Teach me Endo/Repro/Renal Physiology Questions
Chief cells have a unique G-protein calcium receptor _____ on their surface, which regulates this.
(CaR)
FSH binds to granulosa cells to:
-Increase production of enzymes that catalyse the production of steroid hormones, stimulating follicle growth -Increase production of activins, which have a positive feedback effect on the anterior pituitary -Increase production of inhibins, which have a selective negative feedback effect on the pituitary -Help convert androgens to estrogen
In the Zona Fasciculata, the enzyme ___________ catalyses the final step of the reaction that forms Cortisol and Corticosterone.
11β-hydroxylase
The uterine cycle governs the preparation and maintenance of lining of the uterus to receive a fertilised egg. What accompanies sloughing of the endometrium during an endometrial cycle in a normal woman?
A decrease in both estrogen and progesterone
Angiotensin II mediates its cardiovascular effects through which of the following receptors?
AT1-receptor
Which of the following best describes the mechanism by which insulin allows cells to uptake glucose?
Activation of insulin receptor's integrated tyrosine kinase The insulin receptor's beta chains, once stimulated, act as a tyrosine kinase. This kick starts a phosphorylation chain that results in an increase in GLUT4 receptor numbers
ATE ICE (thyroid hormone synthesis)
Active transport Thyroglobulin Exocytosis Iodination Coupling Endocytosis
Active transport of thyroid hormone synthesis
Active transport of Iodide into the follicular cell via the Sodium-Iodide Symporter (NIS). This is actually secondary active transport, and the sodium gradient driving it is maintained by a Sodium-Potassium ATPase.
Which hormone is released from the adrenals following the binding of angiotensin II?
Aldosterone -a mineralocorticoid, a steroid hormone released from the zona glomerulosa of the adrenal cortex.
Which cell type in the Islets of Langerhans secrete glucagon?
Alpha Cells
PTH & Vitamin D synthesis (and Ca2+)
Although PTH does not actively increase the absorption of calcium from the gut it stimulates the formation of vitamin D, which subsequently increases absorption from the gut.
Which channel increases in number under the action of ADH?
Aquaporin 2
Which of the following symptoms best describes GH deficiency?
Arrhythmias, lower muscle mass, reduced energy, low mood
Which factor inhibits ADH release?
Atrial natriuretic peptide (ANP)
The median duration of a menstrual cycle is 28 days with most cycle length between 21 to 35 days. When do progesterone levels rise to their highest point during the female hormonal cycle?
Between ovulation and the beginning of menstruation
Cortisol exerts its effects by which mechanism?
Binding to two GRs before translocating to the nucleus
Where is oxytocin mostly synthesized?
Cerebrum
Which of the following statements are true about the key actions of cortisol?
Cortisol is important for regulating calcium absorption from the gastrointestinal tract, but is also important for limiting new bone formation by osteoblasts
The negative feedback system in the HPA axis works by which mechanism?
Cortisol levels are detected by the hypothalamus and anterior pituitary, which decrease CRH and ACTH production, respectively
coupling in thyroid hormone synthesis
Coupling of MIT and DIT gives the Triiodothyronine (T3) hormone and coupling of DIT and DIT gives the Tetraiodothyronine (T4) hormone, also known as Thyroxine.
How will an increase of ADH impact plasma sodium concentration?
Decrease
As menstruation ends, estrogen levels in the blood rise rapidly. What is the source of estrogen?
Developing follicles
Which of the following occurs during the proliferative phase of the uterine cycle?
During the proliferative phase, estrogen secretion initiates fallopian tube formation, thickening of the endometrium, increased motility of the myometrium and a production of a thin alkaline cervical mucus. Progesterone levels remain low during the proliferative phase.
Endocytosis in thyroid hormone synthesis
Endocytosis of iodinated thyroglobulin back into the follicular cell. Thyroglobulin undergoes proteolysis in lysosomes to cleave the iodinated tyrosine residues from the larger protein. Free T3 or T4 is then released, and the Thyroglobulin scaffold is recycled.
How does the LH surge occur in the menstrual cycle?
Estrogen levels rise to very high, meaning that a positive feedback is exerted on the HPG, rapidly increasing LH secretion but not FSH.
Conn's syndrome is characterised by...
Excess aldosterone secretion
Exocytosis in thyroid hormone synthesis
Exocytosis of Thyroglobulin into the follicle lumen, where it is stored as colloid. Thyroglobulin is the scaffold upon which thyroid hormone is synthesized.
Which hormone is measured to diagnose the menopause?
FSH
ADH exerts its effect on the kidney through which type of receptor?
G protein coupled receptor on the basolateral membrane (Gas) This then activates cAMP to phosphorylate AQP-2 to insert on the apical membrane
Thyronine Binding plasma proteins
Globulin and Albumin
Where are androgens such as DHEA converted to testosterone and estrogen?
Gonads
Through which G protein does angiotensin 2 act in the vasculature?
Gq
The oxytocin receptor is a _____. In brief, activation of this receptor leads to a cascade that results in a significant influx of _____ ions into the cell.
