Genitourinary System and Endocrinology Flashcards
1
Q
What bone is the back of the pelvis?
A
Sacrum
2
Q
What joints are at the front and back of the pelvis?
A
Posterior= sacroiliac joints
Anterior= Pubic symphysis
3
Q
What is the pelvic inlet?
A
The circular ring that is created by the pelvis bones and joints.
It will vary in shape based on sex. More circular in women and more heart shaped in men (due to child birth so the babies head can fit)
4
Q
What are the 2 ligaments of the pelvis?
What holes do they create?
A
Sacrospinous ligament and Sacrotuberous ligament
The greater and lesser sciatic foramen- structures pass through here from the lower limb to the pelvis.
5
Q
What 2 muscles form the walls of the pelvis?
A
Piriformis and obturator internus
6
Q
Where are eggs (female gametes) produced?
A
In the ovaries (gonads)
7
Q
What are fimbriae?
A
They are the boundary between the ovaries and uterine tubes which sweep up the eggs from the ovary and into the uterine tubes.
8
Q
What are the uterine tubes?
A
They transport the egg from the ovary to the uterus
9
Q
What is produced in the testes?
Why are they outside the body?
A
Sperm
They produce sperm at a temperature slightly lower than body temperature hence why they are in the scrotum outside the body. They retract up towards the body if it gets cold.
10
Q
What is in the spermatic cord?
A
Vas deferens (transports sperm to the ureter), artery and vein
11
Q
What 2 muscles form the pelvic diaphragm?
A
Coccygeus
Levator ani (collection of 3 muscles)
12
Q
What is the Pouch of Douglas (rectouterine pouch)?
A
This is the extension of the peritoneal cavity in the space between the posterior wall of the uterus and the rectum. Fluid can accumulate here when there is infection.
13
Q
Where is the urinary bladder located in both sexes?
A
Most anteriorly
14
Q
What are rugae in the urinary bladder?
A
These are folds in the membrane of the urinary bladder which increase the surface area so that the bladder can stretch under an increase in volume.
15
Q
What is the detrouser muscle?
A
This muscle surrounds the urinary bladder and contracts to help force urine out of the bladder
16
Q
What are the 2 glands below the bladder?
A
Prostate gland
Bulbourethral gland
17
Q
What is the ejaculatory duct?
A
This duct releases sperm and prostatic fluid from the prostate into the urethra to form semen.
18
Q
What are the 2 urethral sphincters in men and what is there function?
A
Internal Sphincter: Neck of the bladder- prevents semen from going into the bladder instead out of of the penis during ejaculation.
External Sphincter: Inferior to the prostate= controls urination
19
Q
What is the difference between endocrine hormones and paracrine hormones?
What are autocrine hormones?
A
Endocrine hormones are released into the blood and then travel all over the body while paracrine hormones act on neighbouring cells at a close distance.
Autocrine hormones act on the same cell or a nearby cell that is very close.
20
Q
What is the link between the hypothalamus and pituitary gland?
A
The hypothalamus controls the pituitary gland to release certain hormones depending on the signals that it receives.
21
Q
Where is testosterone produced in men?
A
Testes (in Leydig cells) and remaining 5% in the adrenal glands
22
Q
Do women produce testosterone?
A
Yes although a lot less than men
23
Q
Why do we not want too much testosterone?
A
Possible increased risk of prostate cancer
Baldness on the top of male’s head
24
Q
How is the mechanism of the action of hormones different between a steroid and peptide hormone?
A
Steroid hormones has a slower effect than peptide hormones but it is more permanent as steroid hormones must bind to to DNA and modify transcription where as Peptide hormones just bind to receptors on the cell surface which triggers a 2nd messenger. Therefore, the effects of a peptide hormone are more rapid but only temporary.
25
What is the difference between positive and negative feedback?
Positive feedback is when an output of a pathway amplifies the input to the pathway while negative feedback is when an output inhibits the input to the pathway
26
Where is the pituitary gland in relation to the hypothalamus?
Both structures are found at the base of the brain. The pituitary gland lies inferior to the hypothalamus with the optic chiasm (crossing of the optic nerves) in between.
