summary of ch7 class 10 control & coordination
Answers
Answer:
Neuron consist of 3 parts :
- Axon
- Dendrite
- Cell body or cyton
3 Types of nerves
Sensory nerve, Motor nerve, Relay nerve
Nervous system and its parts:
Central nervous system: It consists of two main parts that is the brain and the spinal cord. They actually control the major part that refers to what to do when to do and how to do i.e a response towards all stimulus.
Voluntary nervous system: It controls all the activities that occur according to the will of person like sitting, posture maintaining etc.
Reflex action
It is defined as the quick, spontaneous and autonomic response. We have receptors in our body that are actually specialized cells sensitive to different stimuli.
Human Brain
- It is the main controlling centre of our body . It is the major part of CNS.
- It is present in a cavity called the skull.
- It is surrounded by a bony box known as the cranium.
- It is covered with membranes called the meninges.
- The fluid present in vacant spaces and between membranes is called the CSF (cerebrospinal fluid).
It is divided into :
Fore brain
Cerebrum : It is the largest part of the brain that is roughly divided into two parts called the cerebral hemispheres . These parts are further divided into small parts that perform different functions:
Olfactory lobes: They are the prominent lobes and they help in producing sensation of smell
Midbrain : It has no sub division and its function is to control some reflex actions .
Hindbrain
Cerebellum : It is also like cerebrum but not too large. We can say it is the second largest part of the brain.Their major function is to control body movements and posture movements.
Pons varolii: It is the small ovoid body located near the brain stem. It controls some aspects of respiration.
Medulla oblongata: It is the stem of the brain. It controls involuntary activities like coughing, sneezing, heart beat etc
Spinal cord
It is the extension of medulla oblongata. The function of the spinal cord is to control reflex actions. In plants also certain movements are seen which are controlled and coordinated by hormones as their bodies are not so complex and advanced.
Phyto-hormones : The hormones present in plants are called phyto-hormones.
Auxin : It is present on tip of the plant. It helps in growth of the plant (cell multiplication ,cell enlargement,cell maturation), breaks seed dormancy.
Gibberellin : It is also a growth hormone. It also promotes the growth of the plant as it increases the height of plant.
Ethylene : It helps in ripening of fruits and vegetables.
Cytokinin: It helps in closing of stomata and breaks seed dormancy.
Abscisic Acid: It is a negative hormone. It retards growth of plant, promotes senescence and it causes premature falling of fruits and vegetables .
Tropic movements
Phototropism : It is the movement caused in plant or plant parts in response to the light.
Geotropism : The movement caused in a plant in response to gravity. Similarly in this root moves towards gravity so it is positively geotropic and stem is negatively geotropic.
Chemotropism : The movement caused in plant in response to a chemical.
Nastic movements: These are the movements that occur in the direction of stimulus.
Photo-periodism :It is the period of light for which the plant is exposed to sunlight.
The other system that is responsible for control and coordination in humans is hormonal system.
Hormones in humans
Hormones are the certain chemicals released in our bodies that help in control and coordination of the body.
Characteristics of hormones :-
They are secreted in small amounts.
- They are secreted by endocrine glands.
- They act only on target organ.
- They are either proteinous , steroids etc.
- They reach target organ through blood
Pituitary gland : It is located in the midbrain. It is also called the master gland of our body as it secrets some important hormones.
Growth hormone : It helps in growth of body. If secreted in excess : gigantism . If secreted in less amount : dwarfism
Thyroxin: Helps in controlling metabolism of fats , proteins and carbohydrates. Malfunctioning of this gland causes thyroid in adults and cretinism in children.
Pancreas: It is located below the stomach. It is the only gland that is endocrine as well as exocrine in function. Its endocrine part is ielts of langhams. Hormones secreted by it are :
Insulin: lowers blood glucose level. Glucagon: Increases blood glucose level. Deficiency of it causes: Diabetes mellitus.
Adrenal gland: It is located on the kidneys. It secretes adrenaline and corticoid . Adrenalin: It prepares the body for action. It is called emergency gland and adrenaline is emergency hormone.
Ovaries : it is female gonad. It secretes oestrogen.
Testis : it is male gonad. It secretes testosterone.
Explanation:
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