Skin + Micturition (SUGER) Flashcards
List some functions of the skin
- mechanical barrier (to infection)
- thermoregulation
- protection against trauma and UV
- vit D synthesis
- regulates water loss
what are the 5 layers of the epidermis?
- corneum (dead keratinised cells)
- lucidum (dead cells containing keratohyalin)
- granulosum (keratohyalin and protein envelope, cell begins dying)
- spinosum (keratin fibres and lamellar bodies)
- basale (mitotic cells migrate up to spinosum)
what is the outermost layer of the epidermis and what is it made of
stratum corneum - corneocytes (differentiated keratinocytes)
what are corneo-desmosomes aka and what do they do to corneocytes
adhesion molecules - keep them together
what is filaggrin derived from
profilaggrin
what does filaggrin produce
natural moisturising factor (NMF)
what are coenocytes filled with
NMF: helps maintain hydration of skin AND maintains acidic env on outer surface of stratum corneum
what is the pH of normal skin and why
5.5 - allows proteases to remain on skim: enables balance of new cells
what are goosebumps
arrestor pili muscle contractions
what is the brick wall model
corneocytes = bricks
corneodesmosomes = iron rods
lipid lamellae = cement
how does vit D defend the skin from bacteria and viruses
essential in prod of anti-microbial peptides
how do allergens trigger skin flare ups
by penetrating into the skin and causing skin to react as they are met with lymphocytes which release inflammation inducing chemicals
what is red skin
dilation of blood vessels (due to lymphocyte activity)
what is itchy skin
stimulation of nerves
what is dry skin
skin cells leaking (due to lymphocyte activity)
how does pH increase on the skin
if profilaggrin thus filaggrin are not present: lack of NMF: lack of water retention in corneocytes: pH increase
what does subcutaneous tissue have
lots of adipocytes
how does acne occur
- 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
how is urine transported to the bladder
through the ureters, propelled by contractions of the ureter wall smooth muscle
what are the detrusor muscles
- smooth muscle found in bladder wall
- remains relaxed to allow the bladder to store urine
- contracts during urination to release urine.
when the bladder is filling, what is parasympathetic input to the detrusor muscles like
minimal
when the detrusor muscle is relaxed, is the internal urethral sphincter open or closed?
passively closed
contraction of ______ can prevent urination even if detrusor muscles are contracting
externa urethral sphincter
where is the external urethral sphincter
just below the internal urethral sphincter, where a ring of skeletal muscle surrounds the urethra
where is the internal urethral sphincter
at the neck of the bladder where the urethra begins
what are the 4 steps of the reflex arc of micturition
- bladder fills with urine, walls stretch
- sensory nerves detect stretch and transmit to spinal cord
- interneurones in cord relay signal to PS efferents (pelvic nerve)
- pelvic nerve acts to contract detrusor muscle thus micturition is stimulated
which ParaSympathetic neurones (cause detrusors to contract)
Pelvic Splanchnic nerve s2-4
which afferent input inhibits the sympathetiC neurones (causes internal urethral sphincter to open)
hypogastriC nerve t1-l2
what are the somatic motor neurones (cause external urethral sphincter to relax)
pudendal nerve s2-4
what is the function of the urinary tract
- to collect urine
- store it under safe low pressure cond
- store until socially acceptable to release
