Explain the following terms cerebrospinal
fluid; peripheral nervous system, central
nervous system, endocrine glands, feedback
mechanism, tropic movement, nastic
movement.
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Answers
Answer –
- Cerebrospinal fluid
The cerebrospinal fluid is present in the membranes that covers the brain called meninges. This fluid helps in protecting the brain from shocks.
- Peripheral nervous system
The peripheral nervous system consists of the spinal cord and nerves. The two types of nerves included in a peripheral nervous system are spinal nerves and cranial nerves. The spinal nerves emerge from the spinal cord and the cranial nerves emerge from the cranium. The peripheral neves are types of nerves which goes from the spinal cord to the arm, hands and legs and feet. The cranial nerves go from the brain to our eyes, mouth, different parts of our head. The spinal nerves goes to different parts of the body below the head. The peripheral nervous system is responsible for the control of reflex actions. The main components of a peripheral nervous system is the spinal cord which starts from the brain and extends to the vertebral column. It 31 pairs of spinal nerves and medula oblongata is the upper part of the spinal cord.
- Central nervous system
This nervous system includes the brain and the spinal cord. The main component here is the brain. The central nervous system include central nerves found in the brain and spinal cord. The brain is the main coordinator centre of the human body protected by the cranium. It consists of three parts namely forebrain, midbrain and hindbrain. The fore brain controls voluntary actions like thinking, learning, emotions, etc. The mid brain controls involuntary actions and reflex movements of neck, head, eyes, etc. The hindbrain consists of 3 parts - cerebellum, ponds and medula; which controls the body movements, postures, respiration and different types of involuntary actions.
- Endocrine glands
The endocrine system in animals helps in the chemical or hormonal transmission of information inside the body. It include certain glands which secrete certain hormones which are necessary for the functioning of a body. The endocrine glands secrete the hormones and through blood the secreted hormone is carried to different parts of the body. They helping help in transmitting chemical signals in the body. Certain hormones released by endocrine glands are : Adrenaline produced by adrenal glands, releasing hormones produced by hypothalamus, oestrogen produced by ovaries, testosterone produced by testis insulin produced by pancreas, thyroxine produced by thyroid gland growth hormones produced by pituitary gland, etc.
- Feedback mechanism
The feedback mechanism helps in the regulation of hormones in the blood. Let us take an example to understand the feedback mechanism. The pancreas is responsible for the production of insulin which helps in production of blood sugar level in the body. When the insulin is produced the self start absorbing more blood sugar, hence the blood sugar level decreases. Now, how the insulin produced is working and what happened as the result of of insulin production - message is sent about it to the pancreas just like a feedback which helps the pancreas to decide whether more insulin has to be produced on the production of insulin has to be stopped. This is what feedback mechanism is.
- Tropic movements
The tropic movement is a type of movement in plants which are directional towards away from the stimulus. It depends on growth. The different types of tropic movements include photo tropism, geotropism, chemotropism, hydrotropism and thigmotropism. The photo tropism is a movement in response of light. The geotropism is a movement in response of gravity. The chemotropism is a movement in response to chemical stimulus. The hydrotropism is a movement in response of water. The thigmotropism is a movement in response to touch. These different types of tropic movements can either be positive or negative. If the movement is towards the stimulus, it is known to be positive, and if it is away from the stimulus, it is negative.
- Nastic Movements
The nastic nastic movements are types of movements which are known to be undirectional movements. It does not depend on growth. The perfect example of nastic movement include mimosa pudica or the touch me not plant. The leaves of touch me not plant closes when we touch it. This movement does not depend on any growth. It happens just because of the movement of water inside the leaves. This happens because of the change of turgidity of the leaves.