Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human Physiology Y3 > Digestion & Absorption of Carbs and Proteins > Flashcards

Digestion & Absorption of Carbs and Proteins Flashcards

1
Q

What are enterocytes?

A

Enterocytes are specialized cells lining the inner surface of the small intestine, where they play a crucial role in the absorption of nutrients and water from digested food.

These cells are a type of epithelial cell with unique structural features that facilitate their functions in nutrient absorption and barrier maintenance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What types of gland is the pancreas?

A

Both exo- and endocrine

Exocrine = enzymes, electrolytes & mucin
Endocrine = insulin, glucagon, pancreatic polypeptides & somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are acinar cells?

A

Specialized cells found in exocrine glands throughout the body, including the pancreas, salivary glands, lacrimal glands, and sweat glands. These cells are responsible for the production and secretion of various substances, including enzymes, hormones, and fluids, into ducts or directly into the external environment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do pancreatic acinar cells do?

A

Secrete peptidases, lipases, alpha-amylases & nucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens if acinar cells don’t work?

A

Malabsorption sydromes occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are ductal cells?

A

These cells line the ducts of exocrine glands and are responsible for modifying and transporting the secretions produced by the glandular cells (such as acinar cells) to their final destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do ductal cells secrete?

A

Pancreatic juice with high concentration of HCO3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the role of HCO3- in pancreatic juice?

A

Regulate the pH of upper intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens if there is a failure in pancreatic juice secretion?

A

Duodenal ulcers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Acinar cells vs duct cells

A

Acinar cells = CCK, ACh causing enzyme and Cl- secretion

Duct cells = secretin = HCO3- secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why does the concentration of HCO3- increase as the rate of pancreatic juice secretion increase?

A

Primarily due to the action of ductal cells in the pancreas, which actively secrete bicarbonate ions into the pancreatic ducts.

This process is regulated by various signalling pathways and mechanisms to maintain the optimal pH environment for pancreatic enzyme activity and digestion in the small intestine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where does the HCO3- secreted into pancreatic juice come from?

A

Plasma
When secretion of HCO3- in pancreatic juice is high = acid tide in the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What enzymes are found in pancreatic juice?

A

Pancreatic alpha-amylase, lipases & proteases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Role of pancreatic alpha-amylase

A

Hydrolyzes, glycogen, starch, complex CH2O
NOT cellulose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe pancreatic lipases

A

All secrete in their active form
Water-insoluble esters require bile salts to work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name water-soluble esters and their properties

A

Short chain fatty acids
Do not require bile salts to be digested

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name some pancreatic proteases

A

Trypsin
Chymotrypsin
Carboxypeptidase A & B

Secreted in inactive zymogen form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What generally stimulates pancreatic secretion?

A

Parasympathetic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What generally inhibits pancreatic secretion?

A

Sympathetic system
Partially mediated by vasoconstriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the phases of pancreatic secretion?

A

Cephalic phase
Gastric phase
Intestinal phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the most important phase of pancreatic secretion?

A

Intestinal phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is the cephalic phase of pancreatic secretion activated?

A

This phase is primarily under neural control and is initiated by the central nervous system in anticipation of food ingestion

Activated through sight, smell or taste of food
Enhanced by vagal stimulation
Secrete substantial amounts of enzymes & HCO3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the gastric phase of pancreatic secretion?

A

The stage of pancreatic enzyme and bicarbonate secretion that occurs in response to the presence of food in the stomach.

This phase is initiated by distension of the stomach wall and the presence of partially digested food (chyme), which triggers neural and hormonal signals that stimulate pancreatic secretion

Release of gastrin to produce low-volume high-enzyme pancreatic secretion

24
Q

Explain why intestinal phase of pancreatic secretion is important?

A

70% of total secretion

25
Q

What stimulates the intestinal phase of pancreatic secretion?

A

CCK & secretin = released from endocrine cells in duodenum ad upper jejunum

26
Q

What is the function of CCK?

A

Potent stimulant of pancreatic enzyme secretion

27
Q

What does potentiated mean?

A

Potentiated typically refers to the enhancement or amplification of a physiological response or effect.

When a substance or stimulus is described as potentiated, it means that its potency or effectiveness has been increased, often through interaction with other factors or mechanisms.

