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Biology > 5 — nutrition in human > Flashcards

5 — nutrition in human Flashcards

1
Q

Nutrition definition

A

the process by which organisms obtain food and energy for growth, repair and maintenance of the body

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2
Q

Ingestion

A

food is taken into the body

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3
Q

Digestion

A

process where large, insoluble, complex food molecules r broken down into smaller, soluble molecules that can diffuse across cell membranes for absorption into body cells, either thru physical or chemical process.

Digestion can be a physical process, which involves the mechanical breakdown of large food pieces into smaller pieces by chewing, peristalsis and emulsification. This increases the food molecules’ surface area to volume ratio for faster chemical digestion. [1]

Digestion can be a chemical process, where food molecules are digested by enzymes into its corresponding products. [1]

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4
Q

Absorption

A

digested products such as glucose and amino acids will be absorbed into the bloodstream thru wall of ileum of small intestine into the bloodstream via active transport n diffusion. (not equal to diffusion) The absorbed food substances, in the bloodstream, will then be diffused into the body cells for assimilation.

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5
Q

Assimilation

A

uptake of absorbed food substances into cells n tissues to be converted into new protoplasm or used to release energy

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6
Q

Egestion/defecation:

A

undigested matter is removed from the body

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7
Q

Emulsion

A

breaking up of fats into small fat droplets

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8
Q

Deamination

A

Amino groups removed from amino acids n converted to urea

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9
Q

Peristalsis

A

rhythmic, wave-like muscular contractions in wall of alimentary canal where the circular and longitudinal muscles contract n relax alternately.

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10
Q

Antagonistic muscles:

A

a pair of muscles whose movements oppose each other

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11
Q

Detoxification

A

The process where harmful substances r converted into harmless substances

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12
Q

Mouth & buccal cavity’s function, secretion and digestion

A

Teeth:
- Breaks up large pieces of food into small round bolus (boli: plural) to increase SA:V of food for enzymes to digest it more efficiently

Salivary glands:(3 pairs)
- Secrete saliva into mouth to be mixed with food by tongue
- Saliva contains mucin which softens the food
- Salivary amylase digests starch to maltose

Tongue:
- Mixes food with saliva
- Rolls food into a bolus to back of mouth to be swallowed

Secretion of saliva, digestion of Carbohydrates:
Starch -(salivary amylase)-> maltose

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13
Q

Oesophagus function, secretion and digestion

A

Peristalsis occurs, helps movement of food along gut + enables food to mix w digestive juices.

  • The inner circular muscles contract, outer longitudinal muscles relax. Wall constricts. Gut is narrower n longer n food is pushed forward.
  • Longitudinal muscles contracts n circular muscles relax, gut dilates, walls widens n shortens, thus widens lumen to allow food to enter.

No secretion, digestion of starch by salivary amylase continues

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14
Q

Stomach function, secretion and digestion

A
  • Bolus enters stomach -> stimulates release of gastric juice by gastric glands -> HCl activates (inactive state of pepsin in stomach; protease) pepsinogen to active pepsin -> digests proteins
  • Peristalsis in walls of stomach churns + break up food & mixes food with gastric juice
  • Inactive pepsinogen only activates with HCl in cavity to prevent self-digestion of gland cells
  • Food remains here for 3-4hrs, partially digested & liquefied: forms chyme, enters duodenum when pyloric sphincter relaxes

Secretion:
Gastric glands in stomach secrete gastric juice: dilute solution of hydrochloric acid (HCl) + pepsin + mucus;

the HCl:
- denatures salivary amylase
- Converts inactive pepsinogen into pepsin
- Prov an acidic medium for action of pepsin
- Kills harmful microorganisms in food
- Pepsin breaks down protein -> short polypeptides

Mucus:
- Prevents contact betw HCl & pepsin with stomach lining
- Moistens food -> easy movement of food

Digestion of Proteins —(Pepsinogen activated to Pepsin by HCl in gastric juice) —> polypeptides

