Medi1000 Set 1

Front 1

The beta cells of the pancreas are good sensors of plasma concentrations of glucose. How is this achieved?

Back 1

GLUT 2 and glucokinase both have much higher Km values (ie lower affinity) than ur average GLUT1,3 and hexokinase. This means they are sensitive to a wider range of change in [glucose]

Front 2

Insulin secretion from beta cells in 6 steps

Back 2

1. glucose enters GLUT 2
2. incr glycolysis = incr ATP
3. inhibition of ATP-sensitive K channel
4. depolarisation
5. v-gated Ca ch Open
6. exocytosis

Front 3

Endocrine cells take up approx how much of the pancreas cell mass?

Back 3

2%

Front 4

Describe insulin synthesis

Back 4

it's a polypeptide hormone. Preproinsulin, proinsulin (A and B chain linked by disulphide bonds, C peptide joins them), cleavage leads to insulin

Front 5

Cell types in the islets of langerhan. Relative abundance and what they secrete

Back 5

Beta cells 60% insulin
alpha cells 25% glucagon
delta cells somatostatin

Front 6

The insulin receptor is what kind of a receptor?

Back 6

tyrosine kinase

Front 7

Define shock, and the formula for a good indicator

Back 7

Shock = multisystem hypoperfusion. HR > systolic BP is a useful indicator

Front 8

An anaphylactic shock is what type of shock? General mechs of this type of shock?

Back 8

Distributive, other eg = septic shock. Systemic vasodilation leads to decr BP, "warm" shock

Front 9

3 main types of shock

Back 9

Hypovolaemic, cardiogenic, distributive (others = neurogenic [resulting in vasodilation], obstructive [obstruction of bld flow to heart or lungs])

Front 10

Shock - Signs and symptoms

Back 10

stage 1 (compensated): pallor, slight anxiety
Uncompensated = ↑ HR, ↓ BP, ↓ pulse pressure. ↑ RR, sweating, cold clammy skin, altered mental state, ↓ cap return, ↓ urine output

Front 11

Isotype of Ig predominant in response to secondary infection

Back 11

IgG

Front 12

Isotype of Ig predominant in response to a primary infection

Back 12

IgM

Front 13

Which Ig isotype works mostly by neutralising ag in the GIT and secretory ducts?

Back 13

IgA

Front 14

Egs of primary immunodeficiency

Back 14

Chronic Granulomatous Disease (neutrophil can’t produce superoxides)
Hyper IgM Syndrome (no class switching)
DiGeorge syndrome (thymic aplasia → T cell deficiency)

Front 15

Secondary immunodeficiency can be caused by?

Back 15

HIV infection → AIDS, malnutrition

Front 16

Define failure to thrive

Back 16

Bottom 3rd-5th percentile on 2 or more occasions

Drop in 2 major percentiles in 6 mths

Front 17

Differences between thick and thin skin

Back 17

Thick skin: hairless, palms and feet, thicker epidermis, has stratum lucidum; interface between dermis and epidermis has ridges = finger prints

Front 18

Layers of the epidermis

Back 18

Stratum germinativum/basale (single layer, stem cells)
Stratum spinosum (start to accumulate keratin and flatten/elongate)
Stratum granulosum (keratohyalin granules – densely staining; nuclei starts to degenerate)
Stratum lucidum (thick skin only)
Stratum corneum (dead anuclear cells packed with keratin)

Front 19

How do keratinocytes come to possess melanosomes?

Back 19

Melanocytes found between cells of stratum germinativum synthesise melanin. Melanosomes are passed to keratinocytes from the melanocyte dendrites.

Front 20

Two layers of dermis

Back 20

Papillary (superficial)

Reticular (the main bulk)

Front 21

Pathogenesis of inflammatory acne vulgaris (4 elements)

Back 21

1. Comedogenesis: abnormal keratinisation of sebaceous follicle epithelium → plugged pilosebaceous unit = white heads (closed comedone) or black heads (opened)

2. ↑ Sebum production (eg. due to androgens in puberty)

3. Proliferation of P. acnes

4. Inflammatory response, can be exacerbated by follicular wall rupture → spillage of contents into dermis

Front 22

What is a sebaceous follicle?

Back 22

Pilosebaceous unit
– secretes sebum direct to skin surface
- produce fine vellus hair
- large sebaceous gland
- widely dilated follicular canal (stratified squamous keratinising epithelium)
- site of Acne!
v.s. sebaceous glands, which secrete sebum into hair follicle

Front 23

Sebum is…?

Back 23

Lipid based secretion, contains triglyceride, cholesterol, protein, electrolyte. Maintains hydration of epidermis and hair, antibacterial. Secreted by sebaceous glands and follicles.

Front 24

What’s wrong with the statement “acnes vulgaris is an infection”?

Back 24

It’s not. it’s an inflammation.

Front 25

Define diarrhoea

Back 25

↑ volume, ↑ frequency and/or Δ consistency

Front 26

Mechanisms of diarrhoea

Back 26

MODES

Malabsorption (→ osmotic diarrhoea; eg. vilous atrophy in celiac disease; lack of digestion/impaired enzyme activity)

Osmotic: eg. lactose intolerance + above for malabsorption)

Deranged motility: increased (→ ↓absorption) or decreased (→ ↑bact growth → bile acid deconjugation → steatorrhoea and diarrhoea)

Exudative/inflammatory: damage to mucosa → inflammation → blood, pus, mucus in faeces eg. dysentery, infections (Salmonella, Shigella, Campylobacter) or inflammatory bowel disease)

Secretory: abnormal ion transport → increase secretion (eg. cholera) or decreased absorption, or both. No structural damage

Mechanisms rarely occur alone

Front 27

Digestion of carbohydrates

Back 27

Amylase (salivary and pancreatic) breaks down polysaccharides → di- and trisaccharide arrive at SI → brush border enzymes cleaves → monosaccharide (maltase, lactase, sucrase)

Glucose and galactose enter brush border cell via cotransporter SGLT 1, fructose via facilitated diffusion through GLUT 5

Front 28

Digestion of proteins

Back 28

Stomach: pepsin and HCl
Duodenum: pancreatic enzymes
SI: peptidases tethered to brushborder → small peptides and aa transported into epithelial cell. intracell peptidase cleaves small peptide into aa

Front 29

Digestion of lipids

Back 29

Lipases (lingual, gastric (min amount)+ PANCREATIC)
Bile salts → emulsification of lipids → ↑ surface area for lipase contact
fatty acids, cholesterol and monoglycerides arrive at SI, diffuse into epithelial cells. Made → TAG → chylomicron and transported to lacteal (too big for capillary) → lymph. Small and medium FA → released straight into blood → bind to albumin.

Front 30

Most absorption of nutrients occurs in which region of the small intestine?

Back 30

Jejunum
Duodenum = some lipid and aa; Ileum = bile salt and vit B12, the only site where these can be absorbed