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| Class 8th Science Chapter 1 Notes For Federal Board 2022 |
Human Organ System
(1) Give Short Question.
Qno1) How does control and coordination of human body takes place.Explain? describe in simple words in a paragraph.
(Ans) Control and coordination of human body takes place.
(1) Nervous system (2) Endocrine System
(1) Nervous System: Nervous system which directs organs of body to preform different function.
(2) Endcorine System: Endocrine system which produces and secretes hormones that regulates all biological process of human body.
Qno2) What are the functions of the cerebrum, thalamus, hypothalamus, pituitary gland, cerebellum, and medulla oblongate ?
Ans) 1: Cerebrum: Cerebrum is the main center of many sensations for example hearing, sight, memory, intelligence, etc.
2: Thalamus: It receives all the impulses from the sensory organs before passing to the cerebrum
3: Hypothalamus: It regulates body temperature appetite blood pressure it also controls heartbeat thirty and hunger.
4: Pituitary Gland: It is a small gland that secretes harmonies.
5: Cerebellum: Cerebellum controls body balance and muscle contraction.
6: Medulla Oblongata: It posterior end is connected to the spinal cord. it controls heartbeat and circulation of blood.
Qno3) Name types of neuron and write their function ?
Ans) There are three types of neuron.
1) Sensory neuron 2) Motor neuron 3) Inter neuron
1) Sensory Neuron: Sensory neuron carry impulses (messages) from sense organs like ear nose skin etc to centeral nervous system.
2) Moter Neuron : Moter neuron carry impulses from central nervous system to muscles glands.
3) Inter Neuron : Inter neuron from synapses connection to transmit impulses from sensory to moter neurons
Qno4) Distinguish between:
(1) A voluntary action and an involuntary action
(2) A reflex action and reflex arc ?
Ans) (1) Voluntary action :
1) Take place with will.
2) Conscious process
3) Uses brain
2) Involuntary action:
1) Take place with out will.
2) Unconscious process.
3) Uses spinal cord.
(2) A reflex action and reflex arc ?
1) Reflex action : An immediate response to a specific stimulus without conscious is called reflex action.
2) Reflex arc : A natural pathway that control the reflexes is called reflexes arc.
SORRY 5 Question not available
Qno6) Which effectors and receptor are invalid in reflex action ?
1) Sneezing 2) Blinking
(1) Sneezing :
Ans) (a) Receptor : Nerves in nasal passage.
(b) Effectors : Eyes , lings , chest , diaphagram.
(b) Blinking :
(a) Receptor : receptor in eyes.
(b) Effectors : muscles that contract eyes to blink.
Qno7) Explain why tongue may be considered as a receptor and effector ?
Ans) 1) Tongue is considered as receptor because it has taste buds which acts as receptor for taste.
2) Tongue is considered as effector because it is a muscular organ having muscles which can respond to a stimulus (action)
Qno8) Discuss whether coughing is a voluntary action or a reflexs action ?
Ans ) Coughing is a reflex action. it is caused by some irritation which activate the different receptors of respiratory system and we cough.
Qno9) Explain function of myelin sheath ?
Ans ) It consist of fat containing cells that insulate the axom. it dose not pass into neight bouring neuron.
Qno10) Analyze the difference between somatic and autonomic nervous system ?
Ans) 1) Somatic nervous system: somatic nervous system consist of cranial and spinal nerve fibers that connect system centeral nervous system to skin and skeltal muscles.
2) Autonomic nervous system: autonomic nervous system includes nerve fibers that connect centeral organs such as heart , stomach , intestine etc to centeral nervous system.
Qno11) Explain why involving a short pathway of action and reaction of reflex arc help and save organism ?
Ans) A reflex action is an automatic and rapid response to stimulus which minimizes and damage from harmful conditions. reflex actions are essential for survival of living organisms.
Qno12) What are excretory products of liver, lungs , kidney and skin ?
Ans) 1) Liver : Liver breaks excessive amino acids into urea that excretes through intestine.
2) Lungs: Lungs excrete out carbon dioxide in form of un oxygenated air.
