CONTROL_AND_COORDINATION_notes _class 10

Biology

1. CONTROL AND COORDINATION
NEURON- It is the structural and functional unit of nervous system.
TYPES OF NEURONS
•SENSORY NEURON The neuron which carries the nerve impulses from the receptors of the sense organs to
the brain or spinal cord are called sensory neurons.
•MOTOR NEURON The neuron which carries nerve impulses from the brain or spinal cord to the effectors
(muscle or glands).
•MIXED NEURON/RELAY NEURON : It is neuron which acts as a link between the sensory and motor
neuron.

2. TERMS
•SYNAPSE – A point of junction between two neurons. It is a contact between the dendrite of one neuron and
the axon of the next neuron.
•RECEPTORS
It is a specialized nerve cell which receives stimulus from the environment.
•EFFECTORS: Any muscle or gland which produces a suitable response to any stimulus.
•STIMULUS : Any change in the environment to which an organism responds.
NEUROMUSCULAR JUNCTION

3. HOW DOES A NERVE IMPULSE TRAVEL IN A NEURON
All information is detected by the specialized tips of the nerve cells called the receptors which are
usually located in the sense organs.
This information which is acquired at the end of the dendrite sets off a chemical response that creates
an electrical impulse .
This impulse travels from the dendrite to the cell body and then along the Axon towards its end.
At the end of the axon, the electrical impulse sets off the release of some chemicals which are
neurotransmitters such as Acetylcholine.
The chemical crosses the synapse and starts a similar electrical impulse in the dendrite of the next
neuron.
NAMES OF RECEPTORS
NAME OF RECEPTOR SENSATION LOCATION
Gustatory Receptors Taste Tongue
Olfactory Receptors Smell Nose
Thigmo Receptors Touch Skin
Thermoreceptor Heat Skin
Phono Receptors Audio Ear
Photo Receptors Light Eye
TYPES OF NERVOUS SYSTEM

4. 1)CENTRAL NERVOUS SYSTEM : (CNS) It consists of th.e brain and spinal cord
2)PERIPHRAL NERVOUS SYSTEM: It consists of the nerves arising from the brain called Cranial nerves
(12 pairs ) and spinal cord called as Spinal nerves (31 pairs)
3)AUTONOMOUS NERVOUS SYSTEM: It is a system which operates automatically or involuntarily. It
includes all those responses which are not under our control. This is divided into :
A) SYMPATHETIC NERVOUS SYSTEM:
B) PARASYMPATHETIC NERVOUS SYSTEM:
The smooth muscles of various internal organs receive both sympathetic and parasympathetic nerve fibres.
Both the systems have involuntary opposing effects. If one system exerts stimulatory effect on an organ the
other system exerts inhibitory effect on that organ .
REFLEX ACTION
Reflex action is an automatic, quick, immediate involuntary response to a stimulus involving only the spinal
cord.

5. REFLEX ARC
The path taken by the nerve impulses in a Reflex action is called as Reflex Arc.
Stimulus Receptors Sensory Neuron Relay Neuron ( Spinal Cord)
Effectors ( Glands/ Muscles) Motor Neurons
BRAIN
•Brain is protected by the cranium which is the bony box in the skull.
• The brain is covered with three membranes called meninges .

6. • The spaces between the membranes is filled with a CerebroSpinal fluid (CSF) that protects the brain and
spinal cord from mechanical shocks.

7. PARTS OF THE BRAIN
The different parts of the brain are
a)FOREBRAIN
b)MID BRAIN
c)HIND BRAIN
a)The forebrain consists of the Cerebrum, Hypothalamus , Pituitary Glands and Olfactory Lobes.
CEREBRUM :
The cerebrum is concerned with thinking, reasoning and intelligence. It consists of two cerebral hemispheres
and has distinct sensory and motor areas for sensing and giving response to stimulus.
It has distinct lobes. And they are:

8. OCCIPITAL LOBE: Visual Perception
TEMPORAL LOBE: Auditory perception
PARIETAL LOBE : Touch, Smell, Temp
FRONTAL LOBE : muscular and facial expressions, speech
OLFACTORY LOBE : Smell
2. MIDBRAIN :Reflex actions of neck and eye.
3. HIND BRAIN : It consists of the following parts:
a.MEDULLA OBLONGATA- Controls all Involuntary actions in the body like coughing, salivation,
vomitting, sneezing, swallowing, and maintaining the blood pressure.
b. PONS- It regulates the respiration.
c.CEREBELLUM- It is called the ‘Little Brain’ and is responsible for coordination and adjustment of
movement and posture. It maintains the balance in the body.

