Matric Notes Biology Class 10th Ch 12 Co-Ordination and Control Long Questions
Q1: Explain the different types of receptor in human beings?
Ans: Receptors:
Definition: Receptors are the organs which receive the changes taking place in our environment. In humans there are many types of receptors which perform different functions.
1: Photoreceptor: It perceives light e.g. eyes.
2: Sonoreceptor: It perceives sound waves e.g. ear.
3: Chemical receptors: It perceives different chemicals e.g on tongue and nose.
4: Mechanical receptors: They perceives pressure mostly found in skin.
Internal receptor: There are other type of receptor which feel pain, hunger, thirst, pleasure, emotions etc.
Photoreceptor(human eyes):
Eye is the organ used as photoreceptor in human body. A pair of eyes is present in human beings which are present in the orbit of the face.
Structure of eye:
They are also known as visual receptor .An eye is a very complex structure.
It is in the form of ball .Eye consists of three layer.
II. Choroid(the vascular layer)
III. Retina(nervous layer)
A. Sclera: The outer most white, tough muscular layer is called sclera, which cover the eyes from outside.
B. Choroid: Choroid is the vascular layer of eye and provide nourishment to the eye. It is black in color which prevent the internal reflection of light. The choroid layer is thick in the anterior part and makes the ciliary body.
1. Iris: The colored portion of the choroid in the anterior center is called the iris.
2. Pupil: In the center of the iris, is a small hole called pupil, which control the amount of light entering the eye .It opens when light is dim and closes when light is bright.
3. Lens: Behind the pupil a lens is present which focus images from different distances on to the retina.
4. Suspensory ligaments: The lens is held by suspensory ligaments which are attached with the ciliary body. The muscles of the ciliary body control the focusing of the lens.
C. Retina: The third innermost layer of the eye is the retina. It contains photoreceptors cells and neurons
i. Types: There are two types of photoreceptor cells i.e. rods and cones.
a. Rods:ods are used to perceive dim light. They give us the image of the object but not its color and detail.
i. Rhodopsin: Rods contain a purplish-red pigments called the rhodopsin. The body synthesizes rhodopsin from VITAMIN A.
If there is a deficiency of vitamin A, the body cannot prepare rhodopsin in the required amounts.
ii. Due to deficiency of rhodopsin, the eyes cannot see clearly in dim light. This problem is called night blindness.
b. Cones: Cones are responsible for visualizing colors.
i. Iodopsin: The cones also contain pigment called iodopsin.
• The sensation of different colors, are produced by various combination of these cones. When all the cones is stimulated equally, a sensation of white light is produced.
o Optic nerve:
Lens focuses the image of the object in front of the eye on the retina which is transmitted to brain by optic nerve. An optic nerve leave the eye at posterior pole of the eyeball.
o Blind spot:
At this spot, photoreceptor cells are not present and hence it is called the blind spot.
Fovea:
At the posterior pole of the eye, opposite to the lens, there is a yellowish spot called the fovea. It is a thin portion of the retina where only cones are densely packed. Here, the visual acuity (resolution) is the greatest. Aqueous chamber:
The space between the cornea and the lens is called the aqueous chamber.
i. Aqueous humor:
It contains a thin watery fluid called the aqueous humor. ii. Vitreous humor:
The space between the lens and the retina is called the vitreous chamber. It is filled with a transparent gel called the vitreous humor.
Sono-receptor: (human ear)
In human beings and other vertebrates a pair of ear is used for listening and catching sound waves.
Structure:
2. Middle Ear
3. Internal Ear
1. External Ear:
The external ear is composed of
2. Auditory nerve
3. Ear drum
i. Pinna: The pinna or ear flap is external cartilaginous structure which collects sound waves.
ii. Auditory nerves: Auditory nerve is the tube which carries the sound waves from pinna to the ear drum.
iii. Ear drum: It is a membrane which separates the outer ear from the outer ear.
2. Middle Ear
The middle ear starts from the ear drum and contain three small bones called ossicles.
Chain like fashion:
These ossicles are attached to one another in a chain-like fashion.
These small bones are:
ii. Incus
iii. Stapes
These bones are the smallest bones of the body. They carry the sound vibration from ear drum to cochlea. Chain like fashion: These ossicles are attached to one another in a chain-like fashion.
i. Malleus: The malleus is attached to the ear drum.
ii. Stapes: The stapes is attached to the oval window of the cochlea.
Oval window: The oval window separates the middle ear from the inner ear.
Eustachian tube: A Eustachian tube connects the middle ear cavity with the pharynx. The Eustachian tube help in equalizing the pressure between the middle ear and the environment.
3. Internal Ear:
Internal ear is the fluid-filled chamber after the oval window.