27
What are the two lobes of the pituitary gland?
Where is the anterior pituitary in relation to the optic chiasm?
The anterior and posterior pituitary.
They are both on the same side.
28
What is the stalk connecting the hypothalamus and the pituitary gland called?
Infundibulum
29
How is the anterior and posterior pituitary glands connected to the hypothalamus?
Anterior lobe= portal vessels connect pituitary and hypothalamic beds
Posterior lobe= nerve fibres originate in the hypothalamus and transport hormones to the posterior pituitary
30
What 2 hormones are released by the posterior pituitary gland and what do they each do?
How are these hormones released?
What type of reflex do both of these hormones cause?
Oxytocin= Controls milk release from lactating breast. Controls uterine contraction at onset of labour.
ADH (also called vasopressin)= Acts on kidneys to reabsorb water in collecting duct.
They are both released from neurosecretory cells (can both be from either nucleus) in response to nerve impulses in the hypothalamus.
A neuro-endocrine reflex
31
What are the 6 hormones released by the anterior pituitary lobe?
Growth Hormone,
Prolactin
Adrenocorticotropic hormone (ACTH)
Thyroid stimulating hormone (TSH)
Follice stimulating hormone (FSH)
Luteinising hormone (LH)
32
What triggers the release of hormones from the anterior pituitary gland?
Releasing hormones from the hypothalamus
E.g.
Corticotropin releasing hormone (CRH)
Gonadotropin releasing hormone (GnRH)
Thyrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Dopamine and Somatostatin inhibit the release of hormones (i.e. SS inhibits growth hormone and Dopamine inhibits Prolactin)
33
As an adult, will you grow taller if you take excess growth hormone?
No, as growth plates at the ends of bone have fused so you will not grow taller.
34
What is the effect of GH as adults?
It boosts protein production, promotes the utilization of fat, interferes with the action of insulin to increase blood sugar levels (protects against hypoglycemia)
35
What are androgens?
A group of hormones that play a role in male traits and reproductive activity but are present in both males and females (just be differing amounts).
Testosterone is the main type of androgen.
36
Where are the adrenal glands found?
There are 2 and each one sits on each of the kidneys and are enclosed in a fibrous capsule surrounded by fat
37
What are the 2 layers of the adrenal glands?
Outer= Adrenal cortex
Inner= Adrenal Medulla
38
What are the 3 distinct zones of the adrenal cortex?
Mineralocorticoids (aldosterone)- influence salt and water balance
Glucocorticoids (Cortisol)- anti-inflammatory
Gondocorticoids (androgens)- secrete androgens
39
What types of hormones are those released by the adrenal cortex?
How are different hormones produced from the same starting molecule?
They are all steroid hormones so are derived from cholesterol and therefore work by altering transcription of mRNA in protein synthesis.
Even though all the hormones are produced from cholesterol, different enzymes lead to different hormone products.
40
What are the main hormones produced in the adrenal glands in males?
DHEA, DHEA-S and androstenedione.
Insignificant amounts (about 5%) of testosterone is made in the adrenal glands.
41
What controls the synthesis of testosterone in the adrenal glands?
The anterior pituitary gland releases ACTH.
42
Do the ovaries make testosterone? What is it immediately converted to?
Yes but it is immediately converted to oestogren
43
What is the primary source of testosterone in females?
The adrenal glands- secrete half the total androgenic requirement
44
What is the effect of excessive production of adrenal androgens in females? How can these be reversed?
This results in masculinisation of females (e.g. acne, facial hair, breast shrinkage)
Anti-androgen drugs block androgen receptors and therefore alleviates some of the symptons
45
What are the 2 major functions of the testes?
What controls these functions
Spermatogenesis- process by which sperm cell development occurs
Steroidogenesis- the process by which cholesterol is converted to steroid hormones (e.g. testosterone)
Both functions under hormonal control from the anterior pituitary gland by:
LH and FSH
46
How is sperm produced?
