SUGER Flashcards
1
Q
What capillaries make up the glomerulus? and therefore the endothelial lining is
A
Fenestrated capillaries
fenestrated
2
Q
What arteriole is blood fed into glomerulus
A
Afferent arteriole
3
Q
What arteriole drains the glomerulus
A
efferent arteriole
4
Q
How many layer are there within the glomerular basement membrane
A
3
Endothelial side
Lamina Rara Interna (Heparan sulfate)
Lamina Densa (Type 4 collagen, laminins)
Lamian Rara Externa (Heparan sulfate)
Podocyte layer
5
Q
What is/isn’t allowed to enter the bowman’s capsule
A
Formed elements not allowed + negatively charged substances
Elements such as H2O, small proteins, nutrients + positively charged substances allowed in
6
Q
What are the layers of the bowman’s capsule ?
A
Parietal (simple squamous epithelial cells)
Visceral (podocytes)
7
Q
What is the space between podocytes called?
A
Filtration slits
8
Q
What protein spans across adjacent podocytes?
A
Nephron because they span across filtration slits they are called Nephron diaphragm
9
Q
What is the role of a mesangial cell?
A
Phagocytose any macromolecule that gets stuck in the slit diaphragm
Contractile ability - afferent/efferent arterioles
Bind to JG cells to secrete renin
10
Q
What is glomerular filtration rate?
A
Plasma volume that is being filtered out of glomerulus and into Bowmans capsule for every 1 minute 125ml/min
11
Q
What factors affect glomerulus filtration rate?
A
Net filtration pressure: Pressing forcing out - Pressure forcing in
Pressure forcing out = glomerular hydrostatic pressure + colloid osmotic pressure
Pressure forced in = colloid osmotic pressure + capsular hydrostatic pressure
Permeability of glomerulus + Surface Area= Filtration Coefficient
GFR= NFP x KF
12
Q
Relationship between NFP & GFR
A
Directly proportional
13
Q
Relationship between GFR and Filtration coeffeicent
A
Directly proportional
14
Q
What makes up the filtration co-efficient
A
surface area + permeability of glomerulus
15
Q
What is the GHP and BP relationship
A
directly proportional and therefore dependent on systemic circulation
16
Q
What is osmolality
A
Volume of particles per kg of solvent
OSMOLALITY = moles/kg
17
Q
What is tubular secretion
A
Substances flowing from blood to kidney tubules (active transport)
18
Q
What is tubular reabsorption
A
Substances flowing from tubules to blood
Active or passive
19
Q
Proximal tubule bulk reabsorption
A
3Na+/2K+ ATPase pumps
Secondary Active transport: Na+ &Glucose/amino acids/lactate channel
Secondary Active transport: Na+ & H+ pump. H+ combines with HCO3- in a proximal convoluted tube to form H2CO3. This then with the enzyme carbonic anhydrase goes to become H20 + CO2
Paracellular transport
Urea is also reabsorbed via lipid
20
Q
What substances have a 100% reabsorption
A
Glucose
Amino Acids
Lactate
21
Q
What is obligatory water reabsorption
A
When the water is following the actual salt into the blood
22
Q
By which transport mechanism is drugs undergo tubular secretion
A
Active transport
23
Q
What is the importance of tubular secretion
A
Might not be able to get rid of that substance because it got reabsorbed too much/or couldn’t filter/lipid-soluble
24
Q
What happens to the osmolality as you go from renal cortex to renal medulla
A
Increases therefore have less H20 in comparison to solutes which is high = hypertonic
25
What two things make up the loop of Henle
Ascending limb
Descending limb
26
What makes up the nephron
Bowman's Capsule, Glomerulus, PCT, DCT, Loop of Henle
27
What is the name of the cotransporter found in ascending limb of Loop of Henle?
Na+/K+/Cl- co transporter
Reabsorbs all of Na+ and Cl- and some of K+ into blood
28
What is the Counter Current Exchange Mechanism
When the ascending limb goes up and pumps out Na+, K+, Cl- with the cotransporter making the medullary interstitial space salty.
This causes the water travelling down the descending limb to leave via aquaporin 1 (obligatory water reabsorption)
Water leaves the descending limb until the kidney tubules plasma osmolality is equal to descending limb isotonic
29
Why cant solutes leave out of the descending limb
Or water leave ascending limbs
The descending limb is impermeable to solutes
The ascending limb is impermeable to water
30
What is the osmolality in the distal convoluted tube
Hypotonic as most of the solutes have left through the cotransporter in comparison to the plasma osmolality
31
What is the vasa recta
peritubular capillary in the medulla
branch of efferent arteriole
slow blood flow
Parallel to the loop of Henle
Involved in the counter current multiplier system
32
What happens in the vasa recta
There is a high concentration of NaCl in the instertial fluid. Moves into the vasa recta as the osmolality increases as you go down vasa recta. At the same time high conc of H20 moves from vasa recta to instertial fluid
As osmolality decreasesas you go up vasa recta NaCl is being pushed out. H2O moves back in
33
Counter Current Multiplier mechanism significance
Prevents the rapid removal of sodium chloride from the medullary interstitial in order to maintain sality gradient
Delivers O2 to tissues
34
How is calcium reabsorbed in the early distal convoluted tubule
Low Ca+ levels detected by chief cells causes parathyroid to secrete parathyroid hormone.
Parathyroid hormone binds to receptors distal convoluted tubule then causes adenyl cyclase mechanism opening up Ca2+ channel.
Calcium reabsorbed then by secondary calcium channel
35
What drug inhibits the sodium chloride symporter in the early distal convoluted tubule
Thiazide
Its a diuretic
36
What does the adrenal gland secrete
Aldosterone
Stimulates: Angiotensin 2, Na+ concentration
Inhibit: Low K+ levels
37
What is distal convoluted tubule impermeable to?
Water
38
What are principal cells responsible for?
