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Biology Sem 1 > The Digestive System > Flashcards

The Digestive System Flashcards

0
Q

What does insoluble mean?

A

Insoluble means that food matter cannot be absorbed into the bloodstream

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1
Q

What does the digestive process do?

A

Converts insoluble food matter into soluble particles

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2
Q

What does soluble mean?

A

Soluble means that food matter/particles can be absorbed by the bloodstream

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3
Q

What does absorption means?

A

When molecules move from the gut into the bloodstream

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4
Q

What is Assimilation

A

When molecules move from the bloodstream into cells

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5
Q

What is Egestion?

A

When I digested food matter is released from the body.

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6
Q

What are the types of digestion?

A

Physical and chemical

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7
Q

Describe physical digestion and list examples.

A

The process where large insoluble food particles/matter are broken down into smaller (but still insoluble) food particles of the same type.
I.e chewing, churning if the stomach, action of bile.

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8
Q

How does bile work?

A

Bile contains alkaline salts, it emulsifies fats/lipids (physical digestion). This increases the surface area which makes chemical digestion far more efficient.

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9
Q

What is chemical digestion?

A

Chemical digestion is where food particles are converted for insoluble to soluble.

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10
Q

What is an example of chemical digestion?

A

Starch(insoluble) — amylase(enzyme)–> maltose(disaccharide-insoluble) —-maltase (enzyme) —> glucose (monosaccharide-soluble)

Diagram in book

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11
Q

What is the digestive pathway?

A

Mouth –> oesophagus –> stomach –> duodenum –> ileum –> large intestine –> anus

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12
Q

What digestion occurs in the mouth? Step 1

A

Physical digestion via chewing

Chemical digestion of starch to maltose via salivary amylase

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13
Q

What role in digestion does the oesophagus have?

A

Responsible for the movement of partially digested food material from the mouth to the stomach.

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14
Q

What is peristalsis?

A

Peristalsis is a wave like contraction process that moves food down the oesophagus.

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15
Q

What is a bolus?

A

Partially digested food material.

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16
Q

What are the two layers of the gut wall called? And what is their role?

A

Longitudinal and circular muscles. When circular muscles contract, the gut wall pinches inwards. When longitudinal muscles contract, the gut wall expands.

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17
Q

What are the in-folded regions in the mucus layer of the stomach called?

A

Gastric glands

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18
Q

What are mucus secreting cells?

A

They produce a protective layer of mucus that lines the stomach. Protects against HCl and pepsin

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19
Q

What is a zymogenic cell?

A

A zymogenic cell produces an inactive enzyme called pepsinogen. This enzyme is made in an inactive form to prevent self-digestion of the cells that produce it.

20
Q

What is another word for self-digestion?

A

Auto-lysis

21
Q

What is an oxyntic cell?

A

An oxyntic cell produces HCl

22
Q

What role does HCl play in the digestive system?

A

Kills harmful bacteria
Converts sucrose to glucose and fructose
Activates pepsinogen

23
Q

What do the alkaline salts in bile do?

A

Assists in shifting the pH of the stomach contents.
Eg 1.5 - 2.0 —- 1 x 10^6. —-> 8.0
Decrease in acidity

24
Q

What is in pancreatic juice and how does it aid digestion?

A

Alkaline salts = help shift pH
Pancreatic amylase = completes the chemical digestion of starch to maltose
Lipase = assists in the chem. digestion of lipids
Trypsinogen = inactive protein digesting enzyme
Peptidase= converts shorter polypeptide chains to do and tri peptides

25
Q

What is a lipid broken down into (triglyceride)?

A

With the use of lipase enzyme, it is broken down into glycerol and fatty acids.

26
Q

What is protease?

A

Any enzyme that digests protein

27
Q

What does the lining of the duodenum wall secrete?

A

Enterokinase and alkaline salts as well as CCK and secretin

28
Q

Describe the chemical digestion in the duodenum

A

Trypsinogen is released from the pancreas, then enterokinase activates it into trypsin, which then breaks down short polypeptide chains (formed in the stomach) to shorter polypeptide chains

29
Q

Describe protein digestion in the stomach

A

Oxyntic cells produce HCl which activates pepsinogen (from zymogenic cells) into pepsin, which breaks protein ( long polypeptide chains) into short polypeptide chains. Pepsin can also contribute to its own activation.

30
Q

What happens when food enters the duodenum

A

Chyme in the stomach, with a pH of 1.5-2, passes through the pyloric sphincter into the duodenum. Bile and pancreatic juice is added to the chyme to bring the pH up to 8. Enterokinase and alkaline salts are secreted by the lining of the duodenum to aid in digestion

31
Q

What is the role of peptidase?

