SUGER Flashcards
1
Q
Name the 3 things to make up the Glomerular Filtration barrier.
A
- Fenestrated capillary endothelium.
- Double layer basement membrane.
- Foot processes of podocytes.
2
Q
Name 5 factors that determine a molecule crossing the filtration barrier.
A
- Pressure.
- Size of the molecule.
- Charge of the molecule (negative molecules are repelled).
- Rate of blood flow.
- Binding to plasma proteins.
3
Q
What force favours glomerular filtration?
A
Hydrostatic pressure of the glomerular capsule.
4
Q
Name 2 forces that oppose glomerular filtration.
A
- Hydrostatic pressure of the bowman’s space.
2. Oncotic pressure of the glomerular capsule.
5
Q
Does the bowman’s space exert an oncotic pressure?
A
No. There are no proteins in the Bowman’s space.
6
Q
What equation could be used to calculate the net glomerular filtration pressure?
A
HPgc - HPbs - πgc
7
Q
What is the definition of glomerular filtration rate?
A
The volume of fluid filtered from the glomeruli into Bowman’s space per unit time.
8
Q
What effect does vasoconstriction of the afferent arteriole have on GFR?
A
GFR will decrease as the HPgc decreases.
9
Q
What effect does vasodilation of the afferent arteriole have on GFR?
A
GFR will increase as the HPgc increases.
10
Q
What effect does vasoconstriction of the efferent arteriole have on GFR?
A
GFR will increase. Efferent arteriolar constriction tends to push blood back to the glomerulus and so increases the HPgc.
11
Q
What effect does vasodilation of the efferent arteriole have on GFR?
A
GFR will decrease as the HPgc decreases.
12
Q
Name 2 ways in which GFR is regulated.
A
- Autoregulation.
2. Tubuloglomerular feedback.
13
Q
What is tubuloglomerular feedback?
A
Macula densa cells of the DCT detect NaCl levels and use this as an indicator of GFR.
NaCl levels increase as GFR increases.
14
Q
What would happen if Nacl levels reaching the macula densa cells were very high?
A
The macula densa cells would signal to the afferent arterioles to vasoconstrict therefore reducing GFR.
15
Q
Where are the macula densa cells located?
A
They are epithelial cells found within the DCT. They sit between the afferent and efferent arteriole of the glomerulus.
16
Q
How could you measure GFR?
A
Look at the excretion of a marker substance.
17
Q
List 3 qualities necessary of a marker substance.
A
- Freely filtered.
- Not metabolised.
- Not reabsorbed or secreted.
18
Q
What substance can be used clinically to estimate GFR?
A
Creatinine.
19
Q
What is the usual value of the filtration fraction.
A
20%
20
Q
Define renal clearance.
A
Volume of plasma from which a substance is completely removed by the kidney per unit time.
21
Q
Name 7 molecules that are reabsorbed in the proximal convoluted tubule.
A
Na+, K+, Cl-, HCO3-, H2O, amino acids, glucose.
22
Q
Is the ascending or descending limb of the loop of henle permeable to H2O?
A
Descending limb.
23
Q
What is the purpose of countercurrent multiplication?
A
To generate a hypertonic medullary interstitium so H2O can be drawn out of the tubules and reabsorbed.
24
Q
What ion is pumped out of the ascending limb into the medullary interstitium?
A
Na+. This increases the medullary osmolarity.
25
What are the 2 cell types found in the collecting duct.
Principal and intercalated.
26
What are the 4 main layers of the epidermis of the skin?
1. Keratinised squames.
2. Granular layer.
3. Spinous layer (the thickest layer).
4. Germinative layer.
27
What is the role of Filaggrin?
Produces natural moisturising factor.
28
Why are protease inhibitors in the skin important?
Protease inhibitors prevent the breakdown of corneodesmosomes.
29
What is the ideal pH of the skin?
5.5
30
How much H2O do we intake in a day?
2.5L
31
How much salt do we intake in a day?
10g
32
What is the equation for plasma osmolality?
2(Na + K) + glucose + urea
33
How is tonicity regulated?
By controlling H20 movement.
34
Is ADH a vasoconstrictor or a vasodilator?
Vasoconstrictor.
35
Briefly describe ADH action.
1. Osmoreceptors in the hypothalamus detect an increase in plasma osmolality.
2. The posterior pituitary is signalled to release ADH.
3. ADH acts on the collecting ducts and increases insertion of aquaporin 2 channels, permeability to H2O increases, more H2O is retained.
36
How is fluid volume regulated?
By controlling Na+ movement.
37
List the 3 main triggers for the release of Renin.
1. Sympathetic stimulation.
2. Low BP detected by afferent arteriole.
3. Low Na+ detected by macula densa cells.
38
What is the function of ACE?
Converts angiotensin 1 into angiotensin 2.
39
Where is aldosterone synthesised?
In the adrenal cortex by glomerulosa cells.
40
Where does aldosterone act?
On the principal cells in the nephron collecting duct.
41
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.
42
What channels do loop diuretics target?
NKCC2
43
What channels do Thiazides target?
NCC
44
Name 3 types of drugs you could give to someone with hypertension.
1. Diuretics.
2. Vasodilators.
3. ACE inhibitors.
45
Name 3 urinary buffers.
1. Ammonium.
2. Phosphate (commonest urinary buffer).
3. Bicarbonate.
46
How does respiratory acidosis effect the ammonium buffer?
The uptake and synthesis of ammonia is increased.
47
Is renal compensation to an acid/base disturbance fast or slow?
Slow. Respiratory compensation is fast.
48
What is the renal compensation mechanism for respiratory acidosis?
Increased ammonia production. H+ secretion increases and HCO3- reabsorption increases.
49
What is the renal compensation mechanism for respiratory alkalosis?
H+ secretion decreases and HCO3- reabsorption decreases.
50
What is the respiratory compensation mechanism for metabolic acidosis?