Maintaining mineral balance in cells
39
What are intercalated A and B cells
maintaining acid-base balance
40
Where intercalated cells found
Collecting duct
41
What do intercalated A cells secrete
What do intercalated B cells secrete
Acid
Base
42
What secretes ADH
Pituitary gland
43
What stimulates the release of ADH
Increase in osmolality
Angiotensin 2
44
What cells do ADH act on and where can the be found?
Collecting duct
Act on principal cells
45
What cells make up collecting duct
Principal cells
Intercalated cells
46
What happens once ADH binds to receptor of principal cells
Stimulates Gs protein
Goes to adenyl cyclase and converts ATP in cAMP
cAMP ----\> pKa
pKa results in the fusion of vesicles containing aquaporins to go to collecting duct membrane
47
What ions depend on the hormone secreted and therefore reabsorbed into blood stream.
Where can this be found
Principal cells
Amount of Aldosterone present depends on Na+ that is being reabsorbed in late distal convoluted tubule
48
What is urea recycling
urea is secreted at the last part of the collecting duct via facilitated diffusion and gets reabsorbed by ascending limb.
Importance:
1, Make concentrated urine
2. Wants to contribute to medullary interstitial gradient
49
What happens to urine
Most goes down collecting tubule
Some gets recycled
50
What is absorbed by Proximal convoluted tube
Na+ (65%)
H2O (65%)
HCO3- (90%)
K+ (60%)
Cl- (50-60%)
Ca+ (60%)
Urea (50%)
Glucose, Amino Acids, Lactase (100%)
51
Vasa recta
parallel to loop of Henle
52
What is secreted into Proximal Convoluted tube
Drugs
H+
NH4+
Creatinine
=All require ATP
53
What is absorbed by Loop of Henle
Descending limb
25% water
Ascending limb
Na+ : 25%
K+ : 30%
2Cl- : 30%
54
What happens in parietal cell of distal convoluted tube when there is low bp
Zona glomerulosa secretes aldosterone
Stimulates genes and secretes 3 proteins in principal cell
One of the proteins allows sodium to enter the principal cell
Another protein allows 3Na+/2K+
Another one is to secrete potassium K+ into the late distal convoluted tube
ADH secretes causes aquaporin to open up
55
Intrinsic renal autoregulation
Myogenic mechanism
Tuboglomerular feedback system
56
Myogenic mechanism renal autoreg
High BP
⇡BP ⇢ ⇡G.H.P ⇢ ⇡G.F.R
⇡BP ⇢ ⇡Stretch⇢ ⇡contraction ⇢ ⇡vasoconstriction ⇢ ⇣GBF ⇢ ⇣GFR
57
⇡BP ⇢ ⇡G.F.R ⇢ high or low NaCl
high
58
Macula Densa
⇑Na+ ⇑Cl-
Adenosine
causes afferent arteriole to constrict by acting on smooth muscle cell- vasoconstriction smaller diameter and therefore lower GBF, less filtration and lower GFR lower NaCl
Inhibits JG cells to secrete renin
59
Macula Densa
⇓Na+ ⇓Cl-
NO PGI2
causes afferent arteriole to dilate by acting on smooth muscle cell - vasodilation larger diameter and therefore ⇡ GBF, ⇡ filtration and ⇡ GFR ⇡ NaCl
Stimulates JG cells to secrete renin
60
Extrinsic renal autoregulation
Sympathetic N.S (⇣SBP)
RAAS
61
Sympathetic nervous system
SNS gets activated when BP is really low
1. Increases heart rate, increases stroke volume to increase cardiac output and bp
2. Causes the vasoconstriction of the afferent arterioles to get more blood flow to other organs
3. Causes vasoconstriction of the systemic arteries via alpha 1 receptor to increase bp triggers renin release from beta 1 receptors
62
Renin Angiotensin Aldosterone ADH System (RAAAS)
When there is low BP.
Low Bp ⇢ Low GFR
JG cells secrete more renin
renin causes angiotensinogen which is secreted by the liver to cleave and become angiotensin 1
Angiotensin 1 combine with Angiotensin converting enzyme (ACE) in the lungs and cleaves it to become angiotensin 2
AT2 affects other systems
63
What does angiotensin 2 do in PSNS? R.A.A.S
In CNS: Increase in thirst
In CNS: This causes the increase of ADH to be secreted by the `pituitary gland affecting the collecting tubule to become more permeable to H20. This increases the BV and therefore BP
In the adrenal cortex: binding to the zona glomerulosa secretes more aldosterone causing the increase of absorption of Na+ and H20 of parietal cells in DCT. This increases the BV and therefore BP
In kidneys: Binds to receptors of efferent arterioles and causes vasoconstriction and therefore increases GFR. Binds to cells of PCT via receptors and causes it to increase the reabsorption of sodium and water. Increasing BV and then BP
In systemic arterioles: causes vasoconstriction, increase in SVR, increase in BP
64
What does ADH do?
Put aquaporins in the tubular membrane, water can therefore be funnelled in tubular cells and into the blood.
65
What makes up the urinary bladder
Detrusor muscle
Internal & External urethral sphincter
urogenital diaphragm
66
Receptors in what muscle of the urinary bladder contain stretch receptos
Detrusor muscle
67
Mechanism of micturition of empty bladder
Receptors in the urinary bladder detect low action potential in the sacral spinal cord S2-S4
Stimulates neurons that will take these ascending fibres upwards into the thoracolumbar region of the spinal cord T11-L2 to synapse with preganglionic motor neurons
Then they synapse on the cell bodies of the inferior mesenteric ganglion
The hypogastric nerve carries impulses and attaches to detrusor muscles (relax). Secretes NE, which attaches to the receptor. NE also binds to receptors on the internal sphincter muscle (contract)
Impulses also carried up pons and cerebral cortex
This stimulates the pontine storage centre and inhibits the pontine micturition centre in the pons
impulses from the pontine storage centre and synapse with inferior mesenteric ganglion. They also carry down to preganglionic motor neurons.
