebellum

Ans:  3

Question (4): Male hormone is ________________. 

1. oestrogen

2. progesterone

3. adrenaline

4. testosterone

Ans:  4

Question (5): Endocrine glands are those which pour their secretions into _________________. 

1. blood

2. ducts

3. sinuses

4. any of the above

Ans:  1

Question (6): In reflex action, the reflex arc is formed by ____________. 

1. muscles - receptor - brain

2. muscles - effector - brain

3. receptor - spinal cord - muscles

4. spinal cord - receptor - muscles

Ans:  3

Question (7): Auxins are _________________. 

1. vitamins

2. enzymes

3. proteins

4. hormones

Ans:  4

Question (8): The cerebellum is concerned with _______________. 

1. conditioning

2. memory

3. coordination and precision

4. intelligence

Ans:  3

Question (9): The endocrine gland also known as 'master gland' is ______. 

1. hypothalamus

2. pituitary

3. pancreas

4. adrenal

Ans:  2

Question (10): Which of the following acts as both endocrine and exocrine glands? 

1. pituitary

2. adrenal

3. pancreas

4. ovaries

Ans:  3

Question (11): Cerebral hemispheres are centres of __________. 

1. balance

2. smell

3. taste

4. thinking

Ans:  4

Question (12): Adrenaline increases _____________. 

1. heart rate

2. blood pressure

3. amount of glucose in blood

4. all the above

Ans:  4

Question (13): Junction of two neurons is called _____________. 

1. synapse

2. end plate

3. axon

4. dendrite

Ans:  1

Question (14): Gibberellins were discovered from ______________. 

1. bacteria

2. fungi

3. algae

4. mosses

Ans:  2

Question (15): Growth hormone is produced in ___________. 

1. hypothalamus

2. pituitary

3. pancreas

4. thyroid

Ans:  2

Question (16): The hormone secreted by the alpha cells of islets of Langerhans is _____________. 

1. glucagon

2. insulin

3. adrenaline

4. thymosin

Ans:  1

Question (17): An involuntary response to a stimulus is known as _______. 

1. jerking

2. reflex

3. conditioning

4. answer

Ans:  2

Question (18): The CNS consists of _______________. 

1. brain

2. spinal cord

3. brain and spinal cord

4. brain, spinal cord and all the nerves

Ans:  3

Question (19): An example of a sex hormone is _________________. 

1. testosterone

2. insulin

3. thyroxin

4. thymosin

Ans:  1

Question (20): Cerebrum is present in the _______________. 

1. fore brain

2. mid brain

3. hind brain

4. partly in a and b each

Ans:  1

Question (21): Cerebellum is situated in ___________. 

1. fore brain

2. mid brain

3. hind brain

4. partly in a and b each

Ans:  3

Question (22): Medulla oblongata is situated in ___________. 

1. fore brain

2. mid brain

3. hind brain

4. partly in b and c each

Ans:  3

Question (23): The grey matter consists of ___________. 

1. nerve cells

2. nerve cell bodies

3. nerve cell bodies and dendrites

4. nerve cell bodies, dendrites and axons

Ans:  3

Question (24): There are ___________ pairs of cranial nerves. 

1. 21

2. 31

3. 41

4. 12

Ans:  4

Question (25): There are ______________ pairs of spinal nerves. 

1. 12

2. 31

3. 21

4. 8

Ans:  2

Question (26): The hormone that is used to keep flowers fresh is _______. 

1. auxin

2. gibberellic acid

3. cytokinin

4. ethylene

Ans:  3

Question (27): The hormone that speeds up the ripening process is ______. 

1. auxin

2. gibberelin

3. cytokinin

4. ethylene

Ans:  4

Question (28): A spinal nerve is a ________________ nerve. 

1. sensory

2. motor

3. mixed

4. long

Ans:  3

Question (29): Ganglion is made up of ___________. 

1. dendrites

2. axons

3. cytons

4. neurons

Ans:  3

Question (30): The preganglionic fibres and the postganglionic fibres are a part of ____________. 

1. central nervous system

2. peripheral nervous system

3. autonomous nervous system

4. endocrine system

Ans:  3

Question (31): Afferent nerves are also called the _______________. 

1. motor nerves

2. sensory nerves

3. mixed nerves

4. association nerves

Ans:  2

Question (32): Efferent nerves are also called as _____________. 

1. motor nerves

2. sensory nerves

3. mixed nerves

4. association nerves

Ans:  1

Question (33): Ganglia are present in _______________. 

1. the dorsal root of spinal cord

2. the ventral root of spinal cord

3. both a and b

4. neither a nor b

Ans:  1

Question (34): The hormone that causes blood sugar level to fall is _______________. 

1. glucagon

2. insulin

3. somatostatin

4. adrenalin

Ans:  2

Question (35): Hormone produced by the ovarian follicle is __________ and in addition ________ is 

produced by the corpus luteum. 

1. oestrogen, progesterone

2. progesterone, oestorgen

3. oestrogen, thyroxin

4. progesterone, thyroxin

Ans:  1

Question (36): The gland that plays a role in 'fight or flight response' is _________________. 

1. pancreas

2. pituitary

3. adrenal cortex

4. adrenal medulla

Ans:  4

Question (37): The unit of the nervous system is _______________. 

1. cyton

2. dendron

3. axon

4. neuron

Ans:  4

Question (38): The processes that conduct signals towards the nerve cell body are the ___________. 

1. fibres

2. axons

3. dendrites

4. all the above

Ans:  3

Question (39): The nodes of Ranvier are ________________. 

1. covering of the nerve fibre

2. swelling along the nerve fibre

3. gaps in the cover of the nerve fibre

4. collection of nerves in the heart

Ans:  3

Question (40): At the synapses, the impulses are always passed from the __________________. 

1. axon to the dendrites

2. dendrites to the axon

3. either way is possible

4. cyton to the dendrites

Ans:  1

Question (41): The lobes - parietal, temporal, frontal and occipetal belong to _________________. 

1. medulla oblongata

2. cerebrum

3. cerebellum

4. hypothalamus

Ans:  2

Question (42): Unconditioned reflex is controlled by the ______________. 

1. brain

2. spinal cord

3. both a and b

4. the autonomic nervous system

Ans:  2

Question (43): Blinking of eyes is a ________________. 

1. reflex action

2. involuntary action

3. voluntary action only

4. can be a or b

Ans:  2

Question (44): The outermost covering of the nerve is called the ________. 

1. perineurium

2. epineurium

3. myelin sheath

4. capsule

Ans:  2

Question (45): The box enclosing the brain is called the _____________. 

1. skull

2. head

3. cranium

4. vertebral column

Ans:  3

Question (46): The kind of nerve carrying impulses from the brain to a gland or a muscle is called 

______. 

1. affector

2. effector

3. mixed

4. none of the above

Ans: 2