important GI Flashcards
what is the blood supply to the foregut?
coeliac trunk
what nerves innervate the foregut?
greater splanchnic nerve T5-9
what is the blood supply to the midgut?
Superior mesenteric artery
what nerves innervate the midgut
lesser splanchnic nerve T10-11
what is the blood supply to the hindgut
Inferior mesenteric artery
what nerves innervate the hindgut
least splanchnic nerve T12
what are rugae
muscular ridges on the stomachs inner surface
what are the 2 openings to the stomach
cardiac and pyloric
what are the 5 parts of the stomach called
cardia, fundus, body, antrum, pylorus
what are the 2 sphincters in the stomach?
cardiac sphincter
pyloric sphincter
what gives the stomach its blood supply?
branches of the coeliac trunk
blood supply to the greater curvature of the stomach
R & L gastroepiploic artery
(R arises from common hepatic artery via the gastroduodenal artery
L is a branch of the splenic artery)
blood supply to the lesser curvature of the stomach
R & L gastric arteries
(L is direct from coeliac trunk
R arises from the common hepatic artery)
where does the fundus of the stomach get it’s blood supply from?
short gastric arteries (branches of the splenic artery)
where do the common bile duct and main pancreatic duct empty into the duodenum
the second part of the duodenum via the major papilla and the flow is controlled by the sphincter of Oddi
what are the 4 parts of the duodenum
superior, descending, inferior, ascending
mucosa of D1 is smooth, whereas the rest has plicae circulares
what proportions do the jejunum and ileum comprise of
2/5 jejunum
3/5 ileum
which is wider the jejunum or ileum?
jejunum
describe the walls of the jejunum vs ileum
jejunum = thick + double ileum = thin
what is the blood supply of the jejunum
long arteries & few vasa rectae
what is the blood supply of the ileum
short arteries & many vasa rectae
describe the arterial blood supply of the large intestine
Ascending = right colic artery from superior mesenteric artery
Transverse = middle colic artery from superior mesenteric artery
Descending – left colic artery from inferior mesenteric artery
Sigmoid = sigmoidal arteries from inferior mesenteric artery
describe the venous drainage of the large intestine
Ascending = superior mesenteric vein Transverse = superior mesenteric vein Descending = inferior mesenteric Sigmoid = inferior mesenteric vein
what is the difference between the longitudinal muscle layer in the small and large intestine
small: continuous
large: not continuous - 3 muscles called tenae coli
which intestine has appendices apiploicae
large
do the small and large intestines have pilicae?
small: yes
large: no
external oblique
- Fibres run inferomedially (as if into your pockets)
- Function = contralateral rotation of the torso
internal oblique
Fibres run superomedially
Function = bilateral contraction compresses the abdomen
Function = unilateral contraction ipsilaterally rotates the torso
transversus abdominus
Function = compression of abdomen
what muscles from aponeurosis - rectus sheath
external/ internal oblique and transversus abdominus form rectus sheath
describe the abdominal wall muscles above the arcuate line
In front = superior oblique, some of internal oblique
Behind = some of internal oblique, transversus abdominus
describe the abdominal wall muscles below the arcuate line
All fascia lies in front
Only peritoneum & transversalis fascia behind rectus abdominus here
where is the transpyloric plane of addison?
crosses many important structure at the level of T1 Gallbladder Pancreas Pylorus Duodenal-jejunal flexure Kidneys
where is McBurney’s point?
2/3s of the way from the umbilicus to the anterior superior iliac spine. This is where the appendix lies in the abdomen.
regions of the abdomen
right/left hypochondriac region, epigastric region, right/left lumbar region , umbilical region, right/left iliac region, hypogastric region
what is found in the foregut
oesophagus, stomach, proximal half of duodenum, liver, gallbladder & biliary tree, pancreas, spleen
what is found in the midgut
distal half of duodenum, jejunum, ileum, caecum, appendix, ascending colon, right 2/3rds of transverse colon
what is found in the hindgut
left 1/3rd of transverse colon, descending and sigmoid colon, rectum, anal canal
histology of the lips
Outer = highly keratinized Inner = less keratinized
histology of the tongue
Ventral = non-keratinising squamous epithelium Dorsal = keratinizing
histology of the tongue papillae
Filiform - anterior 2/3 Don’t contain taste buds Fungiform Mushroom-shaped, at sides & tip Circumvallate Dome-shaped, arranged in V-shape V-shape separates anterior 2/3 & posterior 1/3
cell type in oesophagus
stratified squamous non-keratinising
cell type in stomach
simple columnar
cell type in small and large intestine and rectum
simple columnar
cell type in anal canal
stratified squamous - becomes keratinised at distal end
what are the muscle layers of the oesophagus
longitudinal (outer)
circular (inner)
what are the muscle layers of the stomach
longitudinal (outermost)
circular (middle)
oblique (innermost)
where are chief and parietal cells mainly found ?
