ch6, nutrition in human

Question 1

Food molecules have to be broken down because… (2)

Answer 1

1. membrane of our cells is differentially permeable, need to be broken down to enter the cells
2. food molecules are structurally different, need to break them down and use small molecules to build our own molecules

Question 2

five main processes of nutrition in human

Answer 2

1. ingestion
2. digestion
3. absorption
4. assimilation
5. egestion

Question 3

digestive system consists of ___ and ___

Answer 3

alimentary canal and digestive glands

Question 4

digestive glands produce _____

Answer 4

digestive juices

Question 5

ingestion - process of chewing food is ____

Answer 5

mastication

Question 6

4 types of teeth and their functions

Answer 6

1. incisor - biting and cutting food
2. canine - tearing flesh
3. premolar & molar - crushing and grinding food

Question 7

Dentition refers to..?

Answer 7

the type, number and arrangement of teeth in the jaws

Question 8

A tooth can be divided into three regions:

Answer 8

the crown, neck, root

Question 9

Enamel (3)

Answer 9

• non-living and made mainly of calcium salts
• hardest tissue in our body, protects tooth from wearing down in chewing
• around roots, replaced by cementum, attatches to jawbone through periodontal membrane

Question 10

Dentine (2)

Answer 10

• bone like structure, large amount of calcium salt

- living tissue w strands of cytoplasm

Question 11

Pulp cavity
- contains ___, ___, __
function of blood vessels and nerve fibres?

Answer 11

• living cells, blood vessels, nerve fibres
• blood vessels supply oxygen and nutrients to tooth, remove waste
• nerve fibres detect temperature and pressure

Question 12

Physical digestion

Answer 12

• to break down by physical actions
• doesn’t change chemical structure of food
• increase surface area for digestive juice to act on

Question 13

chemical digestion

Answer 13

• catalysed by enzymes

- into small soluble molecules for easy absorption

Question 14

digestion mainly occurs in ___, ___, ___

Answer 14

mouth cavity, stomach, small intestine

Question 15

digestion in mouth cavity

3 substances + functions

Answer 15

1. salivary amylase - break down starch to maltose
2. mucus - sticky, bind food particles together, moistens and lubricates food for easy chewing and swallowing
3. water - dissolves soluble substances in food, so we can taste it

Question 16

Peristalsis:
1 wall of alimentary canal
2 after swallowed?

Answer 16

1. circular muscles and longitudinal muscles

2. oesophagus contract alternatively to produce a wave-like movement, push food down to stomach

Question 17

Digestion in stomach

2 muscles

Answer 17

1. cardiac sphincter - prevent food from flowing back into oesophagus
2. pyloric sphincter - controls release of food into the duodenum

Question 18

after food enters the stomach, muscles in the stomach wall will ___ to ___, and mix with ___

Answer 18

contract to churn the food

gastric juice

Question 19

Gastric juice contains:

3

Answer 19

1. pepsin - protease which catalyses the breakdown of proteins into peptides
2. hydrochloric acid - provides acidic medium for action of pepsin
   kills most bacteria in food
3. mucus - protects stomach wall from being digested by pepsin or damaged by hydrochloric acid

Question 20

after a few hours in stomach, food becomes creamy liquid called ___

Answer 20

chyme

Question 21

Bile:
A green alkaline fluid produced continuously in __
temporarily saved in ___
it contains no ____

Answer 21

liver
gall bladder
digestive emzyme

Question 22

Bile contains: (3)

Answer 22

1. Bile salts - emulsify lipids into small droplets
2. bile pigments - dont take part in digestion, form from breakdown of haemoglobin, then excreted in faeces
3. Sodium hydrogencarbonate - neutralizes acidic chyme
   provides alkaline medium

Question 23

pancreatic juice
produced by ___ through the ____
contains: (4)

Answer 23

pancreas, pancreatic duct
1. pancreatic amylase - breakdown of remaining starch into maltose
2. pancreatic lipase - catalyses breakdown of lipids into fatty acids and glycerol
3. proteases - breakdown of some proteins into peptides or amino acids
4. sodium hydrogencarbonate - neutralizes acidic chyme
provides alkaline medium

