Skin + Micturition (SUGER)

Question 1

List some functions of the skin

Answer 1

• mechanical barrier (to infection)
• thermoregulation
• protection against trauma and UV
• vit D synthesis
• regulates water loss

Question 2

what are the 5 layers of the epidermis?

Answer 2

1. corneum (dead keratinised cells)
2. lucidum (dead cells containing keratohyalin)
3. granulosum (keratohyalin and protein envelope, cell begins dying)
4. spinosum (keratin fibres and lamellar bodies)
5. basale (mitotic cells migrate up to spinosum)

Question 3

what is the outermost layer of the epidermis and what is it made of

Answer 3

stratum corneum - corneocytes (differentiated keratinocytes)

Question 4

what are corneo-desmosomes aka and what do they do to corneocytes

Answer 4

adhesion molecules - keep them together

Question 5

what is filaggrin derived from

Answer 5

profilaggrin

Question 6

what does filaggrin produce

Answer 6

natural moisturising factor (NMF)

Question 7

what are coenocytes filled with

Answer 7

NMF: helps maintain hydration of skin AND maintains acidic env on outer surface of stratum corneum

Question 8

what is the pH of normal skin and why

Answer 8

5.5 - allows proteases to remain on skim: enables balance of new cells

Question 9

what are goosebumps

Answer 9

arrestor pili muscle contractions

Question 10

what is the brick wall model

Answer 10

corneocytes = bricks
corneodesmosomes = iron rods
lipid lamellae = cement

Question 11

how does vit D defend the skin from bacteria and viruses

Answer 11

essential in prod of anti-microbial peptides

Question 12

how do allergens trigger skin flare ups

Answer 12

by penetrating into the skin and causing skin to react as they are met with lymphocytes which release inflammation inducing chemicals

Question 13

what is red skin

Answer 13

dilation of blood vessels (due to lymphocyte activity)

Question 14

what is itchy skin

Answer 14

stimulation of nerves

Question 15

what is dry skin

Answer 15

skin cells leaking (due to lymphocyte activity)

Question 16

how does pH increase on the skin

Answer 16

if profilaggrin thus filaggrin are not present: lack of NMF: lack of water retention in corneocytes: pH increase

Question 17

what does subcutaneous tissue have

Answer 17

lots of adipocytes

Question 18

how does acne occur

Answer 18

• hypercornification –> corneodesmosomes block hair follicle entrnace
• increased serum production by sebaceous glands
• sebum becomes trapped in narrow hair follicle
• sebum stagnates at pit of follicle (no oxygen)
• anaerobic cond for bacteria to multiply
• irritation, inflammation and attraction of neutrophils –> pus formation

Question 19

how is urine transported to the bladder

Answer 19

through the ureters, propelled by contractions of the ureter wall smooth muscle

Question 20

what are the detrusor muscles

Answer 20

• smooth muscle found in bladder wall
• remains relaxed to allow the bladder to store urine
• contracts during urination to release urine.

Question 21

when the bladder is filling, what is parasympathetic input to the detrusor muscles like

Answer 21

minimal

Question 22

when the detrusor muscle is relaxed, is the internal urethral sphincter open or closed?

Answer 22

passively closed

Question 23

contraction of ______ can prevent urination even if detrusor muscles are contracting

Answer 23

externa urethral sphincter

Question 24

where is the external urethral sphincter

Answer 24

just below the internal urethral sphincter, where a ring of skeletal muscle surrounds the urethra

Question 25

where is the internal urethral sphincter

Answer 25

at the neck of the bladder where the urethra begins

Question 26

what are the 4 steps of the reflex arc of micturition

Answer 26

1. bladder fills with urine, walls stretch
2. sensory nerves detect stretch and transmit to spinal cord
3. interneurones in cord relay signal to PS efferents (pelvic nerve)
4. pelvic nerve acts to contract detrusor muscle thus micturition is stimulated

Question 27

which ParaSympathetic neurones (cause detrusors to contract)

Answer 27

Pelvic Splanchnic nerve s2-4

Question 28

which afferent input inhibits the sympathetiC neurones (causes internal urethral sphincter to open)

Answer 28

hypogastriC nerve t1-l2

Question 29

what are the somatic motor neurones (cause external urethral sphincter to relax)

Answer 29

pudendal nerve s2-4

Question 30

what is the function of the urinary tract

Answer 30

• to collect urine
• store it under safe low pressure cond
• store until socially acceptable to release