transmission of impulses.
- Neurons are the functional units which receive and process information and generate responses.
- Cell body is the centre for all the synthetic activity of the neuron.
- Dendrites arise from the cell body receive information from other neurons and carry this information to the cell body.
- The axon or nerve fibre gives out several branches that end in nerve terminals. These make connect with the dendrites or the axons of another neuron.
- Myelinated sheath prevents the leakage of electrical currents from axon. Myelinated axons conduct impulses much faster than unmyelinated axons.
Man is the most intelligent animal. What could be the fact that helped us to reach such a conclusion?
- Man is the most intelligent animal in animal kingdom.
- This is possible by well development of brain and its marvellous function.
- Human brain has abilities to learn from concepts.
- It understands, applies logic and reason.
- The brain also recognizes patterns and comprehends ideas.
- The human brain has ability in making plans, solving problems, making decisions and retaining information.
- Man is the only animal who uses language to communicate.
- Intelligence enables humans to experience and think.
- It has also consciousness and self-awareness.
The axon of nerve cell in hand is shorter than the axon of nerve cell in leg. Do you support this statement? Why?
- Yes, I support the above statement.
- The axon of nerve cell in hand is shorter than the axon of nerve cell in leg.
- The sciatic nerve is the large nerve in humans and animals. It begins in the lower back and runs through the buttock and lower limbs.
- Sciatic nerve present in the leg is the largest and widest single nerve in the human body. It measures about 1 mt in length.
- Usually the length of leg is more in size than hand. Hence the axon of nerve cell in hand is shorter than the axon of nerve cell in leg.
Organs respond to the external stimulus by a fraction of second. How do you feel about such controlling mechanism of human body?
- Organs responding for the external stimuli by a fraction of second are due to reflex action.
- Reflex actions are very important as they save us from painful or dangerous stimuli.
- Reflex actions or reflexus are fast, immediate automatic and involuntary responses of the body.
- They help in the body as they save us from painful or dangerous stimuli.
- Reflexes occur without our thinking.
- Brain is not involved in the execution of several reflexes.
Ex: Withdrawing our hand when we touch hot subject.
State whether the following actions are voluntary action, reflex action or conditioned reflex.
- Cleaning the table
- Playing on the key board
- Salivating when food is put in the mouth
- We close our ears when we hear unbearable sound
- Blinking: Involuntary action or reflex action.
- Cleaning the table: Voluntary action.
- Playing on the keyboard: Conditioned reflex.
- Salivating when food is put in the mouth: Involuntary or Reflex action.
- We close our ears when we hear unbearable sound: Involuntary or reflex action.
What will happen to the potted plant kept near window in the room?
Draw a diagram of a plant showing phototropism. Explain why plants possess such type of response.
A plant which grows near a window bends towards sun light. Write the reason for it.
- The potted plant which is kept near the window in the room, grows towards light.
- Auxins acts on bending of stem of show a response to the sun light.
- More auxin collects on the light illuminated side of the stem. So cells on that side grow faster.
- On opposite side cells grow slow to make the stem bend.
- Auxins are the plant hormones responsible for the growing of the stem towards light.
- Auxins are synthesized at the tip of the stem (meristematic tissue).
- Bending of the plant towards light is called phototropism.
What happens if all the functions of the human body are controlled only by brain?
Brain controls all the functions of the human body. Comment on it.
- If all actions of the human body are controlled by brain, our body will get harm in dangerou