Skin + Reproductive Flashcards
What are the 4 main layers of the epidermis of the skin?
- Keratinised squames.
- Granular layer.
- Spinous layer (the thickest layer).
- Germinative layer.
What is the role of Filaggrin?
Produces natural moisturising factor.
Why are protease inhibitors in the skin important?
Protease inhibitors prevent the breakdown of corneodesmosomes.
What is the ideal pH of the skin?
5.5
What is the SRY protein called?
Testis determining factor: under its influence male development takes place.
What is the importance of testis determining factor?
Under its influence male development takes place.
What cells are responsible for secreting testosterone?
Interstitial cells of Leydig.
What is the blood supply to the upper 2/3 of the anal canal?
The superior rectal artery (branch of IMA).
What is the blood supply to the lower 1/3 of the anal canal?
The inferior rectal artery (branch of internal pudendal artery).
What part of the anal canal receives autonomic innervation?
The upper 2/3 (lower 1/3 is somatic innervation).
Which anal sphincter receives autonomic innervation and is involuntary?
The internal anal sphincter.
Which urethral sphincter is composed of smooth muscle?
The internal urethral sphincter.
When is the periaqueductal grey suppressed?
In storage. (Active in voiding).
What is the external urethral sphincter?
Skeletal muscle, voluntary sphincter.
Composed of the rhabosphincter and pelvic floor.
Do the urethral sphincters receive parasympathetic or sympathetic innervation?
Sympathetic.
When are the urethral sphincters activated?
In storage - activation causes contraction of the sphincters.
Spermatogenesis: what do type B cells differentiate into?
They differentiate into primary spermatocytes that will then go onto meiosis.
Spermatogenesis: where are type A cells located?
Outside the blood-testes-barrier.
Spermatogenesis: what does meiosis 1 produce?
2 secondary spermatocytes.
Spermatogenesis: what does meiosis 2 produce?
4 spermatids.
What changes does the sperm make with regards to its structure?
- It discards excess cytoplasm.
- Grows flagellum.
- Lots of mitochondria.
- Acrosomes at its head.
What is the function of the epididymis?
Storage and maturation of sperm. Sperm normally stay in the epididymis for 60 days.
What is the affect of FSH on the testes?
Stimulates spermatogenesis and sertoli cells. Sertoli cells produce MIF (mullerian inhibiting factor) and inhibin and activin which acts on the pituitary gland to regulate FSH.
What is the affect of LH on the testes?
Stimulates Leydig cells to produce testosterone.
What is ovulation?
The release of an oocyte from a follicle.
What hormone stimulates ovulation?
LH.
In humans, is the sex of the embryo determined by the sperm or egg?
The sperm - can contribute an X or Y. The egg is always X.
What is the secretory phase?
When the corpus luteum releases progesterone and the endometrium generates blood vessels and proteins etc needed for the implantation of a fertilised embryo.
What is the proliferative phase?
When the endometrium grows rapidly under the influence of oestrogen.
What does the corpus luteum degenerate into?
The corpus albicans.
What is capacitation?
The final stage of sperm maturation that occurs in the female genitalia. Before this spermatozoa would be unable to fertilise an oocyte.
What is block to polyspermy?
After a sperm has fertilised the egg, the egg needs to prevent further sperm fertilising it.
What are the mechanisms to ensure block to polyspermy?
Enzymes are released that harden the zona pellucida and inactivate sperm binding sites.
What hormone does the hypothalamus release that stimulates release of the gonadotropins?
GnRH - gonadotropin releasing hormone.
What cells does FSH act on in males?
Sertoli cells.
What cells does FSH act on in females?
Granulosa cells.
What cells does LH act on in males?
Leydig cells.
What cells does LH act on in females?
Theca cells.
What is the function of sertoli cells?
They release MIF, inhibin and activins (regulate FSH secretion), and androgen binding protein (increases testosterone concentration).
What is the function of granulosa cells?
They convert androgens into oestrogen using aromatase enzyme.
What is the function of leydig cells?
they produce testosterone.
What is the function of theca cells?
They produce androgens (oestrogen precursors) which diffuse into granulosa cells to form oestrogen.
What enzyme converts androgens into oestrogen?
Aromatase.
What is the predominant hormone responsible for the proliferative phase?
Oestrogen.
What is the predominant hormone responsible for the secretory phase?
Progesterone.
Where do primordial germ cells originate from in the embryo?
The epiblast.
Until what week are male and female primitive gonads identical?
Week 6.
What is the mesovarium?
Mesentery attaching the ovary to the posterior broad ligament.
Define menopause.
Cessation of menstruation.
What physiological changes happen in menopause?
There is depletion of the primordial follicles. Oestrogen levels decrease; FSH and LH therefore increase as they’re not inhibited by negative feedback.
What happens to oestrogen levels at menopause?
They fall.
What happens to LH and FSH levels at menopause?
They increase as they’re no longer inhibited by negative feedback.
What are the short-term symptoms of menopause?
Hot flushes, night sweats, palpitations, irritability, lethargy, decreased libido, vaginal dryness, vaginal pH change, dry skin and hair, brittle nails.
What are the long-term symptoms of menopause?
Osteoporosis and increased risk of cardiovascular disease.
Name 4 treatments that can help with the symptoms of menopause.
- HRT.
- Sedatives.
- Calcium supplements.
- Vitamin D supplements.
What hormones are given in HRT?
Oestrogen and progesterone.
What is the advantage of HRT being given as a patch as opposed to orally?
The hormones go straight into the bloodstream and so bypass the liver.
What are the risks of HRT?
Small increased risk of cervical, breast and endometrial cancer.
What are the two main types of stem cells?
- Embryonic stem cells - pluripotent.
- Somatic stem cells - multi-potent.
Name 3 diseases that stem cells could help to cure.
- Parkinsons disease.
- Alzheimers.
- Type 1 diabetes.
What are the 3 main characteristics of stem cells?
- Self renew over long periods.
- Undifferentiated.
- Can generate other cells: pluripotent/multipotent.
Where in the embryo do embryonic stem cells come from?
The inner cell mass.
What are the 3 histological layers of the uterus?
- Endometrium - mucosal lining, pseudostratified columnar.
- Myometrium - smooth muscle wall.
- Perimetrium.
What is the function of the smooth muscle in the myometrium?
It helps the uterus to expand and acts to protect the foetus. It also provides a mechanism for foetal expulsion.
What are the characteristics of the endometrium in the proliferative phase?
Straight glands, no secretions. Stromal and epithelial mitoses.
What are the characteristics of the endometrium in the early secretory phase?
Coiling of glands and subnuclear vacuoles
What is the decidua basalis?
A part of the endometrium invaded by trophoblast.
What is the decidua capsularis?
A part of the endometrium overlying the blastocyst.
What is the decidua parietalis?
Endometrium lining the rest of the uterine cavity.
What invades the decidua basalis?
Syncytiotrophoblast.
What is the role of the syncytiotrophoblast?
Uptake of oxygen and nutrients from the maternal blood.
Release of CO2 and waste products into the maternal blood. The exchange surface is gradually increased during maturation due to branching of the villi.
What is the role of the cytotrophoblast?
Forms solid masses covered by syncytiotrophoblast - primary chorionic villi. These masses become filled with stroma, forming secondary chorionic villi. Capillaries appear in the stroma – tertiary chorionic villi.
What hormonal pathway is likely to be responsible for a decrease in urine production?
Renin angiotensin aldosterone system.
Why is it important that the chorionic villi branch in maturation?
Branching increases the surface area for exchange of nutrients.
Why can a tumour of the pituitary gland affect vision?
The optic chiasm lies just above the pituitary gland and is likely to be affected if there’s a tumour.
What are the two types of hormone?
- Made at response e.g. steroids.
- Stored and released at response e.g. pituitary hormones (peptides).
Where are the receptors for steroid hormones located?
Steroid receptors are intracellular - steroids pass through plasma membranes bound to proteins.
Where are the receptors for peptide hormones located?
On cell membranes.
What are the purposes of the endocrine system?
- Communication between cells.
- Integrates whole body physiology.
- It can make rapid adaptive changes.
- Maintains the metabolic environment.
Briefly describe the mechanism of ACTH.
Hypothalamus -> CRH -> anterior pituitary -> ACTH -> adrenal glands -> cortisol release -> negative feedback on hypothalamus and pituitary.
Briefly describe the mechanism of LH and FSH.
Hypothalamus -> GnRH -> anterior pituitary -> FSH/LH -> sertoli cells, leydig cells/granulosa cells, theca cells -> oestrogen, testosterone, inhibin -> negative feedback on hypothalamus and pituitary.
How would you describe growth hormone secretion from the anterior pituitary?
It is secreted in a pulsatile fashion and increases during deep sleep.
What factors effect growth hormone secretion?
- Starvation.
- Exercise.
- Trauma.
- Hypoglaecemia.
- Deep sleep.
What clinical abnormalities can occur if there is a problem with growth hormone secretion?
- Gigantism.
- Dwarfism.
- Acromegaly.
What would be the effect on TSH if you had an under-active thyroid?
TSH would be high as there would be little negative feedback as less T4 and T3 are being produced.
What would a low TSH tell you about the action of the thyroid?
Low TSH = overactive thyroid.
Lots of T4 and T3 being produced and so there is more negative feedback on the pituitary and less TSH.
What are the 4 cells to make up the islets of langerhans?
- Beta cells: insulin. (70%)
- Alpha cells: glucagon. (20%)
- Delta cells: somatostatin. (8%)
- Pancreatic polypeptide secreting cells. (2%)
What is the importance of the alpha and beta cells being located next to each other in the islets of langerhans?
This enables them to ‘cross talk’ - insulin and glucagon show reciprocal action.
Insulin release is described as biphasic. Describe the two phases.
- Phase 1 - Stored insulin is released rapidly.
- Phase 2 - Slower release of newly synthesised insulin.
What is glucose converted into when it enters a beta cell?
Glucose-6-phosphate.
Describe the mechanism of insulin secretion from beta cells.
Glucose binds to beta cells -> glucose is converted into glucose-6-phosphate -> ADP is converted to ATP -> K+ channels close -> membrane depolarisation -> Ca2+ channels open -> Ca2+ influx -> insulin release.
What substance can tell you if high insulin levels are due to endogenous insulin production?
The presence of C peptide.
What glucose transporter allows glucose uptake into muscle and fat cells?
GLUT-4.
What is a normal blood glucose?
4-6mmol/mol.
What is the short term response to high blood glucose?
Glycogenesis.
What is the long term response to high blood glucose?
Triglyceride production - lipogenesis.
What is the short term response to low blood glucose?
Glycogenolysis.
What is the long term response to low blood glucose?
Gluconeogensis.
Name 3 places where glucose sensors are located.
- Pancreatic islets.
- Medulla.
- Hypothalamus.
What happens to insulin and glucose levels after a meal?
Insulin release increases. Glucose goes to the liver and muscles to replenish glycogen stores. Excess glucose is converted into fats.
What hormones from the hypothalamus stimulate the anterior pituitary to release GH?
GHRH (+ve affect) and SMS (-ve affect).