Question 24

intestinal juice: it is slightly alkaline/acidic?
contains ___, ___. ___
epithelium of small intestine has specialized cells that have ___(x) embedded in their ____, these (x) include ___ and ___

Answer 24

alkaline
water, mucus, sodium hydrogencarbonate
enzymes in their cell membranes
carbohydrates and proteases

Question 25

``` function of intestinal juice (2) ```

Answer 25

1. carbohydrases - breakdown of disaccharides into monosaccharides 2. proteases - catalyse the breakdown of peptides into amino acids

Question 26

structure of small intestine (3)

Answer 26

1. the wall - circular muscles and longitudinal muscles, inner wall highly folded 2. villi - fingerlike projections, has lymph vessel called lacteal, surrounded by network of capillaries 3. epithelium - one cell thick, a lot of microvillis

Question 27

take in complex food and digest in the body. What's this called?

Answer 27

Holozoic nutrition

Question 28

Many fungi and bacteria carry out this. they break down food outside the body then absorb the soluble nutrients into the body. What kind of nutrition?

Answer 28

saprophytic nutrition

Question 29

can be animals, plants, bacteria, live on or inside the body of other organisms and obtain food from them. What is this called?

Answer 29

parasitic nutrition

Question 30

food molecules are absorbed from the ___ into the ____ and ___ through ___ by (which 3) ?

Answer 30

lumen, capillaries, lacteals epithelium active transport, osmosis, diffusion

Question 31

digestion of water and water-soluble food molecules:

Answer 31

water soluble food molecules - diffusion and active transport water - osmosis

Question 32

digeston of lipids and lipid-soluble food molecules:

Answer 32

fatty acids and glycerol by diffusion and recombining -> fine lipid droplets -> lacteal lipid-soluble vitamins by diffusion directly into lacteal

Question 33

adaptaion of small intestine for absorption (5)

Answer 33

1. very long, need sufficient time to complete digestion and absorption 2. highly folded, many villi and microvilli, increase surface area for absorption 3. epithelium is very thin, one cell thick, short distance for diffusion 4. lacteal and capillaries -> absorbed food carried away rapidly 5. peristalsis -> digested food molecules into close contact, keep steep concentration gradient, increase rate of diffusion

Question 34

absorption in large intestine: how? remains of food moved by ____ semi-solid material left is called ___

Answer 34

some of remaining vitamins, water, minerals absorbed into blood in colon. peristalsis faeces

Question 35

how does constipation & diarrhoea form?

Answer 35

remains of food pass through the colon too slowly, a larger portion of water will be absorbed, faeces will be hard if they pass the colon too quickly, larger potion of water will remain in faeces, result diarrhoea

Question 36

assimilation of water soluble molecules: carried by ___ to the ____ through ____ some are ___, other ____...

Answer 36

blood, liver, hepatic portal vein stored, processed then carried away to the heart through hepatic vein and vena cava. Then transported to parts of body through aorta

Question 37

assimilation of lipids & lipid soluble food molecules: carried by ___ to the main ___ they enter the ___ near the neck region, where ___ joins ___. They're then carried by the blood to the ____ through ____, then transported to all other parts of body through ____

Answer 37

lymph, lymph vessel blood, lymph vessel, blood vessel heart, vena cava, aorta

Question 38

Fate of absorbed food - glucose | 2

Answer 38

- broken down by respiration in cells for releasing energy | - excess glucose converted to glycogen in liver and muscles and stored, may convert to lipids

Question 39

Fate of absorbed food - Lipids

Answer 39

- used by cells to make cell membranes and some hormones - act as energy reserve, broken down to release energy when body is short of glycogen - excess lipids stored in adipose tissue around internal organs and under skin

Question 40

Fate of absorbed food - amino acids

Answer 40

- make diff types of proteins for growth and repair, make enzymes and antibodies and hormones - broken down to release energy when carbs and lipids are used up - excess CANNOT be stored, are broken down in liver through deamination

Question 41

egestion

Answer 41

- undigested and unabsorbed materials form faeces - contain dietary fibre, bacteria, secretions from alimentary canal, dead cells from intestinal wall and water - brown bcs of bile pigments - ring of muscles called anal sphincter