Spermatozoa are produced by the testes in the seminiferous tubules. Sperm develop from spermatogonia, which are surrounded and facilitated by large Sertoli cells. The sperm then leaves the seminiferous tubules (site of sperm formation). This happens from Leydig cells which surround Sertoli cells and they are a type of connective tissue which secrete testosterone. Sperm then enters the epididymis where they gain motility and pass to the vas deferens. The sperm combine with prostate fluid and seminal vesicle secretion to create semen
47
What is androgen binding protein?
This is produced by the Sertoli cells and binds to testosterone which carries testosterone out of the seminiferous tubules and into the epididymis where a high conc of testosterone is required for sperm maturation
48
If testosterone doesn't bind to androgen binding proteins, where does it go?
It is released into the blood and binds to Sex hormone binding globulin (SHBG) and albumin where it is then converted to DHT, Androstenedione and Estradiol (a type of oestrogen).
49
What is the role of FSH and LH in the testes?
FSH= stimulates the Sertoli cells to facilitate sperm development
LH= Stimulates the Leydig cells to secrete testosterone (and oestrogen and DHT)
50
How is the hormonal control of testosterone controlled?
By negative feedback.
Testosterone inhibits LH release from the anterior pituitary by decreasing GnRH.
Estradiol and DHT also inhibit GnRH secretion
51
What is the role of Inhibin and Activin?
Inhibin- acts directly on the anterior pituitary to inhibit FSH (no effect on LH)
Activin- stimulates the secretion of FSH
They both therefore have an opposite effect
52
What enzyme converts testosterone to DHT?
5 alpha reductase
53
What is the action of testosterone before birth?
Levels of testosterone determine the sex of the child and promotes descent of the testes onto the scrotum
54
What are the secondary sexual characteristics of testosterone?
Promotes muscle growth
Causes the voice to deepen
Induces hairline changes in men
55
What enzyme converts testosterone to Estradiol?
Where is it widely found?
Aromatase
In adipose tissue which may explain why some obese men have large breasts (due to higher amounts of aromatase)
56
What is the action of Estradiol in males?
Essential for spermatogenesis
Regulates sex drive (libido) and erectile function.
57
What is the difference between primary hypogonadism and secondary hypogonadism?
Primary is where sperm and testosterone concs are below normal and serum LH and FSH concs are above normal (so problem is with the Testes)
Secondary is when there is a problem with the hypothalamus or pituitary gland so there is not enough stimulation of Leydig cells to produce testosterone due to less release of LH.
58
What day does the egg get ejected from the ovaries?
Day 14
59
What are granulosa cells?
They are a type of cell in your ovaries that produce hormones such as progesterone and oestrogen
60
How many eggs do you ovulate every 28 days?
Just one! This is called the dominant follicle. Multiple follicles will be made in each cycle though!
61
What happens do the rest of the follicles that aren't dominant?
They degenerate in a process called atresia
62
How does the egg leave the follicle?
The wall of the follicle and the ovary are in such close proximity that enzymes in the follicle break down the wall of the ovary which creates a hole for the egg to escape out of.
Some women feel pelvic pain this process.
If more than one egg escapes, then this is how you get twins or triplets etc.
63
What happens to the follicle when the egg leaves the ovary?
The follicle continues to increase in size in the ovary as granulosa cells produce more hormones (oestrogen, progesterone and inhibin).
If the egg is not fertilised by sperm: After about 10 days (day 25), the follicles are so big that they start to degenerate by apoptosis.
If the egg is fertilised: the corpus luteum (the large follice) continues to grow and produced oestrogen and progesterone which prepare the inner lining of the uterus (endometrium) for implantation of the fertilised egg in it (this is where the egg develops)
64
What are the 2 main phases of the menstrual cycle?
Follicular Phase and Luteal Phase
65
What is meant by:
Menstrual Phase
Proliferative phase
Secretory Phase
Menstrual Phase- endometrium lining is broken down (day 0-7)
Proliferative Phase- a new layer of endometrium lining grows (day 7-14)
Secretory Phase- endometrium becomes ready for implantation for a fertilised egg (day 14-28)
66
What are the 3 ovarian hormones?