A

To break shorter polypeptide chains into di and tri peptides

32
Q

Describe the layers of the gut.

A

Lumen is the cavity, Muscle layer, mucosa layer, villi and epithelial cells

33
Q

Describe the steps in intercellular digestion.

A

1) disaccharides/di-&tripeptides join with their respective enzymes and are digested into glucose,galactose and amino acids.
2) the glucose,galactose and amino acids join with their relative sodium co transport systems and diffuses through the epithelial cell.
3) the glucose,galactose and amino acids diffuse through the epithelial cell
4) the glucose,galactose and amino acids are absorbed into the blood stream via facilitated diffusion.

34
Q

Why is sodium pumped outside of the epithelial cell?

A

Due to active transport, sodium is pumped outside of the cell. This maintains the low sodium concentration inside the cell. The active transport of sodium requires energy in the form of ATP.

35
Q

Describe the steps in the sodium co-transport system

A

1)Disaccharide is broken down into monosaccharide via enzyme.
2) Sodium moves from a high concentration to a low concentration via its transport protein in the epithelial membrane.
3)monosaccharide (excluding fructose) moves from low concentration to high concentration (inside the cell). Sufficient energy available in the diffusion of sodium to ‘drag’ glucose against its concentration gradient. This is sodium co transport because glucose is being co transported as sodium diffuses (facilitated) across the membrane.
4)

36
Q

How does glucose diffuse how of the cell?

A

As glucose is at high concentration inside the cell, it readily diffuses (facilitated) out of the cell and into the bloodstream.

37
Q

How does fructose get absorbed into the bloodstream?

A

Fructose moves into the epithelial cell via a different mechanism. I.e a facilitated diffusion via a fructose channel.

38
Q

How do monosaccharides and amino acids be absorbed into the bloodstream? And why?

A

They are directly absorbed into the bloodstream from the duodenum and the ileum. These substances are initially transported to the liver via the hepatic portal vain. This is because glucose, primarily, needs to be regulated prior to its entry into the main circulation.

39
Q

How are fatty acids, glycerol and lipids absorbed into the bloodstream?

A

They do not get absorbed directly onto the bloodstream from the gut. Instead, these substances are taken up by the lymph vessels called lacteals. Ultimately, the lacteals fuse to join larger lymph vessels. Eventually, a major lymph vessel (the thoracic duct) joins with the bloodstream and fatty acids, glycerol and lipids are then released into main circulation.

40
Q

List the components of nervous control of digestion

A 
Digestion begins In The mouth with the secretion of saliva. The smell, taste or thought of food results in nervous stimulation of the salivary glands. 
Nervous stimulation(via a section of the vagus nerve) also stimulates gastric juice secretion (containing HCl and pepsinogen). This secretion is in anticipation of food entering the stomach.
When food enters the stomach, the stomach wall is stretched. this stretching of the stomach wall maintains further gastric juice secretion.
41
Q

Describe the process of hormonal control in the stomach.

A

Food entering the stomach stimulates the release of gastric (a hormone) from specialised stomach cells in the bloodstream.
Gastric then circulates around the body only to come back to the stomach.
Gastric then stimulates the stomach cells to release gastric juice for up to 4 hours
(See diagram)

42
Q

Describe the process of hormonal control of digestion in the duodenum.

A

1) when chyme enters the duodenum, secretin and CCK are both secreted into the bloodstream from the wall of the duodenum. These two hormones are then transported to the liver, gall bladder and pancreas.
2) CCK stimulates the release of bile from the gall bladder to the duodenum.
3) secretin stimulates bile production in the liver. The bile is then secreted into the gall bladder for temporary storage
4) secretin also stimulates the release of alkaline juice from the pancreas to the duodenum -to assist in shifting pH.
5) now that the pH in the duodenum is 8, the CCK then stimulates the release of digestive enzymes from the pancreas to the duodenum.
(See diagram)

43
Q

What is the role of gastrin?

A

Stimulates the stomach cells to release gastric juice for up to 4 hours

44
Q

What stimulates gastrin?

A

Food entering the stomach

45
Q

What is the role of CCK?

A

Stimulates the release of bile from the gall bladder to the duodenum
Stimulates the release of enzymes from the pancreas to the duodenum

46
Q

What is the role of secretin?

A

Stimulates bile production in the liver

Stimulates the release of alkaline juice from the pancreas to the duodenum (assists in shifting pH from 2 to 8).

47
Q

What is the role of gastrin?

A

Stimulates the stomach cells to release gastric juice for up to 4 hours

48
Q

What stimulates gastrin?

A

Food entering the stomach

Biology Sem 1 (5 decks)

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