Biology For Class X - Chapter No. 3 - Coordination And Control - Question Answers

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CHAPTER 3: COORDINATION AND CONTROL
Question Answers

Q.1: Define coordination, stimulus, receptors,  response and effectors?
Ans: COORDINATION:
coordination is defined as the process where different units of a system work together to perform a meaningful function.

STIMULUS (pl. STIMULI):
The change in environment takes place due to some factors. theses factors are called stimulus. OR It refers to any factor which cause change either in internal or external environment of the organism. 
In other words, A stimulus is a change in the environment that can be detected by a sense organ and bring about a response.

RECEPTORS:
The changes due to any factor which cause change either in internal or external environment of the organism detected by special cells or organs termed as receptors.
For example:

1. Eyes are photoreceptors (sensitive to light),
2. Ears are sound receptors,
3. Nose is chemoreceptor for gases and
4. Tongue is chemoreceptor for solids and liquids.

RESPONSE:
It is the activity performed by some living organism after analyzing stimulus or stimuli. It is exhibited by organs like muscles, glands etc are termed as effectors.

EFFECTORS:
Response is exhibited by organs like muscles, glands etc., are termed as effectors.

Q.2: Differentiate between stimulus and response?
Ans: Difference Between Stimulus And Response:

S.NO.	Stimulus	Response
1.	A detectable change in the internal and external environment.	Any activity of a living organism that results from an external or internal stimulus.
2.	An event or condition which initiates a response.	Organism's reaction to the stimulus.
3.	It varies by its type, intensity, location and duration.	It can be cellular, physical or behavioural.
4.	Afferent or sensory nerves transmit nerve impulses corresponding to the stimulus.	Efferent or motor nerves transmit nerve impulses corresponding to the response.
5.	Nerve impulses corresponding to the stimulus transmitted towards the central nervous system.	Nerve impulses corresponding to the response transmitted away from the central nervous system.
6.	Sensory organs including eyes, ears, nose, tongues, skin and the internal sensory system are responsible for detecting stimuli.	Effector organs including muscles in the internal organs and hands and legs are responsible for reacting to a stimulus.

Q.3: Describe types of coordination?
Ans: TYPES OF COORDINATION:
There are two types of coordination:

1. Chemical Coordination
2. Nervous Coordination

Both are inter-related and interact with each other to develop proper response.

1) Chemical Coordination:
It takes place by releasing specific, signalling molecules such as hormones by special cells or glands. These molecules are released to stimulate or inhibit other cells or tissues of the body. The target cells must have receptor molecules (special receiving molecules) for signalling molecules.
This kind of coordination is helpful in lower animals as well as plants because of their simple body plans and small size.

2) Nervous Coordination:
It is an advance type of coordination exhibited by most of the animals, which is a consequence of specially designed cell, Neurons. The neurons upon stimulation generate electrochemical signals. Since the signalling is in electric form so it is very rapid.

Q.4: Differentiate between chemical coordination and nervous coordination?
Ans: Difference Between Chemical Coordination And Nervous Coordination:

S.NO.	NERVOUS COORDINATION	CHEMICAL COORDINATION
1.	Activity of Neurons.	Activity of special secretory cells.
2.	Signal type is electro-chemical.	Signal type is purely chemical.
3.	Rapid in action.	Slower in action.
4.	Response is shorter duration.	Response is longer duration.
5.	Advance type of coordination.	Primitive type of coordination.
6.	Exclusively related to animals.	Related to all organisms.
7.	Involves neurotransmitters.	Involves other signalling molecules such as hormones.

Q.5: Explain coordination in lower organisms and plants?
Ans: COORDINATION IN LOWER ORGANISMS AND PLANTS:

• Lower organisms like prokaryotes, protozoa, algae, fungi and plants have chemical coordination through signalling molecules released usually in the form of hormones to regulate the, movements, growth, metabolism, reproduction, etc.
  For Example "Touch me not" Plants:
  Leaves of the ‘touch me not' (Mimosa plant) are closed when touched. After a short while, they restore their original open position. The pressure or touch serves as stimulus while closing down of leaves is the responses.
  
  
• Other responses like growth, reproduction are due to the secretion of hormones by secretory cells and carried via the transport media to their respective target organs.
  For Example “Sunflower” plants:
  Another fascinating movement is the turning towards the direction of the sun in “Sunflower” plants. Its a bit slower movement which is believed to be caused by  phytohormones called Auxins. It causes rapid cell growth in shaded regions of plant.