Chemoreceptors are stimulated enhancing respiration. PaCO2 decreases.
51
What is the respiratory compensation mechanism for metabolic alkalosis?
Chemoreceptors are inhibited reducing respiration. PaCO2 increase.
52
What does erythropoietin (EPO) do?
Stimulates bone marrow, promotes RBC maturation.
53
What is the role of the Kidneys in Vitamin D activation?
Converts 25-OH D into 1,25-diOH D. (Enzyme: 1-hydroxylase)
54
True or False: the ovary lies behind the broad ligament.
True.
55
What is the fornix?
The space between the cervix and the vagina.
56
What is the hymen formed from?
The urogenital sinus.
57
What is the SRY protein called?
Testis determining factor: under its influence male development takes place.
58
What is the importance of testis determining factor?
Under its influence male development takes place.
59
What cells are responsible for secreting testosterone?
Interstitial cells of Leydig.
60
What is meckle's diverticulum a remnant of?
The vitelline duct - connected the midgut to the yolk sac.
61
What is the significance of the Hilton white line?
It separates the non keratinised and keratinised epithelium in the anal canal.
62
When does the anal membrane rupture?
In the 7th week. This allows the upper 2/3 to be continuous with the lower 1/3 of the anal canal.
63
What is the blood supply to the upper 2/3 of the anal canal?
The superior rectal artery (branch of IMA).
64
What is the blood supply to the lower 1/3 of the anal canal?
The inferior rectal artery (branch of internal pudendal artery).
65
What part of the anal canal receives autonomic innervation?
The upper 2/3 (lower 1/3 is somatic innervation).
66
Which anal sphincter receives autonomic innervation and is involuntary?
The internal anal sphincter.
67
Which urethral sphincter is composed of smooth muscle?
The internal urethral sphincter.
68
When is the periaqueductal grey suppressed?
In storage. (Active in voiding).
69
What is the external urethral sphincter?
Skeletal muscle, voluntary sphincter.
| Composed of the rhabosphincter and pelvic floor.
70
Do the urethral sphincters receive parasympathetic or sympathetic innervation?
Sympathetic.
71
When are the urethral sphincters activated?
In storage - activation causes contraction of the sphincters.
72
Spermatogenesis: what do type B cells differentiate into?
They differentiate into primary spermatocytes that will then go onto meiosis.
73
Spermatogenesis: where are type A cells located?
Outside the blood-testes-barrier.
74
Spermatogenesis: what is the function of type A cells?
They replicate by mitosis to ensure a constant supply of spermatogonia to fuel spermatogenesis.
75
Spermatogenesis: what does meiosis 1 produce?
2 secondary spermatocytes.
76
Spermatogenesis: what does meiosis 2 produce?
4 spermatids.
77
What changes does the sperm make with regards to its structure?
- It discards excess cytoplasm.
- Grows flagellum.
- Lots of mitochondria.
- Acrosomes at its head.
78
What collects sperm from the rete testis and transfers it to the epididymis?
The efferent ductules.
79
What is the function of the epididymis?
Storage and maturation of sperm. Sperm normally stay in the epididymis for 60 days.
80
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.
81
What is the affect of LH on the testes?
Stimulates Leydig cells to produce testosterone.
82
What is ovulation?
The release of an oocyte from a follicle.
83
What hormone stimulates ovulation?
LH.
84
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.
85
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.
86
What is the proliferative phase?
When the endometrium grows rapidly under the influence of oestrogen.
87
What does the corpus luteum degenerate into?
The corpus albicans.
88
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.
89
What is block to polyspermy?
After a sperm has fertilised the egg, the egg needs to prevent further sperm fertilising it.
90
What are the mechanisms to ensure block to polyspermy?
Enzymes are released that harden the zona pellucida and inactivate sperm binding sites.
91
What hormone does the hypothalamus release that stimulates release of the gonadotropins?
GnRH - gonadotropin releasing hormone.
92
What is the function of GnRH?
It acts on the anterior pituitary gland stimulating it to release FSH and LH.
93
What cells does FSH act on in males?
Sertoli cells.
94
What cells does FSH act on in females?
Granulosa cells.
95
What cells does LH act on in males?
Leydig cells.
96
What cells does LH act on in females?
Theca cells.
97
What is the function of sertoli cells?
They release MIF, inhibin and activins (regulate FSH secretion), and androgen binding protein (increases testosterone concentration).
98
What is the function of granulosa cells?
They convert androgens into oestrogen using aromatase enzyme.
99
What is the function of leydig cells?
they produce testosterone.
100
What is the function of theca cells?
They produce androgens (oestrogen precursors) which diffuse into granulosa cells to form oestrogen.
101
What enzyme converts androgens into oestrogen?
Aromatase.
102
What is the predominant hormone responsible for the proliferative phase?
Oestrogen.
103
What is the predominant hormone responsible for the secretory phase?
Progesterone.
104
Until what week are male and female primitive gonads identical?
Week 6.
105
What is the mesovarium?
Mesentery attaching the ovary to the posterior broad ligament.
106
Define menopause.
Cessation of menstruation.
107
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.
108
What happens to oestrogen levels at menopause?
They fall.
109
What happens to LH and FSH levels at menopause?
They increase as they're no longer inhibited by negative feedback.
110
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.
111
What are the long-term symptoms of menopause?
Osteoporosis and increased risk of cardiovascular disease.
112
Name 4 treatments that can help with the symptoms of menopause.
1. Hormone Replacement Therapy
2. Sedatives.
3. Calcium supplements.
4. Vitamin D supplements.
113
What hormones are given in Hormone Replacement Therapy
Oestrogen and progesterone.
114
What is the advantage of Hormone Replacement Therapy being given as a patch as opposed to orally?
The hormones go straight into the bloodstream and so bypass the liver.
115
What are the risks of Hormone Replacement Therapy?
