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AS BIO UNIT2 > 2.4 Adaptations For Nutrition > Flashcards

2.4 Adaptations For Nutrition Flashcards

1
Q

Define an autotroph

A

An organism that synthesises its own complex organic molecules from simpler molecules using either light or chemical energy
- photoautotrophs and chemoautotophs

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2
Q

Define hetereotrophs

A

An organism that obtains complex organic molecules by consuming other organisms

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3
Q

Define sapotrophs

A

An organism that derives energy and raw materials for growth from the extracellular digestion of dead or decaying material

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4
Q

Explain parasitic nutrition

A
  • obtaining nutrition from another living organism, the host
  • endoparasites live in the body of the host whereas exoparasites live on the surface
  • host tends to suffer harm and occasionally death
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5
Q

Explain holzoic nutrition

A
  • used by most animals
  • ingest food, digest food and egest the indigestible remains
  • herbivores, carnivores, omnivores
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6
Q

How do single celled organisms like amoeba obtain nutrients?

A
  • diffusion, facilitated diffusion or active transport across cell membrane
  • take in larger molecules and microbes by endocytosis into food vacuoles which fuse with lysosomes
  • indigestible remains egested by exocytosis
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7
Q

Nutrition in single body opening organisms like Hydra

A
  • tentacles paralyse prey
  • tentacles move prey into mouth and into hollow body cavity
  • prey digested extracellularly and products are absorbed
  • indigestible remains are egested through mouth
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8
Q

What is used for many multicellular organisms?

A
  • tube gut
  • posterior and anterior opening
  • variable complexities
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9
Q

Why must food be digested?

A
  • molecules are insoluble and too big to cross membranes and be absorbed by blood
  • many are polymers and must be converted to monomers
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10
Q

What propels food along gut?

A

Peristalsis

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11
Q

What are the functions of the gut?

A
  • ingestion
  • digestion
    —> mechanical and chemical
  • absorption (gut wall to blood)
  • egestion
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12
Q

Outline function of parts of digestive system

A
  • mouth: ingestion, digestions of starch and glycogen
  • oesophagus: carriage of food to stomach
  • stomach: digestion of protein
  • duodenum: digestion of carbs, fats and proteins
  • ileum: digestion of carbs, fats and proteins, and absorption of digested food and water
  • colon: absorption of water
  • rectum: storage of feces
  • anus: egestion
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13
Q

What are the 4 layers surrounding the lumen of the gut?

A

Mucosa, sub mucosa, muscle, serosa

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14
Q

What is serosa?

A
  • outermost layer of the gut
  • tough connective tissue protecting gut wall
  • reduces friction with other abdominal organs
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15
Q

What is muscle?

A
  • inner circular muscles and outer longitudinal muscles
  • make coordinated contractions of the gut known as peristalsis
  • circular muscles contract and longitudinal relax
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16
Q

What is submucosa?

A
  • connective tissue containing blood and lymph vessels which remove absorbed products of digestion
  • nerves that coordinate peristalsis
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17
Q

What is mucosa?

A
  • innermost layer that lines the gut wall
  • epithelium secretes mucus to lubricate and protect the mucosa
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18
Q

Explain the digesting of carbohydrates

A
  • poly to di to mono
  • amylase hydrolyses starch and glycogen to maltose which is hydrolysed to glucose by maltase
  • sucrase and lactase
  • carbohydrate enzymes as the umbrella term
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19
Q

Explain the digestion of proteins

A
  • poly to di to amino
  • protease and peptide enzymes
  • endopeptidases hydrolyse peptide bonds within protein molecules and exopeptidases hydrolyse terminal peptide bonds
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20
Q

Explain the digestion of fats

A
  • digested to fatty acids and monoglycerides by lipase
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21
Q

How is the buccal cavity specialised for digestion?

A
  • mechanical digestion occurs here - food mixed with saliva by tongue and chewed by teeth
    —> saliva contains amylase (digestion of starch and glycogen), HCO3- ions and CO32- ion, and mucus to lubricate food down oesophagus
22
Q

How is the stomach specialised for digestion?

A
  • food kept in by contraction of 2 sphincters (rings of muscle)
  • walls contract rhythmically and mix food with gastric juice secreted by gland in stomach walls
    —> peptidases secreted by zygmogen cells, pepsinogen (inactive) is secreted and activated by H+ ions to pepsin, HCl secreted by oxyntic cells to lower pH of stomach acid and kill bacteria in food, mucus secreted by goblet cells to form a lining that protects the stomach walls from enzymes
23
Q

What are the 2 regions of the small intestine?

A

Duodenum and ileum

24
Q

Where is bile made and stored?

A
  • made in liver
  • stored in gall bladder
25
Q

Describe bile

A
  • no enzymes
  • bile salts which are amphipathic
    —> emulsify lipids to increase SA for digestion by lipase
  • alkaline and neutralises food coming from stomach
26
Q

What is pancreatic juice?

A
  • secreted by islet cells (exocrine glands in pancreas)
  • enters duodenum via pancreatic duct
27
Q

Describe pancreatic juice

A
  • trypsinogen - inactive enzyme converted to the endopeptidase trypsin by enterokinase
  • endopeptidases - hydrolyse proteins
  • amylase - digests any remaining starch to maltose
  • lipase - hydrolyses lipids to fatty acids and monoglycerides
  • sodium hydrogen carbonate - raises pH to make slightly alkaline to neutralise stomach acid and provide appropriate pH for pancreatic enzymes
28
Q

What are villi?