9. HOW DOES NERVOUS TISSUE CAUSE ACTION

10. COORDINATION IN PLANTS
MOVEMENTS IN PLANTS
TROPIC MOVEMENT NASTIC MOVEMENT
The movement or orientation of any part of the plant body
towards or away from the external stimulus.
The movement which occurs in plants
due to the variations in environmental
conditions and difference in turgor
pressure.
It is directional It is non directional
Growth is involved Growth is not involved.
The rate at which the movement occurs is slow It is quick and immediate.
Eg: Growth of stem towards light, growth of roots
towards the soil.
Eg Touch Me Not plant folds when
you touch it.

11. TROPIC MOVEMENTS OR TROPISM
The movement or orientation of any part of the plant body towards or away from the external stimulus.
TYPES OF TROPIC MOVEMENTS
a)PHOTOTROPISM :
The movement of a part of plant body towards or away from the stimulus of LIGHT is called phototropism.
Eg Growth of stem towards the sunlight.
b)HYDROTROPISM
The movement of a part of plant body towards or away from the stimulus of water is called hydrotropism
Eg Growth of roots towards the water.
EXPERIMENT TO DEMONSTRATE HYDROTROPISM
c)GEOTROPISM
The movement of a part of plant body towards or away from the stimulus of gravity is called geotropism
Eg Growth of roots towards the ground .

12. d)THIGMOTROPISM
The movement of a part of plant body towards or away from the stimulus of TOUCH is called
THIGMOTROPISM
Eg: The growth of tendrils against a support in climbers like cucumber, grapes.
e)CHEMOTROPISM
The movement of a part of plant body towards or away from the stimulus of CHEMICAL is called
CHEMOTROPISM
Eg; The growth of pollen tube towards the ovary in flowering plants after pollination.

13. THIGMONASTIC MOVEMENT:

14. The folding of leaves of mimosa plant ( Touch Me Not) is an example of thigmonastic
movement . They change their shape by changing the amount of water in them thus resulting in swelling
or shrinking.
ROLE OF AUXINS IN PHOTOTROPISM

15. PHYTOHORMONES
The chemicals synthesized by plants which are involved in the growth, metabolism and control and coordination in
plants. They are also called as growth regulators.
The different phytohormones are:
a.AUXINS- Cell growth, differentiation and phototropism
b. CYTOKININS: Cell division
c.GIBBERELLINS: Stem elongation . Cell differentiation in presence of Auxins.
d.ABA ( Abscisic Acid) : Growth Inhibitor, Wilting of leaves, Closing of stomata, Promotes seed
dormancy.
e.ETHYLENE (gaseous hormone. ) : Ripening of fruits.
DIFFERENCE BETWEEN CHEMICAL AND NERVOUS CONTROL
CHEMICAL COORDINATION IN ANIMALS

16. NERVOUS CONTROL CHEMICAL CONTROL
It is sent as an electrical impulse along the neuron. It is sent via hormones in the blood.
Information travels rapidly Information travels slowly
Information is directed to specific receptors and
responses are sent to effectors or muscles and glands.
Information spreads throughout the body by blood from
which it reaches to target cells or organs.
Response is immediate Response is slow.
Effects are short lived. Effects are prolonged.
LIMITATIONS OF ELECTRICAL IMPULSES
The electrical impulses will reach only those cells which are conected by nervous tissue not each and every cell of
the body.
Once an electrical impulse is generated in a cell and transmitted the cell will take some time to reset its mechanism.
ENDOCRINE GLANDS: The glands which do not have ducts in them and pour their secretions directly into the
blood. Therefore they are also called ductless glands.