Small increased risk of cervical, breast and endometrial cancer.
116
What are the two main types of stem cells?
1. Embryonic stem cells - pluripotent.
| 2. Somatic stem cells - multi-potent.
117
Name 3 diseases that stem cells could help to cure.
1. Parkinsons disease.
2. Alzheimers.
3. Type 1 diabetes.
118
What are the 3 main characteristics of stem cells?
1. Self renew over long periods.
2. Undifferentiated.
3. Can generate other cells: pluripotent/multipotent.
119
Where in the embryo do embryonic stem cells come from?
The inner cell mass.
120
What are the 3 histological layers of the uterus?
1. Endometrium - mucosal lining, pseudostratified columnar.
2. Myometrium - smooth muscle wall.
3. Perimetrium.
121
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.
122
What are the characteristics of the endometrium in the proliferative phase?
Straight glands, no secretions. Stromal and epithelial mitoses.
123
What are the characteristics of the endometrium in the early secretory phase?
Coiling of glands and subnuclear vacuoles.
124
What is the decidua basalis?
A part of the endometrium invaded by trophoblast.
125
What is the decidua capsularis?
A part of the endometrium overlying the blastocyst.
126
What is the decidua parietalis?
Endometrium lining the rest of the uterine cavity.
127
What invades the decidua basalis?
Syncytiotrophoblast.
128
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.
129
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.
130
Why is it important that the chorionic villi branch in maturation?
Branching increases the surface area for exchange of nutrients.
131
What hormonal pathway is likely to be responsible for a decrease in urine production?
Renin angiotensin aldosterone system.
132
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.
133
Name 6 hormones produced by the anterior pituitary gland.
1. FSH.
2. LH.
3. GH.
4. ACTH.
5. TSH.
6. Prolaction.
134
Name 2 hormones produced by the posterior pituitary gland.
1. ADH.
| 2. Oxytocin.
135
How does the anterior pituitary gland receive its blood supply?
Via a portal venous circulation from the hypothalamus.
136
What are the two types of hormone?
1. Made at response e.g. steroids.
| 2. Stored and released at response e.g. pituitary hormones (peptides).
137
Where are the receptors for steroid hormones located?
Steroid receptors are intracellular - steroids pass through plasma membranes bound to proteins.
138
Where are the receptors for peptide hormones located?
On cell membranes.
139
What are the purposes of the endocrine system?
1. Communication between cells.
2. Integrates whole body physiology.
3. It can make rapid adaptive changes.
4. Maintains the metabolic environment.
140
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.
141
What does thyroid hormone affect?
Increased metabolism, increased sympathetic action, heat production, essential for growth and development too.
142
What effect does prolactin have on dopamine?
It increases dopamine levels - positive feedback effect.
143
Briefly describe the mechanism of prolactin.
Hypothalamus -> dopamine -> anterior pituitary -> prolactin -> mammary glands -> milk production -> positive feedback on dopamine.
144
Briefly describe the mechanism of ACTH.
Hypothalamus -> CRH -> anterior pituitary -> ACTH -> adrenal glands -> cortisol release -> negative feedback on hypothalamus and pituitary.
145
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.
146
How would you describe growth hormone secretion from the anterior pituitary?
It is secreted in a pulsatile fashion and increases during deep sleep.
147
What factors effect growth hormone secretion?
1. Starvation.
2. Exercise.
3. Trauma.
4. Hypoglaecemia.
5. Deep sleep.
148
What clinical abnormalities can occur if there is a problem with growth hormone secretion?
1. Gigantism.
2. Dwarfism.
3. Acromegaly.
149
What does the parathyroid control?
Serum Ca2+. (Hyperparathyroidism -> hypercalcemia).
150
What hormone does the parathyroid secrete and what is its function?
PTH - it increases the absorption of Ca2+ and is secreted when Ca2+ levels fall.
151
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.
152
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.
153
What are the 4 cells to make up the islets of langerhans?
1. Beta cells: insulin. (70%)
2. Alpha cells: glucagon. (20%)
3. Delta cells: somatostatin. (8%)
4. Pancreatic polypeptide secreting cells. (2%)
154
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.
155
What is the function of insulin?
1. Suppresses hepatic glucose output: decreases glycogenolysis and gluconeogensis.
2. Increases glucose uptake into fat and muscle cells.
3. Suppresses lipolysis and muscle breakdown.
156
What is the function of glucagon?
1. Stimulates hepatic glucose output: increases glycogenolysis and gluconeogenesis.
2. Reduces peripheral glucose uptake.
3. Stimulates release of gluconeogenic precursors.
4. Stimulates lipolysis and muscle breakdown.
157
Insulin release is described as biphasic. Describe the two phases.
1. Phase 1 - Stored insulin is released rapidly.
| 2. Phase 2 - Slower release of newly synthesised insulin.
158
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.
159
What is glucose converted into when it enters a beta cell?
Glucose-6-phosphate.
160
What substance can tell you if high insulin levels are due to endogenous insulin production?
The presence of C peptide.
161
What glucose transporter allows glucose uptake into muscle and fat cells?
GLUT-4.
162
Describe insulin action at muscle and fat cells.
Insulin binds to membrane receptors -> intracellular signalling cascade stimulated -> GLUT-4 mobilisation to plasma membrane -> GLUT-4 integrates into plasma membrane -> glucose enters cell via GLUT-4.
163
What is a normal blood glucose?
4-6mmol/mol.
164
What is the short term response to high blood glucose?
Glycogenesis.
165
What is the long term response to high blood glucose?
Triglyceride production - lipogenesis.
166
What is the short term response to low blood glucose?
Glycogenolysis.
167
What is the long term response to low blood glucose?
Gluconeogensis.
168
Name 3 places where glucose sensors are located.
1. Pancreatic islets.
2. Medulla.
3. Hypothalamus.
169
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.
170
What hormones from the hypothalamus stimulate the anterior pituitary to release GH?
GHRH (+ve affect) and SMS (-ve affect).
171
What hormone from the hypothalamus stimulates the anterior pituitary to release LH and FSH?
GnRH.
172
What hormone from the hypothalamus stimulates the anterior pituitary to release ACTH?
CRH.
173
What hormone from the hypothalamus stimulates the anterior pituitary to release TSH?
TRH.
174
What hormone from the hypothalamus stimulates the anterior pituitary to release prolactin?
Dopamine.
175
What can pituitary tumours cause?
1. Pressure on local structures e.g. optic chiasm. Can result in bitemporal hemianopia.
2. Pressure on normal pituitary function; hypopituitary.
3. Functioning tumour can result in Cushing's disease, gigantism and prolactinoma.
176
How much of the total cardiac output does each kidney receive?
10%.
177
What equation can be used to calculate GFR?
GFR = (Um x urine flow rate) / Pm.
- Um = concentration of marker substance (m) in urine.
- Pm = concentration of marker substance (m) in plasma.
178
Give an example of the process of autoregulation in regulating GFR.
Pressure in afferent arteriole increases -> stretches the vessel walls -> contraction of smooth muscle -> arteriolar constriction.
179
Regulating GFR: Why does autoregulation cause arteriolar constriction when the pressure in afferent arterioles increases?
It acts to prevent an increase in systemic pressure reaching the capillaries and so allows GFR to be maintained.
180
What hormones are involved in pregnancy?
1. Human chorionic gonadotropin.
2. Oestrogen.
3. Progesterone.
4. Prolactin.
5. Prostaglandins.
6. Oxytocin.
7. Relaxin.
181
What is the function of human chorionic gonadotropin?
It stimulates oestrogen and progesterone production. The levels of this hormone decrease when the placenta develops and takes over.
182
What is the function of prolactin?
It stimulates the mammary glands to produce milk (lactation).
183
What are the functions of prostaglandins?
They have an important role in labor initiation.
184
What is the function of oxytocin?
Stimulates uterine contraction and milk production stimulated by suckling. It is also thought to help express caring behaviours.
185
What is the function of relaxin?
It is involved in cervical ripening.
186
What are the cardiovascular maternal adaptations?
1. Cardiac output increases.
2. Blood pressure decreases.
3. Uterine blood flow increases.
187
Why does blood pressure decrease in pregnancy?
There is mass vasodilation which reduces the TPR and so BP decreases. (BP=TPRxCO).
188
Why does uterine blood flow increase in pregnancy?
To ensure enough nutrients are delivered to the foetus.
189
What are the adaptations to the skin in pregnancy?
Linea nigra and striae gravidarum/stretch marks may appear on the skin, usually the abdomen. There is also darkening of the areola.
190
What are the maternal adaptations to the veins in pregnancy?
Varicose veins are often present in pregnancy.
191
Define parturition.
Giving birth.
192
What are the 3 layers of the uterus?
1. Perimetrium (inner).
2. Myometrium.
3. Endometrium.
193
Describe cervical ripening.
Softening of the cervix that begins prior to labor. It is necessary for cervical dilation. It occurs under the influence of relaxin and placental hormones.
194
What hormones stimulate cervical ripening?
Relaxin and placental hormones.
195
What are the 2 main stages of labor?
1. Latent: little cervical dilation.
| 2. Active: cervix dilates and opens.
196
What are the sub-divisions of the active stage of labor?
1st - cervix dilation begins.
2nd - cervix is fully dilated and birth begins.
3rd - birth and expulsion of the placenta.
197
What hormones are needed for the initiation of labor?
Prostaglandins and oxytocin.
198
What is the function of PGF2 alpha?
It enhances oxytocin activation.
199
What does the adrenal cortex produce?
Steroid hormones.
200
What does the adrenal medulla produce?
Adrenaline and noradrenaline (catecholamines).
201
What are the 3 layers of the adrenal cortex?
1. Zona glomerulosa.
2. Zona fasciculata.
3. Zona reticularis.
202
What does the zona glomerulosa produce?
Mineralocorticoids e.g. aldosterone.
203
What does the zona fasciculata produce?
Glucocorticoids e.g. cortisol.
204
What does the zona reticularis produce?
Androgens e.g. DHEA.
205
What are steroid hormones synthesised from?
Lipids.
206
What do steroid hormones bind to so they can be transported through the blood?
CBG proteins.
207
Why do steroid hormones bind to CBG proteins?
They are H2O insoluble and so need to bind to CBG for transport through the blood.
208
Where does the anterior pituitary gland originate from?
It is epithelial in origin. Derived from the primitive gut tube.
209
What regulates cortisol synthesis?
ACTH!
210
What is the function of ACTH?
It acts on adrenal glands to stimulate cortisol synthesis.
211
What happens to adrenal glands if there isn't enough ACTH?
They will shrink.
212
What are glucocorticoids released in response to?
Stress!
213
What are the physiological functions of cortisol not in response to stress?
1. Permissive action on smooth muscle cells that surround blood vessels; this helps to maintain BP.
2. Maintains concentrations of enzymes involved in metabolic homeostasis.
3. Anti-inflammatory and anti-immune functions: dampens the immune response.
214
What regulates secretion of adrenaline and noradrenaline?
Autonomic innervation, mainly sympathetic.
215
Name the 2 hypothalamic nuclei whose axons extend into the posterior pituitary gland via the pituitary stalk.
1. Paraventricular nuclei.
| 2. Supraoptic nuclei.
216
Where does the posterior pituitary gland originate from?
Originates from neuronal tissue.
217
What hormones does the posterior pituitary gland secrete?
1. ADH.
| 2. Oxytocin.
218
What is the function of oxytocin?
It is important in the onset of labour, uterine contraction. It produces milk in response to suckling and is thought to be involved in caring behaviours.