A
  • finger like projections on the ileum
  • synthesise digestive enzymes
29
Q

What happens to food coming from the stomach to small intestines?

A
  • lubricated and neutralised by alkaline solutions from cells at the base of the crypts of Lierberkuhn called Brunners glands
30
Q

Role of endo and exo peptidases in the small intestine

A
  • peptidases secreted by villus epithelial cells and digestion continues in the gut lumen
  • dipeptidases in cell surface membranes digest peptides to amino acids
31
Q

Where does absorption occur?

A
  • mainly in the small intestine via diffusion, facilitated diffusion and active transport
32
Q

How are amino acids absorbed in SI?

A
  • epithelial cells by active transport and pass into capillaries by facilitated diffusion
  • water soluble and dissolve into plasma
33
Q

How is glucose absorbed in SI?

A
  • passes into epithelial cells with sodium ions by co transport in facilitated diffusion
  • not all absorbed so some bought into cells by active transport to prevent being egested
34
Q

How are fatty acids absorbed in SI?

A
  • diffuse into epithelial cells and lacteal
    —> lacteal: blindly ending lymph capillary in the villi
  • part of lymphatic system that transports fat soluble molecules to left subclavian vein near heart
35
Q

How are vitamins absorbed by the SI?

A
  • A and B: absorb into blood
  • A,D,E: fat soluble so absorbed into lacteals
36
Q

Use of lipids once digested

A
  • membranes
  • some hormones
  • excess stored
37
Q

Many absorbed substances are taken in hepatic portal vein to liver. What happens to glucose and amino acids?

A
  • glucose to body cells for energy or glycogen storage, excess as fat
  • amino acid taken to cells for PS. Excess cannot be stored so converted to urea and excreted by kidney
38
Q

What are the components of the large intestine?

A
  • caecum
  • appendix
  • colon
  • rectum
39
Q

Explain role of colon

A
  • stores undigested food, bacteria, mucus and dead cells
  • less villi but large role in water absorption
  • vitamin K and folic acid are secreted by mutalistic microorganisms in colon
  • water and minerals absorbed
  • semi-solid material reaches rectum and is egested by defecation
40
Q

Carnivore

A
  • only animals so high protein diet
  • short SI, straight and smooth LI
41
Q

Herbivore

A
  • eat only plant material
  • long SI, pouched LI
42
Q

Describe the dentition of herbivores

A
  • teeth modified to grind plant cell walls before enter stomach
  • grazing herbivore has incisors on lower jaw and the canine teeth are indistinguishable from incisors in shape and size
    —> cut the grass
  • diastema separates front teeth from side teeth (premolars)
  • molars interlock like a W in an M
    —> circular grinding action on horizontal plane over time exposes sharp edged enamel ridges to increase grinding efficiency
    —> open unrestricted lots so teeth contour to grow, replacing worn material
  • smooth skull as no need for jaw muscle
43
Q

Describe dentition of carnivores

A
  • adapted for catching and killing prey, cutting/crushing bones and tearing meat
  • sharp incisors to grip and tear muscle from bone
  • canine teeth are larger and curved, pointed for piercing
  • premolars and molars have cusps which crush
  • specialised cheek teeth called carnassials that are like scissor blades
  • lower jaw moves vertically
  • well developed jaw muscles, protrusions on skull
44
Q

Define a ruminant

A
  • a cud chewing herbivore possessing a ‘stomach’ divided into 4 chambers
    —> rumen is the largest, contains mutualistic microbes
  • adapted to enable digestion of beta glycosidic bonds in cellulose
45
Q

Ruminant digestion of cellulose

A
  • grass cut by teeth, mixed with saliva to form cud
  • food mixed with microbes in rumen - secrete enzymes which digest cellulose to glucose
  • glucose fermented to organic acids that are absorbed in blood

C6H12O6 ——> 2CH3COOH + CH4

  • fermented grass pass to reticulum and reformed to cud, then regurgitate to mouth for more chewing
  • cud to omasum where water and organic acids absorbed to blood
  • the obomasum is true stomach where protein is digested by pepsin
  • SI and LI function comparable to human
46
Q

Structural modifications of the pork tapeworm

A
  • scolex with suckers and hooks to attach to duodenum wall
  • thick cuticle to protect from enzymes and hosts immune system
  • makes enzyme inhibitors
  • reduced gut to allow absorption on whole body
  • hermaphrodite - male and female reproductive organs
  • eggs have resistant shells
47
Q

Why does tapeworm rely on anaerobic respiration?

A

Oxygen levels too low for aerobic in the intestije

48
Q

Features that are important to the functioning of the villus

A
  • microvilli to increase surface area for absorption
  • larger capillary network to maintain diffusion gradient
  • lacteal to absorb lipids
  • thin epithelium for short diffusion pathway
49
Q

Brunners glands and their role

A
  • tubular submucosal glands found in duodenum
  • secrete alkaline solution containing bicarbonate, protect from acidic stomach content
  • could conditions for intestinal enzymes
50
Q

What is food called during digestion

A
  • bolus
  • chyme

AS BIO UNIT2 (7 decks)

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