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Sec 3 Pure Bio > Nutrition in Humans > Flashcards

Nutrition in Humans Flashcards

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Biology 101 flashcards
1
Q

define nutrition

A
  • the process by which organisms obtain food&energy

- needed for growth, repair and maintenance of body

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2
Q

state the 5 processes (in order)

A
  1. feeding/ingestion
  2. digestion
  3. absorption
  4. assimilation
  5. egestion
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3
Q

define feeding/ingestion

A

food taken into body

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4
Q

define digestion

A

large insoluble food molecules broken down into smaller soluble molecules

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5
Q

define absorption

A

digested food molecules absorbed into cells

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6
Q

define assimilation

A

food molecules converted into new protoplasm to provide energy

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7
Q

define egestion

A

undigested food removed from body

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8
Q

the mouth and buccal cavity

A

-food enters body thru the mouth which leads to the buccal cavity

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9
Q

teeth (physical digestion)

2 pts

A
  • chewing action breaks down large food molecules into smaller food molecules
  • increases SA:V allowing enzymes to act on food molecules more efficiently
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10
Q 
salivary glands (chemical digestion) 
(3 pts)
A
  • secretes saliva into mouth
  • saliva flows into buccal cavity via tubes called salivary ducts
  • saliva contains salivary amylase (starch to maltose)
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11
Q

tongue

2 pts

A
  • taste buds help identify and select suitable foods

- mix food with saliva, rolls food into bolus

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12
Q

define the pharynx and where it leads to

4 pts

A
  • connects the buccal cavity to oesophagus and larynx
  • also lead to trachea (windpipe), to lungs
  • part of both respiratory and digestive system
  • food&air pass thru
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13
Q

If both food and air must pass thru the pharynx to enter the oesophagus and trachea, how is food prevented from entering the trachea when swallowing?

A

epiglottis, opens and closes the glottis

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14
Q

what happens during breathing and swallowing?

3 pts

A
  • larynx has a slit-like opening (glottis), covered by a flap-like tissue (epiglottis)
  • breathing: air passes thru trachea, larynx moves downwards, glottis is open
  • swallowing: larynx moves upwards, epiglottis covers glottis, preventing food particle from entering trachea
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15
Q

define the oesophagus and gullet and what it is made of

3 pts

A
  • narrow, muscular tube passes thru thorax (chest) and diaphragm to join stomach
  • wall made up of 2 layers of muscles: longitudinal (outer) & circular (inner)
  • muscles present along the whole gut from the oesophagus to rectum
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16
Q

define longitudinal &circular muscles and what it does

3 pts

A
  • antagonistic muscles (pair of muscles where movements oppose each other)
  • produces long slow contractions
  • these contractions move food along gut via peristalsis
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17
Q

define peristalsis and what it does

3 pts

A
  • the rhythmic, wave-like muscular contractions in the wall of the alimentary canal
  • enables food to be mixed with digestive juices
  • pushes/propels food along gut
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18
Q

define the stomach

3 pts

A
  • a distensible muscular bag
  • thick and well-developed walls
  • when it is fully distended, it sends signals to the brain that it is full
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19
Q

gastric glands

3 pts

A
  • the stomach wall has numerous pits that lead to gastric glands
  • gastric glands secrete gastric juice into stomach cavity
  • gastric juice digests food
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20
Q

sphincters

A

-rings of muscles that contract to retain food in stomach for digestion

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21
Q

cardiac sphincter

A

entrance, relaxes to allow food to enter stomach

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22
Q

pyloric sphincter

A

exit, relaxes to allow chyme (semi-digested food) to leave stomach

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23
Q

what is the small intestine made up of?

A

duodenum, jejunum and ileum

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24
Q

define the small intestine

4 pts

A
  • abt 6m long
  • absorbs more water than large intestine
  • lining of small intestine walls contain glands which secrete digestive enzymes
  • adapted to absorb digested food and water
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25
Q

what is the large intestine made up of?

A
  • consists of the colon and rectum

- abt 1.5m long

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26
Q

state the other glands associated with the gut

A

liver, pancreas, gall bladder

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27
Q

define physical digestion and where it occurs

3 pts

A
  • involves mechanical break-up of food into smaller pieces
  • chewing, churning or peristalsis
  • occurs in mouth and stomach
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28
Q

define chemical digestion and which reaction/s are involved

A
  • involves break-down of large complex molecules into small simple molecules that can be absorbed
  • involves hydrolytic reactions catalysed by digestive enzymes
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29
Q

digestion in the mouth

5 pts

A
  • chewing action by teeth breaks up large pieces of food into smaller pieces, increasing SA:V for amylase to work on
  • tongue rolls food into small, slippery round masses called boli
  • salivary glands in mouth secrete saliva, mixed with food by tongue
  • saliva contains mucin which softens food
  • salivary amylase breaks down starch into maltose
30
Q

digestion in oesophagus

3 pts

A
  • boli are swallowed and passed down into oesophagus via the pharynx
  • peristalsis in walls of oesophagus and gravity push bolus into stomach (physical)
  • amylase in saliva continue to break down starch (chemical)
31
Q

digestion in stomach

2 pts

A
  • when bolus enters stomach, stimulates the release of gastric juice by gastric glands (chemical)
  • peristalsis in walls of stomach churns and breaks down food, mixing food with gastric juice (physical)
32
Q

define gastric juice

2 pts

A
  • dilute solution of hydrochloric acid (pH2), mucus and 2 enzymes (pepsin and rennin)
  • mucus protects stomach lining from hydrochloric acid (absence can result in stomach ulcers)
33
Q

role of hydrochloric acid

4 pts

A
  • denature salivary amylase
  • converts pepsinogen and prorennin into pepsin and rennin respectively
  • provides an acidic medium for action of pepsin and rennin (optimum pH:2)
  • kills harmful microorganisms in food
34
Q

state the actions of pepsin and rennin

2 pts

A
  • pepsin digests proteins into polypeptides

- rennin converts soluble caseinogen into insoluble casein

35
Q

digestion in small intestine

4 pts

A

chyme(semi-digested food) enters duodenum, stimulating the release of:

  • intestinal juice by intestinal glands
  • pancreatic juice by pancreas
  • bile by gall bladder
36
Q

pH level in small intestine

2 pts

A
  • alkaline fluids neutralize the acidic chyme

- alkaline medium needed for the action of intestinal and pancreatic enzyme

37
Q

Gall bladder and bile (Small intestine)

3 pts

A
  • gall bladder releases its stored bile
  • bile passes thru bile duct into duodenum
  • bile salts speed up digestion of fats
38
Q

Pancreas and pancreatic juice

2 pts

A
  • pancreas secretes pancreatic juice

- contains pancreatic amylase, pancreatic lipase and trypsinogen (inactive trypsin)

39
Q

Intestinal juice

2 pts

A
  • secreted by intestinal glands

- contains peptidases, maltase, sucrase, lactase and intestinal lipase

40
Q

how are different foods digested

3 pts

A
  • amylase act on carbohydrates
  • proteases work on protein
  • lipases work on fats
41
Q

how are carbohydrates digested

6 pts

A

mouth: starch to maltose (salivary amylase)
small intestine:
-starch to maltose (pancreatic amylase)
-maltose to glucose (maltase)
-lactose to glucose+galactose (lactase)
-sucrose to glucose+fructose (sucrase)
(end products are simple sugars that can be absorbed into bloodstream)

42
Q

how are proteins are digested

4 pts

A

stomach:
-protein to polypeptides(pepsin)
small intestine:
-trypsinogen to trypsin (enterokinase)
-proteins to polypeptides (trypsin)
-polypeptides to amino acids (peptidases)

43
Q

how are fats digested

5 pts

A
  • bile salts emulsify fats
  • reduce attractive force between fat molecules
  • break down fat into small fat droplets that are suspended in water to form an emulsion
  • increase SA:V of fat molecules, speeding up digestion by lipase
  • fats broken down into fatty acids+glycerol (pancreatic and intestinal lipase)
44
Q

where is the site of absorption?

A

small intestine

45
Q

how is the rate of absorption influenced?

3 pts

A
  • surface area
  • thickness of membrane that separates food substances from blood capillaries
  • concentration gradient of individual food substances
46
Q

3 adaptions that makes absorption more efficient in the small intestine
(3 pts)

A
  • large surface area
  • thin separating membrane
  • steep concentration gradient (diff in conc must be large)
47
Q

how is the small intestine adapted for absorption? (villi)

2 pts

A
  • SA:V ratio increased

- thin walls of villi (1 cell thick), easy for nutrients to pass thru to bloodstream

48
Q

how is the small intestine adapted for absorption? (length of small intestine)
(2 pts)

A
  • length of small intestine (6m) increase time for absorption
  • more time for more nutrients to be absorbed
49
Q

how is the small intestine adapted for absorption? (lacteal/lymphatic capillary)
(3 pts)

A
  • in each villus is a lacteal/lymphatic capillary surrounded by blood capillaries
  • many capillaries present to help carry away absorbed nutrients quickly
  • continual transport of nutrients by capillaries maintain the concentration gradient required for absorption
50
Q

what does the blood capillaries network transport?