It contain two important structure i.e.
i. Cochlea: A coiled tubule called the cochlea.
ii. Semi-circular canals: It is three in number. It help in maintaining the balance of the body.
iii. Organ of corti: The middle chamber of cochlea has the hearing apparatus, called the organ of corti. Special hair cells are present in the organ of corti, which are the receptor cells for sound.
Q2: Describe the structure of human brain.
Ans: Human brain:
Human brain is the main coordinating structure in the body.it is most sensitive and delicate organ of the body. In animals, all life activities are under the control of the brain inside the cranium,
1.Meninges:
The brain is covered by three layers of membranes, collectively called meninges. Their function is to protect the brain from harmful substances.
Cerebrospinal fluid:
The brain contains fluid filled ventricles. The ventricles of the brain are continuous with the central canal of the spinal cord. The fluid with in the ventricles and the central canal of the spinal cord is called the cerebrospinal fluid (CSF). It bathes the neurons of the brain and the spinal cord and cushions against physical and mechanical stresses.
Parts of the brain:
Human brain can be divided into three parts.
1. Forebrain 2. Midbrain and 3. Hindbrain
A. Forebrain
This is the largest area of the brain. It is most highly developed in humans. The following are the neurons packed together the most important parts of this region.
1. Cerebrum:
This is the largest part of the brain right side of the body.
It is divided into two halves, called cerebral hemisphere. These halves communicate with each other by means of a large band, called the corpus callosum.
i. Cerebral cortex:
The outer region of the cerebrum called the cerebral cortex. It has many folds and convolutions, which increase its surface area. It is made of grey matter (containing cell bodies and non-myelinated axons).
Function of cerebrum:
The cerebrum is the most important part of the brain. It receives sensory information processes it, stores some in memory for future use, directs voluntary movements, and is responsible for intelligence, thinking, reasoning and decision making. The speech center is also present in the cerebrum which is unique to human beings.
2.Thalamus:
This is wrapped by the cerebrum. It carries sensory information especially from the eyes and ears and generally from the skin and other internal organs of the body to the limbic system and cerebrum
i. Limbic system:
It is located in an arc between the thalamus and cerebrum. This system processes responses like hunger, thirst fear, anger, tranquility, pleasure and sexual Responses. A portion of the limbic system is also important in the formation of memories.
ii. Hypothalamus
It is a part of the limbic system. It lies below the thalamus.
B. Midbrain:
The midbrain is reduced in human beings and is present under the cerebral hemisphere.
It controls reflex movements of the eyes and hearing reflexes. The midbrain is a rely center that connects the forebrain with the hindbrain.
C. Hindbrain:
Hindbrain consists of cerebellum, pons and medulla oblongata.
Cerebellum:
Cerebellum controls balance of the body and coordinates the voluntary movements of the body as well. We can pick up a book from a table or touch our foot without mistake because of a healthy cerebellum. It is also involved in the learning and memory storage for showing different behaviour.
Pons: Pons is located above the medulla.
Function of pons: It controls transitions between sleep and wakefulness, and the rate and pattern of breathing.
Medulla oblongata: Medulla oblongata is the posterior part of the brain.
Function of medulla oblongata: It controls automatic functions like breathing, heart rate, circulation of blood, blood pressure, swallowing and vomiting.
Q3: Write a comprehensive note on chemical coordination in human beings.
Ans: Pituitary gland:
Shape: It is oval in shape.
Location: It attached to the hypothalamus of the brain.
Size and weighs: It is about the size of a pea seed and weighs about 0.5gm in adults.
Master gland: It is generally known as ‘the master gland’ of the body. Lobes:
It has two main lobes i.e. anterior and posterior.
Anterior lobe of pituitary gland:
It secretes the following hormones.
1: Growth hormones:
This hormone increases the cell division of somatic cells and promotes the growth of the body. It is secreted more in childhood but in adults the secretion become normal. If it is secreted in excess during early life it results in a disorder called gigantism
Its under-secretion in early life causes dwarfism in which the body of the child does not grow.
2: Thyroid stimulating hormone (TSH):
This hormone controls the development and secretion of the thyroid hormone (thyroxin).
3: Adrenocorticotrophic hormone (ACTH):
It acts on the cortex part of the adrenal gland to release the adrenal hormone.
4: Luteinizing hormone (LH):
It is needed for the release of egg cells from the ovary (ovulation) in females. In males, it stimulate the testes to produce sex hormones.
Posterior lobe of pituitary gland:
It secrete the following hormones:
i. Antidiuretic Hormone(ADH) or Vasopressin: This hormone affects the renal tubules to reabsorb large quantities of water from the glomerular filtrate.
ii. Oxytocin: Its main function is to contract the uterus muscles during childbirth. It also stimulates the flow of milk from the breasts during lactation.
