Physiology Flashcards
3 monosaccharides
Glucose
Galactose
Fructose
What bond joins monosaccharides
Glycosidic bond
What breaks down disaccharides
Brush border enzymes
Brush border enzymes are?
And examples
On apical membrane of epithelial membrane
Lactase
Sucrase
Maltase
What happens to monosaccharides
Products of breakdown and digestion
And absorbed by small intestine (small enough)
3 disaccharides examples
And what each is made up of ?
Lactose (glucose and galactose)
Sucrose (glucose and fructose)
Maltose (glucose and glucose)
3 polysaccharides
Starch
Cellulose
Glycogen
Starch is what?
2 types?
Made up of?
Plant storage form of glucose
Alpha-amylose - glucose in straight chains
Amylopectin - glucose in branched chains
Glucose linked by alpha 1,4 glycosidic bonds
Amylase breaks down what?
Found where? 2
Starch
Saliva
Pancreas
Cellulose?
What is it
Made up of?
Dietary fibre
Constituent of plant cell walls
Unbranched linear chains of glucose linked by beta 1,4 glycosidic bonds
Cellulase in body?
Only in certain bacteria found in large intestine
Not in any vertebrate
We need this bacteria to break down cellulose
Glycogen
What is it
Made up of?
Where?
Animal storage of glucose
Made up of glucose linked by 1,4 glycosidic bonds
Excess glucose is stored as glycogen in liver
Glucose blood level
5 mmol/L
Microvilli why have it?
Increase surface area and increase absorption of nutrients
2 membranes of epithelial cells
Apical
Basolateral |_|
2 epithelial cells separated by
Tight junction
Transcellular and paracellular means?
Transcellular- through cells
Paracellular - through tight junctions- between cells
Vectorial transport?
Needs what?
Transport across epithelial cell in one direction
Needs transporter proteins distributed between apical and basolateral membrane
These proteins are placed non randomly
Secondary active transport process means?
Moves 2 different molecules across membrane
Opposite ways maybe
What membrane proteins involved in transporting glucose and galactose across epithelial membrane in small I?
SGLT1 in apical membrane
GLUT2 in basolateral membrane for sugars
And
Na/KATPase pump
If transport is Na dependant what does it mean too?
Water also transported by osmosis in tight junction complex
What membrane proteins are involved in transporting fructose in small intestine epithelial cells?
And is it dependant?
GLUT5 in apical membrane
GLUT2 in basolateral membrane
Not dependant not even Na dependant
Amino acids linked by what?
Peptide bond
O=C-N-H
Small proteins are called?
Di/tri Peptides
What enzymes break down protein and peptides?
Pro teases and peptidases
Endopeptidases?
Exopeptidases ?
Endopeptidase- acts on interior AA not exterior
Into smaller peptidases
Exopeptidases = act on terminal end AA
- aminopeptidase - act on amino end
- carboxypeptidase - act on carboxylate end
Chop off one AA at a time
Proteases example 2
Trypsin
Chymotrypsin
How many essential and non essential AA and what means
9 essential (not made by body) and 11 non essential (made by body)
What membrane proteins used in amino acids transport over small intestine epithelial cells?
SAAT1 on apical membrane
NA DEPENDANT on basolateral membrAne (unknown name)
Na/KATPase pump
What membrane proteins used in di/tri peptides transport in small intestine epithelial cells?
4 and what each transport
NHE3 in apical membrane - Na(in)/Hion(out)crossover
PepT1 in apical membrane - Hion/peptide(both in)
Na/KATPase in basolateral mamebrane - Kin and Na out
unknown in basolateral membrane - peptide out bottom
What is created from peptide transporting?
Due to?
Acid microclimate on apical membrane -closer to its surface
Due to H ion transferred out cycle
Triglycerol made up of?
Glycerol and 3 stearic acids
Issue with lipase?
Water soluble enzyme
Digestion only occurs at surface of fat droplet
So very slow
Lipase from where?
Pancreas
Emulsification does what?
Speed up digestion process of fat
What is emulsification
And why
Diving large droplets into smaller droplets
To increase SA and allow more accessibility for lipase action
Mechanical disruption in stomach does what and how?
Large droplets into small droplet
Smooth muscle contraction grinds and mixes lumenal contents
Emulsifying agents example s
Where they found?