28
Q

What is CCK potentiated by?

A

Secretin
By itself secretin has no effect on CCK

29
Q

What causes secretin and CCK secretion and what are their functions?

A

Chyme in the intestine

Secretion of pancreatic juice rich in bicarbonate = secretin
Secretion of pancreatic juice rich in enzymes = CCK

30
Q

What potentiates the effect of both CCK & secretin?

A

ACh

31
Q

What nerve stimulates pancreatic secretion?

A

Vagus nerve

32
Q

What is a major stimulus for CCK secretion?

A

Amino acids = mainly phenylalanine & tryptophane
Fatty acids
Monoglycerides

33
Q

What is a potent stimulus for the release of secretin?

A

Low pH = less than 4.5

34
Q

What must happen to carbohydrates before being absorbed?

A

They must be digested into monosaccharides before being absorbed

35
Q

What enzymes digest carbohydrates and where are they found?

A

Luminal = alpha-amylase
Mucosal = disaccharidases

36
Q

Where is pancreatic alpha-amylase most concentrated?

A

Duodenum

37
Q

Where does starch digestion begin?

A

Mouth by salivary alpha-amylase

38
Q

What is the rate limiting step of mucosal digestion?

A

Rate for oligosaccharides to be digested into monosaccharides by brush border dissacharidases

39
Q

Where is mucosal enzyme activity greatest?

A

Brush border of jejunum

40
Q

What are the end products of starch and glycogen breakdown?

A

Maltase = glucose
Sucrase = fructose
Lactase = galatose

41
Q

Where has highest capacity to absorb sugars?

A

Duodenum & upper jejunum

42
Q

What mechanism are glucose, galatose & xylose absorbed by?

A

Na+ dependent transport system

43
Q

What mechanism is fructose absorbed by?

A

Facilitated transport

44
Q

What happens to fructose in the epithelial cells?

A

Rapidly converted into glucose & lactic acid = maintaining concentration gradient for diffusion

45
Q

Is monosaccharide absorption regulated?

A

No so can absorb over 5kg sucrose a day

46
Q

What happens in the event of failure to absorb carbohydrates?

A

Results in diarrhoea and intestinal gas
Intestinal gas from bacterial fermentation

47
Q

What is solvent drag?

A

The movement of solvent molecules (usually water) carries solute particles along with it as it flows through a semipermeable membrane or across an epithelial barrier. This process occurs due to the movement of solvent molecules driven by osmotic or hydrostatic pressure gradients, which can drag solute particles along with them

Solvent drag plays a role in carbohydrate absorption by facilitating the movement of water across the intestinal epithelium. As water moves from the intestinal lumen into the epithelial cells and then into the bloodstream, it creates a flow that can carry dissolved carbohydrate molecules with it. This helps to enhance the absorption of carbohydrates from the intestinal lumen into the bloodstream, particularly in regions where carbohydrate concentration is high and water movement is facilitated by osmotic gradients.

48
Q

What happens if you consume lactose when you have lactase deficiency?

A

Accumulation of lactose in bowel lumen
Lactic acid production by bacteria
Increased luminal osmolality
Fluid accumulation in lumen
Luminal distension & enhanced peristalsis
Watery diarrhoea

49
Q

What can be a cause of lactose intolerance?

A

Age = lactase decreases
Congenital = genetic mutation that impairs the production of lactase
Infection = lactase is sensitive to infectious &
inflammatory diseases that affect
intestine

50
Q

Name the enzymes that digest proteins

A

Gastric pepsin
Pancreatic proteases
Enterocytes peptidases

51
Q

Where is most protein digested and absorbed?

A

50% Duodenum & jejunum
20-50% reaches ileum
10% reaches colon

52
Q

What happens to proteins in the colon?

A

Digested by micro-organisms
Protein in stool from bacterial and cellular debris

53
Q

What are proteins digsted into?

A

Small polypeptides & amino acids before being absorbed

Di, tri & tetrapeptides are 3-4x more concentrated than single aa in enterocytes

54
Q

How are digested proteins transported?

A

Na+ dependent transport systems for tri, dipeptides & L-amino acids

55
Q

What form of digested peptides are most absorbed?

A

Tri- & dipeptides are absorbed in greater quantities than amino acids

Human Physiology Y3 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions