These MP Board Class 11th Biology Notes for Chapter 21 Neural Control and Coordination help students to get a brief overview of all the concepts.
MP Board Class 11th Biology Notes Chapter 21 Neural Control and Coordination
→ If the blood flow to brain is interrupted for a few movements unconsciousness may result. Interruption of 1-2 minutes may weaken the brain cells by starving them of oxygen. Neurons are permanently injured if deprived of oxygen for 4 minutes.
→ If blood entering the brain has low glucose level, mental confusion, dizziness, convolutions and even unconsciousness may occur.
→ Myelin is white and made up of phospholipid. It is responsible for the colour of the white matter in brain, spinal cord and nerves.
→ Sir Charles Sherington (1861-1954) was the first person who applied the term synapse to the junctional points between two neurons. Actually synapse is a place of physiological continuity without anatomical continuity.
→ Parkinsonism or Parkinson’s disease is a disease of the basal ganglia deep in the substance of the brain that control movement. It occurs usually in the late middle age. Parkinson’s disease seems to be caused by the malfunction at the synapses.
→ Sciatica is the painful condition of the sciatic nerve or its branches. In this, pain passes from the back or thigh down its length into the leg, foot and toes.
→ Strabismus or Squint is an eye muscle disorder commonly known as crossed eyes. The eyeballs do not move in unison and the image does not fall upon corresponding points of the two retinas. It may be caused due to lack of coordination of the extrinsic eye muscles. As a result, two images are seen, a condition termed diplopia.
→ Taste of chillies, black pepper and hot sauces is not a true sensation. It is mainly a sensation of burning pain produced by the stimulation of pain receptors of the tongue by specific chemical substances in those goods.
→ Image formed on the retina is always inverted.
→ The hair cells in the human ear are variously estimated to be of 13,000 to 54,000 in number each one with about 40 cilia or hair at the receptive side and projecting into the endolymph.
→ The nervous system is derived from embryonic ectoderm.
→ The central nervous system consists of brain and spinal cord developing from neural ectoderm.
→ The brain and spinal cord are covered and protected by connective tissue membranes called meninges.
→ The wall of brain is made up of grey and white matter.
→ Grey matter differs from white matter in having cell bodies and non-myelinated proximal parts , of axons. The white matter contains myelinated parts of axons.
→ We lose our sense of smell when olfactory lobes are removed from brain.
→ The forebrain or prosencephalon is the largest part of the brain and cerebrum is the largest part of the forebrain.
→ The roof of the cerebrum is known as pallium.
→ Cranial nerves are arising from brain. There are 12 pairs of cranial nerves in mammals.
→ The cells of nervous system are called neurons.
→ In mammals, 31 pairs of spinal nerves are present.
→ The processes emerging out from cyton are known to be as dendrites.
→ Middle ear has three bones : (i) Malleus, (ii) Incus and (iii) Stapes.
→ Internal ear is made up of two tubules : (i) Vestibule and (ii) Semicircular tubules.
→ The path of nerve impulse in a reflex action is called reflex arc.
→ An automatic spontaneous involuntary and unconscious action brought about by nervous system is called reflex action.
→ Reflex actions are controlled by central nervous system.
→ Poliomyelitis is an acute viral infection that destroys the cell bodies of motor neurons in the anterior horn of the spinal cord.
→ Rods mainly enable the animal to see in the darkness, therefore rods are present in larger number in nocturnal animals.
→ Cones are chiefly concerned with the distinction in colour and light vision during day time.
→ The rods contain rhodopsin or visual purple pigment, whereas cones contain the iodopsin or visual violet pigment.
→ Acetylcholine functions like that of a synaptic stimulant.