Impulses carry to the detrusor muscle and secrete Ach, increasing Ca+ in muscles and causing contraction.
There are also impulses carried to the anterior ventral horn of the sacral spinal cord and synapse with cell bodies. The impulses travel to the pudendal nerve and bind to nicotinic receptor
68
Main contents of urine
95% H2O
rest are ions
uric acid
drugs
toxins
69
How much urine is stored in an empty bladder
10-20ml
70
What is it called when glucose is in urine
Glycosuria → diabetes mellitus
71
High amounts of protein in the urine
Caused due to an increase in BP glomerulonephritis, heart failure
\>150mg/day urine 1st sign of renal disease
72
Name the 3 things to make up the Glomerular Filtration barrier.
1. Fenestrated capillary endothelium.
2. Double layer basement membrane.
3. Foot processes of podocytes.
73
Name 5 factors that determine a molecule crossing the filtration barrier.
1. Pressure.
2. Size of the molecule.
3. Charge of the molecule (negative molecules are repelled).
4. Rate of blood flow.
5. Binding to plasma proteins.
74
What force favours glomerular filtration?
Hydrostatic pressure of the glomerular capsule.
75
Name 2 forces that oppose glomerular filtration.
1. Hydrostatic pressure of the bowman's space.
2. Oncotic pressure of the glomerular capsule.
76
Does the bowman's space exert an oncotic pressure?
No. There are no proteins in the Bowman's space.
77
What equation could be used to calculate the net glomerular filtration pressure?
HPgc - HPbs - πgc
78
What effect does vasoconstriction of the afferent arteriole have on GFR?
GFR will decrease as the HPgc decreases.
79
What effect does vasodilation of the afferent arteriole have on GFR?
GFR will increase as the HPgc increases.
80
What effect does vasoconstriction of the efferent arteriole have on GFR?
GFR will increase. Efferent arteriolar constriction tends to push blood back to the glomerulus and so increases the HPgc.
81
What effect does vasodilation of the efferent arteriole have on GFR?
GFR will decrease as the HPgc decreases.
82
What is tubuloglomerular feedback?
Macula densa cells of the DCT detect NaCl levels and use this as an indicator of GFR.
NaCl levels increase as GFR increases.
83
Where are the macula densa cells located?
They are epithelial cells found within the DCT. They sit between the afferent and efferent arteriole of the glomerulus.
84
How could you measure GFR?
Look at the excretion of a marker substance.
85
List 3 qualities necessary of a marker substance.
1. Freely filtered.
2. Not metabolised.
3. Not reabsorbed or secreted.
86
What substance can be used clinically to estimate GFR?
Creatinine.
87
What is the usual value of the filtration fraction?
20%
88
Define renal clearance.
Volume of plasma from which a substance is completely removed by the kidney per unit time.
89
How much H2O do we intake in a day?
2.5L
90
How much salt do we intake in a day?
10g
91
What is the equation for plasma osmolality?
2(Na + K) + glucose + urea
92
How is tonicity regulated?
By controlling the H20 movement.
93
Is ADH a vasoconstrictor or a vasodilator?
Vasoconstrictor.
94
How is fluid volume regulated?
By controlling Na+ movement.
95
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.
96
What is the function of ACE?
Converts angiotensin 1 into angiotensin 2.
97
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
98
What channels do loop diuretics target?
NKCC2
99
What channels do Thiazides target?
NCC
100
Name 3 types of drugs you could give to someone with hypertension.
1. Diuretics.
2. Vasodilators.
3. ACE inhibitors.
101
Name 3 urinary buffers.
1. Ammonium.
2. Phosphate (commonest urinary buffer).
3. Bicarbonate.
102
How does respiratory acidosis effect the ammonium buffer?
The uptake and synthesis of ammonia is increased.
103
Is renal compensation to an acid/base disturbance fast or slow?
Slow. Respiratory compensation is fast.
104
What is the renal compensation mechanism for respiratory acidosis?
Increased ammonia production. H+ secretion increases and HCO3- reabsorption increases.
105
What is the renal compensation mechanism for respiratory alkalosis?
H+ secretion decreases and HCO3- reabsorption decreases.
106
What is the respiratory compensation mechanism for metabolic acidosis?
Chemoreceptors are stimulated enhancing respiration. PaCO2 decreases.
107
What is the respiratory compensation mechanism for metabolic alkalosis?
Chemoreceptors are inhibited reducing respiration. PaCO2 increase.
108
What does erythropoietin (EPO) do?
Stimulates bone marrow, promotes RBC maturation.
109
What is the role of the Kidneys in Vitamin D activation?
Converts 25-OH D into 1,25-diOH D. (Enzyme: 1-hydroxylase)
110
What is the diff between a male and female urinary bladder
Female urethra doest have a prostate and an external sphincter
The urethra is also shorter
111
Receptors of urinary bladder involved in micturition
Detrusor muscle: M3 receptor & B3 receptor
Internal sphincter: alpha 1 receptor
External sphincter: nicotinic receptor
112
The three important efferent nerves involved in micturition
Comes from the sacral region: pelvic nerve (parasympathetic) Ach-\> M3 receptor
Increased stimulation leads to contraction of the detrusor muscle
Comes from sacral region: pudendal nerve (somatic) Ach-\> nicotinic
This leads to the external sphincter contract
SNS system: Presynaptic ganglion -\> Post sympathetic fibre (Hypogastric) NA-\> B3 receptor. relaxation of the detrusor muscle
Presynaptic ganglion -\> Post sympathetic fibre (Hypogastric) NA-\> alpha 1 receptor -\> relaxation of internal sphincter
113
The sensory afferent nerve involved in micturition called
Pelvic nerve attached to detrusor muscle
114
Full bladder micturition
115
Voiding Reflex
Afferent nerve fibres send impulses goes to ventral grey horn → interneurons → parasympathetic efferent fibres causes contraction of detrusor muscle
116
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.
117
What is the role of Filaggrin?
Produces natural moisturising factor.
118
Why are protease inhibitors in the skin important?
Protease inhibitors prevent the breakdown of corneodesmosomes.
119
What is the ideal pH of the skin?
5.5
120
What is the SRY protein called?
Testis determining factor: under its influence male development takes place.
121
What is the importance of testis determining factor?
Under its influence male development takes place.
122
What cells are responsible for secreting testosterone?
Interstitial cells of Leydig.
123
What is the blood supply to the upper 2/3 of the anal canal?
The superior rectal artery (branch of IMA).
124
What is the blood supply to the lower 1/3 of the anal canal?
The inferior rectal artery (branch of internal pudendal artery).
125
What part of the anal canal receives autonomic innervation?
The upper 2/3 (lower 1/3 is somatic innervation).
126
Which anal sphincter receives autonomic innervation and is involuntary?
The internal anal sphincter.
127
Which urethral sphincter is composed of smooth muscle?
The internal urethral sphincter.
128
When is the periaqueductal grey suppressed?
In storage. (Active in voiding).
129
What is the external urethral sphincter?
Skeletal muscle, voluntary sphincter.
Composed of the rhabosphincter and pelvic floor.
130
Do the urethral sphincters receive parasympathetic or sympathetic innervation?
Sympathetic.
131
When are the urethral sphincters activated?
In storage - activation causes contraction of the sphincters.
132
Spermatogenesis: what do type B cells differentiate into?
They differentiate into primary spermatocytes that will then go onto meiosis.
133
Spermatogenesis: where are type A cells located?
Outside the blood-testes-barrier.
134
Spermatogenesis: what does meiosis 1 produce?
2 secondary spermatocytes.
135
Spermatogenesis: what does meiosis 2 produce?
4 spermatids.
136
What changes does the sperm make with regards to its structure?
- It discards excess cytoplasm.
- Grows flagellum.
- Lots of mitochondria.
- Acrosomes at its head.
137
What is the function of the epididymis?
Storage and maturation of sperm. Sperm normally stay in the epididymis for 60 days.
138
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.
139
What is the affect of LH on the testes?
Stimulates Leydig cells to produce testosterone.
140
What is ovulation?
The release of an oocyte from a follicle.
141
What hormone stimulates ovulation?
LH.
142
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.
143
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.
144
What is the proliferative phase?
When the endometrium grows rapidly under the influence of oestrogen.
145
What does the corpus luteum degenerate into?
The corpus albicans.
146
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.
147
What is block to polyspermy?
After a sperm has fertilised the egg, the egg needs to prevent further sperm fertilising it.
148
What are the mechanisms to ensure block to polyspermy?
Enzymes are released that harden the zona pellucida and inactivate sperm binding sites.
149
What hormone does the hypothalamus release that stimulates release of the gonadotropins?
GnRH - gonadotropin releasing hormone.
150
What cells does FSH act on in males?
Sertoli cells.
151
What cells does FSH act on in females?
Granulosa cells.
152
What cells does LH act on in males?
Leydig cells.
153
What cells does LH act on in females?
Theca cells.
154
What is the function of sertoli cells?
They release MIF, inhibin and activins (regulate FSH secretion), and androgen binding protein (increases testosterone concentration).
155
What is the function of granulosa cells?
They convert androgens into oestrogen using aromatase enzyme.
156
What is the function of leydig cells?
they produce testosterone.
157
What is the function of theca cells?
They produce androgens (oestrogen precursors) which diffuse into granulosa cells to form oestrogen.
158
What enzyme converts androgens into oestrogen?
Aromatase.
159
What is the predominant hormone responsible for the proliferative phase?
Oestrogen.
160
What is the predominant hormone responsible for the secretory phase?
Progesterone.
161
Where do primordial germ cells originate from in the embryo?
The epiblast.
162
Until what week are male and female primitive gonads identical?
Week 6.
163
What is the mesovarium?
Mesentery attaching the ovary to the posterior broad ligament.
164
Define menopause.
Cessation of menstruation.
165
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.
166
What happens to oestrogen levels at menopause?
They fall.
167
What happens to LH and FSH levels at menopause?
They increase as they're no longer inhibited by negative feedback.
168
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.
169
What are the long-term symptoms of menopause?
Osteoporosis and increased risk of cardiovascular disease.
170
Name 4 treatments that can help with the symptoms of menopause.
1. HRT.
2. Sedatives.
3. Calcium supplements.
4. Vitamin D supplements.
171
What hormones are given in HRT?
Oestrogen and progesterone.
172
What is the advantage of HRT being given as a patch as opposed to orally?
The hormones go straight into the bloodstream and so bypass the liver.
173
What are the risks of HRT?
Small increased risk of cervical, breast and endometrial cancer.
174
What are the two main types of stem cells?
1. Embryonic stem cells - pluripotent.
2. Somatic stem cells - multi-potent.
175
Name 3 diseases that stem cells could help to cure.
1. Parkinsons disease.
2. Alzheimers.
3. Type 1 diabetes.
176
What are the 3 main characteristics of stem cells?
1. Self renew over long periods.
2. Undifferentiated.
3. Can generate other cells: pluripotent/multipotent.
177
Where in the embryo do embryonic stem cells come from?
The inner cell mass.
178
What are the 3 histological layers of the uterus?
1. Endometrium - mucosal lining, pseudostratified columnar.
2. Myometrium - smooth muscle wall.
3. Perimetrium.
179
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.
180
What are the characteristics of the endometrium in the proliferative phase?
Straight glands, no secretions. Stromal and epithelial mitoses.
181
What are the characteristics of the endometrium in the early secretory phase?
Coiling of glands and subnuclear vacuoles
182
What is the decidua basalis?
A part of the endometrium invaded by trophoblast.
183
What is the decidua capsularis?
A part of the endometrium overlying the blastocyst.
184
What is the decidua parietalis?
Endometrium lining the rest of the uterine cavity.
185
What invades the decidua basalis?
Syncytiotrophoblast.
186
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.
187
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.
188
What hormonal pathway is likely to be responsible for a decrease in urine production?
Renin angiotensin aldosterone system.
189
Why is it important that the chorionic villi branch in maturation?
Branching increases the surface area for exchange of nutrients.
190
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.
191
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).
192
Where are the receptors for steroid hormones located?
Steroid receptors are intracellular - steroids pass through plasma membranes bound to proteins.
193
Where are the receptors for peptide hormones located?
On cell membranes.
194
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.
195
Briefly describe the mechanism of ACTH.
Hypothalamus -\> CRH -\> anterior pituitary -\> ACTH -\> adrenal glands -\> cortisol release -\> negative feedback on hypothalamus and pituitary.
196
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.
197
How would you describe growth hormone secretion from the anterior pituitary?
It is secreted in a pulsatile fashion and increases during deep sleep.
198
What factors effect growth hormone secretion?
1. Starvation.
2. Exercise.
3. Trauma.
4. Hypoglaecemia.
5. Deep sleep.
199
What clinical abnormalities can occur if there is a problem with growth hormone secretion?
1. Gigantism.
2. Dwarfism.
3. Acromegaly.
200
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.
201
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.
202
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%)
203
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.
204
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.
205
What is glucose converted into when it enters a beta cell?
Glucose-6-phosphate.
206
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.
207
What substance can tell you if high insulin levels are due to endogenous insulin production?
The presence of C peptide.
208
What glucose transporter allows glucose uptake into muscle and fat cells?
GLUT-4.
209
What is a normal blood glucose?
4-6mmol/mol.
210
What is the short term response to high blood glucose?
Glycogenesis.
211
What is the long term response to high blood glucose?
Triglyceride production - lipogenesis.
212
What is the short term response to low blood glucose?
Glycogenolysis.
213
What is the long term response to low blood glucose?
Gluconeogensis.
214
Name 3 places where glucose sensors are located.
1. Pancreatic islets.
2. Medulla.
3. Hypothalamus.
215
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.
216
What hormones from the hypothalamus stimulate the anterior pituitary to release GH?
GHRH (+ve affect) and SMS (-ve affect).
217
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.
218
How much of the total cardiac output does each kidney receive?
10%.
219
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.
220
What hormones are involved in pregnancy?
1. Human chorionic gonadotropin.
2. Oestrogen.
3. Progesterone.
4. Prolactin.
5. Prostaglandins.
6. Oxytocin.
7. Relaxin.
221
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.
222
What are the functions of prostaglandins?
They have an important role in labor initiation.
223
What is the function of relaxin?
It is involved in cervical ripening.
224
What are the cardiovascular maternal adaptations?
1. Cardiac output increases.
2. Blood pressure decreases.
3. Uterine blood flow increases.
225
Why does blood pressure decrease in pregnancy?
There is mass vasodilation which reduces the TPR and so BP decreases. (BP=TPRxCO).
226
Why does uterine blood flow increase in pregnancy?
To ensure enough nutrients are delivered to the foetus.
227
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
228
What are the maternal adaptations to the veins in pregnancy?
Varicose veins are often present in pregnancy.
229
Define parturition.
Giving birth.
230
What are the 3 layers of the uterus?
1. Perimetrium (inner).
2. Myometrium.
3. Endometrium.
231
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.
232
What hormones stimulate cervical ripening?
Relaxin and placental hormones.
233
What are the 2 main stages of labor?
1. Latent: little cervical dilation.
2. Active: cervix dilates and opens.
234
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.
235
What hormones are needed for the initiation of labor?
Prostaglandins and oxytocin.
236
What is the function of PGF2 alpha?
It enhances oxytocin activation.
237
What does the adrenal medulla produce?
Adrenaline and noradrenaline (catecholamines).
238
What do steroid hormones bind to so they can be transported through the blood?
CBG proteins.
239
Why do steroid hormones bind to CBG proteins?
They are H2O insoluble and so need to bind to CBG for transport through the blood.
240
Where does the anterior pituitary gland originate from?
It is epithelial in origin. Derived from the primitive gut tube.
241
What happens to adrenal glands if there isn't enough ACTH?
They will shrink.
242
What are glucocorticoids released in response to?
Stress!
243
What regulates secretion of adrenaline and noradrenaline?
Autonomic innervation, mainly sympathetic.
244
Where does the posterior pituitary gland originate from?
Originates from neuronal tissue.
245
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.
246
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.
247
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.
248
What is the epithelium of the anal canal above the pectinate line?
Simple columnar.
249
What is the epithelium of the anal canal below the pectinate line?
Stratified squamous.
250
What are the functions of a normal bladder?
Continence, sensation of volume, receptibe relaxation. Voluntary initiation of voiding and complete emptying.
251
What is the bladder composed of?
Multiple segments of smooth muscle with their associated ganglia. Each segment exhibits
spontaneous activity - ‘micromotions’.
252
Can the bladder be denervated?
NO!
253
Which urethral sphincter is composed of skeletal muscle?
External urethral sphincter.
254
External urethral sphincter.
A visceral and somatic control centre for the lower urinary tract.
255
What fibre input does the periaqueductal grey receive?
A delta fibres.
256
What is urinary incontinence?
The involuntary release of urine.
257
Name 2 types of incontinence.
1. Stress incontinence.
2. Urge incontinence.
258
What can stress incontinence be due to?
Sneezing, coughing, exercise.
259
What can cause urge incontinence (desire to urinate)?
Any irritation to the bladder or urethra e.g. a bacterial infection.
260
How long does spermatogenesis take?
Approximately 60 days.
261
What forms the blood testes barrier?
Tight junctions between sertoli cells.
262
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.
263
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.
264
What does semen contain?
Sperm, fructose, fibrinogen, clotting enzymes, fibrinolysin.
265
What is the importance of meiosis in gametogenesis?
It prevents polyploidy and increases genetic variability and so diversity.
266
How many secondary oocytes does each primary oocyte yield?
1 secondary oocyte and 1 non-functional polar body.
267
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.
268
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.
269
What factors can influence puberty?
1. Nutrition (body mass).
2. Leptin, insulin (hormones).
3. Genetics.
4. Exercise.
5. Socio-cultural.
270
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.
271
What is the function of dihydrotestosterone?
Stimulates the differentiation of the male external genitalia. It is secreted by the testis.
272
Menstrual cycle: what is the effect of oestrogen at low levels on the gonadotropins?
Oestrogen is released from granulosa cells and also from the developing and dominant follicle.
273
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.
274
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.
275
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.
276
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.
277
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.
278
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.
279
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.
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
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.
285
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.
286
What is the epithelium of the thick limb of the loop of henle?
Columnar epithelium. Structurally similar to the PCT and DCT.
287
What are tubulopathies?
Mutations of apical sodium transporters.
288
Where in the nephron would be affected by Bartters syndrome?
The loop of Henle.
289
What channels are affected in Bartters syndrome?
NKCC2 channels in the loop of Henle.
290
What is the diuretic equivalent to Bartters syndrome?
Loop diuretics.
291
What are the features of Bartters syndrome?
Hypokalemia, low blood pressure, alkalosis.
292
What channels do loop diuretics close?
NKCC2 - reduced Na+ and K+ secretion.
293
What part of the nephron would be affected by Gitelmans syndrome?
The distal tubule.
294
What channels are affected in Gitelmans syndrome?
NCC.
295
What is the diuretic equivalent to Gitelmans syndrome?
Thiazide.
296
What are the features of Gitelmans syndrome?
Hypokalemia, hypomagnesemia and low blood pressure.
297
What part of the nephron would be affected by Liddles syndrome?
The collecting duct.
298
What channels are affect in Liddles syndrome?
ENaC.
299
What are the features of Liddles syndrome?
Hypertension and Hypokalemia.
300
What atom is crucial in thyroid hormone formation?
Iodine.
301
What cells in the thyroid actively take up iodine in the form of iodide?
Follicular cells.
302
What process needs to occur before T3 and T4 can be released into the blood stream?
Proteolysis.
303
Is more T4 or T3 produced in the thyroid?
T4 (thyroxine).
304
Which molecule is active T3 or T4?
T3 (triiodothyronine).
305
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.
306
Describe the GH/IGF-1 axis.
Hypothalamus -\> GHRH (+) or SMS (-) -\> anterior pituitary -\> GH -\> Liver -\> IGF-1 -\> negative feedback on hypothalamus.
307
What is the function of IGF-1?
It induces cell division.
308
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).
309
What hormones increase in parturition?
Prostaglandins (initiation of labour) and oxytocin (uterine contractions).
310
What does the inguinal canal transmit in females?
The round ligament of the uterus.
311
What is the function of the round ligament of the uterus?
Maintains the anteverted position of the uterus.
312
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.
313
What is the anion gap?
The difference between measured cations and anions: [Na+] + [K+] - [Cl-] - [HCO3-]
314
What pituitary hormone can cause hyperpigmentation?
ACTH.
315
Give 2 tests that can be used to screen for disorders in pregnancy.
1. Ultrasound.
2. Amniocentesis.
316
What is the most abundant glucocorticoid in humans?
Cortisol.
317
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.
318
What hormone causes production of sperm?
FSH.
319
In what specific cell in the testes do sperm mature?
Sertoli.
320
Name 2 hormones that regulate melanin secretion.
1. ACTH.
2. MSH.
321
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.
322
What organelle stores melanin in melanocytes?
Melanosomes.
323
Give 3 histological characteristics of the secretory phase.
1. Spiral arteries.
2. Decidualised stroma.
3. Secretions.
4. Torturous glands.
324
What type of receptor does ACTH act on?
G protein coupled receptor. (All pituitary and hypothalamus hormones act on these receptors).
325
What hormone acts on the uterus in the proliferative phase?
Oestrogen.
326
What changes happen to the endometrium in the proliferative phase?
Growth of the endometrium and myometrium is stimulated. Receptors for progesterone are also stimulated.
327
What hormone acts on the uterus in the secretory phase?
Progesterone.
328
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.
329
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.
330
What are the histological characteristics of the endometrium in the late-secretory phase?
Prominent spiral arteries and decidualised stroma. More secretions and elongated glands.
331
What effects does oestrogen have on the endometrium?
Hyperplasia and hypertrophy of endometrial cells. Also stimulates myometrial growth.
332
Name one hormone from the pituitary gland one from the chorion/decidua that induces labour.
Pituitary – oxytocin.
Decidua/chorion – prostaglandins.
333
What do the macula densa cells release when they detect low NaCl?
Prostaglandins.
Prostaglandins act on granular cells and trigger renin release.
334
What enzyme is found only in the zone glomerulosa?
Aldosterone synthase.
335
What 2 structures make up the metanephros?
1. Metanephric blastema.
2. Ureteric bud.
336
What is dihydrotestosterone?
An active metabolite of testosterone. It modulates external genitalia differentiation -\> penis, scrotum and prostate.
337
What is the ureteric bud an outgrowth of?
The mesonephric duct.
338
What are the start and end products of mitosis in oogenesis?
Start: oogonia.
End: primary oocyte.
339
What are the start and end products of meiosis in oogenesis?
Start: primary oocyte.
Middle: secondary oocyte.
End: 1x ovum.
340
Define tubulopathies.
Mutations of apical Na+ transporters.
341
What part of the nephron is affected by Bartter's syndrome?
The loop of henle.
342
What channels are affected by Bartter's syndrome?
NKCC2.
343
What is the diuretic equivalent to Bartter's syndrome?
Loop diuretics.
344
What are the characteristic features of Bartter's syndrome?
Hypokalemia, low BP, alkalosis.
345
What part of the nephron is affected by Gitelman's syndrome?
The DCT.
346
What channels are affected by Gitelman's syndrome?
NCC.
347
Name 2 hormones that are produced elsewhere but are activated in the kidney.
1. Angiotensinogen.
2. 25-hydroxyvitamin D.
348
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.
349
What are C-cells also known as?
Parafollicular cells.
350
What amino acid and dietary nutrient are needed for hormones to be secreted from the thyroid gland?
Amino acid - tyrosine.
Dietary nutrient - iodine.
351
Name 2 proteins in the blood that hormones from the thyroid gland bind to?
1. Albumin.
2. Thyroxine binding globulin.
352
Name 2 prostaglandins released in labour.
1. PGE2.
2. PGF2-alpha (main one).
353
Give 3 functions of the placenta.
1. Provides nutrition to the foetus.
2. Gas exchange.
3. Waste removal.
4. Endocrine and immune support.
354
Placental abnormalities often require caesarian delivery. What is placenta accreta?
Abnormal adherence, no decidua basalis.
355
Placental abnormalities often require caesarian delivery. What is placenta perceta?
Where the villi penetrate the myometrium.
356
Placental abnormalities often require caesarian delivery. What is placenta praeria?
The placenta overlies the internal os, there is abnormal bleeding.
357
What 2 hormones are secreted in the kidney?
EPO and renin.
358
Give 2 causes of metabolic acidosis.
Ketoacidosis and lactic acidosis.
359
What hormones do acidophils in the anterior pituitary secrete?
GH and prolactin (Somatotrophs and lactotrophs).
360
What hormones do basophils in the anterior pituitary secrete?
FSH, LH, TSH and ACTH. (Corticotrophs, thyrotrophs and gonadotrophs).
361
Give an example of a steroid hormone.
Oestrogen, testosterone, cortisol.
362
Give an example of a peptide hormone.
Insulin, GH, FSH, LH, TSH etc.
363
Which has a faster response, steroid or peptide hormones?
Peptide hormones have a rapid response.
364
Which is stored, steroid or peptide hormones?
Peptide hormones are stored.
365
Importance of hormones during pregnancy
1. Maintains pregnancy
2. Prepares for delivery
3. Prepares for breast feeding e.t.c
366
Important hormones involved in pregnancy
1. B-hCG
2. Oestrogen
3. Progesterone
367
What produces B-hCG
Placenta
368
Physiological changes during pregnancy
Respiratory :
Increase in Intraabdominal pressure.
Increase in tidal volume
More diaphragmatic breathing
Cardiovascular:
Increase CO
Decrease in systemic vascular resistance → Increase SV
Drop-in B.P
Haematological:
Increase in plasma volume (40%)
Increase in red blood cell volume
Increase in clotting factors
MSK:
Increase in BMI
Stretch marks
Lower back pain
Endocrine:
Increase anterior pituitary gland secretion
Pregnancy hormone: Oestrogen, Progesterone, B-hCG
Thyroid
Dermatological
Increase in skin pigmentation
Distension + proliferation of blood vessels
369
Deficiences developed during pregnancy
Anaemia
Gestational diabetes
370
Pituitary gland position
Hanging off hypothalamus connected to the infundibulum
371
Nuclei found in the posterior pituitary gland
Supraoptic nucleus
Paraventricular nucleus
372
What does the supraoptic nucleus secrete?
ADH/ Vasopressin
373
What stimulates the supraoptic nucleus in the hypothalamus
low blood volume
low blood pressure
high plasma osmolality
pain
374
What effect does alcohol have on the supraoptic nucleus
Inhibitory
375
What does the paraventricular nucleus secrete in the posterior pituitary gland
Oxytocin
376
What stimulates the paraventricular nucleus in the posterior hypothalmus
Birthing process
Suckling
Ejaculation
377
What is the hypophyseal portal system
2 capillary beds (primary & secondary capillary plexuses)
Connected in series through an intermediate portal vein
this is the anterior pituitary connection
378
The paraventricular nucleus secretes what in the anterior compartment of the pituitary gland
CRH: Corticotropin-releasing hormone
TRH: Thyrotropin-releasing hormone
379
Action of CRH
Stimulates genes in corticotrope.
Proopiomelanocortin gets broken down into Alpha Milano stimulating hormone (alpha MSH) and adrenocorticotropic hormone (ACTH)
380
Action of TRH
Stimulates thyrotrope to release TSH
381
What does the arcuate nucleus secrete
Growth Hormone releasing hormone
PIH or dopamine
382
The action of Growth Hormone releasing hormone
Causes stimulation of somatotrope to secrete growth hormone
383
The action of PIH or dopamine
Stimulates lactotrope to secrete Prolactin
384
Ganado tropen releasing hormone action
Stimulates Gonadotrope to secrete FSH LH
Depending on the frequency of GnRH: High frequency is LH, lower frequency is FSH
Somatostatin inhibits this
385
Nucleus present in anterior pituitary gland
Paraventricular nucleus
Arcuate nucleus
Preoptic nucleus
386
What does oxytocin bind to in the uterus?