Gq coupled; Calcium
Why do only LH levels, not both LH and FSH levels, increase in response to very high estrogen levels secreted by granulosa cells?
Granulosa cells secrete inhibin alongside high levels of estrogen. This inhibin selectively inhibits FSH production at the anterior pituitary.
_____ _______ support sperm cells and spermatogenesis, including increasing the number of sperm cells and promoting motility and fertility potential of sperm.
Growth factors
When is estrogen in positive feedback?
High estrogen levels (in the absence of progesterone) positively feedback on LH and FSH secretion
Which of the following changes in osmolality are consistent with a diagnosis of Diabetes Insipidus?
High plasma osmolality, low urine osmolality (Diabetes insipidus is diagnosed by the presence of high plasma osmolality and a low urine osmolality.)
How is the corpus luteum maintained in the initial stages of pregnancy?
Human chorionic gonadotropin (HcG) produced by syncytiotrophoblast cells of the embryo exerts a luteinising effect, maintaining the corpus luteum
Which of the following statements correctly describes the HPA axis?
Hypothalamus -> CRH -> corticotropes -> ACTH -> Adrenal cortex -> Cortisol
Which of the following statements best describes the growth hormone axis?
Hypothalamus -> Growth hormone releasing hormone -> somatotrophs -> growth hormone -> liver -> IGF-1
What is the relationship between ADH secretion and blood volume?
Hypovolemic state stimulates ADH secretion
Which of the following would produce an increase in the rate of aldosterone production?
Increase in plasma Angiotensin-II
The following factors increase the rate of aldosterone production within the zona glomerulosa:
Increase in plasma concentration of Angiotensin-II Increase in plasma K+ concentration Decrease in plasma pH (acidosis) Decreased blood pressure, as detected by atrial stretch receptors
The overall metabolic effects of glucagon are typically exerted on the liver:
Increased glycogenolysis Decreased glycogenesis Increased gluconeogenesis Increased ketogenesis It also increases lipolysis in adipose tissue.
Why are post-menopausal women at increased risk of osteoporosis?
Increased osteoclast activity
What is the relationship of ADH with plasma osmolality?
Increased plasma osmolality stimulates ADH release
Bronzing of the palmar creases in Addison's disease occurs by which mechanism?
Increased production of POMC leads to increased production of ACTH and MSH which stimulates pigmentation. In Addison's disease the lack of negative feedback from cortisol means that there is increased production of CRH in the hypothalamus. This then stimulates the anterior pituitary gland to produce more ACTH. ACTH is produced via cleaving of POMC - which also then results in increased MSH production alongside the ACTH. This MSH then stimulates pigmentation. resulting in the hyperpigmentation seen in Addison's disease.
Aldosterone causes which of the following electrolyte changes?
Increased serum sodium, reduced serum potassium It increases the expression of apical epithelial Na+ channels (ENaC) to reabsorb urinary sodium. Furthermore, the activity of the basolateral Na+/K+/ATPase is increased. This causes the additional sodium reabsorbed through ENaC to be pumped into the blood by the sodium/potassium pump. In exchange, potassium is moved from the blood into the principal cell of the nephron. This potassium then exits the cell into the renal tubule to be excreted into the urine.
How does oxytocin induce uterine contraction?
Increasing intracellular Ca2+
Combination of which of the following prevents ovulation of a second follicle during the luteal phase?
Inhibin and progesterone
Which of the following is correct regarding the mechanism of action of sildenafil?
Inhibits cGMP breakdown resulting in increased nitric oxide action
Iodination in thyroid hormone synthesis
Iodination of the Thyroglobulin. Iodide is made reactive by the enzyme thyroid peroxidase. Iodide binds to the benzene ring on Tyrosine residues of Thyroglobulin, forming monoiodotyrosine (MIT) then diiodotyrosine (DIT).
PTH acts directly on bone to increase bone resorption.
It induces cytokine secretion from osteoblasts that act on osteoclast cells to increase their activity.
Which of the following is correct about Addison's disease?
It is a form of hypoadrenalism, a primary endocrine disorder whereby cortisol production is reduced as a result of disease to the adrenal gland
What is the role of estrogen in regulating blood cholesterol level?
It reduces levels of LDL cholesterol but raises HDL cholesterol level. estrogen reduces levels of LDL cholesterol but raises HDL cholesterol levels, offering a protective effect against heart disease. After the menopause, estrogen levels decrease which increases the woman's risk of cardiovascular disease.
LH stimulates the _____ cells in the testes to produce _______, the main male sex steroid hormone.
Leydig; testosterone
In an abnormal short synACTHen test, which result is most definitive of Addison's disease?
Low cortisol 2 hours post ACTH administration
During lactation, oxytocin induces contractions in which cell type?
Myoepithelial cells
___________ are responsible for the breakdown of bone and thus an increase in their activity leads to increased bone breakdown.
