Formative Medical Sciences

what are the features of the anatomical position? (3)

a person standing upright facing forward

arms straight and hands facing forward

feet parallel and toes pointing forwards

what are the 3 anatomical planes?

Sagittal

Coronal

Transverse

what is the sagittal plane?

cuts into left and right

what is the coronal plane?

cuts into anterior and posterior

what is the transverse plane?

cuts into superior and inferior

what is flexion?

a movement that decreases the angle between 2 body parts

what is extension?

a movement that increases the angle between 2 body parts

what is abduction?

a movement away from the midline

what is adduction?

a movement towards the midline

what is medial rotation?

rotation towards the midline

what is another term for medial rotation?

internal rotation

what is lateral rotation?

rotation away from the midline

what is another term for lateral rotation?

external rotation

what is elevation?

to move in superior direction

what is depression?

to move in inferior direction

what is pronation?

palm/body facing down

what is supination?

palm/body facing up

what is dorsiflexion?

flexion at ankle - lifting the toes

what is the plantar surface of the foot?

sole of foot

what is the dorsum of the foot?

top of foot

what is plantarflexion?

extension at ankle - toes pointing down

what is inversion?

movement of sole towards the median plane

what is eversion?

movement of the sole away from median plane

what is opposition?

bringing the thumb and little finger together

what is reposition?

pulling the thumb and little finger back apart

what is protraction?

moving the shoulder anteriorly - reaching out for something

what is retraction?

moving the shoulder posteriorly

what is retropulsion?

food is propelled back into the stomach to be mixed when a wave of contraction closes the pyloric sphincter

what increases gastric motility? (3)

- parasympathetic innervation

- gastrin

- motilin (from mo cells in small intestine)

what decreases gastric motility? (3)

- sympathetic innervation

- secretin

- GIP

what does a vagovagal reflex mean?

both afferent and efferent limbs of the reflex are carried by the vagus nerve

how long does it take to empty stomach?

2-6 hours

why do we need to regulate gastric emptying?

to give enough time for small intestine to:

- H+ neutralisation

- digestion and absorption

what slows down gastric emptying?

presence of fats and H+ in duodenum

do solids or liquids empty faster?

liquids

do isotonic or hyper/hypotonic solutions empty faster?

isotonic

what is vagotomy?

severing of vagus nerve - to decrease gastric acid secretions to reduce stomach ulcers

what is the definition of digestion?

the chemical breakdown of ingested foods into absorbable molecules

what are the 3 types of ingested carbs?

- polysaccharides

- disaccharides

- monosaccharides

what are 2 examples of polysaccharides?

- starch

- glycogen

what are 4 examples of disaccharides?

- sucrose

- lactose

- maltose

- trehalose

what are 3 examples of monosaccharides?

- glucose

- fructose

- galactose

which type of saccharide can intestinal cells absorb?

only monosaccharides

what are the enzymes that break down starch and glycogen?

salivary and pancreatic amylases

which bonds do the amylases break?

a-1,4 glycosidic bonds which are the interior bonds

what are the products of amylase action?

- maltose (disaccharide)

- maltotriose (trisaccharide)

- a-limit dextrins (oligosaccharide)

name 4 enzymes that break down the oligosaccharides into monosaccharides

- glucoamylase (maltase)

- isomaltase (a-dextrinase)

- sucrase

- lactase

where are the enzymes that break down oligosaccharides into monosaccharides released from?

the brush border of enterocytes

what does glucoamylase (maltase) breakdown and into?

breaks down:

- maltose

- maltotriose

- a-limit dextrins

into:

- glucose

what does isomlatase (a-dextrinase) breakdown and into?

breaks down:

- a-limit dextrins

into:

- glucose

what does lactase breakdown and into?

breaks down:

- lactose

into:

- glucose and galactose

what does sucrase breakdown and into?

breaks down:

- sucrose

- maltose

- maltotriose

into:

- sucrose into glucose and fructose

- m&m into just glucose

what protein-digesting enzyme works in the stomach?

pepsin

what does pepsin do?

hydrolyses peptide bonds

is pepsin an endo or exopeptidase?

endopeptidase

where and how is pepsin deactivated?

- in the duodenum

- by the alkaline pH

what are the pancreatic proteases precursors?

- trypsinogen

- chymotrypsinogen

- proelastease

- procarboxypeptidase A

- procarboxypeptidase B

what is the first trigger in precursor activation?

trypsinogen is converted to trypsin by enteropeptidase

where is enteropeptidase released from?

secreted by the duodenal and jejunal mucosa

what does trypsin do?

causes the activation of many other precursors:

- more trypsinogen - trypsin

- chymotrypsinogen - chymotrypsin

- proelastase - elastase

- procarboxypeptidase A - carboxypeptidase A

- procarboxypeptidase B - carboxypeptidase B

which proteases are endopeptidases?

- trypsin

- elastase

- chymotrypsin

which proteases are exopeptidases?

- carboxypeptidase A

- carboxypeptidase B

what is the next stage of protein digestion?

peptidases in on the brush border of enterocytes break down peptide chains further into small peptides and single AAs

can enterocytes absorb small peptide chains?

yes

what happens to the small peptide chains once absorbed?

they are broken down to single AAs inside the enterocytes

what are the 3 main dietary lipids?

- triglycerides

- cholesterol

- phospholipids

what makes digestion and absorption more difficult for lipids?

they are water-insoluble

what are the 3 lipases?

- lingual lipase

- gastric lipase

- pancreatic lipase

how does the stomach help lipid digestion?

- churning breaks down lipids into smaller droplets to increase surface area

where does most lipid digestion take place?

small intestine

does pancreatic lipase have a precursor?

no, it is secreted as the active enzyme

what is the problem with pancreatic lipase in the SI?

it gets inactivated by bile salts because they displace it in the interaction with lipid droplets

how is the problem resolved?

colipase is released which displaces the bile salts

what is pharmacokinetics?

what the body does to the drug

what does pharmacokinetics determine? (3)

- how much drug reaches the target

- how quickly the drug starts to have an effect

- the duration of the effect

what are the different routes of administration? (5)

- oral

- inhalation

- topical (creams)

- injection

- rectal/vaginal

what determines a drugs pharmacokinetics? (4)

Absorption

Distribution

Metabolism

Excretion

what determines the absorption of the drug? (2)

- bioavailability

- gut absorption

what is bioavailability?

the fraction of the administered dose that reaches the systemic circulation unchanged

what is the bioavailability of intravenous administration?

100%

for orally given drugs, what is bioavailability determined by? (3)

- stability in gut contents

- absorption across gut wall

- degree of first pass metabolism

what determines the gut absorption of a drug? (3)

- surface area

- gastric emptying (delayed will increase absorption)

- gut motility (decreased gut motility will increase absorption)

what does distribution mean?

movement and storage around the body

what is the equation for volume of distribution?

Vd = Q/C

C - plasma concentration

Q - dose of drug

Vd - volume of blood

what is the half-life of a drug?

the time taken for the plasma concentration of the drug to fall to half of its original value

what does decreased drug metabolism lead to?

Increased plasma drug conc

Increased biological response

what does increased drug metabolism lead to?

- decreased plasma drug conc

- decreased biological response

decreased renal excretion leads to?

- increased plasma drug conc

- increased biological response

what is drug clearance?

the rate of elimination of the drug from the body in terms of the volume of blood

what is the equation for drug clearance?

clearance = elimination rate/concentration

what are the 4 main stages of the cell cycle?

- G1 phase

- S phase

- G2 phase

- M phase

what is the extra stage that can take place instead of G1 to S phase?

G0

what happens in G0?

cell is dormant - no growth

are all cell cycles stages the same length in different organisms?

no, they can vary

what stages do early embryonic cell cycles lack?

no G1 or G2 phases

do embryonic cell cycles tend to be synchronous or asynchronous?

synchronous

do somatic cell cycles tend to be synchronous or asynchronous?

asynchronous

what happens in the s-phase?

DNA replication

what is an origin in the genome?

a place where DNA replication can start

if a genome has more origins what does this mean for DNA replication?

it can take place faster