DESCRIBE THE STRUCTURE AND FUNCTIONS OF THE VARIOUS PART OF THE MAMMALIAN BRAIN. (20MKS)

-
 Describe the structure and functions of the various part of the mammalian brain. (20mks) 
Cerebrum ; - Controls learning intelligence, reasoning, thought, 
memory, speech, vision, hearing, smell, taste
-Also controls voluntary movements, movement of lips, limb, neck etc;  
Hypotahlamus; - Controls body temperature ability to sleep and wake up/appetite   osmo regulation/secretion of hormones;
Pitiutary gland; - Secretes hormones like ADH/F.S.H/L.H/prolactin/oxytocin;
Thalamus ;- Is a relay centre that integrates sensory impulses from eyes, ear, skin ;  and sends the impulse  to sensory cortex of cerebrum;
                        [Acc contains receptors for pain and pleasure.] 
 Olfactory lobes ; Control sense of smell ; 
Ventricles ; which contain  cerebrospinal fluid which supplies food nutrients and oxygen; to tissues of brain and remove metabolic waste from brain  tissues ; fluid acts as shock absorber for the brain;
Optical lobes ; control movement of the eye ;
Cerebellum ; controls body balance, movement, posture ;
Medulla oblongata; controls involuntary movement sneezing vomiting, blood circulation, breathing movement; 
Meninges; for protection; 
Arachnoids layer; secretes  cerebrospinal fluid for oxygen supply, which absorbs shock and nutrients supply;

Comments

Post a Comment

Popular posts from this blog

(a) Define digestion. [2 m] (b) Describe the digestion of a piece of ugali in a human digestive system from the mouth until its assimilation. [18mks]

-
(a) Define digestion It is break down of complex insoluble; v food substance into simple soluble food substances; v 2max (b) Describe the digestion of ugali; Digestion of ugali begins in the mouth;v ugali is chewed by the teeth to increase large surface areav for action of salivary amylase / ptyalin; vThe food mixes with saliva produced by salivary glands;v Saliva contains mucus and enzyme ptyalin. Mucus moistens, softens and lubricates the food;v ptyalin speeds up the conversion of starch to maltose;v ugali is made into bolus in the mouth;v The bolus moves along the oesophagus and prestalsis / by contraction and relaxation of circular and longitudinal muscles into the stomach;v The digestion continues until ugali become acidic since the stomach does not contain carbohydrase / carbohydrate digesting enzymes no digestion of ugali takes place here.v Ugali now...
Read more

Explain how structures of the human ear are adapted to their functions. (20 marks)

-
Image
The pinna;- is funnel shaped to trap sound waves; cartilaginous to maintain the funnel shape; collects and directs sound waves into the external auditory meatus ear; The external auditory canal; - a tube connected to the pinna that directs sound waves from the pinna to the eardrum lining the auditory canal; has hair that trap foreign particles; The canal contains wax-secreting cells; and hair which traps dust particles; and pathogenic bacteria hence prevent them from getting into the ear; The eardrum; - has a thin tough membrane; that easily vibrates when hit by sound waves; transferring them into vibrations. The ear ossiscles; - they act like a layer and they easily move forward and backward to amplify sound vibrations that hit them; The suspensory ligaments; - suspends the ear ossicles and prevents excessive vibration that would otherwise damage the inner parts of the ear; The eustachian tube - it connects the middle ear with the pharynx; and it equalises air pressure between...
Read more

EXPLAIN HOW ABIOTIC FACTORS AFFECT PLANTS. (20MKS)

-
 Explain how abiotic factors affect plants. (20mks) Abiotic factors. Wind; -On a windy day rate of transpiration increases since wind carries away water vapour leaving surrounding of leaves with low humidity; the lower the humidity the more the space in the atmosphere for water molecules to occupy. - Wind disperse fruits, seeds and spore; - Wind is an agent of pollination. - Strong winds break branches of trees and may even uproot some trees; Temperature; -Enzymes work best at optimum temperature; changes in temperature hence influence rate of photosynthesis/respiration; and other enzyme controlled biological reactions. -In aquatic environment temperature affects the percent of dissolved gases. Light; - green plants need light for photosynthesis; - some plants need light for flowering; photoperiodism; - some seeds (lettuce) require light for germination; - light affects opening and closing of stomata; which affects transpiration; gaseous exchange and photosynthesi...
Read more