219
What hypothalamic nucleus contains cells responsible for oxytocin?
Paraventricular nucleus.
220
What hypothalamic nucleus contains cells responsible for ADH?
Supraoptic nucleus.
221
What is the affect on ADH secretion if osmolarity increases?
ADH secretion will increase.
222
What are the physiological functions of cortisol in response to stress?
1. Mobilises energy sources: increases protein catabolism, lipolysis and gluconeogenesis. This help to maintain blood glucose levels.
2. Enhanced vascular reactivity; maintains vasoconstriction with noradrenaline.
3. Suppresses inflammatory and immune responses.
4. Inhibition of non-essential functions e.g. growth and reproduction.
223
Why is there increased cortisol released in response to stress?
Stress poses a threat to homeostasis. Cortisol acts to maintain BP, provide extra energy sources and to shut down non-immune functions so homeostasis can be maintained.
224
Why is infertility a consequence of stress?
When someone is stressed, their cortisol levels increase, the extra cortisol acts to shut down non-essential functions such as reproduction and so can result in infertility.
225
Give 5 actions of angiotensin 2.
1. Vasoconstriction.
2. Increases Na+ reabsorption.
3. Stimulates the adrenal cortex to release aldosterone.
4. Stimulates ADH release.
5. Increase sympathetic activity.
226
Describe the process of vitamin D activation.
Dietary vit D -> plasma vit D -> 25-OH D (conversion occurs in the liver with the enzyme 25-hydroxylase) -> 1,25-diOH D (conversion occurs in the kidney with the enzyme 1-hydroxylase) -> plasma 1,25-diOH D
227
What does the mesonephric ridge form?
Mesonephric tubules: these recieve a glomerulus and bowmans capsule forms.
228
What does the metanephric blastema form?
Excretory units - nephrons.
229
What causes the kidneys to ascend from the pelvis to the abdomen in the embryo?
1. Reduction in body curvature.
| 2. Growth of the lumbar and sacral regions.
230
During embryonic life what structure is responsible for the excretion of waste products?
The placenta - not the kidneys!
231
Describe the migration of primordial germ cells.
Originate in the epiblast and migrate through the primitive streak. They migrate along the dorsal mesentery of the hind gut to reach and invade the genital ridge by the 6th week.
232
What ligament attaches the uterus to the pelvic wall?
The broad ligament.
233
What does the broad ligament divide the pelvic cavity into?
1. The uterorectal pouch.
| 2. The uterovesical pouch.
234
What does the vagina develop from?
Upper 1/3 - mullerian duct. Lower 2/3 - urogenital sinus.
235
What causes the mullerian duct to degenerate in the male?
Sertoli cells release MIF.
236
What line marks the junction between the upper 2/3 and lower 1/3 of the anal canal?
The pectinate line.
237
What is the epithelium of the anal canal above the pectinate line?
Simple columnar.
238
What is the epithelium of the anal canal below the pectinate line?
Stratified squamous.
239
What are the functions of a normal bladder?
Continence, sensation of volume, receptibe relaxation. Voluntary initiation of voiding and complete emptying.
240
What is the bladder composed of?
Multiple segments of smooth muscle with their associated ganglia. Each segment exhibits
spontaneous activity - ‘micromotions’.
241
Which urethral sphincter is composed of skeletal muscle?
External urethral sphincter.
242
Describe what happens in micturition.
The bladder fills and stretch receptors are stimulated. Afferent impulses stimulate parasympathetic action of detrusor muscle; it contracts. The urethral sphincters relax, this is mediated by inhibition of the neurones to them. The PAG is stimulated.
243
What is the periaqueductal grey?
A visceral and somatic control centre for the lower urinary tract.
244
What fibre input does the periaqueductal grey receive?
A delta fibres.
245
What is urinary incontinence?
The involuntary release of urine.
246
Name 2 types of incontinence.
1. Stress incontinence.
| 2. Urge incontinence.
247
What can stress incontinence be due to?
Sneezing, coughing, exercise.
248
What can cause urge incontinence (desire to urinate)?
Any irritation to the bladder or urethra e.g. a bacterial infection.
249
Define spermiogenesis.
The differentiation of spermatids into spermatozoa. The process involves cell remodelling.
250
How long does spermatogenesis take?
Approximately 60 days.
251
What forms the blood testes barrier?
Tight junctions between sertoli cells.
252
What is the function of the blood testes barrier?
It prevents the movement of cytotoxic agents from the blood into the lumen of the seminiferous tubules. This ensures proper conditions for germ cell development.
253
Describe the hypothalamo-pituitary-testicular-axis.
GnRh from hypothalamus acts on the anterior pituitary to release LH and FSH. LH acts on Leydig cells stimulating testosterone release. FSH acts on sertoli cells stimulating inhibin release. Inhibin and testosterone have a negative feedback affect on the hypothalamus and anterior pituitary.
254
What does semen contain?
Sperm, fructose, fibrinogen, clotting enzymes, fibrinolysin.
255
What is the importance of meiosis in gametogenesis?
It prevents polyploidy and increases genetic variability and so diversity.
256
Describe oogenesis.
Oogonia undergo mitotic divisions in utero. The oogonia develop into primary oocytes and begin a meiotic division by replicating their DNA. They do not complete meiosis 1 in the foetus = meiotic arrest. At puberty there is renewed activity in the ovaries and those oocytes destined for ovulation complete meiosis 1. Meiosis 2 occurs if the secondary oocyte is fertilised; this will produce one ovum.
257
How many secondary oocytes does each primary oocyte yield?
1 secondary oocyte and 1 non-functional polar body.
258
Why does each primary oocyte yield only one secondary oocyte?
Because only one ovum can be yielded per primary oocyte. The secondary oocyte divides into one ovum and a second polar body.
259
Describe the hormonal changes that occur at puberty.
1. Increased amplitude of GnRH and GHRH.
2. Increased levels of FSH, LH and sex steroids.
3. Increased levels of growth hormone.
260
What factors can influence puberty?
1. Nutrition (body mass).
2. Leptin, insulin (hormones).
3. Genetics.
4. Exercise.
5. Socio-cultural.
261
Describe the hypothalamo-pituitary-ovarian-axis?
GnRh from hypothalamus acts on the anterior pituitary to release LH and FSH. LH acts on theca cells stimulating androgen release. Androgen diffuses from theca to granulosa. FSH acts on granulosa cells stimulating the conversion of androgen into oestrogen (aromatase enzyme). Inhibin is also released from granulosa cells. Inhibin and oestrogen have a negative feedback affect on the hypothalamus and anterior pituitary.
262
What is the function of dihydrotestosterone?
Stimulates the differentiation of the male external genitalia. It is secreted by the testis.
263
What are the 2 phases of the menstrual cycle?
1. The follicular phase.
2. The luteal phase.
The phases are approximately equal in length and are separated by ovulation.
264
What happens in the follicular phase?
The mature follicle and secondary oocyte develop.
265
What is the luteal phase?
It occurs after ovulation until corpus luteum death.
266
Menstrual cycle: what causes oestrogen levels to rise in the follicular phase?
Oestrogen is released from granulosa cells and also from the developing and dominant follicle.
267
Menstrual cycle: what is the effect of oestrogen at low levels on the gonadotropins?
At low levels oestrogen inhibits gonadotropin release.
268
Menstrual cycle: what is the effect of decreasing FSH levels in the follicular phase?
Decreasing FSH levels cause the non-dominant, immature follicles to degenerate.
269
Menstrual cycle: what is the effect of oestrogen at high levels on the gonadotropins?
At high levels oestrogen exerts a positive feedback on gonadotropin secretion, this stimulates the LH surge.
270
Menstrual cycle: what is the effect of the LH surge?
Stimulates ovulation.
271
Menstrual cycle: why do progesterone and oestrogen levels increase following ovulation?
The ruptured follicle has transformed into a corpus luteum which releases large amounts of progesterone and oestrogen.
272
Menstrual cycle: why do LH and FSH levels decrease after ovulation?
They are inhibited by the high progesterone and oestrogen concentrations.
273
Menstrual cycle: what is the importance of the low LH concentration in the luteal phase?
Low but adequate LH acts to maintain the corpus luteum.
274
Menstrual cycle: what causes oestrogen and progesterone concentrations to fall towards the end of the luteal phase?
The corpus luteum degenerates into the corpus albicans if fertilisation does not occur. Therefore progesterone and oestrogen are no longer released.
275
Menstrual cycle: why do FSH levels increase at the end of the cycle?
The fall in progesterone and oestrogen concentration means FSH is no longer inhibited and so its plasma concentration begins to rise.
276
Menstrual cycle: why does the corpus luteum not degenerate if fertilisation occurs?
When the blastocyst implants the invading trophoblast cells release human chorionic gonadotropin (hCG). This acts to maintain the corpus luteum throughout pregnancy.
277
What is capacitation?
The final stage of sperm maturation that occurs inside the female reproductive tract. Before this stage the sperm would be unable to fuse with the egg.
278
What is the acrosome reaction?
Many sperm move through granulosa cells to bind with the zona pellucida. This binding triggers acrosomal enzymes from the sperm's head to digest through the zona pellucida. The sperm advances through; the first sperm to penetrate the entire zona pellucida and to reach the egg's plasma membrane will fuse.
279
What is the function of block to polyspermy?
It is a mechanism to prevent the entry of additional sperm fusing with the egg.
280
Describe the mechanism of block to polyspermy.
1. The egg releases contents of secretory vesicles by exocytosis.
2. Enzymes from the vesicles enter the zona pellucida and inactivate sperm binding sites and harden the zona pellucida.
281
Describe implantation.
The blastocyst implants into the endometrium on day 6. The trophoblast cells overlying the ICM invade the endometrium. Nutrient rich endometrial cells provide the metabolic fuel for early embryo growth until the placenta takes over.
282
hCG stimulates oestrogen and progesterone levels to increase rapidly in pregnancy. What are their functions?
- Oestrogen: prepares the uterus and regulates progesterone levels.
- Progesterone: inhibits uterine contractility so the foetus is not delivered prematurely.
283
What is the effect on LH and FSH of high oestrogen and progesterone levels throughout pregnancy?
Inhibits LH and FSH and so prevents further menstrual cycle's during pregnancy.
284
How does PTH increase serum Ca2+?
1. It increases bone resoprtion meaning more Ca2+ is released into plasma.
2. It acts on the kidneys to increase Ca2+ reabsorption meaning less is excreted in the urine.
3. It stimulates the enzyme 1-hydroxlyase and so increases 1,25-diOH D formation. This compound increases absorption of Ca2+ into the blood from the intestine.
285
PTH action affects serum calcium and phosphate. What is the mechanism that prevents serum phosphate from increasing too much?
It inhibits the reabsorption of phosphate ions in the kidney leading to increased excretion of phosphate ions in the urine.
286
What would happen if Nacl levels reaching the macula densa cells were very low?
The macula densa cells release prostaglandins to act on granular cells which then release renin. Renin release activates RAAS leading to increased GFR.
287
You have isolated a part of the nephron from the lumen of which large quantities of glucose and amino acids are re-entering the circulation. What part of the kidney are you studying?
Proximal convoluted tubule - bulk reabsorption occurs here.
288
Whilst looking at the lumen of the nephron you find some epithelial cells that flat rather than cuboidal. What part of the nephron are you looking at?
The thin limb of the loop of henle - flat epithelium.
289
What is the epithelium of the thick limb of the loop of henle?
Columnar epithelium. Structurally similar to the PCT and DCT.