body of stomach
layers of intestine - out to in
muscularis propria
submucosa
mucosa
lumen
histology of the duodenum
Few plicae circularis Broad and leaf-like villi Few goblet cells Brunner's glands - Secrete alkaline mucus, Neutralises chyme, Only found in duodenum Long crypts
histology of the jejunum
Close-packed plicae circularis Long, narrow villi Finger-like Many goblet cells Short crypts Lymph nodes at lamina propria
histology of the ileum
Fewer plicae circularis
Shorter villi
Goblet cells increase towards distal end
Peyer’s patches- Large, In submucosa, Lymphoid tissue, Only found in ileum
histology of the colon
All the colon looks the same Little folding No villi Mucosa contains closely packed crypts Abundant goblet cells Muscularis externa
what is the function of saliva
Lubricant – for mastication
Maintaining oral pH – bicarbonate/carbonate buffer system, pH 6.2-7.4
Begin starch digestion – alpha amylase
Anti-bacterial – lysozyme
what are the 2 different types of secretions in salvia
Mucous = mucins for lubrication Serous = alpha amylase for starch digestion
parotid gland
Serous secretion
CN IX parasympathetic
sublingual gland
Mucous secretions
CN VII parasympathetic
submandibular gland
Mixed secretions
CN VII parasympathetic
minor glands
Predominantly mucous, some serous
serous acinus
Dark staining nucleus
Nucleus in basal third
Small central duct
Secrete: water & alpha amylase
mucous acinus
Pale staining - “foamy” Nucleus at base Large central duct Secrete: mucous (water & glycoproteins) Found in submandibular & sublingual glands
what are acini
secretory cells
what are intercalated ducts
Connect acini to striated ducts
striated ducts
Microvilli – highly folded
Mitochondria energy for active transport
HCO3- and K+ secreted
Na+ and Cl- absorbed
what do striated ducts lead to
interlobar (excretory) ducts
mucous cells
secrete mucous
function: lubrication, protection of mucosa
parietal cells
secrete: gastric acid (HCl) and intrinsic factor
functions: HCL - digestion, activates pepsinogen, kills pathogens
intrinsic - absorption of B12 in terminal ileum
chief cells
secrete: pepsinogen
functions: converted to pepsin - protease enzyme for digestion
enterochromaffin like cells
secrete: histamine
function: stimulates HCl secretion
G cells
secrete: gastrin
function: stimulates HCl secretion, stimulates histamine secretion
D cells
secrete: somatostatin
function: inhibits HCl secretion
what are the 4 stages of gastric acid secretion
Cephalic stage ON
Gastric stage ON
Gastric stage OFF
Intestinal phase OFF
intestinal phase
In duodenum Distension Low pH Hypertonic solutions Amino acids + fatty acids All decrease HCl secretion via: Parasympathetic nerve inhibition (less Ach), Somatostatin
conversion of pepsinogen to pepsin
Converted by: HCl Pepsin Moist efficient conversion when pH <2 20% of total protein digestion Increases surface area for later digestion
what is the empty stomach volume
50 ml
what is the maximum stomach volume after eating
1.5L
what is gastric motility mediated by
Ach (parasympathetic – Vagus nerve)
Nitric Oxide & Serotonin (enteric)
describe peristalsis
Ripple movement begins in body More powerful contraction wave in antrum Pyloric sphincter closes Not much chyme can enter duodenum Antral contents forced back to body – mixing
what do the interstitial cells of cajal do?
Pacemaker cells – determine frequency of peristaltic contractions
3x per minute
what increases the strength of gastric contractions?
