nutrition in humans

Question 1

what is nutrition

Answer 1

the process of obtaining food to release energy for growth, repair,and maintenance of the body

Question 2

define ingestion

Answer 2

when food is taken into the body

Question 3

define absorption

Answer 3

when digested food molecules are absorbed into the cells

Question 4

define assimilation

Answer 4

when absorbed food molecules are converted into new protoplasm or used to provide energy

Question 5

define egestion

Answer 5

the process of removing undigested food materials from the body

Question 6

define peristalsis

Answer 6

the rhythmic, wave like muscular contractions in the wall of the alimentary canal

Question 7

define deamination

Answer 7

the process by which amino groups are removed from amino acids and converted to urea

Question 8

define detoxification

Answer 8

the process of converting harmful substances into harmless ones

Question 9

describe the functions of the liver (4 functions)

Answer 9

1. regulation of blood glucose concentration
2. production of bile
3. deamination of amino acids
4. breakdown of alcohol

Question 10

describe the structure of the mouth

Answer 10

salivary glands in the mouth secretes saliva, which contains salivary amylase to digest starch into maltose
saliva also softens the food
the chewing action of the teeth breaks up the large food pieces into smaller food pieces to increase Sa:V to speed up enzyme reaction.
the tongue helps to mix the food with the saliva. it also rolls the food into boli for swallowing

Question 11

what is the pH of the mouth, stomach, and small intestine (duodenum)

Answer 11

7
1-2
8-9

Question 12

describe digestion of starch

Answer 12

starch is digested by salivary amylase to maltose
maltose is digested by maltase to get glucose

Question 13

describe the digestion of protein

Answer 13

protein is digested by pepsin into polypeptide
polypeptide is then digested by peptidase into amino acids

Question 14

describe the digestion of fat

Answer 14

fat is emulsified by bile into smaller fat droplets. the smaller fat droplets are then digested by intestinal lipase into 3 fatty acids and 1 glycerol

Question 15

what is the structure of the oesophagus

Answer 15

it is a narrow, muscular tube that extends to the stomach.
the muscles push food along the gut by peristalsis,
the rhythmic, wave-like muscular contractions in the wall of the alimentary canal. peristalsis is caused by the alternate contractions of the circular and longitudinal muscles in the walls

Question 16

how does digestion take place in the stomach

Answer 16

gastric juice contains hydrochloric acid and pepsin.
peristalsis in the stomach walls break up food and mix the food with gastric juice.
pepsin found in gastric juice digests protein. its optimum ph is in the stomach as it is acidic

Question 17

what is the structure of the stomach

Answer 17

a distensible muscular bag with a pyloric sphincter located at the place where the stomach joins the small intestine. the ring contracts and relaxes to allow food to pass from the stomach into the small intestine
the muscular walls contain gastric glands that secrete gastric juice.
gastric juice contains hydrochloric acid and pepsin.
the stomach is lined with a protective layer of mucus to protect frm hydrochloric acid
(peristalsis in the stomach walls break up food and mix the food with gastric juice.
pepsin found in gastric juice digests protein. its optimum ph is in the stomach as it is acidic)

Question 18

what is the purpose for gastric juice in the stomach

Answer 18

gastric juice contains dilute hydrochloric acid (pH2), which stops action of salivary amylase by denaturing it, activates pepsinogen into pepsin, provides an acidic medium for pepsin action, and kills potentially harmful microorganisms in food.

Question 19

what is the structure of the small intestine

Answer 19

it is a 6m long coiled up tube with 3 segments (duo,jeje,ile)
with folded inner walls with finger-like projections called villi

Question 20

how does digestion take place in the small intestine?

Answer 20

chyme entering the duodenum stimulates:
the pancreas to secrete pancreatic juice
the gall bladder to release bile
the epithelial cells in the small intestine to produce intestinal juice.

