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biology > human nutrition > Flashcards

human nutrition Flashcards

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1
Q

what’s a balanced diet

A
  • diet containing all the required nutrients
  • in suitable proportions
  • and the right amount of energy
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2
Q

state causes of scurvy and rickets

A

scurvy - lack of vit c
rickets - lack of vit d

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3
Q

main organs of the digestive system
alimentary canal and associated organs.

A

Alimentary canal
Mouth, oesophagus, stomach, small intestine, large intestine

Associated organs
Salivary glands, pancreas, liver

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4
Q

Describe the function of the organs in the alimentary canal
Mouth

A

Mouth
* inital site for ingestion using teeth, lips, tongue.
* Teeth bite and grind into food into smaller pieces, increasing S.A
* Begins physical digestion
* Tongue mixes food w saliva.

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5
Q

Describe the function of the organs in the alimentary canal
Oesophagus

A

Oesophagus
* 2 tubes leading down from back of mouth, the one in front is trachea.
* Behind trachea is oesophagus; takes food down to stomach.

  • Hole in centre of oesophagus, down which food can pass = lumen.
  • Entrance to stomach from oesophagus is closed by a sphincter muscle. Muscle relaxes to let food pass into stomach. Contracts to close entrance.
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6
Q

Describe the function of the organs in the alimentary canal
Stomach

A

Stomach
* Strong muscular walls, which contract & relax to mix the food with enzymes and mucus.
* Contains goblet cells = secrete mucus.
* Enzymes produced = proteases (by stomach walls) = pepsin = optimum pH 2 = chemical digestion
* Hydrochloric acid (produced by stomach walls) = pH 2 = kills harmful microorganisms in food = provides acidic pH for optimum enzyme activity

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7
Q

How long does the stomach store food? How does it let food pass into small intestine?

A
  • 1-2 hours
  • Spinchter muscle relaxes, lets partly digested food move into duodenum
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8
Q

Describe the function of the organs in the alimentary canal
Small intestine - Duodenum

A

Duodenum
* Pancreatic duct leads from pancreas into duodenum into which pancreatic juice flows into duodenum. Chemical digestion continues in duodenum.

  • Liver secreted bile, stored in gall bladder.
  • When food enters duodenum, the bile flows along bile duct and is mixed with food in duodenum.
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9
Q

What is the role of bile? Does it do physical/chemical digestion?

A
  • emulsifying fats and oils
  • to increase the surface area
  • for chemical
    digestion
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10
Q

Describe the function of the organs in the alimentary canal
Small intestine - Ileum

A

Ileum
* where all digested nutrients are absorbed into blood
* water is also absorbed into blood.

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11
Q

Describe the function of the organs in the alimentary canal
Large intestine - Colon, Rectum, Anus

A

Colon
* Absorbs water that still remains in food.

Rectum
* Stores undigested food as faeces.
* These are egested from body through the Anus

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12
Q

Describe the function of the associated organs in digestive system
Salivary glands

A

Salivary glands
* Secrete saliva, mixture of water, mucus, amylase.
* Water helps dissolve substances in food, allows taste.
* Mucus helps chewed food bind together to form a bolus, lubricates it so it easily slides down oesophagus.
* Amylase digests starch.

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13
Q

Describe the function of the associated organs in digestive system
Pancreas

A

Pancreas
* Secretes pancreatic juice that flows down pancreatic duct into duodenum.
* Pancreatic juice contains enzymes that help with chemical digestion of food in duodenum.
* It is an alkaline mixture.

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14
Q

Describe the function of the associated organs in digestive system
Liver

A

Liver
* Secretes bile; yellowish green, watery.
* Alkaline.
* Bile emulsifies fats and oils to increase the S.A for chemical digestion. Which is physical digestion.
* Neutralizes the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action.

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14
Q

Describe the function of the associated organs in digestive system
Gall bladder!

A

Gall bladder
* where bile is stored
* when food enters duodenum, flows along bile duct; mixed with food in duodenum.

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14
Q

define ingestion, digestion, absorption, assimilation, egestion

A

Ingestion
* taking in of substances e.g food or drink into body.