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15
Q

Small intestine function

A
  • Chyme enters duodenum -> stimulates release of alkaline fluids: pancreatic juice + bile + intestinal juice
  • Alkaline medium needed for action of intestinal + pancreatic enzymes
  • Abt 6m long
  • Bile emulsifies large fat globules into small fat droplets to increase SAtV ratio for faster digestion of fats by lipase to form fatty acids + glycerol. (Phys digestion)
  • Ileum is the main region of absorption for end products of digestion

Fats:
- Large fat globules —(bile salts)-> small fat globules —(intestinal & pancreatic lipase)-> fatty acids + glycerol

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16
Q

Liver function, secretion and digestion (not part of digestive system)

A

Function: Produces & secretes bile.

Bile
- Alkaline, greenish-yellow liquid
- Made up of bile salts + pigments which speeds up fat digestion by emulsification of fats
- Bile pigments r waste products removed with faeces
- Not an enzyme
- Flows into duodenum via bile duct
- Bile salts lower surface tension of fats, reduce attractive forces betw fat molecules -> break into tiny fat droplets suspended in water, forming an emulsion.
- Bile emulsifies large fat globules into small fat droplets to increase SAtV ratio for faster digestion of fats by lipase to form fatty acids + glycerol.

No digestion.

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17
Q

Gall bladder function (not part of digestive system)

A
  • Temporarily stores bile produced from liver
  • When contraction occurs, bile would flow thru bile duct n enter duodenum
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18
Q

Pancreas function, secretion and digestion (not part of digestive system)

A

Produce + secretes:
- pancreatic juice
- Hormones
- Insulin
- Glucagon

Pancreatic juice contains enzymes that aids in digestion of carbs, proteins n lipase
- Pancreatic amylase
- Pancreatic lipase
- Trypsin

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19
Q

If duodenum in SI is blocked

A
  • Carbohydrates & protein digestion not affected
  • Bile cannot enter duodenum from gall bladder -> no bile present to emulsify fat into smaller fat globules -> smaller SAtV ratio for lipase to act on -> slower digestion of fats by lipase
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20
Q

SI secretion

A
  • Epithelial cells in SI produce + secretes intestinal juice containing enzymes:
    • Maltase
    • Sucrose
    • Lactase
    • Peptidases
    • Intestinal lipase
    • Enterokinase
  • Secretes pancreatic juice by pancreas (enters duodenum from pancreatic duct) + bile from liver (stored in gall bladder->passes thru bile duct) + intestinal juice by intestinal glands
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21
Q

SI digestion

A

Carbohydrates:
(End products: simple sugars: glucose, fructose, galactose)
- Starch -(pancreatic amylase)-> maltose -(maltase)-> glucose
- Lactose -(lactase)-> glucose + galactose
- Sucrose -(sucrase)-> glucose + fructose

Proteins:
- Proteins —[trypsinogen -(enterokinase in intestinal juice)-> trypsin] —> polypeptides— (peptidases)-> amino acids

Fats:
- Large fat globules —(bile salts)-> small fat globules —(intestinal & pancreatic lipase)-> fatty acids + glycero

22
Q

Gall bladder blocked

A

Crystallisation of bile components causes gallstones to form in gallbladder, causing blockage.

Gall bladder blocked
- Pancreatic juice cannot enter duodenum from pancreas -> reduced digestion of starch, lipids + proteins
- Bile cannot enter duodenum from gall bladder -> no bile present to emulsify fat to smaller fat globules -> smaller SAtV ratio for lipase to act on -> slower digestion of fats by lipase

23
Q

Gastric bypass surgery:

A

weight loss surgery by restricting amt of food stomach holds + changing gut hormones -> feel full longer, suppress appetite -> reversal of obesity-caused metabolic syndrome

24
Q

Describe the digestion and absorption processes of x in mammals. [6] (formula)