2 pts

A

amino acids and glucose to body

51
Q

what does the lacteal/lymphatic capillary transport?

1 pt

A

fats to body

52
Q

how are nutrients absorbed in small and large intestine?

2 pts

A

diffusion and active transport

53
Q

diffusion in small and large intestine

2 pts

A
  • glucose, other monosaccharides and amino acids diffuse into blood capillaries
  • glycerol and fatty acids diffuse into epithelium combined to form minute fat globules which enter the lymphatic capillary
54
Q

what happens to undigested and unabsorbed matter and what is the process called?
(2 pts)

A
  • stored temporarily in rectum and discharged as faeces thru anus
  • discharging of faeces from body is known as egestion (undigested matter) or defecation, not excretion (metabolic waste like urea/CO2)
55
Q

how are nutrients absorbed and utilized?

hepatic portal vein and lymphatic capillaries

A
  • blood capillaries that supply small intestine untie to form hepatic portal vein
  • the vein transports sugars and amino acids to liver
  • lymphatic capillaries join to form larger lymphatic vessels, which discharge fats into bloodstream
56
Q

state the absorbed food products

3 pts

A

glucose, fats, amino acids

57
Q

how is glucose utilised?

A

used for respiration to produce energy for cellular activities

58
Q

what happens to excess glucose?

A

converted to glycogen and stored in liver and muscles

59
Q

how is amino acids utilised?

A

synthesis of proteins and protoplasm for growth and repair of cells

60
Q

what happens to excess amino acids?

A

cannot be stored and is deaminated in liver to form urea

61
Q

how is fats utilised?

A

synthesis of cell membrane

62
Q

what happens to excess fat?

A

stored in fat tissues or adipose tissues

63
Q

state the functions of the liver

5 pts

A
  • regulation of blood glucose concentration
  • production of bile
  • deamination of amino acids
  • storage of iron
  • detoxification
64
Q

regulation of blood glucose concentration (liver)

3 pts

A
  • keeps blood glucose conc constant (70-90mg/100ml og blood)
  • liver stimulated by insulin(lowers bg) and glucagon(increase bg) to store and release glucose respectively
  • regulates metabolism of carbohydrates
65
Q

how does insulin control carbohydrate metabolism?

3 pts

A
  • too much glucose in blood, islets of Langerhans (pancreas) secrete insulin
  • liver converts excess glucose into glycogen
  • bg level decreases
66
Q

how does glucagon control carbohydrate metabolism?

3 pts

A
  • too little glucose in blood, islets of Langerhans (pancreas) secrete glucagon
  • liver converts glycogen into glucose
  • bg level increase
67
Q

why do we experience hunger pangs? (regulation of blood glucose concentration)
(3 pts)

A
  • when brain receives blood low in glucose, sends impulses to stomach
  • strong contractions of empty stomach occur (hunger pangs)
  • when bg conc rise, strong contractions stop, hunger pangs disappear
68
Q

production of bile (liver)

2 pts

A
  • liver produces bile which emulsifies fats

- stored temporarily in gall bladder before use

69
Q

deamination of amino acids (liver)

5 pts

A
  • liver uses amino acids to synthesize proteins such as albumins, globulins, fibrinogen (major blood proteins)
  • amino group of amino acids removed (deamination) and converted to urea in liver
  • deamination is the process by which amino grps(NH2) are removed from amino acids and converted to urea
  • carbon residues of amino acids from deamination converted to glucose in liver
  • excess glucose formed in this way is converted to glycogen
70
Q

storage of iron

3 pts

A
  • when rbc wear out, destroyed in spleen, haemoglobin is sent to liver to be “recycled)
  • breakdown of haemoglobin produces iron which is stored in the liver and used in the synthesis of new rbc
  • breakdown of haemoglobin produces bile
71
Q

detoxification of liver

2 pts

A
  • process of converting harmful substances into harmless products to not poison our cells
  • enzyme alcohol dehydrogenase converts alcohol into acetaldehyde which can be broken down during respiration to energy for cell activities
72
Q

state the harmful effects of excessive alcohol consumption

4 pts

A
  • symptoms of drunkenness
  • stimulates acid secretion in the stomach, increased risk of stomach ulcer
  • cause liver cirrhosis, liver cells are destroyed and replaced with fibrous tissue
  • frequent intake may lead to addiction

Sec 3 Pure Bio (16 decks)

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