Gastrin
Gastric distension – mechanoreceptors
what decreases the strength of gastric contractions
Duodenal distension Increase in duodenal fat Increase in duodenal osmolarity Decrease in duodenal pH Increased sympathetic NS stimulation Decreased parasympathetic NS stimulation
what are some protective mechanisms of gastric mucosa
Alkaline mucus on luminal surface
Tight junctions between epithelial cells
Rapid cell replacement of damaged cells by stem cells present in base of pits
Feedback loops for regulation of gastric acid secretion
what is the consequence of an insufficient defence of the gastric mucosa
peptic ulcers
what are some causes of peptic ulcers
Helicobacter pylori infection
NSAIDs
Chemical irritants (alcohol, bile salts)
Gastrinoma
what is the Basal metabolic rate (BMR)
The amount of energy needed to stay at live rest
Roughly = 24kcal/Kg/day
what factors increase BMR
Being overweight, Fever, being male, pregnancy, caffeine, hyperthyroidism, exercise, low temperature
what factors decrease BMR
Increase in Age, being female, malnutrition/starvation, hypothyroidism
how do you calculate BMI and what is a normal BMI and obese
weight/height ^2
normal = 18.5-25
obese = 30-40
what are the fat soluble vitamins
A,D,E,K
Absorbed along with fat – in micelles
Absorbed in ileum
what are the water soluble vitamins
B,C
Absorbed in jejunum
Except B12 – terminal ileum
vitamin B12 absorption
B12 ingested orally
Intrinsic factor produced by parietal cells in stomach
B12 binds to intrinsic factor
Intrinsic factor binds to specific sites on epithelia cells in terminal ileum
B12 absorbed via endocytosis
vitamin A
functions: cellular growth, vision ect.
sources: liver, dairy , ect.
consequences: night blindness, growth retardation ect.
vitamin C
function: collagen synthesis, antioxidant ect.
sources, citrus fruit, green veg, potatoes
consequences: scurvy, bleeding gums, aching bones
vitamin B12
functions: erythrocyte formation, DNA synthesis, brain development
sources: meat & fish, eggs, milk
consequences: pernicious anaemia
vitamin D
function: calcium absorption in gut, resorption in kidneys
sources: plants, UV
consequences: frequent bone fractures, muscle weakness and bone pain
vitamin E
function: antioxidant, protects cell walls
sources: nuts & seed, vegetable oils
consequences: muscle weakness, degeneration of retina
vitamin K
function: formation of clotting factors (1972) in liver
sources: green leafy veg, meet, eggs, cereal
consequences: gum bleeding, easy bruising
digestion of carbohydrates
begins at mouth (alpha amylase at pH 6.7)
95% of digestion in small intestine (pancreatic alpha amylase via pancreatic duct - broken into disaccharides)
enzymes on luminal membranes of SI epithelial cells breakdown di into monosaccharides
where are carbs absorbed
broken down into monosaccharides then absorbed into bloodstream
protein digestion and absorption
starts in stomach (pepsin pH 1.6-3.2) small intestine (pancreatic enzymes e.g. trypsin) digested into free fatty acids by exopeptidases FFA then absorbed into blood stream
water absorption
80% in SI
98% of fluid load is reabsorbed
how is sodium absorbed
Active transport
Co-transport with glucose, amino acids etc.
Na+ absorption enhances osmotic gradient for water absorption
how is potassium absorbed
passive diffusion
how is chloride absorbed
Active transport – in exchange for bicarbonate (HCO3-)
This makes the intestinal contents more alkaline
iron storage
Iron is bound to TRANSFERRIN after being absorbed by duodenal epithelial cells
Most is utilised by the body, rest is stored
Most stored iron is in the liver
More specifically, in Kupffer cells
Stored in cells as FERRITIN
iron distribution
50% is in haemoglobin
25% is in haem-containing proteins
25% is in liver ferritin
glycogen storage
Liver maintains blood glucose levels
Excess glucose is stored as glycogen
Formation is stimulated by insulin release
Breakdown is stimulated by glucagon release
Liver is normally stores 100g of glycogen
300g is stored in skeletal muscle
xenobiotics definition
A foreign chemical substance not normally found or produced in the body which cannot be used for energy requirements
e.g. drugs
microsomes definition
They’re fragments of endoplasmic reticulum with attached ribosomes
microsomal enzymes are found in microsomes
phase 1 reactions
Makes the drug more HYDROPHILLIC to be excreted by kidneys
Introduce/ expose hydroxyl (-OH) and other polar groups
Carried out via oxidation, reduction, and hydrolysis
Reactions facilitated by MICROSOMAL enzymes
Cytochrome P450
Important type of microsomal enzyme
Uses haem group (Fe2+) to oxidise substances
Cytochrome p450 reductase - transfers electron from NADPH to CYP450 using flavoprotein
phase 2 reactions
Conjugation reactions:
- Attachment of substituent groups
- Inactive products
- Catalysed by transferases
- Significantly increases hydrophilicity
Glucuronidation reactions:
Adding a glucuronic acid group
Increases hydrophilicity
Done by glucuronosyltransferase/ UGT
UDPGA is an essential co-enzyme for glucuronidation reactions
Most phase 2 reactions are done by NON-MICROSOMAL enzymes.