Question 21

what enzymes does pancreatic juice contain

Answer 21

pancreatic amylase, trypsin, and pancreatic lipase

Question 22

what enzymes does the small intestine produce

Answer 22

maltase, peptidase, intestinal lipase

Question 23

why is the optimal pH for small intestine 8-9

Answer 23

it stimulates the pancreas to secrete pancreatic juice, and the gall bladder to release bile.
the alkaline fluids neutralise the acidic chyme
and provide a suitable environment for the action of the pancreatic and intestinal enzymes

Question 24

what does bile do

Answer 24

emulsifies fat into smaller fat droplets, increasing sa:v for lipase to act on, speeding up the rate of fat digestion

Question 24

what does bile do

Answer 24

emulsifies fat into smaller fat droplets, increasing sa:v for lipase to act on, speeding up the rate of fat digestion

Question 25

how is the small intestine adapted for absorption?

Answer 25

1. thin walls to speed up absorption of digested food substances
2. large surface area for absorption
   the small intestine is long to ensure sufficient time for absorption
   its inner surface is folded
   the folds have villi
   the epithelial cells of villi have microvilli
3. digested food substances continually transported away
   by capillaries and lacteals in villi, it maintains a concentration gradient for absorption

Question 26

describe the structure of a villi

Answer 26

small finger-like projections on the numerous folds on the inner wall. in each villus is a lymphatic capillary surrounded by blood capillaries. lymphatic capillary transports fats while blood capillaries transport sugars and amino acids away from the intestine

Question 27

how is the concentration gradient of the absorption of digested food substances maintained

Answer 27

in each villus is a lymphatic capillary surrounded by blood capillaries. lymphatic capillary transports fats while blood capillaries transport sugars(glucose) and amino acids away from the intestine. the continual transport of digested food substances help to maintain the concentration gradient

Question 28

what food substances are digested in the small intestine

Answer 28

sugars, amino acids, fatty acids, and glycerol

Question 29

what does the large intestine do

Answer 29

absorbs water and mineral salts

Question 30

what does the hepatic portal vein do

Answer 30

transports nutrient-rich blood from the small intestine to the liver
(mostly sugars and amino acids)

Question 31

what does the hepatic vein do

Answer 31

distributes the remaining glucose and amino acids around the body

Question 32

what is glucose used for in the body

Answer 32

glucose is used by cells for respiration to release energy

Question 33

what are amino acids used for in the body

Answer 33

used by cells to form new protoplasm for growth and repair, and to form enzymes and hormones

Question 34

explain how the liver regulates blood glucose concentration

Answer 34

the liver keeps the amount of glucose in the blood constant, esp after a heavy meal or after fasting.
when there is too much glucose in blood, insulin is secreted, which stimulates the liver cells to convert glucose into glycogen for storage, thus decreasing the blood glucose concentration
when there is too little glucose in the blood, glucagon is secreted and the liver converts glycogen to glucose to be released into the bloodstream, thus increasing glucose concentration in the blood

Question 35

what happens to excess sugars and amino acids

Answer 35

most absorbed sugars are converted to glycogen and stored in liver
excess amino acids are deaminated

Question 36

explain how the liver deaminates amino acids

Answer 36

the process where amino groups are removed from amino acids and converted to urea. urea is removed from the body in the unrine. the remains of the amino acids are converted into glucose in the liver. excess glucose is converted into glycogen

Question 37

what is fat used for in cells

Answer 37

1. synthesis of protoplasm (cell membranes)
2. respiration for energy when glucose is insufficient
3. excess fats are stored in adipose tissues

Question 38

explain breakdown of alcohol in the liver.

Answer 38

the liver cells contain an enzyme called alcohol dehydrogenase, which breaks down alcohol into acetaldehyde, which can be broken down further to compounds that can be used in respiration to provide energy for cell activities

Question 39

what are the effects of excessive consumption of alcohol on the digestive and nervous systems

Answer 39

excessive consumption could lead to liver cirrhosis.
a condition where liver cells are destroyed and unable to function, which can lead to liver failure and death