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Foundations of Human Biology 1 > Week 3 Digestive System > Flashcards

Week 3 Digestive System Flashcards

1
Q

GASTROINTESTINAL TRACT ORGANS

A

Mouth Throat Oesophagus Stomach Large Intestine Small Intestine Rectum Anus

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2
Q

ACCESSORY ORGANS

A

ACCESSORY ORGANS are the SALIVARY GLANDS, the PANCREAS, the LIVER, and the GALLBLADDER

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3
Q

MOUTH

A

The GASTROINTESTINAL TRACT starts at the MOUTH with mastication (chewing) breaking food into smaller pieces. It also releases some enzymes to start carbohydrate digestion

secretes mucus

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4
Q

PHARYNX/THROAT and OESOPHAGUS

A

The PHARYNX/THROAT and OESOPHAGUS swallow and transport food from the mouth to the stomach

secretes mucus

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5
Q

STOMACH

A

The STOMACH begins digestion by releasing acid and mixing food

secretes gastric juice containing HCl pepsin and mucus

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6
Q

SMALL INTESTINE

A

The SMALL INTESTINE is made of the duodenum, jejunum and ileum, the majority of digestion and absorption occurs

secretes mucus salt enzymes

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7
Q

bile duct

A

The bile duct is a tube that carries bile from the liver and gallbladder, through the pancreas, and into the small intestine.

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8
Q

LARGE INTESTINE

A

The LARGE INTESTINE, or colon, absorbs the last of the water and salt and converts the luminal contents into faeces which end up in the rectum and anus

secretes mucus

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9
Q

MOTILITY

A

MOTILITY refers to muscular contractions that mix and move food along the digestive tract. Movements can be propulsive, such as peristalsis, or mixing, such as segmentation

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10
Q

SECRETION

EXOCRINE & ENDOCRINE GLANDS

A

SECRETION includes both exocrine and endocrine functions in both the gastrointestinal tract and accessory organs.

EXOCRINE glands secrete their substances through ducts into the body’s surfaces. ENDOCRINE glands secrete their substances directly into the bloodstream

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11
Q

DIGESTION

A

DIGESTION breaks down the three macromolecules; protein, carbohydrate and fat. Occurs via hydrolysis

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12
Q

hydrolysis

A

where a molecule is split into two by adding molecules of water via the catalytic actions of enzymes

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13
Q

ABSORPTION

A

ABSORPTION absorbs digestion end products with water and electrolytes to transfer to blood and lymph. Primarily occurs in the small intestine

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14
Q

BASIC STRUCTURE OF THE WALL OF THE GASTROINTESTINAL TRACT

A

Mucosa: MUCOUS MEMBRANE

LAMINA PROPRIA: LYMPHOID TISSUE

MUSCULARIS MUCOSA

THE SUBMUCOSA

MUSCULARIS EXTERNA:
INNER CIRCULAR LAYER
LONGITUDINAL LAYER SEROSA

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15
Q

MUCOSA

A

THE MUCOSA consists of the MUCOUS MEMBRANE, a protective barrier of epithelial tissue containing specialised cells for absorption or secretion.

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16
Q

LAMINA PROPRIA

A

LAMINA PROPRIA is a thin middle layer of connective tissue containing tiny blood vessels and LYMPHOID TISSUE

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17
Q

MUSCULARIS MUCOSA

A

MUSCULARIS MUCOSA is a very thin layer of smooth muscle that upon contraction can expose different areas of surface folding

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18
Q

THE SUBMUCOSA

A

THE SUBMUCOSA is a thick layer of connective tissue which gives elasticity and contains larger blood and lymph vessels and a nerve network

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19
Q

MUSCULARIS EXTERNA

A

MUSCULARIS EXTERNA is the smooth muscle on the outermost layer of the tube made up of the INNER CIRCULAR LAYER which decreases the diameter for contraction, and the outer LONGITUDINAL LAYER which decreases the length of contraction

20
Q

SEROSA

A

SEROSA is a thin layer of connective tissue that secretes serous fluid for lubrication. This prevents friction between the digestive tract and the surrounding viscera

21
Q

MECHANICAL DIGESTION

A

MECHANICAL DIGESTION: mastication (chewing) breaks food into small pieces, increasing the surface area for biochemical digestion

22
Q

BIOCHEMICAL DIGESTION

A

BIOCHEMICAL DIGESTION: starts chemical digestion of carbohydrates with amylase, breaking down long carbohydrate molecules into shorter chains

23
Q

SALIVA

A

SALIVA is 99.5% water, electrolytes and proteins. The water and mucus moisten food, flush away food particles, and act as a solvent. Also, contains lysozyme, an antibacterial enzyme, and bicarbonate as a buffer to neutralise acids

