Q18 of 216 Page 473

i. Name the part of brain which controls

A. voluntary action,


B. involuntary action.


ii. What is the significance of the peripheral nervous system? Name the components of this nervous system and distinguish between the origin of the two.


iii. A. Identify the glands that secrete


• Insulin


• Thyroxin


B. Explain with an example how the timing and amount of hormone secreted are regulated in human body.

i) The part of brain which controls


A. voluntary action is cerebellum.


It controls and coordinates voluntary movements like body posture, balance, coordination, etc.


B. involuntary action is medulla.


It deals with autonomic functions of the body like breathing, heart rate etc.


ii) The peripheral nervous system is responsible for connecting the Central nervous system to the sensory and other organs of the body. Information is carried via the nerves of the PNS to and fro from the CNS to the organs.


The components of this nervous system are: the somatic nervous system and the autonomic nervous system and all the nerves lying outside the brain and spinal cord. The somatic nervous system is composed of nerves connecting the voluntary skeletal muscles to the sensory receptors of the body. The autonomic nervous systemhas the sympathetic and para-sympathetic nervous system responsible for regulating involuntary body functions.


The Autonomic Nervous Systemregulates the connections between the brain, spinal cord and organs, on the other hand, the Somatic Nervous System connects the external sensory organs through the brain and to the muscles.


iii) The glands that secrete:


• Insulin - Islets of Langerhans within the pancreatic gland.


• Thyroxin- Thyroid gland


The timing and amount of hormone secreted are regulated in human body. For example: Insulin is a secretion by the pancreas. It is responsible for maintaining the glucose level in the blood. If glucose level is high, more insulin is secreted and vice versa. Hormonal secretion is regulated by feedback mechanism. Another example is of parathyroid that secretes parathormone to raise the calcium level in the serum. When serum level gets high then negative feedback mechanism comes into play and signal is passed to decrease the secretion of the parathormone.


More from this chapter

All 216 →
16

i. In the formation of compound between two atoms A and B, A loses two electrons and B grains one electron.

A. What is the nature of bond between A and B?


B. Suggest the formula of the compound formed between A and B.


ii. On similar lines explain the formation of MgCl2 molecule.


iii. Common salt conducts electricity only in the molten state. Why?


iv. Why is melting point of NaCl high?

 17

Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also give reason why carbon compounds are generally poor conductors of electricity.

OR


i. State the meaning of functional group in a carbon compound. Write the functional group present in (a) ethanol and (b) ethanoic acid and also draw their structures.


ii. Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen can take place. Stating the essential conditions required for an additional reaction to occur write the chemical equation giving the name of the reactant and the product of such a reaction.

 19

i. List the parts of the human eye that control the amount of light entering into it. Explain how they perform this function.

ii. Write the function of retina in human eye.


iii. Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organise groups to motivate the community members to donate their eyes after death?

 20

i. Define electromagnetic induction.

ii. Two coils P and S are wound over the same iron core. Coil P is connected to battery and key and the coil S is connected to galvanometer. Draw a suitable diagram of this arrangement and write your observations when:


A. Current in the coil P is started by closing the key.


B. Current continues to flow in coil P.


C. Current in coil P is stopped by removing the key.


Explain the reason for such observations.


OR


Briefly explain an activity to plot the magnetic field lines around a bar magnet. Sketch the field pattern for the same specifying field directions.


A region A has magnetic field lines relatively closer than another region B. Which region has stronger magnetic field. Give reason to support your answer.