EXCEPT for glucuronidation which is done by a MICROSOMAL enzyme
albumin
Most common plasma protein 2 main functions:
- Maintain colloid osmotic pressure
- Binding & transporting
large/hydrophobic molecules
what is the purpose of the glucose-alanine cycle
The purpose of this cycle is to move proteins from muscles to the live when glycogen stores are low
urea cycle steps
- Ammonia and CO2 are added to ornithine
- Another ammonia is then added to citrulline to make arginine
- Arginine is cleaved by arginase into urea and ornithine and the cycle goes around again
how is energy stored
Triglycerides – 78%
Protein – 21%
Carbohydrate – 1%
Low density lipoproteins (LDL)
Formed in plasma
Main cholesterol carrier
Delivers cholesterol to all cells in body
Essential for cell membrane and steroid hormone production
High density lipoproteins (HDL)
Formed in liver
Removes excess cholesterol from blood and tissues delivering it to the liver to be secreted into bile
“Good” cholesterol
very low density lipoproteins
Synthesised in hepatocytes
Deliver triglycerides from liver to adipocytes
what does lipoprotein lipase do
- Hydrolyses triglycerides in lipoprotein into 2 free fatty acids and 1 monoglyceride molecule
what does hepatic lipase do
Found in the liver and adrenal glands Converts IDL (intermediate density lipoprotein) into LDL thereby packaging it with more triglycerides to be released in the body
where does fatty acid beta oxidation occur and what is it
It is the catabolism of fatty acids to produce energy
Occurs in mitochondria of hepatocytes
bile
Produced and secreted by LIVER hepatocytes
Emulsifies fats
Excretory pathway e.g. hormones
Stored and concentrated in the GALL BLADDER by absorbing NaCl & H2O
Secreted under the action of cholecystokinin (CCK)
CCK released in response to increased fatty acid conc in duodenum
bile constituents
Bile salts Lecithin (a phospholipid) HC03- Cholesterol Bile pigments e.g. bilirubin
Enterohepatic circulation
95% of secreted bile salts are recycled
Bile salts enter intestinal tract via bile
Reabsorbed by Na+ coupled transporters
Majority of reabsorption is in terminal ileum and some in jejunum
Returned to liver by hepatic portal vein (HPV) to be used again in bile
Small amount of bile salts escape (5%)
Liver synthesises new bile salts from cholesterol
what colour is bilirubin
yellow
what do old erythrocytes break down into
heam and globin then heam forms bile pigments e.g. bilirubin
stages of bilirubin metabolism
- RBCs ingested by macrophages/ Kupffer cells
- Haemoglobin broken down into haem and globin
- Globin broken into amino acids – used to make new RBCs in bone marrow
- Haem is further broken down into biliverdin and Fe2+ & CO. Catalysed by haem oxygenase (HO)
- Biliverdin (green pigment) is reduced by biliverdin reductase to make unconjugated bilirubin
- Unconjugated bilirubin (UCB) is bound to albumin and transported to liver
- Undergoes glucuronidation to make conjugated bilirubin. Catalysed by enzyme UDP Glucuronyl Transferase (UDPGT)
- Conjugated bilirubin (CB) is now soluble and is dissolved in bile
- Excreted into the duodenum with the rest of the bile
- Intestinal bacteria in terminal ileum REDUCE the CB into urobilinogen
- Urobilinogen is lipid-soluble. 10% is reabsorbed into blood, bound to albumin, transported to liver, and oxidised to urobilin
- Urobilin is re-cycled into bile or transported to kidneys and excreted in urine (responsible for yellow urine colour)
- Remaining 90% of urobilinogen is OXIDISED by a different intestinal bacteria into stercobilin
- Stercobilin is excreted in the faeces (responsible for brown colour)
what are the exocrine functions of the pancreas
Acini of pancreas produce digestive enzymes
Released via pancreatic duct into duodenum
what are the endocrine functions of the pancreas
Islet of Langerhans produce insulin, glucagon & somatostatin
Large role in regulating glucose
what does the exocrine pancreas secrete ?
