Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Theme 1: The Alimentary System > Salt and water transport and its control > Flashcards

Salt and water transport and its control Flashcards

(44 cards)

Start Studying
1
Q

Overview of fluid movement in the GI tract

A

Net fluid entering: 8.5L/day

Net fluid absorbed by bowel: 8.4L/day

Net fluid loss via stool: 100ml/day

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

Large intestine absorption

A

Reabsorbs 2L/day

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

Jejunum reabsorbs

A

Na+

K+

Cl-

H2O

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

Ileum secretes

A

HCO3-

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

Ileium absorbs

A

H2O

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

Colon reabsorbs

A

Na+

Cl-

H2O

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

Colon secretes

A

K+

HCO3-

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

Absorption of water

A

Water transported through intestinal membrane by diffusion

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

Chyme hypoosmotic

A

Water is absorbed through intestinal mucosa into blood of the villi

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

Chyme hyperosmotic

A

Water transferred by osmosis to make chyme isoosmotic with the plasma

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

Epithelial lining

A

Simple columnar epithelium

Heterogenous population of cells

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

Four major types of epithelial cells making up intestinal mucosa

A

Enterocytes

Endocrine cells

Goblet cells

Paneths cell

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

Functions of intestinal epithelium

A

Barrier: enterocytes

Secretion of digestive enzymes: enterocytes

Nutrient absorption: enterocytes

Water and electrolyte exchange: enterocytes

Mucus secretion: goblet cells

Sensory and endocrine function: enteroendocrine cells

Innate immune function: paneth cells

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

Structural properties of enterocytes

A

Epithelial cells polarised

  • apical sides face lumen and has microfolds
  • basal side rests on basal membrane and communicates with blood stream and lymphatic lacteals
  • lateral side is in contact with neighbouring cells
  • apical and basolateral membranes separated by tight junctions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Tight junctions

A

Restrict passive flow of solutes after secretion and absorption

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

Types of epithelial transport

A

Paracellular pathway

Transcellular pathway

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

Transcellular transport

A

Move molecules and water through cells

Drives ion flux and established concentration gradients which dictates passive transport of water and solutes

May work against electrochemical gradient

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

Paracellular transport

Study These Flashcards
A

Movement of solutes and water through tight junctions

Dictated primarily by electrochemical gradient

19
Q

Channels

Study These Flashcards
A

Fluid filled pores built of protein aggregates

Gated: have a part that opens and closes and regulates ion entrance

Ion specific

Transport based on electrochemical gradient

20
Q

Carriers

Study These Flashcards
A

Proteins that facilitate the movement of specific solutes across the membrane through conformational changes

Energy independent transport based on concentration gradient of energy dependent trasnport

Single molecule, co-transport or exchange

21
Q

Pumps

Study These Flashcards
A

Transport proteins that move ions and other solutes across the membrane against the electrochemical gradient

Use energy by hydrolysis of ATP (ATPases)

Exchange

22
Q

Passive transport

Study These Flashcards
A

Movement of solutes down its electrochemical gradient

Movement through openings of ion channels, carriers that facilitate diffusion or permeability of tight junctions

23
Q

Solvent drag

Study These Flashcards
A

Water leaks from the lumen through paracellular space to reach osmotic equilibrium on the basolateral side

Water flow pulls additional solutes from the luminal to the basolateral space

Takes place in upper small intestine where tight junctions are the leakiest

24
Q

Active transport

Study These Flashcards
A

Energy dependent

Transepithelial transport of NA+ using combination of Na+/K+ ATPase on the basolateral membrane

Depletes Na+ inside the cell

Na+ channel or nutrient/ Na+ cotransporter on apical side brings more Na+ in based on the concentration gradient created by the ATPase

