Digestion & Intestinal Absorption Flashcards
(49 cards)
1
Q
Primary functions of digestive system
A
- Digestion
- Absorption
- Secretion
- Motility
2
Q
- Contain endocrine and exocrine cells
- Detect nutrients and secrete hormones
- Where nutrients absorbed
A
Epithelium
3
Q
- Loose connective tissue
- Provide support
A
Lavria Propria
4
Q
- Layer of smooth muscle
- Helps with motility
A
Muscularis Mucosa
5
Q
Point at which CHOs and amino acids enter circulation
A
Blood and lymphatic vessels
6
Q
Network of neurons for control of muscular activity
A
Submucosal plexus
7
Q
Contraction narrows lumen
A
Circular muscle
8
Q
- Innervated autonomically
- Connected submuscal plexus
A
Myenteric externa
9
Q
Contraction shortens tract
A
Longitudinal muscle
10
Q
Mucosa
A
- Epithelium
- Lavria propria
- Muscularis mucosa
11
Q
Submucosa
A
- Blood and lymphatic vessels
- Submucosal plexus
12
Q
Muscularis Externa
A
- Circular muscle
- Myenteric externa
- Longitudinal muscle
13
Q
- Connective tissue surrounding outer surface of tract
- Sheets of connective tissue connect it to abdominal wall and hold GI tract in place
A
Serosa
14
Q
Gastrointestinal Wall
A
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
15
Q
Digestion phases
A
1 - Cephalic phase 2 - Mouth 3 - Saliva 4 - Pharynx 5 - Oesophagus 6 - Epiglottis 7 - Sphincters 8 - Peristalsis 9 - Stomach 10 - Small intestine 11 - Colon 12 - Rectum
16
Q
- Brain’s anticipation of food
- Saliva production increases - parasympathetic
- Stimulation of gastric juice secretion & insulin secretion
A
Cephalic phase
17
Q
- Mechanical breakdown
- Mixing of food with saliva
- Salivary amylase - CHO
- Antibacterial action
A
Mouth
18
Q
- Bicarbonate - neutralise acid
- Mucus - lubricates and protects from abrasion
- Salivary amylase - CHO
- Lysozyme - destroy bacteria
A
Saliva
19
Q
Prevent aspiration into trachea
A
Epiglottis closes
20
Q
Prevent air and stomach contents entering oesophagus
A
Sphincters at bottom of pharynx and opening to stomach
21
Q
- Food moves towards stomach due to progressive muscular contraction
- Compresses lumen and forces food along
A
Peristalsis
22
Q
- Mechanical breakdown of food into chyme
- Secretion of HCl - kill bacteria
- Peptin begins protein digestion
- Gastric lipase - digestion of fat
- Temporary storage site
A
Stomach
23
Q
- Chemical digestion all nutrients - pancreatic and brush border enzymes
- Absorption of end-products, water, ions, vitamins
- Secretion of hormones
- Secretion of bicarbonate-rich fluid
A
Small intestine
24
Q
- Absorption of ions and water
- Transformation of chyme into faeces
- Storage of faeces
A
Colon
25
Pancreas
- Secretion of pancreatic juice
- Proteases
- Pancreatic lipase
26
Gall Bladder
Storage and concentration of bile
27
Liver
- Secretion of bile
* Bile salts
* Phospholipids
* HCO3
- Processing of absorbed nutrients
28
Presence of CHO in GI tract is an important factor for insulin secretion
Incretin Effect
29
- Stimulated by nutrients in small intestine
- Secreted by K cells in duodenum & jejunum
- Stimulates insulin secretion
GIP
30
- Stimulated by nutrients in small intestine
- Secreted by L cells in ileum
- Promotes insulin release
- Inhibits glucagon release
- Delays gastric emptying
- Suppresses appetite & energy intake
GLP-1
31
Fat
- 100,000 kcal
- 12kg adipose tissue
- 300g muscle triglyceride
- 4.4g in blood
32
Carbohydrate
- >3200 kcal
- 350-700g muscle glycogen
- 5g in blood as glucose and lactate
33
- Increases whole body utilisation
- Maximum rate = 105g/h
- Reduces gut discomfort
- Improves performance
Sucrose
34
Stomach
- Mucus cells
- Parletal cells
- Chief cells
- Enterochromaffin-like cells
- D cells
35
Alkaline solution released with mucus to protect stomach lining
Mucus cells
36
Intrinsic factor necessary for Vitamin B12 absorption
Parletal cells
37
- Secretes pepsinogen
| - Pepsinogen activated by acidic environment
Chief cells
38
Release histamine to stimulate HCl secretion
Enterochromaffin-like cells
39
Secrete somatostatin
D cells
40
- Secreted in gastric pit as pepsinogen
- Activated by acidic environment
- Breakdown proteins into 2-4 amino acids
- Feedback loops prevent self-digestion
Activation of pepsin
41
- Stimulation by acetylcholine
- Gastrin released, stimulates release of histamine, stimulates HCl production
- When high HCl, somatostatin released. Inhibits histamine, ECL cell and G cell
- Enterogastric reflex
* Pylous detects food enters intestine
* Stimulates negative feedback loop
HCl Production
42
Fat digestion
```
1 - Emulsified
2 - Hydrolysed by lipase
3 - Temporarily stored as micelles
4 - Transported into epithelial cells
5 - Re-esterified to triglycerides
6 - Packaged as chylomicron
7 - Transferred into lymphatic system, then bloodstream
```
43
Protein digestion
1 - Protein digested by pancreatic proteases & peptidases
2 - Small peptides absorbed via H dependent transport / amino acid enter via Na dependent transport protein
3 - Peptides broken down into amino acids
4 - Amino acids transported into blood
44
- Rhythmic contraction of longitudinal muscles
- Greater mixing of material
- Net flow through small intestine
Segmentation in small intestine
45
- Segmentation increased in ileum with gastric emptying
| - After majority absorbed, peristalsis increases
Gastroileal reflex
46
- Moves undigested material to large intestine
| - Prevents bacteria remaining too long
Migrating Myoelectric Complex (MMC)
47
Small intestine motility
- Segmentation
- Gastroileal reflex
- MMC
48
- Primary storage of material prior to defecation
- Some digestion
- Fluid absorption concentrates faetal matter
Large intestine
49
Large intestine motility
- Ileocecal sphincter
- Segmentation
- Intense contraction across transverse colon