Osteoclasts
PTH increases Ca2++ reabsorption in the kidney
PTH increases the amount of calcium absorbed from the Loop of Henle and distal tubules.
Excess growth hormone secretion is best characterized by which of the following statements?
Patients have raised blood pressure, large hands, and may have to undergo brain surgery
Which of the following is NOT synthesised in the adrenal medulla?
Phenylalanine
From where is oxytocin released into the bloodstream?
Posterior pituitary
From which structure is anti-diuretic hormone (ADH) released in response to angiotensin II?
Posterior pituitary
Where is ADH stored and released into the circulation?
Posterior pituitary glandWhich cell type in the Islets of Langerhans secrete glucagon?
Which of the following statements about prolactin production is most accurate?
Produced by lactotrophs despite no hypothalamic stimulation
What is thought to cause primary dysmenorrhoea?
Prostaglandins releasing spiral artery vasospasm
Which factor is mainly responsible for decrease in estrogen levels during the menopause?
Reduced sensitivity of the ovary to circulating gonadotropins During the menopause, there is a reduced number of follicles in the ovary hence, there is decreased available binding sites to circulating gonadotropins (FSH, LH). Ultimately, due to reduced sensitivity of the ovary to the gonadotropins the production of estrogen is reduced.
Which of the following types of hyperparathyroidism best describes a high plasma PTH concentration secondary to low plasma calcium concentrations?
Secondary hyperparathyroidism
FSH drives sperm production in the _____ cells of the testes (spermatogenesis), as well as synthesis of proteins important for the production and action of steroid hormones.
Sertoli
What are the key regulatory factors of growth hormone secretion?
Sleep, GHRH, somatostatin, nutrition
What are the main direct actions of growth hormone?
Stem cell differentiation, glycogenolysis, lipolysis
Testosterone has numerous effects, including:
Stimulates formation of sperm (spermatogenesis) in the testes Maintenance of libido (sexual drive) Development of secondary sexual characteristics (pubic, axillary and facial hair) Growth of external genitalia Deepening of voice Muscle growth Bone growth Promotion of anabolic reactions
What is the general mechanism for release of adrenaline from the adrenal medulla?
Stimulation of Chromaffin cells by sympathetic nervous system directly
Prolactin release is stimulated by which of the following mechanisms?
Suckling causes disinhibition of prolactin release
Which of the following is most likely to cause hypoparathyroidism?
Surgical removal of parathyroid tissue
What is the primary function of the Zona Reticularis?
Synthesis of androgens
Which of the following best describes the primary function of the Zona Glomerulosa?
Synthesis of mineralocorticoids
ACE inhibitors mediate their antihypertensive effects through which of the following mechanisms?
They reduce the levels of Angiotensin II
Thyroglobulin in thyroid hormone synthesis
Thyroglobulin (Tg), a large protein rich in Tyrosine, is formed in follicular ribosomes and placed into secretory vesicles.
What is the action of angiotensin II binding at the arterioles?
Vasoconstriction
From which layer of the adrenal gland is aldosterone released?
Zona Glomerulosa
Glucagon binds to a specific glucagon receptor in the cell membrane, a G Protein Coupled Receptor (GPCR). This activates the enzyme _______ _______ which increases cAMP intracellularly. This activates protein kinase _ which phosphorylates and activates a number of important enzymes in target cells.
adenylate cyclase; A
P450 aromatase
an enzyme that converts testosterone into estradiol.
Testosterone promotes what type of reactions?
anabolic
Where does ADH exert its effect?
collecting duct
Where does aldosterone act?
collecting duct
Zona Fasciculata secrete the _____.
glucocorticoids Cortisol and Corticosterone.
Which of the following is a symptom of phaechromocytoma?
hypertension
The "fight or flight response" is a key survival mechanism, and causes a number of physiological changes, such as ____ _____ _____ and _____ ______ in liver and muscle tissue.
increased cardiac output; increased glycogenolysis
Acetylcholine ________ glucagon secretion
inhibits
This is achieved in a number of ways, such as increasing the size and number of ________ within cells, increasing Na-K pump activity and increasing the presence of β-adrenergic receptors in tissues such as cardiac muscle.
mitochondria
There are two posterior pituitary hormones, _____ & ______, which are released by periventricular and supraoptic nuclei.
oxytocin and antidiuretic hormone (ADH),
Aldosterone acts on the ________ of the collecting ducts in the nephron.
principal cells
estrogen in the presence of __________ exerts negative feedback on the HPG axis
progesterone
Aldosterone acts within the tubule cell to increase the transcription of Na+/K+-ATPase and ENaC (epithelial sodium channels), promoting ...
re-absorption of Na+ and excretion of K+.
What are the changes observed in the genital organs during the menopause?
reduced estrogen level has a direct role in causing vaginal atrophy and thinning of the myometrium.
What does FSH not aid in forming in males?
testosterone
LH binds to _____ cells on developing follicles as well as granulosa cells.
theca
Androgen binding protein (ABP)
which maintains high levels of testosterone locally in the luminal space of the seminiferous tubules.