By Mrs. Ayesha Arif-Vice Principal
(Jauhar Progressive School)

Q.6: Define human nervous system and its major divisions. OR Describe centralized nervous system?
Ans: HUMAN NERVOUS SYSTEM:
Human nervous system like other vertebrates is “centralized-type nervous system” (CNS). It is the most complicated type. Stimuli from various organs of the body are sent simultaneously its control center or central nervous system where they are integrated, analyzed and processed to develop command in the form of response.
Centralized nervous system consists of two major divisions:

1. Central Nervous System (CNS)
2. Peripheral Nervous System (PNS)

1. Central Nervous System (CNS):
It is the major command and control center to which stimuli are reported and decisions are made and conveyed to effectors organs. 

Components of Central Nervous System:
It consists of two main components:

• Brain and
• Spinal Cord

2. Peripheral Nervous System (PNS):
It consists of cables which arise from the central nervous system and connect it to different organs of the body. Each cable is termed as Nerve. Each nerve consists of bundles of axons of both sensory and motor neurons.

Types of Peripheral Nervous System:
The PNS consists of:

1. Somatic Nervous System:
   It is associated with skeletal muscles and glands.  It controls all the voluntary activities of the body such as contraction of skeletal muscles and movement of joint.
   
   
2. Autonomic Nervous System:
   It is associated with involuntary functions like digestion, breathing, etc. These functions are vital for maintaining life processes.

Q.7: Discuss the detailed structure of human brain? OR Write a detailed note on human brain an draw well labelled diagram.
Ans: HUMAN BRAIN
Brain is the most main component of Central Nervous System. It is the major command and control center of our body.
Brain is protected in three ways:

1. Cranium: Bones of the skull provide protection to the brain.
2. Meninges: Beneath the cranium, the brain and spinal cord are wrapped in three protective membranes made up of tough connective tissues called meninges.
3. Cerebrospinal Fluid (C5F): Inside the brain, between the layers of meninges, there are empty cavities or ventricles filled with plasma like fluid called Cerebrospinal Fluid (CSF). It also provides a cushion-like protection to the brain.

PARTS OF BRAIN:
Human brain consists of Following important parts

• Fore Brain
  (i) Cerebrum
  (ii) Thalamus
  (iii) Hypothalamus
  (iv) Hippocampus
  (v) Amygdala
  
• Mid brain
  (vi) Optic lobes
• Hind brain
  (vii) Cerebellum
  (viii) Medulla oblongata

 i. CEREBRUM:
It is the largest part of the brain where all important decisions are made. It is divided into two halves called hemispheres.

• Right cerebral hemisphere:
  The right cerebral hemisphere regulates the left side of the body.
• Left cerebral hemisphere:
  The left cerebral hemisphere regulates the right side of the body.

Each cerebral hemisphere consists of 

i. An outer grey matter or cerebral cortex and
ii. An inner white matter 

• Cerebral Cortex OR Grey matter:
  Cerebral cortex or grey matter is the outer part of cerebrum and is grayish in colour and consists of cell bodies of neurons.
• White Matter:
  The inner part is called the white matter. White matter is whitish and consists of cell processes which are hair like growths.

Function of cortex:
The cortex is associated with thoughts, plans, actions and determination.

Part of Cortex:
Functionally, It can be divided into four sections or lobes, viz.:

1. Frontal lobe:
   It is associated with thoughts, emotions, etc.
   * Motor control (premotor cortex)
   * Problem solving (prefrontal area)
   * Speech production (Broca's area)
   
   
2. Parietal lobe:
   It is associated with different sensations like pressure, temperature, language processing, etc.
   * Touch perception (somatosensory cortex)
   * Body orientation and sensory discrimination.
   
   
3. Temporal lobe:
   It is involved in hearing and speech.
   * Auditory processing (hearing)
   * Language comprehension (Wernicke's area)
   * Memory / information retrieval.
   
   
4. Occipital lobe:
   It is associated with vision.
   * Sight (Visual cortex)
   * Visual reception and visual interpretation.

Function of Cerebrum:

1. Cerebrum is concerned with seat of intelligence, memory, learning, reasoning and overall control of all voluntary actions.
2. It involved in all conscious activities.
3. It co-ordinates different senses together.

ii. THALAMUS:
Thalamus lies inside the brain just above hypothalamus.
Functions:

1. It is also called the clearing house of sensory impulses.
2. It guides the stimuli towards appropriate part of the cortex.

iii. HYPOTHALAMUS:
Hypothalamus is the part of limbic system which is called Thermostat of the body.
Functions:

1. Hypothalamus regulates life maintaining functions like blood pressure, body temperature, hunger, thirst etc.
2. It plays vital role in maintaining homeostasis of the body.
   
   

iv. HIPPOCAMPUS:
Hippocampus is involved in long term memory.

v. AMYGDALA:
It is a deep seated small area.
Function:

1. It is involved in emotions (pain, pleasure, etc.)

vi. MID BRAIN:
In human mid brain is relatively smaller. It consists of the optic lobes which are represented by four small bodies.
Functions:

1. It involves in integration of visual and olfactory (smell) stimuli.
2. It is also collaborator of spinal cord with fore brain.

vii. CEREBELLUM:
It is highly convoluted structure located on the dorsal side just below the cerebrum.
Functions:

1. Balance and coordination
2. It controls the precision in movement of the muscles for balance and maintains the position of the body in relation to gravity.
3. Activities like writing, drawing, painting, dancing, crafting have become possible due to its elaborate structure in human.

viii. MEDULLA OBLONGATA:
Medulla oblongata lies just above the spinal cord.
Functions:

1. It is the control center for automatic activities like breathing, heart-beat, blood pressure, coughing, swallowing, hiccupping, digesting food, etc. Such activities are termed as Reflexes.

ix. PONS:
It lies on the ventral side of medulla oblongata.
Functions:

1. It helps in controlling the facial muscles as well as helps in sleep and wakening.

BRAINSTEM
Mid brain, medulla oblongata and Pons are collectively known as brainstem. It connects cerebrum to spinal cord.
Function:
• Involuntary responses

Q.8: Write a short note on spinal cord?
Ans: Spiral Cord:
It's a butterfly shaped, thick whitish, long tube like structure which arises from medulla oblongata and extends down through the vertebral column.

Parts of Spinal Cord:
The spinal cord is differentiated into two areas.

• White Matter
• Gray Matter

Unlike brain,  in cross section, its outer portion is whitish called white matter while inner is grayish or gray matter. The grey matter has the shape of an "H". Like brain, it is also wrapped in meninges and bathed in cerebrospinal fluid.
Function:

1. It acts as a mini control center for few reflexes.
2. It also acts as express way for flow of information from brain to the different parts of the body and vice versa.

Q.9: What do you know about neurons.
Ans: Definition Of Neuron:
The special cells of nervous system are termed as neurons. Neurons are the chief structural and functional unit of nervous system.
Function: Each neurons is specialized to generate and conduct neuronal signal or  nerve impulse.

Structure of Neurons:
Neurons are different from each other according to size and shape but the structure of neuron consists of two parts:

1. Soma or Cell Body
2. Cell processes

1. Soma OR Cell Body:
   * Each neuron has a cell body or soma comprised of plasma membrane, cytoplasm and nucleus. Various organelles embedded in the cytoplasm.
   * Functions:
   The cell body or soma is the main nutritional part of the cell necessary for growth of neuron.
2. Cell Processes:
   * They are hair like projections given out from soma. Cell processes usually have insulated coverings, termed as Myelin Sheath to ensure the uninterrupted transmission of nerve impulse.
   * Types Of Cell Processes:
   They are of two types:
   i. Dendrites:
   From the soma, a large number of small threads like terminal branches are arises are called Dendrites.
   Functions: Dendrites receive stimulus and convey it to the soma.
   
   ii. Axon:
   The unbranched, single elongated cytoplasm process which usually arises opposite to dendrites called Axon.
   Functions: Axon transmits the commands either to some other neurons or some effector cells.

Q.10: Define and explain reflex action?
Ans: Reflex Action:
The automatic involuntary and rapid response which occur either due to internal or external stimuli are called Reflex Action.
In other words, "The automatic, pre-programmed responses regulated by CNS are termed as reflex actions. Some of them are directly regulated by brain while others by spinal cord."
It minimize any damage to the body from potentially harmful conditions, such as: Touching something hot. Reflex actions are therefore essential to the survival of many organisms.

Parts of Reflex Action:
Reflex action follow this general sequence and does not involve the conscious part of the brain. This is why response is so fast.