Progesterone, Inhibin and oestrogen
67
What are the 2 gonadotropic hormones?
FSH and LH
68
What does LH do to theca cells?
LH causes theca cells to produce androstenedione which is then converted to estradiol by aromatase (in granulosa cells) causing oestrogen levels to increase.
69
How does oestrogen affect the endometrium?
Oestrogen causes the endometrium to proliferate (grow) back up after being broken down in the menstrual phase
70
Why is there a small dip in FSH and LH just before day 14?
High levels of oestrogen in the blood tell the brain that follicles are big so they don't need to produce as much FSH and LH
71
Why is there a spike in LH just before day 14?
What is this called?
This is because oestrogen levels are very high so brain then wants to produce LH. This causes the follicle to rupture resulting in the egg being released.
Luteal surge
72
Why is the spike in FSH just before day 14 not as high as LH?
This is because inhibin inhibits the amount of FSH that is released but has virtually no effect on LH
73
What does the follicle become when the egg is released?
It becomes the Corpus Luteum
74
Why does the amount of oestrogen produced decrease after day 14?
What hormone is now the primary product of the corpus luteum?
This is because the follicle is no longer a follicle anymore and becomes the corpus luteum which does not produce as much oestrogen (still some produced though)
Progesterone
75
What is the main role of progesterone?
It prepares the endometrium for implantation of an egg (stimulates the development of spiral arteries that mean the embryo will eventually have good access to nutrients from the mother's bloodstream)
It also reduces the contractility of the uterus so the embryo doesn't get expelled out of the mother's body too early.
76
Why are levels of FSH and LH low during the luteal phase?
This is because the corpus luteum releases hormones that supress them.
Inhibin conc is also high which inhibits FSH release
77
What happens near the end of the luteal phase when there is no fertilisation of the egg by sperm so the corpus luteum starts to atrophy?
Progesterone and oestrogen levels drop as corpus luteum no longer produces it
This causes LH and FSH to start increasing again (due to negative feedback)
Endometrium is about to break down in menstruation (this is the period)
78
If the egg is fertilised, how come the endometrium does not break down?
The embryo produces HcG (Human chorionic gonadotropin) which keeps the corpus luteum alive so it keeps producing progesterone and oestrogen to maintain the endometrium for the pregnancy. This means that menstruation (the period) does not occur.
79
What hormone is responsible for thick and sticky cervical mucus that is hostile to sperm?
Oestrogen
80
What is the role of FSH?
Stimulates oestrogen synthesis by granulosa cells within the ovarian follicle
81
What is Tonicity?
This is the ability of an extra cellular solution to make water move into or out of a cell by osmosis is known as tonicity.
82
Where does water move when a cell is hypertonic? hypotonic? Isotonic?
Hypertonic- water moves out of the cell as higher solute conc outside of cell
Hypotonic- water moves into the cell as higher solute conc inside of cell
Isotonic- stays the same as same conc in and outside of cell
All these terms refer to when you have 2 solutions with a membrane while the molarity, osmolarity etc. terms refer to when you have 1 solution
83
What is meant by molarity?
Moles/ 1 litre of solution
84
What is meant by molality?
Moles/ 1kg of solvent
85
What is meant by osmolarity?
What is meant by a high osmolarity?
Osmoles (number of solutes)/1 litre of solution
A high osmolarity means that there is a lower water volume and high solute concentration.
86
What is meant by Osmolality?
Osmoles (number of solutes)/1kg of solvent
87
What is reabsorbed at the Proximal Convoluted tubule?
Sodium ions (and therefore bring water with it), amino acids and glucose
88
What is reabsorbed in the descending limb of the loop of Henle?
Water
89
What is reabsorbed in the ascending limb of the loop of Henle?
Sodium, chloride and potassium ions (by active transport)
Impermeable to water.
This makes the medulla salty which results in a water potential gradient being created for water to move out of the descending limb and into the medulla (counter current multiplier)
90
What is reabsorbed in the distal convoluted tubule?
Sodium and chloride ions
91
What is the juxtaglomerular apparatus?
