Brainscape's Knowledge GenomeTM

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


See full index

Digestive System Module > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

What are the 4 concentric tunics/layers of the gut tube?

A
  1. Mucosa
    a) Epithelium
    b) Lamina Propria
    c) Muscularis Mucosae
  2. Submucosa
  3. Muscularis Externa
  4. Adventitia/Serosa (Visceral Peritoneum)
    +series of glands outside of tube proper (empty secretions into tube)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is located outside of the 4x concentric tunics/layers of the gut tube?

A

Outside tube proper, is series of glands, which empty secretions into the tube

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

What is the function of the mucosa’s epithelium?

A
  1. Protection- multiple layers (if you lose superficial wont bleed/sacrificial layer)
    oesophagus, stomach, salivary glands, pancreas, liver, small intestines
  2. Secretion
  3. Absorption
    -combination dependant on area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of the mucosa’s lamina propria?

A
  1. Support-
    a) mechanical support through CT/collagen (structural and physical support)
    b) functional support (BV nerves lymphatics embedded in CT)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the function of the muscularis mucosae?

A

Boundary between mucosa and submucosa

1. Movement: “muscle of the mucosa”. allows movement Independent of peristalsis to occur

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

What is the function of the submucosa?

A

Loosely arranged in gut to allow expansion when bolus of food moves through gut tube
(Same function as Lamina Propria)
1. Support-
a) mechanical support through CT/collagen (structural and physical support)
b) functional support (BV nerves lymphatics embedded in CT)

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

What is the function of the Muscularis Externa?

A
  1. IC/OL usually (Inner Circular and Outer Longitudinal)
    Exception: Stomach (additional inner oblique)
  2. INvoluntary Control of Smooth muscle
    Exception: a) Oesophagus when swallowing voluntary b) anal sphincter
    Sphincters= usually thickening of IC inner Circular layer of Muscularis Externa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the role of sphincters?

A

Gate keepers
control flow and direction and timing and amount of substance
going from one end of the tube to another
-usually thickening of IC (inner circular) layer of Muscularis Externa

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

Adventitia

A

Outer most CT connective tissue covering
of any organ, vessel or other structure
-(vessel): Tunica Adventitia outer most layer of BV, connecting BV to adjacent structures

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

Serosa

A

“Visceral Peritoneum”
Slippery outer covering for gut tube
2x layered
outer mesothelium sits on a bed of CT connective tissue

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

Production of Serous Fluid

A

Peritoneum produces 7Litres of serous fluid every day
Is reabsorbed and Recycled
Aberent/changes to serous fluid production= Ascites and Peritonitis

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

Ascites

A

Unusual conditions (e.g. liver disease, heart failure, electrolyte imbalance)

(esp. with cirrhosus/other liver diseases)
- can be drained/managed
- cancer patients can also display ascites
a) (change in blood hydrostatic pressure causes) Accumulation of fluid (in peritoneal space)
b) abdominal swelling
c) distortion of visceral organs
- distented obvious superficial BV (portal hypertension)

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

Peritonitis

A

Physical damage, chemical irritation, bacterial invasion (complication from surgery)
Inflammation interferes with normal function

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

Nervous control of gut

A

Enteric System Nervous Plexi:
a) Submucosal (Meissner’s) nerve plexus (embedded in submucosa)
b) Myenteric (Auerbach’s) nerve plexus (b/w IC and OL of muscularis externa)
- Gut’s own Enteric NS (controls itself/second brain). Own afferent and efferent nerves
-heavily under Autonomic NS influence (ANS) (each salivary gland receives both sympathetic and parasympathetic stimulation)
Increase:
a) sight and thought of food (preparation, presentation, smell, taste, chewing)
b) nausea
Decrease:
a) Fatigue, Sleep, Fear, Dehydration, Exercise

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

Sympathetic N S

A 
XMX
eXercise
eMotion
eXcitement
Inhibits gut function
• Predominates at times
of activity/stress
• Diverts blood to brain
and muscles
-secretion of a small volume of viscous saliva containing high enzyme concentrations (not mucous to lubricate)
-reduced volume produces sensation of dry mouth
-blood vessels are constricted (restricts blood flow and secretion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Parasympathetic N S

A 
PSL
rePletion
reSt
reLaxation
Promotes gut function
• During and after
mealtimes
• Stimulate secretion and
transportation in the gut
tube
-accelerates secretion (make saliva), resulting in the production of large amounts of watery saliva
-myoepithelial cells contract
-increased blood flow (sustains demand for metabolism)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Magnified histological slide of lobule (40x)

A

Cross section through alveoli/acini of gland (sea of acini)
2x predominant different cell populations
Dark and lightly staining

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

Three major salivary glands

A
  1. Parotid. ~25% of saliva. Serous only (dark) - Munks virus preferential target
  2. Submandibular. ~70% Serous and Mucous
  3. Sublingual. ~5% Serous and Mucous
    - proportion of 2x cell populations determines whether secretions are watery/serous or sticky/mucousy/viscous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Serous Acinus

A
  1. Watery
  2. Central darkly staining nuclei
  3. Dark staining acini = Zymogen Granules in cytoplasm of cells (in serous acini)
    Zymogen granule = enzyme
    b) Predominant enzyme= Amylase (CHO)- particularly in salivary gland.- helps to break down carbohydrates and sugars -good substrate for bacterial growth
  4. Myoepithelial cells: surrounding base of acini cells. Modified epithelial cells. Contractile- help to squeeze acini contents into lumen/propel secretions along
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mucous Acinus

A
  1. Viscous/sticky
  2. Peripheral flattened nuclei
  3. Lightly staining acini: (peripheral flattened nuclei as) Light staining mucous granules occupying most of cytoplasm (pushing nuclei to periphery)
  4. Myoepithelial cells: surrounding base of acini cells. Modified epithelial cells. Contractile- help to squeeze acini contents into lumen/propel secretions along
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Striated Ducts

A

Intralobular
Basal infoldings of membranes
Aligned Mitochondria (gives striated appearance)
-Metabolically active
- Active transport
Function: Exchange Na and Cl of K and HCO3-(Bicarbonate)

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

What are the 7x key components of Saliva?

A
  1. Enzyme (serous acini)
  2. Mucous (mucous acini)
    - carbohydrate-rich glycoproteins (mucins)
  3. Bicarbonate (striated ducts)
    - 99% water
    - assortment of ions, buffers, metabolites, enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the 3x key functions of saliva?

A
  1. Lubrication
  2. Protection
    a) bacterial adhesion(mucous) and secretion(acidic) (bicarbonate ions HCO3- help counteract bacterial acidic secretions)
    b) vomit (acidic) (bicarbonate ions HCO3- help counteract regurgitated gastric contents)
  3. Digestion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Salivary Mucous

A

Carbohydrate-rich glycoproteins

  • help lubrication
  • prevent bacterial adhesion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Puking

A

Oral cavity water rash/influx of saliva

  • Reflex protective mechanism
  • influx of alkaline basic saliva as last line of defence against acidic regurgitation
26
Q

Salivary Bicarbonate

A

Helps counteract

  1. bacterial acidic secretions
  2. acidic vomit/regurgitated gastric contents
    - Puking:Oral cavity water rash/influx of saliva
    - Reflex protective mechanism
    - influx of alkaline basic saliva as last line of defence against acidic regurgitation
27
Q

Salivary Lysozyme

A

Break down bacterial cell walls

28
Q

Salivary Lactoferin

A

Ion Kelater

-helps fight ion dependant bacteria

29
Q

IgA

A

Immunoglobulin A

Helps fight bacteria and viruses

30
Q

Salivary Amylase Enzyme

A

Amylase: Active range ph 4-11 (optimal ph in middle)
-breaks down sugars into monomers/basic units.
-sugars good substrate for bacterial growth.
therefore breaking down sugars: 1. aiding digestion.
2. indirectly reducing substrate available for bacterial consumption

31
Q

Salivary Lypase Enzyme

A

Lipase: optimal ph 4.0
- fat break down.
relatively lower pH
-therefore more active in stomach than oral cavity

32
Q

Salivary Kallikrein Enzyme

A

Protease
not really involved in enzyme
-cleave and activate another pro-enzyme
-eventually increases blood flow/supply to salivary glands
(need to increase blood flow to sustain demand for metabolism)

33
Q

Xerostomia

A

dry mouth

  1. Mumps (virus which preferentially targets parotid glands)
  2. Salivary duct calculi (stones)
  3. Salivary gland tumours (usually benign)
  4. Sjogern’s syndrome (SHOH-grinz)- autoimmune condition/generalised dryness
  5. Medications
34
Q