290
What is the full name of T4?
Thyroxine.
291
What are tubulopathies?
Mutations of apical sodium transporters.
292
Where in the nephron would be affected by Bartters syndrome?
The loop of Henle.
293
What channels are affected in Bartters syndrome?
NKCC2 channels in the loop of Henle.
294
What is the diuretic equivalent to Bartters syndrome?
Loop diuretics.
295
What are the features of Bartters syndrome?
Hypokalemia, low blood pressure, alkalosis.
296
What channels do loop diuretics close?
NKCC2 - reduced Na+ and K+ secretion.
297
What part of the nephron would be affected by Gitelmans syndrome?
The distal tubule.
298
What channels are affected in Gitelmans syndrome?
NCC.
299
What is the diuretic equivalent to Gitelmans syndrome?
Thiazide.
300
What are the features of Gitelmans syndrome?
Hypokalemia, hypomagnesemia and low blood pressure.
301
What part of the nephron would be affected by Liddles syndrome?
The collecting duct.
302
What channels are affect in Liddles syndrome?
ENaC.
303
What are the features of Liddles syndrome?
Hypertension and Hypokalemia.
304
What is the full name of T3?
Triiodothyronine.
305
How many iodine molecules does thyroxine contain?
4.
306
How may iodine molecules does triiodothyronine contain?
3.
307
What atom is crucial in thyroid hormone formation?
Iodine.
308
What cells in the thyroid actively take up iodine in the form of iodide?
Follicular cells.
309
In the follicles, what cells does iodide bind to?
Tyrosine residues on thyroglobulin molecules.
310
What happens when TSH acts on the thyroid?
T1 and T2 molecules are cleaved from their thyroglobulin backbone and join to create T3 or T4.
311
What process needs to occur before T3 and T4 can be released into the blood stream?
Proteolysis.
312
Is more T4 or T3 produced in the thyroid?
T4 (thyroxine).
313
Which molecule is active T3 or T4?
T3 (triiodothyronine).
314
More T4 is produced than T3 in the thyroid. What process produces T3 elsewhere?
As T3 is more active it can be produced peripherally from the conversion of T4.
315
Briefly describe thyroid hormone synthesis.
Follicular cells take up iodide. Iodide diffuses to colloid which contains thyroglobulin. Iodide is oxidised to iodine. Iodine attaches to tyrosine residues within thyroglobulin. Tyrosine either binds 1 or 2 iodine molecules forming MIT or DIT. Thyroid peroxidase stimulates MIT and DIT binding forming T3 and T4. Proteolysis of thyroglobulin releases T3 and T4 into the ECF and then into the blood.
316
What enzyme stimulates T3 and T4 formation in the thyroid?
Thyroid peroxidase.
317
What 2 molecules can combine to form T3?
MIT+DIT
318
What 2 molecules can combine to form T4?
DIT+DIT
319
Describe the GH/IGF-1 axis.
Hypothalamus -> GHRH (+) or SMS (-) -> anterior pituitary -> GH -> Liver -> IGF-1 -> negative feedback on hypothalamus.
320
What is the function of IGF-1?
It induces cell division.
321
What is the decidual reaction?
Following implantation of the blastocyst there is differentiation of endometrial cells adjacent to the blastocyst: decidual basalis (cells invaded by syncytiotrophoblast), decidua capsularis (cells overlying blastocyst), decidua parietalis (cells lining the rest of the uterine cavity).
322
What hormones increase in parturition?
Prostaglandins (initiation of labour) and oxytocin (uterine contractions).
323
What does the inguinal canal transmit in females?
The round ligament of the uterus.
324
What is the function of the round ligament of the uterus?
Maintains the anteverted position of the uterus.
325
Give 2 reasons why the pH of the skin needs to be maintained at about 5.5.
1. The low pH switches on protease inhibitors that prevents corneodesmosome breakdown.
2. The low pH also stimulates lipid processing. Lipids prevent H2O loss.
326
What is the anion gap?
The difference between measured cations and anions: [Na+] + [K+] - [Cl-] - [HCO3-]
327
What pituitary hormone can cause hyperpigmentation?
ACTH.
328
Which hormone that affects blood pressure is produced in the lungs?
Angiotensin 2. (ACE in the lungs converts angiotensin 1 to angiotensin 2).
329
Aldosterone causes the release of which hormone from the pituitary?
ADH.
330
Give 2 tests that can be used to screen for disorders in pregnancy.
1. Ultrasound.
| 2. Amniocentesis.
331
What is the most abundant glucocorticoid in humans?
Cortisol.
332
Name the effect cortisol has on three other hormones.
1. Adrenaline - up-regulates beta2 receptors therefore potentiates adrenaline.
2. Insulin - inhibits. Cortisol acts to increase blood glucose.
3. Glucagon - activates. Cortisol acts to increase blood glucose.
333
What hormone causes production of sperm?
FSH.
334
In what specific cell in the testes do sperm mature?
Sertoli.
335
Name 2 hormones that regulate melanin secretion.
1. ACTH.
| 2. MSH.
336
Give 6 functions of the skin.
1. Barrier to infection.
2. Protection against trauma.
3. Protection against UV.
4. Thermoregulation.
5. Vitamin D synthesis.
6. Waterproof.
337
What organelle stores melanin in melanocytes?
Melanosomes.
338
Give 3 histological characteristics of the secretory phase.
1. Spiral arteries.
2. Decidualised stroma.
3. Secretions.
4. Torturous glands.
339
What cells in the parathyroid detect Ca2+ levels?
Chief cells.
340
What does ANP inhibit the release of?
Renin.
| ANP is a vasodilator and acts to decrease blood pressure.
341
What type of receptor does ACTH act on?
G protein coupled receptor. (All pituitary and hypothalamus hormones act on these receptors).
342
What hormone acts on the uterus in the proliferative phase?
Oestrogen.
343
What changes happen to the endometrium in the proliferative phase?
Growth of the endometrium and myometrium is stimulated. Receptors for progesterone are also stimulated.
344
What hormone acts on the uterus in the secretory phase?
Progesterone.
345
What changes happen to the endometrium in the secretory phase?
It becomes a secretory tissue: endometrial glands are coiled and filled with glycogen, blood vessels become more numerous and spiralled. Progesterone also inhibits myometrial contractions to ensure that
a fertilized egg can safely implant once it arrives in the uterus.
346
What are the histological characteristics of the endometrium in the mid-secretory phase?
Tortuous glands, vacuoles above and below the nucleus, stroma-oedema and secretions.
347
What are the histological characteristics of the endometrium in the late-secretory phase?
Prominent spiral arteries and decidualised stroma. More secretions and elongated glands.
348
What effects does oestrogen have on the endometrium?
Hyperplasia and hypertrophy of endometrial cells. Also stimulates myometrial growth.
349
Name one hormone from the pituitary gland one from the chorion/decidua that induces labour.
Pituitary – oxytocin.
| Decidua/chorion – prostaglandins.
350
What do the macula densa cells release when they detect low NaCl?
Prostaglandins.
| Prostaglandins act on granular cells and trigger renin release.
351
What enzyme is found only in the zone glomerulosa?
Aldosterone synthase.
352
What 2 structures make up the metanephros?
1. Metanephric blastema.
| 2. Ureteric bud.
353
What is the ureteric bud an outgrowth of?
The mesonephric duct.
354
What is dihydrotestosterone?
An active metabolite of testosterone. It modulates external genitalia differentiation -> penis, scrotum and prostate.
355
What are the start and end products of spermiogenesis?
Start: spermatid.
End: spermatozoa.
356
What are the start and end products of spermatogenesis?
Spermatogonia undergo mitosis forming primary spermatocytes. Type B primary spermatocytes undergo meiosis forming secondary spermatocytes and then spermatids.
357
What are the start and end products of mitosis in oogenesis?
Start: oogonia.
End: primary oocyte.
358
What are the start and end products of meiosis in oogenesis?
Start: primary oocyte.
Middle: secondary oocyte.
End: 1x ovum.
359
Which layer of the endometrium is shed in the menstrual cycle?
Stratum functionalis.
360
Define tubulopathies.
Mutations of apical Na+ transporters.
361
What part of the nephron is affected by Bartter's syndrome?
The loop of henle.
362
What channels are affected by Bartter's syndrome?
NKCC2.
363
What is the diuretic equivalent to Bartter's syndrome?
Loop diuretics.
364
What are the characteristic features of Bartter's syndrome?
Hypokalemia, low BP, alkalosis.
365
What part of the nephron is affected by Gitelman's syndrome?
The DCT.
366
What channels are affected by Gitelman's syndrome?
NCC.
367
What is the diuretic equivalent to Gitelman's syndrome?
Thiazides.
368
What are the features of Gitelman's syndrome?
Hypokalemia, hypomagnesemia, low BP.
369
What part of the nephron is affected by Liddle's syndrome?
The collecting duct.
370
What channels are affected by Liddle's syndrome?
ENaC.
371
What are the characteristic features of Liddle's syndrome?
Hypokalemia and increased BP (too much Na+ reabsorption).
372
Name 2 hormones that are produced elsewhere but are activated in the kidney.
1. Angiotensinogen.
| 2. 25-hydroxyvitamin D.
373
How does increased serum sodium affect calcium reabsorption in the kidney?
There would be increased calcium reabsorption. Calcium is coupled with sodium reabsorption in the proximal tubules.
374
What are the 6 stages of implantation?
1. Apposition.
2. Attachment.
3. Differentiation of trophoblast.
4. Invasion of endometrium.
5. Decidual reaction.
6. Maternal recognition.
375
What are C-cells also known as?
Parafollicular cells.
376
What amino acid and dietary nutrient are needed for hormones to be secreted from the thyroid gland?
Amino acid - tyrosine.
| Dietary nutrient - iodine.
377
Name 2 proteins in the blood that hormones from the thyroid gland bind to?
1. Albumin.
| 2. Thyroxine binding globulin.
378
Name 2 prostaglandins released in labour.
1. PGE2.
| 2. PGF2-alpha (main one).
379
Give 3 functions of the placenta.
1. Provides nutrition to the foetus.
2. Gas exchange.
3. Waste removal.
4. Endocrine and immune support.
380
Placental abnormalities often require caesarian delivery. What is placenta accreta?
Abnormal adherence, no decidua basalis.
381
Placental abnormalities often require caesarian delivery. What is placenta perceta?
Where the villi penetrate the myometrium.
382
Placental abnormalities often require caesarian delivery. What is placenta praeria?
The placenta overlies the internal os, there is abnormal bleeding.
383
What 2 hormones are secreted in the kidney?
EPO and renin.
384
Give 2 causes of metabolic acidosis.
Ketoacidosis and lactic acidosis.
385
What hormones do acidophils in the anterior pituitary secrete?
GH and prolactin (Somatotrophs and lactotrophs).
386
What hormones do basophils in the anterior pituitary secrete?
FSH, LH, TSH and ACTH. (Corticotrophs, thyrotrophs and gonadotrophs).
387
Give an example of a steroid hormone.
Oestrogen, testosterone, cortisol.
388
Give an example of a peptide hormone.
Insulin, GH, FSH, LH, TSH etc.
389
Which has a faster response, steroid or peptide hormones?
Peptide hormones have a rapid response.
390
Which is stored, steroid or peptide hormones?
Peptide hormones are stored.
391
What is the function of aldosterone?
It acts on the principal cells of the collecting duct and increases transcription of ENaC channels and H+/K+ ATPase pumps. More Na+ is reabsorbed and more K+ is secreted, H2O is retained -> blood pressure raised.
