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:))))))) Flashcards

1
Q

what are DEXA scans?

A

= two different, low energy x-ray sources; more precise and accurate calculation of density

a) the denser the bone the fewer the x-rays get to detector
b) used for diagnosis of osteoperosis (health condition that weakens bones)
c) can measure BMI and fat (more precise soft tissue measurements)

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2
Q

what are the different types of x-ray contrast media?

which makes tissue denser / less denser?

A

contrast media

  • use air to reduce density of hollow organ soft tissue (esp. GI system): creates negative contrast
  • e.g. can see large intestine more

OR
- can make tissue denser: liquid contrast media used are barium and iodine. non-toxic substances that contain elements of high atomic number - increased atomic number

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3
Q

what is method and what does barium sulphate and iodine highlight when used as contrast media?

A

1. barium sulphate:

  • highlight: GI system
  • method: swallow barium meal / enema

2. iodine - angiography

highlights: blood vessels
method: injection of iodine

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4
Q
A
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5
Q

what does MRI show what are the two types?

A
  • v high soft tissue contrast
  • get two views: T1: normal anatomical structure and T2: good for pathology - can see water in bone (oedema)
  • *T1:**
    a) in brain: good gray/white matter contrast (fat: white = myelin, yellow = bone marrow etc)
    b) white is fat
  • *T2: pathology.**
    a) white is fluid (water)
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6
Q

what is the contrast medium for MRI?

which scan does it give more detail in?

A

gadolinium contrast

  • changes relaxation time of H ion spin
  • gives more detail in T2
  • gadolinium highlights breakdowns of blood brain barrier (normally cant go through them)
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7
Q

what is doppler ultrsound?

A

shows blood flow direction:

- red = towards transducer

- blue = away from transducer

can measure blood flow

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8
Q

which ducts drain into the duodenum?

A

pancreatic and bile ducts drain into duodenum

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9
Q

how do you describe the different organs that located with the peritoneum?

A
  • organs stuck to the posterior abdomen wall: peritoneum covers the anterior surface of the organ (these organs = retroperiotneal organs)
  • organs that are full covered: intraperitoneal organs
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10
Q

what are the intraperitoneal folds?

A

GO: greater omentum fold

LO: lesser omentum fold

M: mesentery folds

MC: mesocolon fold

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11
Q

what is the epiploic foramen?

A

The epiploic foramen (also called the foramen of Winslow) is a passage between the greater sac (peritoneal cavity proper) and the lesser sac (omental bursa), allowing communication between these two spaces.

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12
Q

what is a drug?

A

any substance that interacts with a molecule or protein that plays a reg. role in living systems:

  • hormones: endogenous drugs
  • poisons
  • toxins are poisons of biological origins
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13
Q

which systems do inverse agonists work in?

A
  • only work on systems that are constitutively active: autonomic NS and histomine systems
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14
Q

which type of pharmocological antagonists:

  1. reduces agonist efficacy?
  2. reduces agonist potency?
A
  1. reduces agonist efficacy: non-competitive antagonist
  2. reduces agonist potency: competitive antagonist
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15
Q

what is a physiological antagonist? e.g.?

A

physiological antagonist: two drugs that have exactly opposite actions via different pathways

  • e.g. adrenaline when have allergic reaction (oppposite effect and pathways to histamines)
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16
Q

what type of drug is heparin?

A

chemical antagonist

  • binds to thrombin and inactivates it: stops thrombin to going to clotting cascade
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17
Q

what do most drugs tend to be?

what are their properties?

A

weak acid or weak base (incomplete dissociation in water)

  • less H and negative charges (than strong acid)
  • undissociated form of acid / base
  • lipid soluble
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18
Q

a protonated (less dissociated / proton still there) weak acid is more X soluble?

an un-protonated (more dissociated / proton left) strong acid is more X soluble?

what happens to a protonated drug in the kidney?

A
  1. lipid soluble (liphophilic)
  2. water soluble (hydrophilic)
  3. almost all drugs are filtered by kidneys
    - protonated drug in kidney: reabsorbed back into blood
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19
Q

what can affect the action of a drug?

what are the three sub categories of ^?

A

other drugs
- allosteric interactions: indirectly affect receptor -> affect efficacy or binding affinity

  • allosteric activators; increase activation of receptor
  • allosteric inhibitors: decrease activity of the receptor
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20
Q

what is EC50?

A

Half maximal effective concentration (EC50) refers to the concentration of a drug, antibody or toxicant which induces a response halfway between the baseline and maximum after a specified exposure time.[1]

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21
Q

where do drugs with large / small VD distributed to?

A

Large VD: distributed to tissues (fat / bones)

Small VD: distributed to blood

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22
Q

why may drugs stay in the blood as opposed to going to tissues? (2)

A
  1. molecule is too large to leave
  2. molecule binds preferably to v (albumin) / less to tissue proteins
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23
Q

what is the relationship between drugs working and proteins in the blood?

A
  • drugs are only active when unbound to proteins: unbound drugs are excreted quickly
  • drug bound to protein: pharmacologically inactive. non-diffusable, non-metabolised and non excreted
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24
Q

what can happen to other drugs in body if you stop / start a drug that binds to proteins?

explain using warfarin (anticoagulant) and phenytoin (anti seizure) drugs

A

changes the level of the other protein bound drugs

e.g. warfarin (anticoagulant) and phenytoin (anti-seizure):

  • both normally bind to albumin (low VD)
  • for surgery: stop warfarin = more sites on albumin for phenytoin to bind
  • patient may have seizure
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25
Q

what also can effect the distribution of drugs? (for unbound drugs)

A
  • *unbound:**
  • capillary structure (blood brain barrier)
  • chemical nature of drug
  • blood flow through tissues (hydrophobic drugs0
  • presences of non active binding drugs
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26
Q

name 4 clinically important receptors for each main type of receptors

A
  • ligand gated ion channel: GABAA receptor
  • g-protein coupled receptors: B-adrenoreceptor
  • kinase-linked receptors (like tyrosine): VEGF receptor
  • nuclear receptors: Oestrogen receptor
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27
Q

what type of molecules bind to intracellular receptor proteins?

how work?

give 4 e.g.s of these signal molecules

A
  1. steriod hormones
  2. thryoid hormones
  3. retinoids
  4. vitamin D

all hydrophobic signal molecules (hydrophilic drugs cant pass through cell membrane)

work by:

a) activating nuclear receptors: can bind to DNA regions
b) regulate gene transcription

28
Q

what is a) tolerance? b) tachyphylaxis?

how do ^ occur?

A

. tachyphylaxis: acute tolerance from rapid and repeated admin of drugs in short intervals (the image)

  1. tolerance: chronic longer term admin can reduce drug effect (e.g. alchohol)

mechanisms for tolerance or tachyphylaxis:

  1. receptor desensitized or loss of receptors
  2. receptor internalisation (degraded in lysosome)
  3. increased metaboloic degradation of drug
29
Q

how can we regulate amount of receptor on membrane?

A

via process of B Arrestin mediated internalisation:

  • B-arrestin binds to gcpr
  • B-arrestin desensitised
  • B-arrestin internalised
  • B-arrestin recyled
    OR
    -B-arrestin degraded
30
Q

what protein regulates the amount B-adrenoceptor at the membrane?

A

B-arrestin

31
Q

which method of administration of drugs goes straight into the CSF?

A

intrathecal (into CSF )

32
Q

which family of enzymes undergoes oxidation reaction in biotransformation?

A

cytochrome P450 family enzymes

33
Q

what happens to drugs if reabsorbed back into bile?

if phase 1 drug? phase 2 drug?

A

if goes back via bile:

  • goes back into GI system:

i) phase 1 drug: reabsorbed from GI system and goes back to liver 4 further met.
ii) phase 2 drug: exits via defecation

34
Q

what is clearance?

how calculate?

A

clearance: rate of elimination in relation to the drug concentration

clearance = rate of elimination (through urine) / concentration remaining (in blood plasma)

35
Q

how do u work out 1/2 life of a drug?

A
36
Q

what are two different types of dosing?

A
  • *loading dose:**
  • larger than normal dose
  • gets to therapeutic range quicker (emergencies)
  • mainly for drugs with large vol. of distribution
  • *maintenance dose:**
  • small fixed dose
  • maintains drug in therapeutic range
37
Q

what are NANC neurons?

where found?

what are the NTs used ? (probs dont need to know exact)

A
  • NANC = non-adrenergic non cholinergic neurons (NTs aren’t adreneric or cholinergic class)
  • location: peripheral tissues - smooth muscle in GI, airways and reproductive tracts
  • NTs: nitric oxide, ATP, 5HTP, neuropeptide Y
38
Q

explain structure of nicotinic receptor

where are the different a subunits found (awareness)?

A

- pentameric sodium ion channel

  • *- 2 alpha subunits:**
  • alpha 3 found on autonomic ganglia
  • alpha 1 found on neuromuscular junction
  • alpha 4 & 7 found in CNS

- 3 beta subuits

39
Q

which receptors do both acetylcholine & carbachol work on? what does this mean as a consq?

what is carbachol used to treat?

A
  • work at both nicotinic and muscarinic receptors: have an effect on both para and sympathetic NS
  • carbachol: treats glaucoma
40
Q

how many types of muscarinic receptors are there? which ones are inhib/ excitatory? - what are second messengers for inhibit / excitatory?

A

5 types:

  • M1 = excitatory: 2nd messenger = IP3 & DAG
  • M2 = inhibitory: 2nd messenger = cAMP
  • M3 = excitatory: 2nd messenger = IP3 & DAG
  • M4 and M5 in CNS (dont need to know)
41
Q

what does clostridium botulinum bacteria do?

how effect?

A

botulinium toxin (botox)

  • prevents ACh release: stops synapse signalling
  • irreversble
  • can be used for XS sweating, overactive bladder or muscle spasms
42
Q

what do sympathomimetics do?

what are two important classes?

A

produces a similar response as noradrenaline and adrenaline on the sympathetic NS

classes:

  • *i) monoamines
    ii) catecholamines (e.g. noradrenaline, adrenoline)**
43
Q

what type of receptors are adrenoreceptors? what does that mean ?

A

GCPR - can have excitatory or inhibitory response (depending on 2nd messenger system)

44
Q

what do cholinesterase inhbitors do?

A
  • stimulate GI function
  • cognitive enhancers (given to AD patients)
  • skeletal muscle activity
45
Q

what variants of adrenoreceptors are there? which are pre / post synaptic? excitatory or inhbitor?

A
  • *alpha**:
  • alpha 1: postsynaptic excitatory
  • alpha 2: presynaptic. inhbits further release of noradrenaline
  • *beta**:
  • beta 1: postsynaptic excitatory
  • beta 2: postsynaptic excitatory
  • beta 3: postsynaptic excitatory
46
Q

which muscarinic receptor is found in the eye, lung and gut? what is agonist / antagonist drug for thAT has effects on them

A

M3:

  • *i) eye:**
  • pilocarpine: pupil constrict (agonist)
  • tropicamide: pupil dilates (antagonist)
  • *ii) lungs:**
  • ipatroprium: lungs conflate (antagonist)
  • *iii) gut:**
  • neostgimine: gut more moveable (antagonist)
  • scopolamine: inhibits peristalsis - antispasmodic (agonist)
47
Q

what is thalidomide? how was it involved in tragedy?

A
  • prescribed as sedative or hypnotic:
  • S-thalidamide = effective sedative
  • *- R-thalidamide** = teratogenic (an agent that can disturb the development of the embryo or fetus​)

both given - made disformities

48
Q

what is ECM made from?

A

▪ Collagens: Major protein of the body (25%) and The ECM

▪Elastin: Provides elasticity and resilience to tissues such as the arteries, lungs, tendons, skin, and ligaments

▪Glycoproteins:
Molecules made up of proteins and carbohydrates e.g., laminin and fibronectin
Found on the surface of the lipid bilayer of cell membranes (cell surface)

▪Proteoglycans:
Molecules made up of a core protein attached to glycosaminoglycans (GAGs)
Found in connective tissues

49
Q

what does integrin do?

A

it is a adhesion protein, found in lipid bilayer of cells. helps to hold up the cell on the ECM

50
Q

what do actin filaments do? where found?

A

found in cytoplasm, part of cytoskeleton:

  1. cause the cell to be held in place
  2. structural support
51
Q
A
52
Q

can you give two examples of when cells migrate?

A
  1. embryo development
  2. cancer development
53
Q

what is structure of collagen like?

A

Triple helical structure formed by 3 peptide chains

: ▪every 3rd amino acid is glycine

▪Gly-X-Y (proline-hydroxyproline)

54
Q

what do changes in ECM characteristics show?

what is fibrosis?

A

too much ECM - assocaited with chronic disease

fibrosis: too much ECM - becomes tough

55
Q

explain difference between fibrillar and non-fibrillar collagen

A
  • *non-fibrillar collagen:**
  • *-**forms microfibrils or mesh-like structures.
  • therefore is used for anchorage of cells and filtration
  • major structural components of basement membranes - relatively thin layers of ECM
  • *fibrillar collagen:**
  • forms well-organised banded fibrils, with provide high tensile strength. therefore is used for major components in tendons, ligaments, skin etc
56
Q
A
57
Q

what is Osteogenesis imperfecta?

how is Osteogenesis imperfecta formed?

A

brittle bone disorder

in type 1 collagen: single base mutations cause Gly to convert to bulky amino acid. this prevents the corrected triple helix formation of collagen into fibrils. therefore is loose triple helix

58
Q

what are the two types ofOsteogenesis imperfecta?

A
  • *Type 1:**
    a) autosomal dominant
    b) most common - 50% of cases
    c) mildest type
    d) COL1A1 & A2 genes are mutated on chr. 17 and 7 respectively. causes an amino acid change - looser collagen chain and looser triple helix.
  • *Type 2:**
  • more severe - babies born with so many broken bones they die.
  • usually new mutation
  • dominant if affected individuals survive
59
Q
A
60
Q

what is structure of elastin like?

A
  • rich in glycine and proline - like collagen, but has more valine which interacts with hydrophobic domains, therefore makes it elastic.
  • elastin fibres are normally covered by the glycoprotein fibrillin.
  • can stretch in 2D.
  • when in relaxed state, fibres are jumbled. when stretch - stretches out and gives flex.
61
Q
A
62
Q

what is Marfan syndrome?

A

-rare genetic disease (1/10000)

- fibrillin protein is mutated and usually absent:

characteristics:
tall stature, long arms and legs, arachnodactyly (spider fingers), loose joints, floppy cardiac valves, eye problems, aortic aneurysms

63
Q

what are roles of glycoproteins in ECM?

A

receptors of cell surfaces for:
- bacteria, viruses and toxins. START immune response

hormones

strength and support to ECM

slime layer of bacteria and flagella

64
Q
A
65
Q

what are laminin and fibronectin and what are their roles?

A

both glycoproteins

1. laminin:

  • cell adhesion to the ECM.
  • cell migration
  • cytoskeleton organisation

2. fibronectin
cell adhesion to the ECM.
cell migration
cell shape
cell differentiation
cytoskeleton organisation

66
Q

what are proteoglycans?

how do proteoglycans change with age?

A
  • *proteoglycans:**
  • Proteoglycans form large aggregates within tissues made up of lots of side chains of negatively charged GAGs
  • peptide chain with covalently bound sugars. - mainly made of GAGs (glycosaminoglycans)
  • 95% carb, 5% protein
  • GAG side chains have sulphate group - gives a negative charge. this attracts water and so water moves into ECM
  • gel forming components of ECM.

with age:
decrease with age
- shorter core and fewer side chains
- draw and hold less water in tissue
- more likely to be damaged
e.g. in vertebral discs lose water - THIS IS WHY YOU GET SMALLER IN AGE

  • *with healing:**
  • They are upregulated in damaged areas
  • They cause oedema associated with the original injury
  • They provide nutrients and growth
67
Q
A

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