1. Receptor: (Skin) receive stimuli.
2. Sensory Neuron: It carries message from receptor to the Central Nervous System (CNS) or spinal cord.
3. Relay Neuron: found in brain or spinal cord, between sensory and motor  neurons.
4. Motor Neuron: It carries message from Central Nervous System (CNS) to the effector.
5. Effector: (Muscle of gland) which perform action (response).

Path Of Reflex Action OR Reflex Arc:
Definition: The pathway of a reflex action is termed  as 'Reflex Arc'.

• In complicated reflexes, the reflex arc may involve one or numerous inter-neurons in between sensory and motor neuron. The shortest path of a reflex action, such as knee-jerk involves two neurons, a sensory neuron and a motor neuron.
• Working Of reflex arc:
  * A receptor in the skin detects a stimulus (the change in temperature).
  * Sensory neurons send electrical impulses through relay neurons, located in the spinal cord.
  * Relay neurons in the spinal cord connect sensory neurons to motor neurons.
• * Motor neurons send electrical impulses to an effector.
  * The effector produces a response (muscle contracts to move hand away).

Examples of Reflex Actions:

1. If our hand touches any hot object, it is quickly withdrawn.
2. Secretion of hormones from the gland.
3. Blinking of eyes.
4. Contraction and expansion of lungs.
5. Knee jerk
6. Sneezing, hiccup, cough etc.

Q.11: Explain reflex action with the help of an experiment of shin muscle of frog using battery?
EXPERIMENT: Contraction of shin muscle (leg muscle) of Frog using battery.
Observation:

• Muscles contract when signals are provided through neurons by nervous system.
• In this experiment, a shin muscle is removed from dissected frog and is placed in methylene blue solution in a petri dish.
• We observe that when we artificially stimulate it by supplying power of a 12 volts D.C. battery, it contracts.

Apparatus:

• Dissecting box
• Frog
• Dissecting tray
• Petri-dish
• 12 volt D.C. charged battery
• Wires

Procedure:

• Dissect out a pithed frog to expose its shin muscles.
• Remove the shin muscle with sciatic nerve carefully and place in stretched condition in petri-dish.
• Connect the battery with wires and then touch the shin muscle at its beginning and end with wires.
• Now observe the muscle contraction.
• Repeat the experiment for three times.

Conclusion:

• Muscles contracts when provided signals through neurons by nervous system.

Q.12: Explain the structure of human eye in detail
Ans: Human Eye:
The eye is an important and most complex sense organ. It is photoreceptor and the organ of sight. It works on the principle of a simple camera, which collect light reflected from any object in front and help us see that object.

Structure of Human Eye:
A human eye is roughly 2.3 cm in diameter and is almost a spherical ball filled with some fluid. Each eye lies in a bony socket for protection. It consists of the following parts:

Sclera:

• The tough outer coat or layer which covers each eye called the sclera (white part of the eye).
• Working: It protects eyes.

Cornea:

• In front, the sclera becomes transparent is called cornea.
• Working: Light enters the eye through the cornea.

Aqueous humor:

• Behind cornea, lies a small chamber called aqueous humor. It is filled with watery fluid.

Iris:

• At the back of aqueous humor, lies  coloured ring-like structure known as the iris.
• The colour of the iris actually indicates the colour of the eye.
• Working: The iris also helps regulate or adjust exposure by adjusting the iris.

Pupil:

• A small central hole in the iris is known as a pupil. The pupil appears blackish.
• Its size is controlled by the help of iris.
• Working: It controls the amount of light that enters the eye.

Lens:

• Immediately behind the iris is a transparent crystalline convex structure called a lens.
  
• Working: It diverts light to a layer of sensory cells or retina.

Ciliary body:

• Lens is suspended by a ring of circular muscles known as ciliary body.
• Working: The contraction of ciliary muscles cause changes in the shape of lens to adjust focus light on the retina.
  

Vitreous humor:

• Behind the lens, there is a main cavity of eye ball filled with clear gel, called vitreous humor.

Retina:

• The innermost layer of eye is retina. It has sensory cells, rods and cones.
• Working: The image is formed on retina by cornea and lens. Sensory cells, rods and cones upon stimulation convert light signals into nerve impulses and report them to the brain.

Q.13: What are pupil reflex and accommodation?
Ans: Pupil reflex:

• The pupil adjusts itself depending upon the intensity of light.
• In case of bright light, it protects the retina by constricting itself so less amount of light falls on retina.
• In dim light condition, the pupil dilates to allow more light to fall on retina.

Accommodation:
It is an automatic process of altering focus to get sharper image of the near objects. The ciliary muscles contract allowing the elastic lens to become thicker and more convex. With age, the lens loses its elasticity and as a result, accommodation becomes increasingly difficult.

Q.14: Write down the role of vitamin A with vision?
Ans: Role of Vitamin A With Vision:
Vitamin A or retinal is required for proper vision and needed for sensory cells of retina. It also helps the cornea to be well lubricated. Deficiency of vitamin A could lead to corneal ulcers and blindness.

Q.15: Describe the defects of vision?
Ans: DEFECTS OF VISION:
Eye-Sight Defect:

1. Short-Sightedness (Myopia):
   Short-sightedness or myopia refers to the difficulty in focusing distant object while the near objects are focused normally.
   
   
2. Long-Sightedness (Hyperopia):
   Long- sightedness or Hyperopia is the difficulty in focusing closer objects while distant vision is clear.

Treatment:
Both can be diagnosed and corrected by using appropriate glasses or contact lenses.

Colour blindness:

• Its a deficiency of vision in which one cannot distinguish certain colours such as blue and yellow or red and green.
• It is due to the defect in cones of retina.
• The vision may be normal in a colour blind person, yet the most common problem is driving because of their inability to distinguish red and green traffic light.

Q.16: Describe Contribution of Ibn-al- Haitham and Ali- Ibn- Sina about the structure of eye and treatment of ophthalmic diseases (eye disorder)?
Ans: Contribution of Ibn-al-Haitham about the structure of eye and treatment of ophthalmic diseases:

• Ibn-al-Haitham was known as the "father of modern optics" due to great contribution in principles of optics and visual perceptions.
• He was a great Muslim mathematician, philosopher, astronomer and physicist of 11^th century.
• He was the first person to consider vision as a result of bouncing back of light from an object and then enters our eyes.
• Books: His most important book on optics was "Kitab-ul-manazir".

Contribution of Ali-Ibn-Isa about the structure of eye and treatment of ophthalmic diseases:

• He was one of the most important Muslim ophthalmologists of medieval times.
• Book: In his famous book "Memorandum of the oculists" on ophthalmology, he described more than hundred different eye diseases and their treatment.

Q.17: Explain the structure and function of human ear in detail. Also draw well labelled diagram of human ear
Ans: Human Ear:

EAR:
Ear is a sensory organ of hearing and balance. 
Parts of Human Ear:
It consists of three parts:

1. Outer ear
2. Middle ear
3. Inner ear
   

OUTER EAR:
It consists of:

1. Pinna: The pinna is composed of folds of skin and cartilage. It leads into the ear canal which is closed at the inner end by tympanic membrane.
2. Ear canal: Ear canal has hair and it produces wax to trap dust and small foreign bodies.
3. Tympanic membrane or ear drum: The tympanic membrane which is also called the eardrum separates the outer ear from the middle ear. When sound waves reach the tympanic membrane they cause it to vibrate. The vibrations are then transferred to the tiny bones in the middle ear.

Function Of Outer Ear: The outer ear collects and transmits sound waves. 

MIDDLE EAR:
The middle ear consists of :

1. a small cavity containing three small moveable bones, i) malleus, ii) incus and iii) stapes.
2. It is connected to inner nasal cavity through a small tube, called the Eustachian tube.
   

Function Of Middle Ear: The middle ear receives sound waves from air outside and transmits it into the fluid in the inner ear.

INNER EAR:
The inner ear consists of:

1. A front membranous cochlea: It is associated with hearing.
2. A rare, three semicircular canals: They are deep inside the skull bones and are associated with balance.

Function Of Inner Ear: Both cochlea and semicircular canals are fluid filled and contain sensory hair cells. These cells transform sound waves into nerve impulse.

Q.18: Write down the role of ear in balance?
Role of ear in balance:
Semi circular canals are sensitive to gravity, position and movement of head. Any of such changes are detected and reported to the brain through nerve fibers. The three semicircular canals are inter connected and lie at right angle to each other. They are connected to a swollen part called the vestibule. Semicircular canals and vestibule are involved in maintaining balance of the body in relation to gravity.

Q.19: Lightning appears first in thunderstorm. Give reason?
Ans: Light And Sound In A Thunderstorm:
In a thunderstorm,  the lightning and its acoustic effect on ground appear with interval. Since the light travels much faster than sound, the lightning appears first and the sound of thunder is heard after a short while.