HCO3- (bicarbonate) – neutralises chyme
Digestive enzymes
Zymogens (precursor enzymes)
HCO3 - secretion from pancreas
Protects duodenum from gastric acid
Buffers chyme to a suitable pH
Stimulated by secretin release
Pancreatic duct cells secrete HCO3- into the duct lumen via Cl-/HCO3- exchanger
HCO3- comes from the disassociation of H2CO3 (carbonic acid)
The Cl- is recycled back into the lumen via a CFTR channel
what is CCK
principle stimulus for delivery of pancreatic enzymes into duodenum
cephalic phase of secretion
Sensory experience
Seeing and eating food
Parasympathetic vagus nerve stimulation to acinar cells
Produce digestive enzymes
gastric phase of secretion
Presence of food within stomach
Parasympathetic X nerve stimulation to acinar cells
Produce digestive enzymes
where does the foregut start and end?
mouth to common bile duct
where does the midgut start and end?
common bile duct to 2/3rds of the transverse colon
where does the hindgut start and end?
2/3rds transverse colon to the anal canal
what 2 planes does embryonic folding occur and in what week ?
horizontal - 2 lateral body folds
medial - cranial + caudal
week 4
what forms the GI tract (embryology)
endoderm + visceral mesoderm
how is the primitive gut tube formed?
endoderm moves towards the midline and fuses - incorporating the dorsal part of the yolk sac
what does the endoderm give rise to in the GI tract?
epithelial lining of digestive tract
hepatocytes of the liver
endocrine and exocrine cells of the pancreas
what does the visceral mesoderm give rise to in the GI tract?
muscle, connective tissue & peritoneal components of the wall of the gut
connective tissue for the glands
describe how the mouth arises from the foregut
embryo is temporarily closed by the oropharyngeal membrane which at the end of week 4 ruptures to form the mouth
describe the formation of the vitelline duct
midgut is connected to yolk sac then at week 5 the folding continues, yolk sac narrows into a stalk - vitelline duct
describe how the anus arises from the hindgut
hindgut temporarily closed by cloacal membrane - 7w this ruptures to form the anus
where do the pharyngeal arches extend from
oropharyngeal membrane to respiratory diverticulum
what week do the pharyngeal arches develop
4th & 5th
what are the pharyngeal arches formed from
mesenchymal tissue which are invaded by cranial neural crest cells
describe the coverings of the pharyngeal arches
external - endoderm (pharyngeal clefts)
internal - ectoderm (pharyngeal pouches)
1st pharyngeal arch - innervation, muscles, bone
- Innervation: Mandibular nerve (V3 - i.e third branch of trigeminal (V) • Muscles: mastication, tensor tympani, digastric, myolohyoid
- Bone: maxilla, mandible, incus, malleus
2nd pharyngeal arch - innervation, muscles, bone
- Innervation: Facial nerve (VII)
- Muscles: facial expression, stapedius, stylohyoid
- Bone: stapes, styloid and lesser horn of hyoid cartilage
3rd pharyngeal arch - innervation, muscles, bone
- Innervation: Glossopharyngeal nerve (IX)
- Muscles: stylopharyngeus of the pharynx
- Bone: body & greater horn of hyoid cartilage
4th pharyngeal arch - innervation, muscles, bone
- Innervation: Superior laryngeal nerve of Vagus nerve (X)
- Muscles: Cricothyroid
- Bone: thyroid cartilage & epiglottic cartilage
6th pharyngeal arch - innervation, muscles, bone
- Innervation: Recurrent laryngeal nerve of Vagus nerve (X)
- Muscles: All muscles of the larynx except the cricothyroid
- Bone: cricoid cartilage, arytenoid cartilages, corniculate & cuneiform cartilage
describe the development of the oesophagus
w4 - respiratory diverticulum gets divided by tracheoesophageal septum into respiratory primordium and dorsal oesophagus
describe the dorsal mesentery (embryology)
lower foregut, midgut, major part of hindgut - suspended from posterior abdominal wall
describe the ventral mesentery (embryology)
foregut - derived from septum transversum - liver develops in it and later divides it into the lesser omentum and falciform ligament
what causes the thinning of the dorsal mesentery
stomach rotations - is now called greater omentum
what is the epiploic foramen
small opening where the greater and lesser sacs can communicate
innervation of the nasopharynx
maxillary nerve
innervation of the oropharynx
IX (glossopharyngeal)
innervation of the laryngopharynx
X (vagus)
first stage of swallowing
voluntary
food compressed against roof of mouth and pushed back by tongue
buccinator & supra hyoid muscles manipulate food and elevate hyoid bone - flatten floor of mouth
second stage of swallowing
involuntary
nasopharynx closed by soft palate being elevated
- Impulses from the swallowing centre
inhibit respiration, raise the larynx and close the glottis - keeping food from entering
the trachea
As the tongue forces the food farther back
into the pharynx the food tilts the epiglottis
backward to cover the closed glottis -
third stage of swallowing
involuntary
The sequential contraction of the constrictor muscles (circular) followed by the depression (return) of the hyoid bone and pharynx
Before food can enter the oesophagus the upper oesophageal sphincter relaxes - immediately after the food has passed through the sphincter closes, the glottis opens and breathing resumes
describe the gag reflex
- The reflex elevation of the pharynx - often followed by vomiting cause by irritation of the oropharynx - the back of the tongue
- Reflex arc between the glossopharyngeal (IX) and the vagus (X) nerves
factors affecting the composition & amount of saliva produced
circadian rhythm type & size of gland duration and type of stimulus diet drugs age gender
what salivary glands are continuously active?