Hypersalivation

A

Watery brash

  1. Associated with many conditions (inc. peptic ulceration & IBD)
  2. Medications
  3. Toxins
35
Q

Meth mouth

A

bad teeth
destruction of salivary glands (protection and digestive functions)
a)loss of protective features (amylase, mucous, bacteria in oral cavity etc)

36
Q

Function of Oesophagus

A

Rapid transport (peristalsis) of food bolus to the stomach
Straight tube about 25cm long
Thick muscular walls
Protective lining
Contains glands
Collapsed outline with submucosal folds when empty-only expands when bolus travels through
-folds stretch out flat as food descends to the stomach

37
Q

Epithelium of Oesophagus

A

Thick sacrificial stratified squamous epithelium (6-8 layers)
Non-keritinized in humans
-small number of keratohyalin granules, not dont undergo true cornification
–>
Transitions into Cuboidal/columnar (as approaches stomach)

38
Q

Muscularis Mucosae of Oesophagus

A

Upper: Absent/rare
Near stomach: developed
Longitudinal smooth muscle + elastic network (discontinuous in places)
Permits independant movement and folding of mucosa- which aids digestion and absorption
-poorly preserved(not well definied)/discontinuous in some places

39
Q

Muscular Externa of Oesophagus

A

2x thick coats -inner and outer
-Not always circular and longitudinal respectively
-Inner= many spiral and oblique bundles
Outer= also irregularly arranged in many places
Top 1/3 =mostly skeletal (myocites and striations) (voluntary control, voluntary contractions)
Middle 1/3= mixed skeletal and smooth
Inferior 1/3= mostly smooth
Peristalsis vs Segmentation
Sphincters - upper and lower.
-physiological > anatomical.
-NO obvious muscle thickening
-Lower sphincter area has some increase in inner muscle coat
-Tonal contraction

40
Q

Peristalsis

A
  1. Contraction of circular muscles behind bolus
  2. Contraction of longitudinal muscles ahead of bolus
  3. Contraction in circular muscle layer forces muscle forward
    - peristalsis propels materials along the length of the digestive tract by co-ordinated contractions of the circular and longitudinal layers
41
Q

Segmentation

A

Segmentation movements primarily involve the Circular muscle layers

  • these activities churn and mix the contents of the digestive tract
  • but do NOT produce net movement in a particular direction
42
Q

Oesophageal covering

A

Adventitia
-Not lined by mesothelial cells
-b/w trachea and oesophagus
-except for 1-2cm b/w diaphragm and stomach
Retroperitoneal: Anterior and Left Lateral surfaces covered by peritoneum/serosa

43
Q

Oesophageal Nerves

A

ANS
Autonomic NS
Co-ordinates movements involved in swallowing

44
Q

5x Gastrooesophageal diseases

A
  1. Achalasia - aperistalsis of oesophagus with a failure of the lower oesophageal sphincter to relax on swallowing
  2. Neurological disorders (brainstem), neuromuscular disorders, extreme old age
  3. Gastro-oesophageal disease (GORD)
  4. Reflux oesophagiti
  5. Barett’s oesophagus
45
Q

Swallowing

A

If swallowing goes down wrong tube
-cough- lungs trying to expel fluid from airtube/trachea
Epiglottis prevents choking whilst ingesting. Covers glottis/entrance to trachea. Helps redirect food down correct tube
“Barium swallow”
Trachea-normally open. Anterior to oesophagus

46
Q

Trachea

A

Normally open
C-shaped cartilage ring- helps to keep it permenantly open -even when -ve pressure allowing us to breath in and out
-Trachealis muscle
Anterior to oesophagus
Adventitia (not lined by mesothelial cells) b/w itself and oesophagus

47
Q

Oesopageal Submucosa

A
  • Loosely packed= can expand an compress as required

- if densely packed= little flexibility for movement

48
Q

Chronic Oesophagitis –> Barretts Oesophagus

A

Gastric Oesophageal Reflux reduce
gastric juices reflux back into oesophagus
normally lower oesophageal sphincter prevents (but not fool proof)
-chronic gastric acid exposure= lead to pesophagitis (oesophagus inflammation)
-stratified squamous epithelium protects against Physical abrasion Not Chemical
Ulcer = epithelium digested away
Chronic acid Exposure: Transformation/Metaplasia from stratified squamous –> glandular/stomach like epithelium
-Precursor to oesophageal cancer
Adenocarcinoma (from Barrett’s Oesophagus)