A
  • Physical digestion of x begin at the mouth, via chewing, to increase the surface area to volume ratio for faster chemical digestion of proteins in the stomach by [enzyme]. [1]
  • [enzyme] in the [mouth/stomach], will chemically digest x into [y]. [1]
  • Pancreatic/ intestinal [enzyme] found in SI will chemically digest the remaining x into [y] in the duodenum. [1]
  • [enzyme], produced by the small intestine, will chemically digest the [y] into [product]. [1]
  • The [product] will be absorbed into the villi epithelial cells and into the bloodstream.[1]
  • By active transport and diffusion. [1]
25
Q

Describe the role of bile in digestion process. [3]

A
  • Bile is involved in the physical digestion of fat molecules. [1]
  • Bile salts in bile emulsify large fat globules into smaller fat droplets. [1]
  • This will increase the fat molecules’ surface area to volume ratio for faster chemical digestion by pancreatic and intestinal lipase into glycerol and fatty acids. [1]
26
Q

Digestion of proteins

A
  • Protein is broken down into short polypeptides by pepsin in stomach and trypsin in SI -> further broken down into amino acids by peptidases in SI
  • Absorbed into bloodstream thru wall of ileum by active transport n diffusion
27
Q

Digestion of carbs

A

Starch is broken down into maltose by salivary amylase in mouth and by pancreatic amylase in SI -> further broken down by maltase (intestinal juice) into glucose.

28
Q

CAQ: Y amt of fat doesn’t decrease immediately aft entering duodenum

A
  • Time is needed for bile to emulsify larger fat globules into smaller fat globules to increase SAtVR for faster digestion by lipase to digest fats into fatty acids + glycerol.
  • Lipase needs an alkaline env to digest fats. Chyme needs to be neutralise b4 lipase can act on it.
29
Q

Absorption of nutrients at SI

A
  • Glucose & amino acids diffuse/absorbed by active transport into blood capillaries
  • Glycerol & fatty acids diffuse into epithelium, combine to form minute fat globules n enter lymphatic capillary
30
Q

Adaptations of SI for efficient absorption

A

SI: 1. Presence of numerous villi (s: villus) on epithelium cells to increase SAtV ratio -> faster absorption

Villi: 2. Presence of microvilli on epithelial cells -> further ^SA:V -> faster absorption rate

Villi: 3. Villi r has a one cell thick epithelial wall -> Prov shorter diffusion distance for absorption of digested food substances into the bloodstream

Villi: 4. Many blood capillaries (BC) and lacteal present in each villus
- BC: to absorb glucose n AA n transport them away
- Lacteal/ lymphatic capillary absorb n transport fats to body
- To help transport absorbed glucose + amino acids + fats quickly -> maintain steep conc gradient for diffusion & active transport
- Diffusion + AT: Glucose & amino acids into blood capillaries (AT when: lower conc in lumen of SI than in BC)
- Diffusion: glycerol & fatty acids into epithelium, combine to form minute fat globules that enter lacteals

Villi: 5. Epithelial cells contain many mitochondria. -> Prov energy for active transport of nutrients into villi

SI: 6. Length of SI is abt 6m -> Increases time for absorption of digested food substances

31
Q

Explain how the villus is adapted in absorption of digested nutrients in mammals. [4]

A

A. Villi r finger-like projections in SI that increase SAtV ratio for faster absorption

  1. Each villus has a one-cell-thick epithelial wall → to provide a shorter distance for faster absorption of digested nutrients. [1]
  2. Presence of numerous microvilli on the epithelial cells of the villus → to increase its surface area to volume ratio for faster absorption of digested nutrients. [1]
  3. Each villus has a lacteal → for the absorption and transport of fat molecules. [1]
  4. Each villus is rich in blood capillaries → for faster absorption of glucose and amino acids. [1]
  5. There is a continuous blood flow to maintain a steep concentration gradient → for faster absorption of digested nutrients into the blood capillaries by diffusion. [1]
32
Q

Desc how fat globules enter villus

A

Fatty acids & glycerol enter by diffusion across epithelium where they combine to form tiny fat globules b4 entering lacteal.