Q.20: What is the endocrine system? Name some important endocrine glands found in human body?
Ans: ENDOCRINE SYSTEM:
Endocrine system is an important means of chemical coordination. It is defined as: The ductless gland in the body of vertebrates, which secrete hormones directly into the blood or in body fluids are called endocrine glands or ductless glands. Endocrine gland carries hormones to their target tissues or organs. They constitute a system called Endocrine System.

Hormones:
The secretion of gland is called hormone. The hormones usually required in small quantity. They act like chemical signals or chemical messengers for target organs either stimulating or inhibiting their function.

ENDOCRINE GLANDS OF HUMAN BODY:
Following are important endocrine glands in human body, which are located in different locations in our body:

1. Pituitary Gland
2. Thyroid Gland
3. Pancreas
4. Adrenal Gland
5. Gonads
   i. Testis
   ii. Ovaries

Q.21: Describe structure, location and function of the pituitary gland?
Ans: Pituitary Gland:
Pituitary gland  is located in brain and considered to be very important. it is also called "master gland" because it secretes number of hormones which influence upon other endocrine glands also besides other organs. It is a small pea size gland. It consists of:

• Anterior Lobe Or Anterior Pituitary gland
• Posterior Lobe Or Posterior Pituitary gland

i. Anterior Lobe OR Anterior Pituitary Gland:
It has number of hormone secreting cells. Its important hormones and their effects with target organs are as follows:

1. Follicle Stimulating Hormone (FSH):
   Effect: FSH stimulates gonads to develop gametes.
   Targeted organs: are Testis and Ovaries.
   
   
2. Luteinizing Hormone (LH):
   Effect: This hormone helps in development and release of gametes.
   Targeted organs: are gonads.
   
   
3. Thyroid Stimulating Hormone (TSH):
   Effect: This hormone stimulates thyroid glands.
   Targeted organs: are Thyroid glands.
   
   
4. Growth Hormone (GH) OR Somatotropin Hormone (STH):
   Effect: It regulates growth in children and the normal body structure. It also control many metabolic processes, such as protein synthesis, involved in growth of bones and soft tissue inadults.
   Targeted organs: are bones, cartilages, muscles etc.
   
   
5. Adrenocorticotropin Hormone (ACTH):
   Effect: It stimulates adrenal cortex.
   Targeted organs: are adrenal cortex.
   
   
6. Melanocyte Stimulating Hormone (MSH):
   Effect: It stimulates pigmentation (melanin) in skin.
   Targeted organ: is skin.

OR

ii. Posterior Lobe OR Posterior Pituitary gland:
It is actually stores and releases some hormones of hypothalamus. Few neurons of hypothalamus store and secrete their hormones from posterior pituitary gland. Following hormones are secreted:

1. Antidiuretic Hormone (ADH):
   It stimulates the re-absorption of water by tubules of kidney and thus decreases the amount of urine passed.
   It maintains the blood pressure, blood volume and tissue water.
   
   
2.  Oxytocin:
   It stimulates contraction of smooth muscles as well as social behaviour.

Q.22: Write a short note on Thyroid gland? Or What do you know about thyroid gland?
Ans: Thyroid Gland:
Thyroid gland is a butterfly shaped gland located on trachea in the base of neck. It consists of two lobes, one on either side of trachea. It secretes two main hormones.

1. Thyroxine:
   * It has iodine as its important constituent.
   * It regulates the rate of the metabolic activities of cells.
   * It regulates the physical growth and mental development in children.
   * It increases the oxygen consumption and production of heat.
   
   
2. Calcitonin:
   * Calcitonin released in response to high level of calcium blood, and lowers the blood calcium.
   

Disorder of Thyroid Gland (Deficiency):

• Mental Retardation: Due to deficiency of thyroxine,  physical and mental retardation occur in children.
• Goiter: If the intake of iodine in diet is low in adult, thyroid gland works more than normal to produce more thyroxine. As a result, the thyroid become swollen and gradually enlarges in size. This abnormal condition is termed as “goiter”.

Q.23: What do you know about pancreas? OR Discuss the gland involved in regulation of blood glucose and how?
Ans: Pancreas: 
Pancreas is the gland which involved in regulation of blood glucose.