49
Q

Oesophageal Varices

A

Portal hypertension due to elevated pressure in liver, due to obstruction chirrosus
=Backflow of blood into Dilated BV
-Weak veins, over worked andover filled
Very dangerous- bleed and heamorahage easily
-massive blood loss (with serious consequences)

50
Q

Stomach

A 
Storage tank
Secretion, Sterilisation and Digestion
-some absoportion
J-shaped bag
approx 1.5L capacity
4x key (3x histologically distinct) regions - Cardia, fundus, Body, Pylorus
2x Sphincters: LOS Lower Oesophageal Sphincter + Pyloric Sphincter
Additional Inner Oblique layer
51
Q

Rugae

A

Transient folds of the stomach
Empty= prominant
Full/contracting = less

52
Q

Cardia

A

cardiac glands
Mucus
“buffer zone”

53
Q

Body

A 
Parietal (Oxyntic) glands
-HCL
-Intrinsic Factor
-Pepsinogen
-Somatostatin
"business end" -where Acid is produced
-fundus and body is often where most activities are restricted to
-digestion + chewing to produce Chyme
54
Q

Pylorus

A

Pyloric Glands

  • Pepsinogen
  • Mucus (predominant)
  • Gastrin
  • Somatostatin
  • dont want chyme to be conc. acid, therefore mucus production
55
Q

Simple columnar mucous cells of the stomach

A

Of surface and pits
Elongated nucleus
Insoluble, Alkaline/neutral glycoprotein
forms a protective mucous bicarbonate barrier sheet above the epithelium
1. -Produces mucous coat/gel layer. a) Mechanism of defence to stop stomach from digesting itself.
b) helps trap bicarbonate HCO3-, to counteract acidic lumenal contents
2. -Protects itself by high rate of differentiation and replacement by Undifferentiated stem cells when damaged
3. -enriched phospholipids in membrane, acting as additional barrier
4. -Prostaglandins: derivatives of fatty acids. Hormone like activity. E2 especially is protective, stimulating production of mucous and phospholipds
5. Helicobacterum Pylori= Major cuase of stomach ulcers, a) produces urease, which converts blood’s urea into ammonia, which attacks and degrades mucous coat. b) produces toxins damages epithelial cells c) releases ulcerogens (PAF Platelet Activating Factor) which is negative.

56
Q

Mucous Neck cells of the stomach

A 
of gastric glands
Expanded apex
Basal Nucleus
Soluble
Acidic glycoproteins secreted when food is present (like dissolves like, when there is active digestion the slighlty acidic mucous helps it to digest better
Mucous granules are less densely packed
57
Q

Undifferentiated stem cells of the stomach

A

Simple columnar Epithelium protects itself by high rate of differentiation and replacement by Undifferentiated stem cells when damaged
+
Differentiates into specialised Parietal/Oxyntic cells

58
Q

Parietal cells of the stomach

A

Oxyntic cells
Releases HCl, intrinsic factor
Intracellular canaliculi
1. HCl: a) Sterilise food b) acidify environment.
-chief cell’s Pepsinogen pre-enzymes are converted by acidic environment (created by parietal cell’s HCl) into active pepsin
-aberent/insufficent parital cell activity/insufficient HCl production = Decreased Digestion + LEss bacteria killes leading to Gastroenteritus
2. Intrinsic Factor: Vit B12 absorption = needed for RBC heamatopoiesis (aberent parietal acitivity can lead to Pernicious Anaemia (autoimmune diseases that attack parietal cells themselves))
OH- converted to HCO3-. exchanged for Cl-. diffuses into venous blood leaving that stomach
-Produces protective bicarbonate ion

59
Q

Chief cells of the stomach

A

Zymogenic cells
Pepsinogen (inactive form of pepsin enzyme) secreted into gland’s lumen
-Pepsin= helps cleave proteins
Zymogen granules

60
Q

Enteroendocrine cells

A 
Secretory granules
G cells= gastrin
ECL cells= histamine
D cells= somatostatin
Hormone liberated through basal lamina into capillaries of lamina propria

Digestive System Module (38 decks)

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