Digestion
* breakdown of food

Absorption
* movement of nutrients from intestines into blood

Assimilation
* uptake and use of nutrients by cells

Egestion
* removal of undigested food from body as faeces

15
Q

define physical digestion

A
  • the breakdown of food into smaller pieces
  • without chemical change
  • to the food molecules
16
Q

Why is physical digestion useful

A

increases the surface area of food
* for the action of enzymes in
chemical digestion

17
Q

Describe the functions of the types of human
teeth in physical digestion of food

A

Incisors
* sharp edged, chisel shaped at front of mouth
* used for biting and cutting food

Canines
* pointed teeth at either side of incisors
* used for gripping and teaar food

premolars
* broad, ridged surfaces, found between canines and molars
* grinding food to increase S.A

molars
* similar to premolars; larger, with broad ridged surfaces found towards back of mouth
* grinding food to increase S.A

18
Q

stucture of human teeth:
enamel; function

A

Enamel
* hardest subtance made by animals. covers surface of a tooth
* difficult to break or chip. can be dissolved by acids

19
Q

stucture of human teeth:
dentine; function

A

Dentine
* Under enamel is layer of dentine
* it is a living tissue; has channels in it which contain living cytoplasm

20
Q

stucture of human teeth:
pulp; function

A

Pulp
* in the middle of tooth, there’s nerve and blood vessels.
* blood vessels supply cytoplasm in dentine with nutrients and oxygen.

21
Q

stucture of human teeth:
nerves and blood vessels; function

A

Nerves
* allow teeth to sense pressure and pain

Blood vessels
* supply cytoplasm in dentine with nutrients and oxygen

22
Q

stucture of human teeth:
cement; function

A

cement
* part of tooth thats embedded in gum is covered with cement.
* has fibres growing out of it.
* fibres attach tooth to bone in jaw, allow it to move slightly during mastication.

23
Q

define chemical digestion

A
  • breakdown of large insoluble molecules
  • into small soluble molecules
24
Q

role of chemical digestion

A
  • producing small soluble molecules that can be absorbed
25
Q

function of enzymes
amylase
protease
lipase

A

Amylase
* breaks down starch to simple reducing sugars

Protease
* breaks down proteins to amino acids.

Lipase
* breaks down fats and oils to fatty acids and glycerol.

26
Q

state where in the digestive system these are secreted and where they act:
Amylase
Protease
Lipase

A

Amylase
* Salivary glands; acts in mouth
* Pancreas; acts in duodenum

Protease
* Walls of stomach; acts in stomach
* Pancreas; acts in duodenum

Lipase
* Pancreas; acts in duodenum

27
Q

Describe the digestion of starch in the digestive system:
amylase, maltase

A

Amylase
* breaks down maltose to maltase

Maltase
* breaks down maltose to glucose on the epithelium lining the small intestine.

28
Q

Describe the digestion of protein in the digestive system:
proteases

A

Pepsin
* breaks down protein in acidic conditions of the stomach

Trypsin
* breaks down protein in the alkaline conditions of small intestine.

29
Q

In what region are the nutrients absorbed?

A

Small intestine

30
Q

Where is most water absorbed?

A
  • small intestine
  • but some also absorbed from colon
31
Q

describe structure of villi
location

A
  • inner wall of small intestine
  • cell membrane on each villus folded to form many tiny microvilli.
  • it is on these membrnaes that maltase acts, breaking down maltose into glucose molecules.
32
Q

function of villi and microvilli

A
  • absorb digested nutrients into blood
  • they increase the internal surface area for absorption which increases rate at which nutrients can be absorbed
33
Q

what is the function of lacteal in villus/villi

A
  • absorbs fatty acids and glycerol
34
Q

function of capillaries in villus

A
  • Glucose, amino acids, fatty acids, glycerol, vitamins, mineral ions and water are absorbed.
  • These substances pass into blood capillaries inside the villus.
  • The blood capillaries from all villi link up to join a vein called the hepatic portal vein. it takes all these substances to the liver.

biology (25 decks)

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