24
Q

ENZYMATIC HYDROLYSIS:

A

ENZYMATIC HYDROLYSIS: A molecule is split into two by adding molecules of water via the catalytic actions of enzymes. Digestive enzymes are specific to bonds they can hydrolyse

25
Q

STOMACH:

A

STOMACH: Hydrochloric acid (HCl) inhibits amylase, halting biochemical digestion

Produces chyme

26
Q

SMALL INTESTINE

A

The small intestine contains villi: folds in the small intestinal wall, with a lamina propria with blood vessels and lymphatic vessels, covered with small intestinal epithelial absorptive cells, ENTEROCYTES

27
Q

Enterocytes

A

Enterocytes also have small projections called microvilli which make up the brush border
The large surface area and transport mechanisms of enterocytes in the small intestine allow for absorption

28
Q

Pancreas

A

Pancreatic amylase into small intestine for digestion

29
Q

BREAKDOWN OF POLYSACCHARIDES

A

Amylase from saliva and pancreas breaks down polysaccharides into disaccharides
Indigestible polysaccharides,
form indigestible fibre or
are broken down by the gut microbiome

30
Q

BREAKDOWN OF DISACCHARIDES:

A

Disaccharidases in the brush border of the small intestine breakdown disaccharides into monosaccharides

31
Q

MONOSACCHARIDE ABSORPTION

A

absorbed into the enterocytes through sodium-glucose cotransporter symporter (SGLT)

passively enters cell
through a protein called GLUT-5

monosaccharides exit the cell by passive facilitated diffusion via a protein called GLUT-2

32
Q

Carbohydrate Digestion

A

Mouth breaks down food
Saliva and amylase break down carbohydrates and neutralise bacteria and acid
Stomach churns food
Small intestine breaks down further using pancreatic amylase and absorbs via microvilli on enterocytes using a Na+ dependant symport

33
Q

Protein Structure

A

Amino acids with peptide bonds between them. On one end is the amino terminal, and on the other end is the carboxy terminal.

34
Q

STOMACH

A

Secretes gastric juice, containing HYDROCHLORIC ACID and PEPSINOGEN

35
Q

HYDROCHLORIC ACID

A

Secreted from parietal cells

Kills bacteria, denature proteins and activates pepsinogen

Tight junctions between epithelial cells of the stomach, mucous, and bicarbonate protect the stomach from HCl

36
Q

PEPSINOGEN

A

secreted by chief cells in the stomach

Activated by HCl to form pepsin. forming process where pepsin molecules activate pepsinogen to form more pepsin

Pepsin splits certain amino acid linkages in proteins to release peptide fragments

37
Q

PANCREAS

A

Secretes proteolytic enzymes (trypsinogen) into the small intestine

Enteropeptidase in the small intestine converts trypsinogen into trypsin.

Trypsin then activates other pancreatic enzymes

38
Q

PROTEIN HYDROLYSIS
ENDOPEPTIDASE
EXOPEPTIDASE

A

ENDOPEPTIDASE hydrolyse peptide bonds within the protein molecules, forming two smaller peptide chains
EXOPEPTIDASE hydrolyses peptide bonds at the terminals of the protein molecules.

39
Q

PROTEIN ABSORPTION

A

Amino acids are absorbed across enterocytes with symporters which are selective for different amino acids

peptides entering the cell that wasn’t hydrolysed
broken down by intracellular peptidases

Amino acids then enter the circulation by simple diffusion

40
Q

Protein Digestion

A

Pepsinogen creates pepsin in the stomach breaking down amino acids in proteins
Trypsinogen from the pancreas converts to trypsin and activates other pancreatic enzymes to hydrolyse proteins within or at the terminals
Then absorbed across enterocytes and Na+ dependant symport and entering circulation via simple diffusion

41
Q

Fat
triglycerides

A

Dietary fat comes in the form of large fat globules composed of triglycerides

The triglycerides are turned into liquid chyme in the stomach

42
Q

SMALL INTESTINE

A

Chyme
stimulates enteroendocrine cells to secrete a pair of hormones
hormones then stimulate
gallbladder, causing bile to travel through the bile ducts into small intestine

43
Q

BILE

A

BILE is made by the liver and stored and concentrated in the gallbladder
Bile emulsifies fats to prevent fat molecules from clumping together increasing are for enzymes to break them down into fatty acids and monoglycerides

44
Q

pancreas

A

the pancreas is also triggered by hormones from enteroendocrine cells to release pancreatic juice including lipases

45
Q

Fat absorption

A

micelles carry the end product of fat digestion to cell membrane to diffuse through, then resynthesising into triglycerides coated in lipoprotein to form chylomicrons

Foundations of Human Biology 1 (4 decks)

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