2: Thyroid gland:
Location: The thyroid gland is situated above the larynx. It consists of two lobes, one on each side of the larynx. It secretes two hormones.
i. Thyroxin:
This hormone increase the metabolism of the body and produces heat in the body. It promotes growth, hence it is secreted more in young age. Thyroxin is an iodine containing compound.
Under-secretion: If thyroxin is produced less than the required amount, cellular metabolism slow. It results in lethargy, weight gain, low heat rate and body temperature.
Over-secretion: If thyroxin is produced more than required, cellular metabolism become faster than normal. It results in weight loss and high blood pressure, heart rate and body temperature.
ii. Calcitonin:
It stimulates the transfer of calcium ions from the blood to bone, where the calcium ions can be used to generate bone tissue. In this way, calcitonin maintain blood calcium level.
3. Pancreas:
Pancreas has both endocrine and exocrine activity.
As an exocrine gland: As an exocrine gland it is part of digestive system and produces pancreatic juice which help in digestion of food.
As an endocrine gland: As an endocrine gland it secretes two hormones insulin and glucagon.
Insulin: Insulin decreases blood glucose level either by metabolizing it or by converting it into lipids and protein, if the body fails to produce insulin it leads to condition called diabetes mellitus.
Glucagon: Glycogen works opposite to insulin and increases blood glucose level. It promotes the breakdown of glycogen to glucose in the lever and muscles.
Q4: Discuss any two disorder of the eye.
Short sightedness (Myopia) The disorder of eye in which a person can see a near object clearly but cannot see the far object clearly is known as short sightedness. It is also known as near sightedness.
Technically, it is called Myopia.
Causes: In short sightedness the eye ball becomes usually long. Due to this the light rays are focused in front of retina. Due to above cause a blurred (not clear) image is formed.
Correction: The short sightedness is corrected by using concave lenses in glasses. These concave lenses focus the rays on retina and the person can see again correctly.
Long sightedness Hypermetropia:
The disorder of eye in which a person can see the far object clearly but cannot see the near object clearly is known as long sightedness.
It is also known as far sightedness. Technically, it is called as hypermetropia.
Causes: In long sightedness the eye ball becomes usually short. Due to this the light rays are focused behind retina. Due to above cause a blurred image (not clear) is formed.
Correction: The long sightedness is corrected by using convex lenses in glasses. These convex lenses focused the rays on retina and the person can see again correctly.
Q5: Describe the causes, symptoms and treatment of paralysis?
Ans: Paralysis: Paralysis is a vascular disease of the brain.
Causes:
2. Due to rupturing of blood vessel in the brain because of high blood pressure.
Parts effected:
2. The patient of paralysis is unable to move the muscle of one side of their body or both sides.
3. Paralysis may also effect the arms or legs, and sometime the whole body.
Symptoms:
2. Impairment or loss of vision.
3. Memory loss.
4. Confusion
5. Loss of balance or co-ordination
6. Poor balance and dizziness
7. Sudden numbness or weakness of an arm, leg or side of the face.
Treatment:
2. This existing treatment only help a person to adapt to this way of life by making them independent.
3. Patient are given physiotherapy to improve their muscle weakness.
4. Mobility aids such as wheelchairs and orthoses (braces designed to improve the function of a limb) are also used for patients of paralysis.
Q6: Describe the causes, symptoms and treatment of epilepsy?
Ans: Epilepsy (fits or mirgi): This is the type of functional disorder of the nervous system in which suddenly excessive discharge of the nerve impulses takes place from the brain.
Seizures: The improper bursts of impulses from neurons which cause the body to behave strangely are called seizures peoples generally called it fits.
Symptoms:
2. Some have convulsions (shaking of the body) or may lose consciousness.
3. The body become rigid and stiff.
4. The patient’s hands are clenched and they frequently bites their tongues. Period of attack:
Epilepsy usually causes before the age of 30.
Causes:
Epilepsy may be caused by the following:
2. Severe head injuries.
3. Strokes.
4. Brain infection.
5. Drug abuse.
Treatment:
1. In the treatment for epilepsy, seizures are controlled.
Anti- epileptic drug (AEDs) are used for the treatment of epilepsy.
AEDs do not cure epilepsy, but can prevent seizures from occurring
Q7: Explain the mechanism of vision by the eyes?
Ans: The light rays coming through the cornea and lens make an image on the retina. The photoreceptor cells that is rods and cones of the retina produce nerves impulses in the neurons presents in the retina. The axons of these neurons are part of the optic nerves. The optic nerves carries information in the form of nerve impulses from the retina to the cerebrum of the brain. Here, the impulses are processed produced a meaningful sensation of shape and color.
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