• Pancreas is about 6 inches long, leaf-like in structure located in the abdominal cavity in between stomach and small intestine.
• It is both exocrine as well as endocrine gland in nature.

Regulation Of Blood Glucose:
The endocrine part consists of patches  of cells called "Islets of Langerhan's". It is involves in regulating glucose metabolism.

Hormones Secreted By Pancreas:

• Insulin: In response to high level of glucose in blood, pancreas secretes insulin which helps in decreasing the blood glucose levels.
  Disorders of Insulin: Due to deficiency of insulin, a diseased appeared called Diabetes mellitus.
• Glucagon: If there is low level of blood glucose, than pancreas secretes glucagon which increases the glucose level up to normal

The regulation of blood glucose through insulin and glucagon is a type of negative feed-back in which opposite effect is observed in relation to stimulus.

Q.24: Write a note on adrenal gland?
Ans: Adrenal Gland:
Adrenal gland is located one on the top of each kidney. It is triangular shape and consists of two glands:

1. Adrenal Cortex:
   The outer part of adrenal gland is called Adrenal Cortex.
   Function: Adrenal cortex secretes number of steroid (lipid) hormones necessary for regulation of body metabolism, maintenance of water and salts.
   Hormone (Secretion):
   * Cortisol is one of the important hormone secreted by adrenal cortex in response to illness or inflammation of any tissue. It stimulates glucose production.
   
   
2. Adrenal Medulla:
   The inner part of adrenal gland is called Adrenal Medulla.
   Function: Adrenal medulla works under the influence of sympathetic nervous system. It responds to emergency conditions to produce so called "fight or flight response".
   Hormone (Secretions):
   * Adrenaline OR Emergency Hormone: Adrenal Medulla produces many hormones which are secreted in stress situation. They are collectively called as Adrenaline or Emergency Hormones, which resulting in an increase in blood glucose level by breaking down of glycogen. As a result, the body responds to the emergency situation quickly. It dilates the blood vessels of muscles, heart and brain and constricts those of kidneys and skin so that more blood is supplied to the muscles, heart and brain.

Q.25: Write short note on gonads?
Ans: Gonads:
They are reproductive organs, viz., testis in males while ovaries in females. They also function as endocrine glands and are involved in gametes formation and hormones secretion.

1. Testis:
   Each testis is oval shaped structure located in a pouch of skin scrotum.
   Testis are the male reproductive organs.
   Secretion:
   Testis produced hormone called Testosterone which is a type of androgen hormone.
   Functions:
   Testosterone is responsible for development of secondary characteristics in boys like appearance of moustache and beard, deepening of voice, etc. 
   
   
2. Ovaries:
   Each ovary is the size of a grape located in lower abdominal cavity on either side of uterus.
   They are female reproductive organs but they acts as endocrine glands.
   Secretion:
   Ovaries secrete two hormones called as:
   1. Estrogen: Estrogen is responsible for development of secondary characteristics in girls like development of breasts and sharpening of voice, etc.
   2. Progesterone: It maintains and prepares uterus for pregnancy.

Q.26: What is diabetes mellitus? Explain some ways of its management.
Ans: DIABETES MELLITUS
It's a disorder in which pancreas produces insufficient or no insulin. As a result, the level of glucose in blood becomes very high.

Symptoms:

• High level of glucose (sugar) in blood.
• The excess amount of glucose is excreted in urine so the frequency of passing urine increases many times.
• The patient feels very thirsty and hungry.
• In the absence of using or storing glucose by the cells, the patient losses weight and get tired.
• Disturbance of the body's osmotic equilibrium.

WAYS TO MANAGE DIABETES MELLITUS

• Balanced Diet
• Exercise
• Medication
• Blood Glucose Monitoring

Dietary Management of Diabetes:

• Dietary Management and appropriate amount of physical activity play important roles in diabetic control.
• Balanced diet with a variety of foods.
• “3 Low, 1 High” principle, i.e low fat, low sodium (or salt), low sugars and high fibre.
• Reduce intake of saturated fat, trans fat and sodium can lower the risk of developing heart diseases and hypertension.
• Controlling intake of energy for the purpose of weight reduction or maintenance.

Insulin Treatment:
In case of low blood insulin, it can be administered through injecting insulin derived from animals.
Some patients may show allergic reactions to this animal-insulin. It has been overcome by using pure human insulin made by genetically altered bacteria.