What they do?
Bile salts
Phospholipids
secreted in bile
Prevents small droplets reforming and aggregating and they are amphiphatic so repel and prevent this
Micelles size
4-7 micro m
RBC size
Michelle made up of?
Monoglyceride
Fatty acids
Emulsifying agents(bile salt, phospholipids)
What does the Micelle do?
Travels to surface (acid microclimate) and releases free FA and monoglyc.
And they diffuse across apical membrane
Unabsorbed ones taken back up and recycled until all absorbed
They breakdown and reform
Is the micelle absorbed?
No micelle is too large
They are extra cellular and big
Why we form micelle?
Allow travelling through aq solution to cell
Free FA and monoglyc. Can’t do that
Stages in cell once FA and monoglyc. Enter
- Enter sER and reformed into triglycerol by sER enzymes
- These are emulsified by amphiphatic protein to prevent clumping
- Triglycerol droplets transported thru vesicles to Golgi apparatus
- Exocytosis out of BL membrane
- Extra cellular called CHYLOMICRONS
- These enter lacteal and transported to lymph system
CHYLOMICRONS
What happens to them and why?
Extra cellular fat
ALSO
Contains phospholipids, cholesterol and fat soluble vitamins
Enter lacteal as too large for capillary
Vesicles made from?
Formed by sER membrane
Fat soluble vitamins examples
How absorbed ?
A D E K
Same process as fat
Water soluble vitamins examples
How is absorbed
B GROUP
C
FOLIC ACID
Absorbed By passive diffusion or carrier mediated transport
Vitamin B12
Function? And stored ?
How absorbed
Deficiency is what?
Needed for RBC maturation and function and stored in liver as storage
Complex combined with Intrinsic factor absorbed in end of small intestine(ileum) via transporters
Deficiency leads to pernicious anaemia
Minerals for example?
Na k Mg Ca Fe
How much of eaten iron is absorbed
10%
How is iron absorbed
Via DMT1 apical transporter in duodenal epithelial cells
-some bond to ferritin to form protein iron complex
And becomes trapped as a storage in cell
-unbound iron transferred out of bL membrane at bottom and bind to transferrin in blood and transported to liver
How is iron blood levels controlled?
Mechanism
Ex ap,e of what happening if hyperaemia and anaemia
The binding of iron to ferritin is modulated depending on body irons level
Hyperaemia - increase ferritin and more stored in cell
Anaemia - decrease in ferritin and more released out of cell
How is chewing innervated?
Somatic nerves
Voluntary inner sting skeletal muscle of jaw
Chewing seen as a ?
Explain
Reflex -
Presence of food and pressure of food against gums detected by mechanoreceptors and inhibit jaw muscles and contract
Cycle
Saliva secreted by what?
3 pairs of glands
Parotid
Submandibular
Sublingual
What is in saliva? 5
Water Mucins Alpha-amylase Electrolytes Lysozyme
Electrolytes?
Minerals in body that have charge
Balances amount of water in body
Maintains ph/tonicity
Lysozyme?
Natural occurring enzyme in saliva which kills bacteria by cleaving polysaccharide component of bacterial cell walls
Bacteriocidal
Water and mucins role in saliva?
Water - softens and moistens dilutes substances
Mucins- viscous solution, lubricant function
Salivary glands made up of?
Types of secretions?
3 types of acini
Acini and ducts
2 types of secretions - serous and mucous
ACINI
Mixed
Serous
Mucous
What nerves innervate and action on salivary glands?
Para and symp.
Both stimulatory
No inhibitory
Parasympathetic innervation of salivary glands?
Cranial nerves (facial) and (glossopharyngeal) Stimulates watery saliva secretion
REST/DIGEST
Sympathetic innervation of salivary glands?
Non-watery, viscous and sticky saliva
Controlled by separate adrenoreceptors
Alpha1 -high mucous content
beta2-high amylase content
What is saliva release like?
Reflex control
Presence of food in mouth detected by chemoreceptors and pressure receptors and activate saliva
Role of upper and lower oesophageal sphincter?
Regulate movement of material in and out of oesophagus
When is it Adventitia?
She outside peritoneal cavity
Where are submucosal glands found only?
