6.1 Digestion and Absorption Flashcards

1
Q

mouth

A

Voluntary control of eating and swallowing

Mechanical digestion by chewing

Chemical digestion by saliva

Saliva moistens food to make a bolus

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2
Q

Salivary glands

A

Produces saliva

Saliva digests starches (contains amylase)

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3
Q

Esophagus

A

Movement of food by peristalsis (waves of muscle contractions) from the mouth to the stomach

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4
Q

Stomach

A

Muscle contractions churn contents (mechanical digestion)

Stomach acid kills foreign bacteria and other pathogens in food

Initial stages of protein digestion by the enzyme pepsin

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5
Q

Small intestine - duodenum (start of SI)

A

Bile from liver and gallbladder neutralize stomach acid and emulsifies fats.

Pancreatic amylase and lipase digests carbohydrates and fats

Trypsin digests polypeptides

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6
Q

Small intestine - ileum (lower half of SI)

A

Absorbs nutrients into the blood via the villi and microvilli

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7
Q

Pancreas

A

Secretion of lipase, amylase and protease into the SI
Neutralizes acidic chyme using sodium bicarbonate

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8
Q

Liver

A

Secretion of bile used to break up lipid droplets

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9
Q

Gallbladder

A

Storage of bile from liver and regulated release of bile into SI

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10
Q

Large intestine

A

Reabsorption of water into the blood
Formation of feces

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11
Q

Rectum

A

Storage of feces

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12
Q

Anus

A

Release of feces

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13
Q

Peristalsis

A

a series of muscle contractions that moves food through the alimentary canal

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14
Q

Peristalsis steps

A
  1. Contraction of longitudinal muscle expand the lumen in front of the food giving it space to move into.
  2. Contraction of circular muscles behind the food propels it forwards.
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15
Q

In the small intestine peristalsis also…

A

mixes food with enzymes and forces the products of digestion into contact with the wall of the intestine

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16
Q

The pancreas synthesises the three main types of digestive enzyme:

A

amylase to digest starch

lipases to digest lipids

proteases to digest proteins and polypeptides

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17
Q

Release of enzymes mediated by…

A

hormones created and secreted by the stomach

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18
Q

Digestive enzymes are created in…

A

pancreatic gland cells on ribosomes on the rough ER and processed by Golgi and secreted by exocytosis

19
Q

Ducts within the pancreas merge into…

A

larger ducts and pancreatic duct which release pancreatic juice into the small intestine

20
Q

large food molecules need to be…

A

digested before the nutrients can be absorbed

21
Q

type of reaction to digest?

22
Q

products of digestion are

A

soluble, small enough for absorption to blood and tissues

23
Q

pancreas enzymes

A

Amylase
starch —> Maltose

Lipase
triglycerides —> Fatty acids, glycerol

Phospholipase
phospholipids —-> fatty acids, glycerol, phosphate

Protease
proteins, polypeptide —-> Shorter peptides

24
Q

Small intestine enzymes

A

Nuclease
DNA, RNA —> Nucleotides

Maltase
Maltose —> Glucose

Lactase
Lactose —> Glucose, galactose

Sucrase
Sucrose —> Glucose, fructose

Exopeptidase
Peptides —> dipeptides

Dipeptidase
Dipeptides —> Amino acids

25
Mucosa
inner lining, includes villi
26
Submucosa
connective tissue (between the mucosa and muscle)
27
Muscular layer
inner circular and outer longitudinal muscle perform peristalsis
28
Serosa
protective outer layer
29
Epithelial cells
single outer layer of cells on each villus
30
Many villi protrude into the lumen, greatly increasing the...
surface area for absorption.
31
Absorption:
the uptake of molecules into the blood from the lumen of the ileum.
32
Microvilli
on the surface of each cell to increase surface area even further.
33
Lacteals (lymph vessels)
Allow for rapid absorption and transport of lipids.
34
Capillaries close to epithelium
Short path for diffusion, rich supply of blood
35
Rich blood supply
Maintains concentration gradients between lumen and blood.
36
Single-cell layer of epithelial cells
Short path for diffusion
37
villi absorbs both...
vitamins and minerals
38
Fatty acids Monoglycerides
transport: Simple diffusion Once inside epithelium cells, fatty acids combine with monoglycerides to which cannot diffuse back into lumen on SI
39
Fatty acids
transport: Facilitated diffusion via transmembrane proteins Once inside epithelium cells, fatty acids combine with monoglycerides to which cannot diffuse back into lumen on SI
40
Glucose
transport: Facilitated diffusion via glucose channels Polar molecules, large so simple diffusion cannot occur
41
Sodium
transport: Active transport Na+ pumped into epithelial cells
42
Sodium and glucose
transport: Sodium-glucose cotransporter Facilitated diffusion Transfer Na+ and glucose together
43
The digested glucose is absorbed and then transported to various body tissues (process)
Glucose is co-transported* with sodium ions into the epithelial cells (of the villus). Glucose moves by facilitated diffusion into the lumen of the villus. Glucose then diffuses a short distance into the adjacent capillaries where it dissolves into the blood plasma. Blood in the capillaries moves to to venules then to the hepatic portal vein which transports the glucose to the liver. The liver absorbs excess glucose which it converts to glycogen for storage.