This is the junction where the distal convoluted tubule and glomerulus overlap. This functions to control blood pressure.
92
What do we reabsorb into the collecting duct?
Water and Urea (hold onto some urea to increase osmolarity in the kidney to help drive the reabsorption of water down a water potential gradient)
93
What are peritubular capillaries?
These move randomly around the kidney to reabsorb nutrients from the convoluted tubules, loop of Henle and collecting duct. They branch off from the efferent arteriole.
94
Where is the urine most concentrated in the loop of Henle?
At the bottom as the urine gets concentrated in the descending limb as water is reabsorbed and diluted in the ascending limb.
95
What are the three principle mechanisms that control GFR?
Renal autoregulation, neural regulation and hormonal regulation
96
How does the JGA regulate GFR?
A stimulus disrupts homeostasis
Macula densa cells of JGA detect decreased delivery of Na+, Cl- and water.
This then causes the JGA to cause afferent arterioles to constrict which decreases blood flow through glomerulus
Causing a decrease in GFR
97
What is the effect of angiotensin II on arteriole pressure?
In low concentrations of angiotensin II, this increases GFR as afferent arteriole dilates and efferent arteriole constricts.
In high concentrations of angiotensin II, this decreases GFR as afferent arteriole constricts and efferent arteriole dilates
98
What is meant by renal autoregulation of GFR?
What are the 2 main mechanisms for this?
This means that even when there is larger changes in arterial blood pressure, mechanisms maintain a constant GFR over normal blood pressure ranges
Myogenic mechanism- increases in BP, stretch the afferent arteriole smooth muscle. This contraction reduces the diameter of the arteriole returning the GFR to its previous level in seconds. Moderated by vasoactive agents produced by endothelial cells.
Tubuloglomerular feedback- Elevated BP raises the GFR so fluid flows too rapidly through the renal tubule so Na+ and Cl- and water are not reabsorbed. The macula densa cells detect this and release ATP which is converted to adenosine (vasoconstrictor) which causes the afferent arterioles to constrict and reduce GFD
99
How does adenosine causing vasoconstriction of the afferent arteriole?
Due to the presence of an adenosine-1 receptor on the afferent arteriole which adenosine binds to when it is released by macula densa cells.
100
Explain how neural regulation of GFR is affected when at rest, with moderate sympathetic stimulation and extreme stimulation (exercise or haemorrhage)?
At rest- renal blood vessels are maximally dilated because sympathetic activity is minimal (renal autoregulation is in charge)
Moderate- both afferent and efferent arterioles constrict equally which decreases GFR
Extreme- vasoconstriction of afferent arterioles reduces GFR which lowers urine output and permits blood flow to other tissues.
101
What effect does Atrial Natriuretic peptide (ANP) have on GFR?
Stretching of the atria that occurs with an increase in blood volume causes hormonal release of ANP. This causes relaxation of glomerular mesangial cells increasing capillary surface area and increasing GFR.
Therefore more sodium is excrete.
102
What is the RAAS system?
Renin-angiotensin-aldosterone system
Renin is released by macula densa cells in response to reduced stretch in the afferent arteriole and when there is reduced delivery of sodium to the ascending limb.
Renin converts angiotensinogen to angiotensin I
Angiotensin I is converted to angiotensin II
Angiotensin II reduces GFR by constricting the afferent arteriole
Angiotensin II enhances absorption of Na+ in the PCT
Promotes aldosterone production which causes principal cells of CD to reabsorb more Na+
Increases blood volume by increasing water reabsorption
Therefore less sodium is excreted.
103
What are some examples of Na+ mediators for excretion?
Natriuretic hormone- released by brain and primarily by the ventricles when extracellular fluid volume increases. Inhibits Na/K ATPase in vascular smooth muscle and renal cells- causing vasoconstriction and inhibiting sodium reabsorption
Intrarenal Prostaglandin system- prostaglandins enhance GFR and decrease sodium reabsorption by the ascending limb of loop of Henle and cortical collecting duct.
104
What factors increase the concentrating power of the loop of Henle?