Oesophageas
And duodenum
Muscularis externa made up of?
Inner circular and outer longitudinal
Receptive relaxation of stomach means?
Relaxation of thin elastic stomach muscle of fundus and body initiated by relaxation of LOS and entry of bonus into stomach
Done by vagus nerve
As stomach vol increases what happens to its pressure ?
No change
Functions of stomach?5
Temporary storage Dissolve food and initiate digestion Control delivery into small I- no dumping syndrome Produces IF Sterilises eaten food by acid
Without stomach we won’t be able to?
Eat large amounts of food and process it gradually !
Pyloric sphincter role?
Prevents against dumping syndrome
Controls what enters duodenum
Muscles externa layers of stomach?
Longitudinal OUT
Circular
Oblique IN
Why oblique muscle extra in stomach?
For more powerful contraction and breakdown of food
Rugae of stomach?
Innermost folds of wall
Luminal surface of stomach?
Most inner surface of stomach lined by epithelium = gastric glands and their cells
Fundus is like?
Thin and stretchy and elastic
3 cells inside gastric glands? And what each secrete
Mucous neck cells (secrete mucus) Parietal cells (secrete HCl) Chief cells (secrete pepsinogens)
Gastric pits?
Open into gastric glands
Where is myenteric and submucosal plexus found?
Myenteric - between circular and longitudinal muscle layers
Submucosal - between circular and submucosal layer
Function of antrum of stomach
Where all the mixing and grinding occurs
And gastrin secreted by g cells
Proton pump?
H ion out and k in
Carbonic anhydrase does what?
Enzyme that catalysts co2 and water forming carbonic acid
Regulation of proton pump by what?
Explain each
Stimulatory hormones
Gastrin - endocrine from g cells
Histamine -paracrine
Acetylcholine -neural(parasympathetic.)
Inhibitory hormones
Prostaglandins
What phases control and involve gastric HCl secretions?
Cephalic phase -in head thinking/seeing about food
Gastric phase-food in stomach
Intestinal phase - food in intestine
Cephalic phase
Sight smell and taste of food triggers vagus nerve
Which acts on g cells and releases gastrin and triggers ACh
Local gastrin and ACh prescience then act on ecl cells and release histamine
All acting on parietal cells to increase acid released
Role of cephalic phase though?
Protective measure to prep stomach before food enters
Gastric phase?
When food inside stomach Still triggering more HCl
By distension of stomach triggering vagus nerve
Peptides in stomach triggering g cells
Local gastrin and ACh presence triggering ECL cells
Submucosal glands release what in duodenum
Secretin and GIP and CCK
What triggers response to reduce acid in duodenum in intestinal phase
Acid in duodenum and Fat/CHO in duodenum
Pepsinogen is
Pepsin in inactive form
What activates and deactivates chief cells to release pepsinogen?
Acidic environment in stomach activates pepsin and deactivated by neutral pH
What regulates pepsin secretion
Same as HCL secretion
Gastrin
Histamine
ACh
All increase pepsin secretion
How is mucus secreted into stomach and creates what?
Mucus secreted by neck cells onto surface of stomach lumen
Creates thick layer coat slidy surface for harmful surface
Mucus thick layer coat in stomach lumen effect?
Rich in bicarbonate which creates neutral ph at surface of stomach lumen
Deactivates pepsin and neutralises acid near surface
Protects against gastric acid corrosion and pepsin digestion
Intrinsic factor produced by
Parietal cells
Gastric motility
Persistaltic waves from body into antrum to move food
How is antrum mixing brought about?
Contraction of pyloric sphincter where food hits and is recycled and continues to mix as forced back up
Peristaltic rhythm generated by what in stomach?
By pacemaker cells in longitudinal muscle layer
BER ?
Basic electrical rhythm
Each part of gut has its own BER
How is peristaltic waves conducted in stomach?
By slow waves through gap junction along longitudal muscle layer
Longitudinal muscle cells connected by tight junction
Need above threshold to induce AP and later on a contraction
What two things trigger increase contraction and what one thing decreases contraction in stomach?
Gastrin hormone increases contraction
Dissensions of stomach wall increases contraction
Fat AA or acid in duodenum inhibits contraction
Why do we need to neutralise acid in duodenum
Due to digestive enzymes needing a optimum neural pH
How neutralisation of acid in duodenum occurs
Bicarbonate HCO3 secreted from brunners glands cells SUBMUCOSAL glands
Neutralises acid
Accessory pancreatic duct for?
In case other is blocked
Variable in people
Common bile duct from where?
GB
Two types of cells in pancreas that enters pancreatic duct?
Acinar - enzyme secrete
Duct cell- secrete bicarbonate
Zymogens?
Where
Enzymes stored in inactive forms
How it’s stored in acinar cells
How is inactive zymogen activated in small I?
Inactive enzyme from pancreas trypsinogen goes to small I
Enterokinase enzyme on surface of apical membrane of duodenum epithelial cells converts trypsinogen to trypsin
Trypsinogen then converts all zymogens into active enzyme forms in small I
Why stored as zymogens in pancreas?
To prevent pancreas autodigesting
Nucleases -?
Elastase-?
Phospholipases?
Lipases?
Nucleases -hydrolyses DNA and rna
Elastase -collegan digestion
Phospholipases- phospholipids to FA
Lipases - triglycerides to FA and monoglyc.
What controls zymogen secretion
CCK
Released in reposted to FAt/AA in duodenum
And stimulates zymogen release
For digestion
How many lobes of liver
4 lobes
Right and left
Caudate -
quadrate-
Porta of liver and where
On inferior surface and where entry/exit of vessels into/out liver
What enters liver?
And leaves liver
Portal vein
Hepatic artery
Hepatic vein
What joins to form common bile duct
Common hepatic duct and cystic duct
What separates left and right lobes of liver
3 ligaments of liver
Falciform ligament and end with round ligament at bottom
And coronary ligament on top surface
Round ligament remnants of?
Umbilical vein that exists in free edge of falciform ligament
Bare area of liver
Small area on diaphragmatic surface surrounded by coronary ligament
With no connective tissue covering it
How do vessels and ducts follow through liver
Follow septa throughout liver -
Network of connective tissue
Septa divides liver into what
Hexagonal lobules
Portal trains where?
Corners of hexagonal lobules
Hepatic portal vein
Hepatic artery
Hepatic duct
What forms hepatic veins
And drains into what
Central veins joining
Then draining into Ivc
Hepatic cords made up of?
Hepatocytes
Bile canaliculus?
Lie between cells within each cord
Where bile runs out from centre and to bile duct
Hepatic sinusoids?
Open channels between cords - blood channels
Where processing can happen
What type of blood in hepatic portal vein?
Oxygen low
High nutrients
Blood
Hepatic artery blood type
Oxygen rich
Lack of nutrients
Blood
What is occurring at sinusoids
Mixing of high oxygen and low nutrient blood
With
Low oxygen and high nutrient blood
Sinusoids interact with what?
With hepatocytes where processing occurs
Hepatocytes functions ? 4
Bile synthesis
Nutrient storage (glycogen, fat, B12, iron)
Nutrient inter conversion for requirements
Detoxification - is accident,y ingested toxic stuff - dump into bile for release out of other end
Function of liver ?
Production and secretion of bile
6 components of bile
Bile acids Lecithin Cholesterol Bile pigments Toxic stuff Bicarbonate released by liver duct cells
But both can’t look too beautifull
Lecithin ?
Fat essential for cells and breaks fat dietary down
Bile pigments such as?
What is it? For?
Bilirubin
Yellow substance forms after RBC breaks down and travels to liver
Breakdown product
Reason why poo is brown and pee is yellow - excreted out
Bile acids how made?
And used?
Bile acid made from cholesterol by hepatocytes
Bile acid is unsoluble then combines with glycine/taurine to form bile salt = soluble
Secreted into bile duct and into small I
What happens to bile salts?
Reabsorped where?
Recycled via enterhepatic circulation
Some 5% lost in faeces and rest is recycled via portal vein
Reabsorbed in ileum area
Function of gall bladders?
And how does it do it?
Concentrates bile by absorbing water and Na+
What does sphincter of oddi do?
Controls release of bile and pancreatic juice into duodenum
CCK affect on oddi and gallbladder and pancreas?
Relaxes oddi
Contracts gallbladder and bile secretion triggered
Triggers acinar cells in pancreas to realease enzymes
What occurring in each segment of small I?
Duodenum- gastric acid neutralisation and digestion and iron absorption
Jejunum- nutrient absorption
Ileum- nacl absorption and dehydration of chyme, absorbs left overs(B12, bile acids)
Why called small intestine?
Smaller diameter
Plicae?
Numerous folds of mucous membrane on small I wall
Why have plicae?
Increases SA helps mixing and gets nutrients closer contact to epithelial cells
What are crypts?
Invagination of epithelium around villi and lined with younger epithelial cells
Stem cells are here
What it means when they say epithelial cells have short life span?
Mucousal surface constantly shredding and renewing the epithelial cells
Turnover rapid
Like an elevator from crypt to villus top and down death
Where are crypts found?
Small I
2 cells found on villi in small I?
Goblet - give mucous layer acid microclimate
Absorptive
Where does laminate propria lie?
Epithelium on LP
Provides support and nutrients to it
Epithelium type in small I
Simple columnar epithelium
Type of epithelium in stomach?
Simple columnar epithelium
Villus does what?
Crypt cell does what?
Villus absorbs
Crypt cell secretes Cl and water
Water absorption needs what?
Water secretion needs what?
Absorption Na gradient
Secretion Cl gradient
What does small I do with water?
Absorbs it - villus
Secretes it - crypt
How is water secreted out in small I?
Secretes out by passive diffusion
Using Cl channel called CFTR as a driver to push water out
Why is water secretion important in digestion? 4
Maintains lumenal contents in liquid state
Promotes mixing of nutrients with enzymes
Dilutes and washes away any injurious substances
Helps absorption and promotes it
What is cftr?
Cl channel to drive water secretion
What protein activates and opens cftr?
Protein kinase A
Two types of intestinal movements
Segmentation
Peristalsis
Can segmentation and peristalsis occur at same time?
No either or
Segmentation intestinal movement describe
Allows what
When occurs
Back and forth contraction and relaxation
Of short intestinal segments
Relaxed areas contract then relax
Allows for thorough mixing of contents
During a meal or aftermath
Difference between segmentation and peristalsis what are they contracting
Segmentation - contract circular muscles
Peristalsis-Contract Longitudinal muscles
Small I how does it contract
Like stomach and has pacemaker cells in longitudinal muscle layer
BER. Is subthreshold and needs input to fire AP
What determines strength of contraction of small I muscle ?
Action potential frequency
BER what happens as you go down intestine
Decreases
Effect of parasympathetic and sympathetic nervation on small I contraction
Para. - increase contraction
Symp. - decrease contraction
What nerves innervate small I muscles contraction? 3
Parasympathetic
Sympathetic
ENTERIC NERVOUS SYSTEM
When does peristalsis in small I occur
After absorption of nutrients
Between meals
When does segmentation occur in small I
While during a meal while absorbing
Migrating motility complex is what?
Pattern of peristaltic activity travelling down small I
During periods between meals
As one MMC ends another begins
What cessation of mmc
Arrival of food in stomach initiates segmentation
Role of MMC?
Why is it good? Important?
To clean out small I and sweep left overs out and undigested material out and transfer to large I
This tops bacteria colonisation in small I
What triggers start of MMC?
Motilin hormone
Motilin is high means
Nutrients absorbed is low
Law of intestine - how is bolus always moved
Into area of relaxation towards colon
Gastricileal reflex is what ?
Explainnsteps
- Gastric emptying into small I
- Triggers segmentation activity in ileum
- Opening of ileocaecal sphincter
- Entry of chyme into large I
- Distension of colon wall as fills
- Reflex contraction of sphincter to prevent backflow into small I
Gastroileal reflex is what type of reflex?
Long
From gastric to large I !!!
Colon parts 4
Ascending
Transverse
Descending
Sigmoid
What is the muscles layers like in colon?
Circular is complete and longitudinal is incomplete
Teniae coli?
What happens when these contract?
3 Bands along length of colon -strips of longitudinal muscle
When they contract they form haustra pouches
Caecum function?
Appendix is projection from it
No function
Villi in large intestine?
No villi
Just straight deeper crypts with lots of goblet cells
Why lots of goblet cells in large I?
Mucus creates flat slimy,slippery surface for solid faeces to slide out
What is rectum?
Straight muscular tube between sigmoid and anus
Epithelium of rectum?
Simple columnar epithelium
Which Muscalaris is thicker anus or rectum?
Rectum is less thicker than anus
Flow from rectum out from body?
Rectum Anal canal Internal anal sphincter External anal sphincter Anus
Internal anal sphincter difference with external anal sphincter?
Internal = smooth muscle we can’t control it External = skeletal muscle we can control it
Epithelium change in anus
Simple columnar to
Stratified squamous epithelium (cheeks of bum)
What happens with water in large I?
Absorption of water by Na gradient
Dehydrates chyme to form solid faecal pellets
Why does bacteria colonise in large I
Due to long residence in colon
Role of bacteria in large I?
Outcome of it?
Fermentation/breakdown of undigested carbohydrates/undigested material
To form bio products -
Short chain FA for energy
Vit K for blood clotting
Gas - nitrogen/CO2 farts
Mass movement contraction ?
Material entering rectal wall from colon
A wave of contraction
What triggers defaecation reflex?
Distension of rectal wall sensed by mechanoreceptors increase urge to defaecate
Defaecation reflex innervation explain?
Parasympathetic only via pelvic splanchnic nerves
No sympathetic influence
Defaecation reflex steps explain
Contraction of rectum and distension of wall
Relaxation of internal and contraction of external sphincter
Increased peristaltic activity in colon to push more into rectum to increase urge
Pressure increases on external sphincter and relaxes under voluntary control
Expulsion of faeces
What is constipation
Find it hard to poo don’t go to toilet often
No absorption of toxins from faecal material too
Distension of rectum for too long
What is diarrhoea
Faeces too liquid
Leads to dehydration as losing too much fluid
Causes of Diarrhea?
Explain mechanism
Bacteria e.g. - e.coli, cholera
Produce protein toxins that turn on crypt cells on MAX so secrete lots of water and CL
And so water swamps the lumen
Infected crypt cells essentially
Treatment of diarrhoea?
Oral rehydration therapy
Salt and sugar solution Na/glucose
This Will drive water absorption and rehydration in villi cells
GAHS score? TELLS U WHAT
glasgow alcoholic hepatitis
-preducts mortality in patients with alcoholc hepatitis
end stage liver disease?
cirrhosis with low albumin, prolonged prothrombin time, raised bilirubin, ascites, encephalopathy
prothrombin time?
test to see how long takes blood to clot
cholecystitis?
inflamed gall bladder
alcohol withdrawal from when?
24hrs onwards
features of alcohol withdrawal?
sweating hypertension nausea weakness vomiting anxiety
ascites caused by?
portal hypertension
low serum albumin - causing low plasma pressure
what reduces risk of further bleeding?
beta-blocker
hellers myotmy?
cut muscles of LOS - allowing food to pass into stomach
how to diagnose toxic megacolon?
transverse colon distended over 5cm and patient is systemically unwell
pSc associated with more In IBD?
UC
IS TRYPSIN released by pancreatic cells?
NO
released as trypsinogen
and covnerted to trypsin in duodenum by enzyme
cellulase in a vertebrate?
does not exist - no vertebrate has cellulase in them
stomach dimension does what to gastric secretion?
increases it
what stimulates bicarbonate from brunners glands?
secretin
pepsin requires what environment to work?
acidic environment
cck does what?
cause gb to contract and relaxing of sphincter of oddi
conjoint tendon formed by?
internal oblique and transversus abdomnis
direct hernia?
weakness of abdominal wall
inguinal canal posterior wall formed by
posterior wall- transversals fascia
anterior wall - external oblique
encephalopathy caused by lack of what vitamin?
B1
MAIN REASON FOR ASCITES?
PORTAL HYPERTENSION
treatment of ascites?
sodium restriction
fluid retention
side effects of opioids?
constipation
how does pancreatitis affect glucose levels?
HYPERGLYCEMIA
SIDE EFFECT OF PPI?
C DIFF infection risk
what level of neutrophils in ascites indicate Ab needed in SBP?
more than 250 cells per mm3
when does it hint to be churns disease?
when affects stuff along the whole git - mouth to anus