3) Kidney: Kidney remove urea and other nitrogenous products from blood. they also expels salts and water.
4) Skin: Skin excretes excessive water and salts in from of sweating.
Qno13) Elaborate the ways to take care of kidneys ?
Ans) 1: Always eat fresh and healthy food.
2: Drink a lot of water .
3: Avoid use of jack food and carbonated drinks.
4: Monitor blood pressure and sugar level.
5: Don,t smoke
6: Reduce excessive use of medicine.
Long question
Qno1) Explain difference between centeral nervous system and peripheral nervous system?
Ans) (1) Centeral Nervous System:
Centeral nervous system consist of brain and spinal cord brain is protected inside skill while spinal cord is protected by backbone both brain and spinal cord make up the centeral nervous system.
(2) Pheripheral Nervous System:
Peripheral nervous system includes nervous arising from brain and spinal cord. these are of two types.
(1) Cranial Nerves (2) Spinal Nerves
(1) Cranial Nerves :
There are 12 pair cranial nerves of arising from brain. The cranial nerve may be sensory nerve moter nerve or mixe.
(2) Spinal Nerves
There are 31 pair of spinal nerves which pass along vertebral coloumn. They carry impulse to all parts of body and also bring impulses from all parts of body.
Qno2) Explain the parts, structure and function of the brain in detail in a tabular form ?
Ans) Human brain consist of three main parts.
1-Fore Brain 2-Mid Brain 3-Hind Brain
1-Fore Brain
Fore brain consists of three main parts.
1) Cerebrum 2) Thalamus 3) Hypo Thalamus
1) Cerebrum:
Cerebrum is main part of fore brain. It is main center of various sensation e.g hearing, sight, smell,intelligence etc
2) Thalamus:
It receives all the impulse ( message) from a sensory organs before passing it to cerebrum.
3) Hypo Thalamus:
It regulates body temperature appetite food, blood pressure etc. It control hearts beats and secretes hormones.
2) Mid Brain:
Mid Brain is just mass of track.it acts acts as a relay station for passing messages between cerebrum and spinal cord.
3) Hind Brain:
1) Cerebellum
2) Pons
3) Medulla
1) Cerebellum:
Cerebellum is situated under the cerebrum it controls balance and muscles contraction.
2) Pons:
Pons is a small lobe like structure. it functions with medulla to regulate breathing rate.
3) Medulla or Medulla Oblongate
It lies below cerebrum. It posterior end is connected to spinal cord. It controls heart beats, circulate of blood etc.
Qno3) Explain the internal structure of kidney. Draw its labelled diagram ?
Ans) Kidney:
A human kidney consist of two main regions. The dark outer region is called cortex and inner thicker region is called medulla. The medulla consist of 12 to 16 conical structures called renal pyramids.
Important Parts of Kidney
Some important parts of kidney are
1) Renal Capsule:
It is a thick membrane in which kidney is enclosed .It surrounds and protects the kidney
2) Cortex:
It contains bowman's capsule and glomeruli.
3) Medulla:
It contains loop of halne U shaped tube to collect liquid wastes and collective ducts
4) Renal Pyramids:
These are cone shaped areas in medulla and opens into renal pelvis.
5) Renal Pelvis:
It is dust that collects liquid waste materials in form of urine.
6) Ureter:
Ureter are tubes that carry waste material urine from kidneys to gall bladder.
Qno4) Explain what happens in side the nephrons , in a flow chart or a concept map ?
Ans) Nephrons is structural and functional unit of kidney. It consists of three moan parts.
1) Bowman's Capsule 2) Glomerulus 3) Tubular portions
1) Bowman's Capsule
Each nephron begins in a cortex called bowman's capsule. It is a double wallet structure which surrounds glomerulus.
2) Glomerulus
The renal artery divides into a large number of small capillaries in bowman's capsule. This tuft a blood capillaries is called glomerulus.
3) Tubular Portion
The bowman's capsule leads into a short coiled called proximal convulated tubule.The U shaped portion of tubule is called loop of henle this tubule passes back and coils again and is called distal convulated tubule.
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