Q.27: Define feedback and its types? Show the feedback of stimulus and response with help of flow diagram?
Ans: Feedback System:
The check and balance system in a body is called feedback system. Hormones secretion is regulated through feedback control so that they are secreted whenever required.

Types of Feedback System:
There are two type of feedback systems working in the body.

1. Negative Feedback Control:
   It refers to the opposite effect in relation to the stimulus.
   For example, if there is an increase in blood glucose level (effect), the pancreas would secrete insulin (response) which will bring down the blood glucose to its set point.
   
   
2. Positive Feedback Control:
   It refers to enhancement of the effect in relation to stimulus.
   For example, when an infant sucks the nipple of his mother's breast, she secretes hormone to secrete milk. Continuous sucking increases the hormonal secretion several folds.

Steps Involved In Feedback System:
The feedback system has the following steps: 

• Stimulus
• Receptor (Five senses)
• Modulator (CNS)
• Effector (Muscles, glands etc)
• Response

Q.28: Describe nervous disorders.
Ans: Nervous Disorders:
The abnormalities which appear in brain, spinal cord, central nervous system and peripheral nervous system causes diseases called Nervous Disorders.
Depending upon the nature of disorders, they could be of two common types:

1. Vascular (e.g. paralysis) and
2. Functional (e.g., epilepsy)

Paralysis:
It is characterized by partial or complete loss of controlled movement caused by the inability to contract one or more muscles. It may be accompanied by loss of sensation.
Cause:

1. The most common cause is either bleeding (hemorrhage) or blood clot in the specific part of brain.
2. It could be a result of injury to brain, spinal cord or nerves.

Treatment:

• It can be treated through proper medication if diagnosed the exact cause.
• Physiotherapy of the affected muscles is required otherwise muscles may degenerate.

Epilepsy:
It is a brain disorder in which there is temporary alteration in one or more function or recurrent seizures. As a result, the victim may become unconscious with stiffness of the body and then twitches or jerks uncontrollably.
Cause:

1. It is due to the abnormal electrical activity in brain.
2. Stimulus like sudden flash light on eyes is also associated with cause of the epilepsy.

Treatment:

• The frequency of seizures can be reduced by using proper medication.

Q.29: Why does the intelligence level of persons differ from each other, even though the components of brain are same?
Ans: The intelligence level of persons differs from each other, even though the components of the brain are the same.
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can be described as the ability to perceive or infer information, and to retain it as knowledge to be applied towards adaptive behaviours within an environment or context.

In Human brain, cerebrum is considered to be the seat of intelligence, all the conscious activities and memory. Its outer part, cortex or gray matter consists of cell bodies of neurons. The cortex is associated with thoughts, plans, actions and determination.

Differences in intelligence have so far mostly been attributed to differences in specific brain regions. A new study says that in intelligent persons, certain brain regions are more strongly involved in the flow of information between brain regions, while other brain regions are less engaged.

Individuals also vary in their cognitive abilities for example; academic success and professional careers are attributed to a considerable degree to individual differences in intelligence. These differences from person to person is occur with differences in the patterns of integration among functional modules of the brain regions, among them the prefrontal cortex activation changes of which are reliably associated with individual differences in intelligence.

Recently, it is reported that in more intelligent persons two brain regions involved in the cognitive processing of task-relevant information (i.e., the anterior insula and the anterior cingulate cortex) are connected more efficiently to the rest of the brain. Another brain region, the junction area between the temporal and parietal cortex that has been related to the shielding of thoughts against irrelevant information, is less strongly connected to the rest of the brain network.

Our brain is functionally organized into modules in a very similar way: There are sub-networks of brain regions - modules - that are more strongly interconnected among them while they have weaker connections to brain regions from other modules. "This is similar to a social network and sub-network of families or circles of friends. Within these sub-networks or modules, the members of one family are more strongly interconnected than they are with people from other families or circles of friends.

The study reveals that in more intelligent persons certain brain regions are more strongly involved in the exchange of information between different sub-networks of the brain for important information to be communicated quickly and efficiently. On the other hand, brain regions that are more strongly 'decoupled from the rest of the network in more intelligent people. This may result in better protection against distracting and irrelevant inputs. It is possible that due to their biological predispositions, some individuals develop brain networks that favour intelligent behaviours or more challenging cognitive tasks. However, the frequent use of the brain for cognitively challenging tasks may positively influence the development of brain networks.


Source: Special Thanks To Sir Syed Arif Ali