33
Q

Factors affecting absorption rate in villus

A
  • Total surface area of villi
  • Thickness of epithelium
  • Steepness of concentration gradient
34
Q

Impact of reduced villi and diet accommodation to medical condition

A
  • Reduced villi decrease SAtV ratio in absorption of digested nutrients like glucose, amino acids, fat globules formed from fatty acids and glycerol.
  • Absorption of digested nutrients is slower compared to normal.
  • Patient suffer from malnutrition
35
Q

Why prolonged gastric problems like excess acid production will lead to weight loss

A
  • Excess acid in chyme gg to SI will change SI pH to non-optimum pH in SI
  • Pancreatic and intestinal digestive enzymes will denature
  • Reduced digestion n absorption of nutrients leading to weight loss
36
Q

State dietary adjustments for XX health problems

A
  • Eat smaller but frequent meals to reduce stomach workload for digestion
  • Avoid alcohol consumption to reduce inflammation of stomach lining (depends on qs)
  • Ingestion of digestive enzymes supplement with each meal to aid in digestion of nutrients in stomach and SI (depends on qs)
37
Q

Function of amino acids

A
  • used to form enzymes + hormones
  • converted to cytoplasm for growth n repair of worn-out parts of body
  • Excess r deaminated in liver
38
Q

Hepatic portal vein function

A
  • Transports absorbed glucose to liver -> most of glucose r excess -> [insulin produced by pancreas stimulates] liver to convert excess glucose to glycogen n stored; glucose transported by hepatic vein to diff parts of body
  • Transports absorbed amino acids to liver -> excess amino acids converted to urea (found in urine produced by kidney) by deamination in liver -> transported by hepatic vein to diff parts of body
39
Q

Function of fats

A
  • IF ENOUGH GLUCOSE: fats not broken down n used to build protoplasm like cell membranes
  • IF GLUCOSE IN SHORT SUPPLY: fats broken down to prov energy needed for vital activities in body
  • Excess fat stored in adipose tissues beneath skin n around heart & kidneys
    • Adipose tissues protect organs by acting as shock absorbers
40
Q

Describe the functions of the liver

A

CARBS METABOLISM:
A. The liver helps to regulate the blood glucose concentration in the blood plasma with the aid of insulin and glucagon.

  • If the blood glucose concentration is higher than the norm, the islets of Langerhans in the pancreas will be stimulated to release more insulin. [1] This stimulates the liver to convert excess glucose into glycogen for storage in liver and muscles. [1] Hence, blood glucose level decreases and returns back to the norm. [1]
  • If the blood glucose concentration is lower than the norm, the islets of Langerhans in the pancreas will be stimulated to release more glucagon. [1] This stimulates the liver to convert stored glycogen into glucose, which is released into the bloodstream. [1] Hence, blood glucose level increases and returns back to the norm. [1]

B. Deamination of amino acids
- amino acids used to synthesise plasma proteins such as prothrombin and fibrinogen in liver that is essential for blood clotting
- excess amino acids undergo deamination in liver
- Amino group of amino acids are removed n converted to urea in liver.
- urea excreted in kidneys.
- Carbon residues of amino acids from deamination r converted to glucose in the liver.
- Excess glucose will be converted and stored as glycogen in the liver.

C. Produces bile, which emulsifies large fat globules into smaller fat droplets for subsequent faster chemical digestion of fat molecules into fatty acids and glycerol by lipase.