25
Concept 1: Na+/K+/ATPase
Critically important transport found on the basolateral aspect of the enterocyte Drives sodium out of the cell Creases a Na+ electrochemical gradient between enterocyte and lumen
26
Concept 2: Na+ coupled transport
Na+ gradient created by Na+/K+ ATPase allows Na+ coupled transport from lumen into cell Secondary active transport couples uphill movement of glucose/ aa to downhill movement of Na The process electrogenic
27
Oral rehydration solution
Utilising mechanism of glucose coupled sodium absorption Carrier specific Na+/glucose transporter (SGLT 1) preserved in most diarrheal diseases and forms basis for oral rehydration therapy SGLT 1 binds two Na molecules to one glucose molecule transporting them into the cell
28
Concept 3: NaCl cotransport mediated by two transport proteins
NaCl absorbed in conjugation with export of H and HCO3- Relies on Na+/K+ ATPase to establish electrochemical gradient Na+/H+ exchanger works in conjunction with HCO3-/Cl- exchanger Allows NaCl absorption
29
Concept 4: Cl- secretion occurs in conjunction with basolateral Na+/K+/2Cl- transport
Involves coupled import of Na+/K+/2Cl- Intracellular Cl- increases so is secreted via apical Cl- channels (CFTR) Na+/K+ ATPase drives Na+ gradient allowing further Cl- secretion through apical CFTR
30
Concept 5: water follows NaCl
Transport of ions, mainly NaCl leads to direction of fluid flow across tight junctions Water will travel through intercellular tight junctions in the setting NaCl absorption
31
Secretion of water
In the small intestine Cl- secretion drags Na+ and water across the tight junction (not in colon)
32
Jejunum transport
The highest absorption of Na+; coupled with nutrient absorption Solvent drag is an important mechanism
33
Ileum transport
Similar to jejunum The highest absorption of NaCl
34
Colon transport
Apical side: Na+ channels Apical side: K+ channels Aldosterone increases synthesis of Na+ channels .. increased K+ secretion.. hypokalaemia
35
Nature of absorbing epithelium
Intestinal mucosa highly folded to generate villi - duodenum: broad and ridge-like - jejunum: tall - ileum: shorter Brush border increases surface area
36
Cholera toxin on electrolyte and H2O reabsorption
CFTR Cl- channel opening regulated by cAMP Cholera toxin stimulate excess production of cAMP in crypt cells - massive influx of Cl- - Na+ follow to form osmotically active NaCl - followed by h2O secretion- more than can be reabsorbed SECRETORY DIARRHOEA
37
Large intestine- water and electrolyte absorption
Driven by Na+/K+ ATPase Na+ entry by - Na+ channels - Na+/H+ antiport Diffusion under aldosterone control- increases Na+ channels Cl-/HCO3- provide buffer for acid Tight junctions ensure no ion backflow Na+ Cl- create osmotic gradient for transcellular water movement
38
Na+ transport
Absorption - through Na+/H+ exchangers - nutrient coupled - through electrochemical Na+ channels in distal colon Secretion - in small intestine (Cl- secretion drags Na+ and water across tight junction)
39
K+ transport
Absorption - through K+/H+ exchangers - through K+ channels Secretion - in colon through K+ channels, increased in pathophysiological conditions
40
Gastrointestinal infections
Diarrhoea caused by: - bacterial enterotoxin - inflammation
41
Bacterial enterotoxins
Cause secretory diarrhoea by interacting with receptors and signal transduction pathways in enterocytes - secretion exceeds absorption
42
Bacterial enterotoxins
Cholera toxin Heat liable E.coli toxin Salmonella toxin Campilobacter toxin Heat stable E.coli toxin Yersina toxin
43
Cystic fibrosis
Autosomal recessive disease Deletions in CFTR gene Sticky mucus and high viscosity of lumenal contents Often presents as intestinal obstruction and meconium ileus in newborns
44
Lactose intolerance
Lactase deficiency Lactose not digested so remains in the lumen Osmotic diarrhoea

Theme 1: The Alimentary System (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions