Extra SUGER PHYS Flashcards
Name the 3 things to make up the Glomerular Filtration barrier.
- Fenestrated capillary endothelium.
- Double layer basement membrane.
- Foot processes of podocytes.
What effect does vasoconstriction of the afferent arteriole have on GFR?
GFR will decrease as the HPgc decreases.
Where are the macula densa cells located?
They are epithelial cells found within the DCT. They sit between the afferent and efferent arteriole of the glomerulus.
Define renal clearance.
VOLUME of PLASMA from which a SUBSTANCE is completely REMOVED by the KIDNEY per unit time.
What ion is pumped out of the ascending limb into the medullary interstitium?
Na+. This increases the medullary osmolarity.
Briefly describe ADH action.
- Osmoreceptors in the hypothalamus detect an increase in plasma osmolality.
- The posterior pituitary is signalled to release ADH.
- ADH acts on the collecting ducts and increases insertion of aquaporin 2 channels, permeability to H2O increases, more H2O is retained.
List the 3 main triggers for the release of Renin.
- Sympathetic stimulation.
- Low BP detected by afferent arteriole.
- Low Na+ detected by macula densa cells.
Where is aldosterone synthesised?
In the adrenal cortex by glomerulosa cells.
it is a Mineralocorticoid
Where does aldosterone act?
On the principal cells in the nephron collecting duct.
What is the function of atrial natriuretic peptide (ANP)?
ANP is a renal vasodilator. It inhibits aldosterone release induced by Angiotensin 2 and it closes ENaC channels.
What is the role of the Kidneys in Vitamin D activation?
Converts Calciol from the Liver into Calcitriol , in the Presence of PTH
(Enzyme: 1-hydroxylase)
What layer of the trilaminar disc are the kidneys derived?
Intermediate mesoderm.
What part of the trilaminar disc are the bladder and urethra formed?
The endoderm.
What layer of the trilaminar disc forms the male and female genitalia?
Intermediate mesoderm.
What is the indifferent stage?
When the Wolffian and Müllerian ducts are both present. It is impossible to tell the sex of the embryo.
Untill teh 6ht week
What cells are responsible for secreting testosterone?
Interstitial cells of Leydig.
When do leydig cells start producing testosterone?
Week 8.
What does testosterone stimulate?
Differentiation of the Wolffian duct.
Why does the Müllerian duct degenerate?
Due to Anti Mullerian Hormone, Being secreted from the Sertoli cells which causes a regression of the Mullerian System
What layer of the trilaminar disc is the upper 2/3 of the anal canal derived from?
Endoderm.
What layer of the trilaminar disc is the lower 1/3 of the anal canal derived from?
Ectoderm.
Spermatogenesis: what do type B cells differentiate into?
They differentiate into primary spermatocytes that will then go onto meiosis.
Spermatogenesis: what is the function of type A cells?
They replicate by mitosis to ensure a constant supply of spermatogonia to fuel spermatogenesis.
Spermatogenesis: what does meiosis 1 produce?
2 secondary spermatocytes.
Spermatogenesis: what does meiosis 2 produce?
4 spermatids.
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 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 capacitation?
The final stage of sperm maturation that occurs in the female genitalia. Before this spermatozoa would be unable to fertilise an oocyte.
What cells does FSH act on in females?
Granulosa 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 are the characteristics of the endometrium in the proliferative phase?
Straight glands, no secretions. Stromal and epithelial mitoses.
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 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.
Anchor the growing fetus to the maternal uterine tissue.
Name 6 hormones produced by the anterior pituitary gland.
- FSH.
- LH.
- GH.
- ACTH.
- TSH.
- Prolaction.
Name 2 hormones produced by the posterior pituitary gland.
. ADH.
2. Oxytocin.
How does the anterior pituitary gland receive its blood supply?
Via a portal venous circulation from the hypothalamus.
Describe the thyroid axis.
Hypothalamus releases TRH -> anterior pituitary is stimulated to release TSH -> thyroid -> thyroxine (T4) -> T3 production -> T4 and T3 have a negative feedback effect on the hypothalamus and pituitary.
Briefly describe the mechanism of prolactin.
Hypothalamus -> dopamine -> anterior pituitary -> prolactin -> mammary glands -> milk production -> positive feedback on dopamine.
Briefly describe the mechanism of ACTH.
Hypothalamus -> CRH (Corticotropin-releasing hormone) -> anterior pituitary -> ACTH (adrenocorticotropic hormone ) -> adrenal glands -> cortisol release -> negative feedback on hypothalamus and pituitary.
ACTH also has negative feedback on Hypothalamus (short loop)
How would you describe growth hormone secretion from the anterior pituitary?
It is secreted in a pulsatile fashion and increases during deep sleep.
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?
What do they secrete?
- Beta cells: insulin. (70%)
- Alpha cells: glucagon. (20%)
- Delta cells: somatostatin. (8%)
- Pancreatic polypeptide secreting cells. (2%)
What is the function of insulin?
- Suppresses hepatic glucose output: decreases glycogenolysis and gluconeogensis.
- Increases glucose uptake into fat and muscle cells.
- Suppresses lipolysis and muscle breakdow
What is the function of glucagon?
- Stimulates hepatic glucose output: increases glycogenolysis and gluconeogenesis.
- Reduces peripheral glucose uptake.
- Stimulates release of gluconeogenic precursors.
- Stimulates lipolysis and muscle breakdown.
Describe the mechanism of insulin secretion from beta cells.
Glucose binds to beta cells (GLUT 2) -> glucose is converted into glucose-6-phosphate, Glycolysis, Krebs and OP happens -> ADP is converted to ATP -> ATP inactivates K+ channels, so they close close -> membrane depolarisation -> Ca2+ channels open -> Ca2+ influx -> Ca2+ binds to insulin secretory granules –> insulin release.
What is glucose converted into when it enters a beta cell?
Glucose-6-phosphate.
What substance can tell you if high insulin levels are due to endogenous insulin production?
How does it work?
The presence of C peptide. It connects alpha and beta chains to make PROINSULIN
when it is cleaved - insulin will become active, and it circulate in the blood.
So high blood active insulin = high C peptide
What is the long term response to low blood glucose?
Gluconeogensis.