17. EXOCRINE GLANDS: The glands which have ducts in them and pour their secretions through the ducts.EG :
Salivary glands, Sweat glands, Liver.
HETEROCRINE GLAND or MIXED GLAND /DUAL GLAND:
The glands which are both exocrine and endocrine gland. EX: Pancreas, Ovary, Testis .
ENDOCRINE SYSTEM IN HUMANS

18. ENDOCRINE GLANDS IN HUMANS
NAME OF GLAND LOCATION HORMONE FUNCTION

19. HYPOTHALAMUS
GLAND
BRAIN RELEASOR
HORMONE
Stimulates the anterior and intermediate lobe
of pituitary gland to secrete hormones.
INHIBITING
HORMONES
Inhibits anterior and intermediate lobe of
pituitary gland to secrete hormones.
PITUITARY
GLAND (MASTER
GLAND)
BRAIN a. STIMULATING
HORMONES
i FSH (Follicle
Stimulating
Hormone)
Stimulates spermatogenesis and
oogenesis in males and females
respectively.
ii.TSH (Thyroid
Stimulating
Hormone)
Stimulates Thyroid gland to produce
Thyroxine.
b. GROWTH
HORMONE
Deficiency-
DWARFISM
Oversecretion-
GIGANTISM
It regulates protein metabolism and growth
of bones in the body.
PINEAL GLAND BRAIN MELATONIN Sleep and wake up cycle.
Working of gonads

20. THYROID GLAND NECK THYROXINE Maintains the BMR as it regulates the
protein and carbohydrate metabolism
Less secretion- Hypothroidism
More secretion – hyperthyroidism
GOITRE- Iodine deficiency disorder
THYMUS GLAND
(Shrinks with age)
THYMOSINE Stimulates development of lymphocytes that
increases the resistance to infections.
PANCREAS Between
stomach and
small intestine
INSULIN
Deficiency leads to
Diabetes Mellitus
Decreases the blood glucose level
GLUCAGON Increases Blood Glucose level
ADRENAL
GLANDS
ABOVE THE
KIDNEYS
ADRENALINE
(Emergency Hormone)
Helps to cope with stress, anxiety .Increases
the metabolism in emergency situations.
The effects of adrenaline secretion are
increase in heart beat, blood pressure,
breathing rate and blood sugar level.
NORADRENALINE Decreases the metabolism.

21. GONADS
a) OVARY IN
FEMALES
ABDOMEN OESTROGEN It develops the genital organs and is
responsible for secondary sexual
characteristic features in females.
It also stimulates the formation of
eggs or ova in females.
ABDOMEN PROGESTERONE It stops egg production during
pregnancy by from the ovaries.
It also helps in attaching the
foetus to the uterus.
It takes care of all development
in the females body during
pregnancy.
b) TESTIS In malesABDOMEN TESTOSTERONE It promotes Spermatogenesis.
It is also responsible for all secondary sexual
characteristic features in males.

22. HORMONAL DISORDERS
GOITRE -
CAUSE :It is caused by iodine deficiency. The thyroxine hormone cannot be synthesised by the thyroid gland in the
absence of Iodine. Usually prevalent in people living in hilly and mountainous area as diet is deficient in Iodine.
SYMPTOMS – Inflammation of Thyroid gland , Swollen neck, Lethargy, and Weight gain.
CURE: Having food rich in Iodine like Seafood, Iodized Salt.
Hormonal Disorder of Growth Hormones.
GIGANTISM – Excess secretion of growth hormone by Pituitary gland .
DWARFISM – Less Secretion of Growth Hormone by Pituitary gland.
DIABETES MELLITUS - Less secretion of Insulin from pancreas.

23. FEEDBACK MECHANISM or HOMEOSTASIS
The timing and amount of hormones released or regulated by the endocrine glands by the feedback mechanism.
EXAMPLE 1 :
When we eat a carbohydrate rich meal , the blood sugar level increases. It stimulates the pancreas to secrete Insulin. The
insulin stimulates the target cells to take up the extra glucose which is either utilized in respiration or stored as Glycogen.
In this way blood sugar level is brought back to normal.
CARBOHYDRATE RICH MEAL
GLUCOSE LEVEL INCREASES IN BLOOD

24. BETA CELLS OF PANCREAS SECRETE INSULIN
INSULIN STIMULATES CELLS TO TAKE UP GLUCOSE
GLUCOSE LEVEL FALLS IN BLOOD
EXAMPLE 2
EXTERNAL STIMULUS
HYPOTHALAMUS RELEASES THYROTROPHIN RELEASING HORMONE (TRH)
STIMUALTES THE PITUITARY GLAND TO SECRETE TSH
TSH STIMULATES THE THYROID GLAND TO PRODUCE THYROXINE
IF thyroxine level is excess in the blood, it exerts a negative feedback effect on Hypothalamus and Pituitary Gland to
secrete less amount of TRH and TSH respectively and as a result Thyroxine level decreases.