submandibular
sublingual
minor
what are unstimulated components of the salivary system dominated by?
submandibular components
when does the parotid gland become the main source of saliva
only when stimulated
where is the parotid gland located?
between:
- Zygomatic arch
- Sternocleidomastoid
- Ramus of mandible
where is the parotid duct located?
crosses masseter muscle and pierces through the buccinator muscle
opens near 2nd upper molar
what structures pass through the parotid?
- External carotid artery
- Retromandibular vein
- Facial nerve
describe the anatomy of the submandibular glands
Two lobes separated by mylohyoid muscle - larger superficial lobe and a smaller deep lobe in the floor of the mouth
empties at the sublingual papillae
where are the sublingual glands located?
Located in the floor of the mouth between mylohyoid muscles and oral mucosa of floor of mouth
what is secreted in the glands in the upper , thin portions of the body of the stomach
mucous, hydrochloric acid (parietal cells) and the enzyme precursor pepsinogen (chief cells)
what is secreted in the lower thicker antrum of the stomach
gastrin
what is pepsinogen mediated by
input from the enteric
nervous system via neurotransmitter ACh
(parasympathetic)
what is gastroparesis
delayed gastric emptying
what is the absoptive state
- During which ingested nutrients enter the blood from the GI tract - During this state, some of the ingested nutrients provide the energy requirements of the body and the remainder is added to the body’s energy stores to be called upon during the next postabsorptive state
what is the postabsorptive state
During which the GI tract is empty of nutrients and the body’s own stores must supply energy
what is a microsome
small particle consisting of endoplasmic reticulum to which ribosomes are attached
what is an example of a microsomal enzyme
Cytochrome P450
describe non-microsomal enzymes
mainly phase II reactions
located in the cytoplasm and mitochondria of hepatocytes in the liver
involved in all conjugation reactions except glucuronidation
e.g. protein oxidases
lipophilic definition
to be able to pass through plasma membranes to reach metabolising enzymes
what is glucuronidation
adding a glucuronic acid group to the drug to make it more hydrophilic
what is produced in overdose of paracetamol
NAPQI
what are the 4 starling forces
- Capillary hydrostatic pressure (favouring fluid movement out of the
capillary) - Interstitial hydrostatic pressure (favouring fluid movement into the
capillary - Osmotic force due to plasma protein concentration (favouring fluid
movement into the capillary) - Osmotic force due to intestinal fluid protein concentration (favouring
fluid movement out of the capillary
describe lysosomal protein breakdown
reticulo-endothelial system of the liver
Sinusoidal endothelial cells remove soluble proteins and fragments from the blood
through the fenestrations known as sieve plates on their luminal surface - they are
important for removing; fibrin, fibrin degradation products, collagen & IgG
complexes. In liver these proteins are fused into lysosomes - containing lysozyme which are hydrolytic enzymes that break down the protein into
amino acids
- Kupffer cells - phagocytose particulate matter thereby packaging them in to phagosomes in the cell which contain hydrolytic enzymes which will break down the protein into amino acids
ubiquitin-proteasome pathway
cytoplasm of cells
Proteins targeted for degradation by the attachment of ubiquitin to the protein. directs the protein to a
proteasome - which unfolds the protein and breaks it
down into small peptides
what is in the hepatic triad
hepatic artery and vein & common bile duct