D. Detoxification of harmful substances to harmless substances.
- Harmful substances like alcohol broken down by liver to make harmless, as it can cus dmg to digestive system + slow down brain functions
- Liver cells contains an enzyme which breaks down alcohol to compounds that can be used in respiration, prov energy for cell activities

E. Breakdown of hormones
- Hormones r broken down in the liver aft serving their purposes

41
Q

Impacts of alcohol to the digestive system

A
  • LT(long term): Alcohol stimulates acid secretion in stomach -> excess stomach acid increase risk of gastric ulcers
  • LT: Alcoholic cirrhosis caused by too much alcohol may lead to haemorrhage in liver, liver failure n death
    • Cirrhosis: disease which liver cells destroyed n replaced wif fibrous tissue, making liver less able to function
42
Q

Impacts of alcohol to nervous system

A
  • ST(short term): Alcohol is a depressant and slows down some brain functions. Its effects vary from 1 person to another.
  • ST: Reduced self control. Ppl r carefree n may do things they regret aft effects of alcohol worn off.
  • Reduces reaction spd, Longer reaction time; Slurred speech, blurred vision + poor muscular coordination. Judgement deteriorates, tend to underestimate speed -> May drive faster with less caution, reactions r slower. Higher tendency for drunk drivers to involve in traffic accidents.
43
Q

Long term impacts of alcohol on brain

A
  • Wet brain: type of dementia caused by brain dmg
    • Alcohol interferes wif absorption of vitamin B1 in SI
      • V B1: part of an enzyme needed to break down sugar to release energy for brain activities (eg in conduction of nerve impulses)
  • Shrinkage of brain volume
    • Brain becomes smaller, esp region associated with memory n reasoning
  • Heavy consumption of alcohol during pregnancy may interfere with the development of the foetus’ brain -> may lead to lifelong physical, mental and behavioural problems.
44
Q

Social implications of alcohol

A

Alcoholics may,
- end up neglecting their work and families.
- exhibit violent behaviour, especially towards family members.
- be at a higher risk of committing crimes.

45
Q

Describe the long term and short term effect of excessive alcohol consumption on the human body. [6]

A

Short term - any 3 of the following 4 points:
- Poor coordination
- Slows down rate of reaction
- Increases reaction time
- Reduced self-control
Long term - any 3 of the following 4 points:
- Liver cirrhosis
- Alcohol addiction
- Increases the risk of gastric ulcers
- Withdrawal symptoms

46
Q

Describe the functions of the liver. [5]

A

Produces bile, which emulsifies large fat globules into smaller fat droplets for
subsequent faster chemical digestion of fat molecules into fatty acids and
glycerol by lipase. [1]
Regulates the blood glucose concentration with the aid of insulin and
glucagon. [1]
The liver uses amino acids to synthesize plasma proteins such as prothrombin
and fibrinogen, which are essential for the clotting of blood. [1]
After the worn-out red blood cells are destroyed in the spleen, the
haemoglobin will be released and transported to the liver. At the liver, haemoglobin will be broken down to produce iron and bile. Iron will be stored
in the liver. [1]
Liver is involved in the detoxification of harmful substances, such as alcohol,
into less harmful substances. [1]

47
Q

What is the function of hydrochloric acid in the stomach?

A

the HCl:
- denatures salivary amylase
- Converts inactive pepsinogen into pepsin
- Prov an acidic medium for action of pepsin
- Kills harmful microorganisms in food
- Pepsin breaks down protein -> short polypeptides

48
Q

What is the function of mucus in the stomach?

A

Mucus:
- Prevents contact betw HCl & pepsin with stomach lining
- Moistens food -> easy movement of food

49
Q

Suggest how gallstones may affect the digestion of fats

A

Gallstones may block the bile duct, preventing bile from entering the duodenum. Absence of bile to emulsify fats from large fat globules to small fat droplets to increase sa:v reduces efficiency of fat digestion.

50
Q

Gluten can affect the SI causing villi to decrease in size and number. Suggest and explain what effect this would have on the functioning of alimentary canal.

A

Reduced absorption and assimilation of digested food by glucose and active transport due to reduce in size and number of villi and thus a decrease in the total sa:v.

51
Q

Suggest a reason for the reduction in number of cases of serious liver diseases over the years

A

Better education on public
Implementation of policies such as increased alcohol tax.
Better health treatments or facilities available.

Biology (18 decks)

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