Increased length of loop of Henle (e.g. desert animals who need to reabsorb lots more water)
Increased capacity of NKCC2 pump in the ascending limb
Reduced flow rate (GFR) through loop so more time for absorption
105
How does ADH affect permeability of the thin ascending and descending limbs of the loop of Henle and the medulla segment of the collecting duct?
Increased ADH makes these part more permeable to Urea so more urea is reabsorbed which increases the osmolarity of the surrounding fluid so more water is reabsorbed due to a steeper water potential gradient.
106
Explain how ADH is released?
Osmolarity of plasma increases (high solute concentration)
Detected by osmoreceptors in hypothalamus
Hypothalamus and posterior pituitary release ADH
Principle cells in the collecting duct become more permeable to water which increase water reabsorption so there is a decrease in plasma osmolarity.
107
Explain the action of ADH in the collecting duct?
What are 3 other actions of ADH?
ADH binds to V2 receptor on basolateral membrane of collecting duct cell
Activates adenyl cyclase to convert ATP to cyclic AMP (via G protein)
cAMP is a second messenger for activating protein kinases which phosphorylate certain proteins involved in cytoskeleton element which then appear to mobilise vesicles containing the channel protein Aquaporin 2.
Aquaporin 2 makes the membrane more permeable to water so more water is reabsorbed.
ADH increases the activity of sodium reabsorption (NKCC2) in thick ascending limb of loop of Henle
ADH increases the permeability of inner medullary collecting duct to urea
ADH acts on another receptor (V1) involving calcium mobilization promoting vasoconstriction in smooth muscle (increasing BP)
108
What is the vasa recta?
This is the blood vessel that runs in the opposite direction (counter current) to the flow of the renal filtrate
109
What is creatinine?
Creatinine is a waste product of creatine (supplies energy to the muscles). It is removed entirely by the kidneys. It can therefore be used to estimate GFR.
110
What are the 3 layers of the filtration membrane in the nephron?
Glomerular endothelium- has fenestrations in it which allow all components of blood plasma through except blood cells
Glomerular basement membrane- prevents filtration of larger proteins
Slit membranes between pedicels of podocytes-prevents the filtration of medium sized proteins
111
Where is most of the reabsorption of sodium?
In the Proximal convoluted tubule.
112
What symporters are in the membrane of the thick ascending limb of the loop of Henle?
Na+K+Cl- (NKCCT 'triple cotransporter') reabsorbs these ions.
113
What ions are reabsorbed in the DCT?
Na+ and Cl- in Na+Cl- symporters
Calcium is also reabsorbed via a sodium-calcium counter transport carrier which then drives calcium to move into cells lining the DCT by facilitated diffusion.
114
Is calcium reabsorbed in the collecting duct? How?
Yes through leakage channels in principal cells. Aldosterone increase Na+ and water reabsorption.
115
What day of the menstrual cycle is ovulation likely to occur?
Day 14
116
What hormones cause a decrease in FSH during the follicular phase?
Why is this important?
Inhibin
Oestrogen- This is because FSH stimulates the release of oestrogen by granulosa cells so as oestrogen conc increases, this negatively feedbacks to FSH.
This prevents too many follicles from developing during each cycle.
117
Where is HCG produced?
HCG is produced in the trophoblast cells which surround the developing embryo.
118
Why do HCG levels drop off after about 8 weeks?
This is because the placenta is the primary producer of progesterone and HCG is no longer required to maintain the corpus luteum.
119
What is meant by intracellular and extracellular fluid and which category has a higher proportion of bodily fluid?
Intracellular= fluid within cells
Extracellular = fluid outside of cells (e.g. interstitial fluid or blood plasma)
A high proportion of fluid in the body is found intracellulae
120
Where is aldosterone released from? Why? What effect does this have.
From the adrenal gland in response to a decrease in blood volume. It stimulates the reabsorption of sodium (and therefore water follows) in the kidney leading to increases in blood volume.
121
How can glucose be a diuretic?
In the case of diabetes, there is more glucose present than the kidney can recover which increases the osmolarity of urine which means less water is reabsorbed so therefore more urine is produced.
122
