Explore topic-wise InterviewSolutions in .

Correct Answer is: (a) 12, 31

(d) hypothalamus

The nervous system of human has two parts: 

1. Central Nervous System (CNS): It consists of the brain and the spinal cord. The brain lies protected inside the skull while the spinal cord is protected within the vertebral column. 

2. Peripheral Nervous System (PNS): It consists of nerves arising from the spinal cord (spinal nerves) and the brain (cranial nerves). These nerves link the central nervous system with the various body organs.

(a) Olfactory nerve: The sense of smell is present in the epithelial layers of the nasal  chambers. The sense of smell is carried to the brain by the olfactory nerve. They arise  from the anterior ends of the olfactory lobes and are distributed to lining of nasal  chambers.  

(b) Optic nerve: It carries the reflection of the object from the retina to the brain. The  image formed on the retina is in a reverted position and the correct picture is formed in  the brain as the object is. The optic nerves arise from the side of diencephalon. They  innervate the retina of the eye and are sensory in nature.  

(c) Facial nerve: It carries message and all expressions of the face, mastication work  alone by the teeth, movement of the neck and the activities of the salivary glands to the  brain. It arises from the side of medulla. On the whole facial nerves are mixed in nature.

1. Cerebrum

2. Cerebellum

3. Medulla oblongata

• Endocrine glands secrete vital chemical substances called hormones. There is a strong impact of hormones upon human behavior. 
• Hormones are responsible for certain behaviours or the absence of reactions.
• Over (hyper) or under (hypo) secretion of hormones may lead to a variety of problems.
• e.g. Hypersecretion of insulin and glycogen hormones by the pancreas reduces blood sugar levels. It results in hyperglycemia, wherein a person lacks energy and motivation, may faint and go to coma. Conversely, in the case of hyposecretion, a person gets diabetes. He becomes quite hungry and feels very tired and restless. He also shows irritated behaviour and faces frequent and uncontrolled urination.

The functions of the five endocrine glands are as follows:

Thyroid gland: It secretes thyroxin which maintains the rate of metabolism.

Parathyroid gland: It secretes parathyroxin which maintains calcium as well as phosphate balance. 

Pancreas: It secretes insulin and glycogen that is responsible for maintaining blood sugar levels.

Adrenal gland: Cortex secretes cortin or cortisone which maintains the level of water, sugar, and sodium. The medulla secretes adrenalin (which is associated with fear) and noradrenaline (which is associated with anger). Medulla plays important role in emotional excitement. 

Gonads (sex gland): Testes in males secrete androgen and testosterone. These hormones are responsible for secondary sex characteristics in males. Their voice becomes hoarse. They also get mustaches and beards. Ovaries in females secrete estrogen and progesterone. These hormones are responsible for secondary sex characteristics in females. As a result, feminine looks develop and menarche begins.

The brain consists of three major parts, viz. hindbrain, midbrain, and forebrain. Its functions are as follows: 

i. Hindbrain

• Cerebellum: It helps in maintaining body posture and balance as well as aids in the coordination of movements. 
• Brain stem: Medulla oblongata controls the breathing rate, pulse rate, blood pressure, and digestion. Pons helps to transmit messages between the cerebellum and cortex.
• Reticular activation system: It is the ‘Alarm clock’ of the body. It maintains wakefulness, concentration, and alertness.

ii. Midbrain: 

It sends information to the upper part of the brain and controls eye movements.

iii. Forebrain:

• Cerebrum: Cerebral cortex controls higher-order mental processes such as attention, perception, learning, memory. The surface of the cerebral cortex is divided into right and left hemispheres. Neurons from the right hemisphere control the left side of the body and vice versa. Left hemisphere controls language, spatial relation, and pattern recognition. 
• Four lobes: Frontal lobe controls motor actions, thinking, memory and reasoning. The parietal lobe helps us in understanding information regarding skin. The occipital lobe controls our vision. The temporal lobe is responsible for hearing, understanding language, and memory for language.

Important parts of the hindbrain and their functions are as follows:

Cerebellum: It helps in maintaining body posture and body balance. It also helps in the coordination of the movements. 

Brain stem: Medulla oblongata controls the breathing rate, pulse rate, blood pressure, and digestion. Pons sends and receives information from the lower parts of the brain. It helps to transmit messages between the cerebellum and cortex. 

Reticular activation system: Its main function is to maintain wakefulness, concentration, and alertness.

1. False – Axons are the longest fibres that conducts impulses away from the cell body. 

2. False – Autonomic nervous system is a part of central nervous system. 

3. True 

4. False – Cerebellum controls the voluntary actions of our body. 

5. True

6. False – Brain is covered and protected by meninges. 

7. True 

8. True 

9. True

The hindbrain is formed of three parts. Cerebellum, Pons and Medulla Oblongata.

The changes in the environmental condition that are detected by the receptors present in the body is called stimulus.

(a) Stimulus: Any change in the environment that usually results in change in the activity of the body.

Impulse: A wave of electrical disturbance that runs through the nerves.

(b) Receptor: The nerve cell on receiving the stimulus sets up the waves of impulses towards the central nervous system.

Effector: Any muscle or gland on receiving the impulse from the brain (or the spinal cord), contracts or secretes.

(c) Motor nerve: It contains only motor neurons,

Example: Nerves going to the muscles of the eyeball.

Sensory nerve: It contains only sensoiy neurons.

Example: optic nerve of the eye.

• The sympathetic nervous system prepares our body to face stressful and threatening situations. It prepares us for a ‘flight or fight reaction. On the other hand, the parasympathetic nervous system takes over when the situation becomes normal,

Example: 

• Situation: Suppose you are chased by a dog. 
• Sympathetic nervous system: Due to the functioning of this system, your heartbeat and palpitation increase. You also start to sweat.
• Parasympathetic nervous system: When PNS takes over, your heart rate, palpitation, and sweating become normal. You regain a cool and composed state due to the functioning of this system.

Correct Answer is: (b) Neuron

(b) sareolemma

(i) (C) 31

(ii) (A) hormones

(iii) (B) children

(iv) (C) Grave’s disease

(v) (A) Glycogen

(a) Sensory nerve – afferent

(a) Nervous coordination: By nerves and brain

(b) Chemical coordination: By hormones

The structural and functional unit of nervous system is a

2. Nephron

2. Acquired relfex

(i) (A) Nucleus

(ii) (C) Serotonin

(iii) (A) higher-order

(iv) (A) two

(v) (A) Medulla oblongata

(vi) (B) Midbrain

The path taken by nerve impulse to accomplish reflex action is called a Reflex arc.

(a) Assertion is correct and reason is wrong.

(d) Both assertion and reason are wrong.

Reflex actions occur under the control of

3. spinal cord

The coloured part of the eye is called

2. iris

(a) Hypothalamus