smooth muscle of the myometrium
causing it to contract and therefore help during birthing process
387
Oxytocins involvement in lactation
Binds to the mammillary bodies of breasts send signals to the hypothalamus
Results in milk ejection during lactation
Stimulated by suckling
388
Oxytocin has a ____ half life
short
so regulated frequnetly
389
What receptor does ADH bind to the principal cell of the collecting tube
What receptor does ADH bind to in blood vessels
Vasopressin type 2 receptor
Vasopressin type 1 receptor
390
Steps of ADH activation
Stimulus sends receptors to the hypothalamus
The supraoptic nucleus causes ADH to be secreted
Binds to V2 receptors
Stimulates Gs protein which binds to GTP and gets activated
This then binds to adenyl cyclase and converts ATP into cAMP activating pKa
pKa then goes and inserts into vesicles containing aquaporin 2 into the apical membrane
increases H20 Permeability of collecting duct
391
Effects of stimulation of ADH
Stimulated by low blood pressure or high plasma osmolality
In blood vessels: Increase vasoconstriction and therefore peripheral resistance and therefore increase blood pressure
In kidneys: Causes the increase of plasma volume and therefore BP
392
Hormones of the anterior pituitary gland
FLAT PIG
FSH
LH
ACTH
TSH
Prolactin
GH
393
What nucleus secrete growth hormone
Arcuate nucleus
394
What inhibits/ stimulates prolactin
inhibits PIH or dopamine (arcuate nucleus)
stimulates: thyrotropin-releasing hormone (paraventricular nucleus)
Stimulates: oestrogen + breastfeeding
395
How does iodide enter from the blood into follicles of the thyroid gland
secondary active transport
396
What does thyroid peroxidase do?
Iodide oxidation: turns iodide ions into iodine
Iodination: puts I2 onto amino acids on tyrosine amino acids
Fuses DIT + DIT = T4 (Throxine)
Fuses MIT + DIT = triodothyronin
397
What is it called when a tyrosine amino acid has:
one iodide group
two iodide group
Monoiodotyrosine
Diiodotyrosine
398
What makes up the thyroid hormone?
T4 thyroxine +
T3 triiodothyronine
399
How is T3 + T4 made from tyrosine molecule
Tyrosine is broken down into T3 + T4 components via lysozyme enzymes
400
Thyroid synthesis steps
1. TRH release from paraventricular nucleus from hypothalamus
2. Anterior pituitary to release from TSH
3. TSH stimulates follicle cells of the thyroid to synthesise thyroglobulin
4. Iodide trapping
5. Oxidation of iodide via thyroid peroxidase
6. Iodination of tyrosine amino acids
7. Couple of the DIT + MIT
8. Endocytosis of thyroglobulin with T3 + T4
9. Lysosomal enzymes cleave T3 + T4 out of thyroglobulin
10. Exocytosis of T3 + T4 into blood plasma
401
How does T3 act
Inducing gene transcription and protein synthesis
402
What does the Thyroid hormone do?
Promotes normal bone growth + maturation
Promotes muscular function and development
Increase basal metabolic rate/ O2 usage
Promotes normal C.O
Promotes an increase in synapses/myelinations/dendrites
Promotes G.I motility + secretions
Promotes normal hydration of skin
403
What cell is stimulated by low calcium levels
Chief cells
404
What does it mean when there is low blood calcium
Stimulates the parathyroid to secrete parathyroid hormone
405
How does the Parathyroid hormone affect kidneys
Increases calcium reabsorption decreasing Ca2+ excretion
Excreting phosphates as well
406
The indirect effect of the parathyroid hormone
1. When exposed to sunlight 7 dehydrocholesterol gets drawn into the blood and broken down into Cholecalciferol
2. Goes into the liver to become 25-OH Cholecalciferol
3. Parathyroid hormone stimulates an enzyme in the kidney which together with 25OH cholecalciferol becomes 1,25 diOH Cholecalciferol (calcitriol)
1. Calcitriol is the active form of vitamin D
407
What makes up the adrenal cortex
Zona glomerulosa
Zona Fasiculata
Zona Reticularis
408
What stimulates the adrenal cortex
Angiotensin 2 (1st)
low Na+ or high K+ (2nd)
ACTH (3rd)
Both undergo GS protein mechanism e.t.c to produce pKa which phosphorylates cholesterol conversion of ….
409
What is aldosterone derived from and what type of hormone is it?
Cholesterol
Steroid hormone
410
What inhibits Zona glomerulosa
Atrial natriuretic peptide
411
What hormones are corticosteroids
steroid hormones produced in the adrenal cortex
Cholesterol is the Precursor
412
What does aldosterone do?
Increase Na+ absorption
Decrease K+
Increase H2O absorption
413
Where is aldosterone produced
Zona glomerulosa
414
Where is cortisol secreted
Zona fasciculata
415
What stimulates Cortisol secretion
ACTH
undergoes same action as with aldosterone
416
What is cortisol derived from?
cholesterol
417
Steroid hormones transported around blood
Steroid hormones need carrier proteins to travel within the blood
418
What does zona glomerulosa secrete
Mineral corticoids (Aldosterone)
419
What does zona fasiculata secrete
Glucocorticoids (Cortisol)
420
What does zona reticulosa secrete
Gonadocorticoids (Androgens)
421
What stimulates zona fasiculata
422
What does cortisol do
Protein catabolism
Suppresses immune system
Lipolysis
423
Gonadocorticoids are …
weak
424
Adrenogens act on
Weak and therefore act as precursor
Fmelaes to release oestrogen
Males release testosterone
Libido effect
425
What feedback system does cortisol induce
Negative feedback system
426
Primary stimulant for sympathetic nervous system
Short term acute stress
Fight or flight
427
What contains sympathetic nerve fibers
Ventral grey horn of the spinal cord
428
What do chromaffin cells of the adrenal cortex convert tyrosine into
Epinephrine (80%)
Norepinephrine (20%)
429
What does epinephrine do once secreted by the adrenal cortex
Binds to the liver and through Gs protein… results in glycogenolysis and gluconeogenesis increasing glucose in blood
Increases BP and lypolysis
430
What is a heterocrine gland and given example
Has both endocrine and exocrine function
Pancreas
431
What cells do the endocrine portion of the pancreas have (Islets of Langerhans)
Alpha cell-glucagon
Beta cells-Insulin
432
What is beta pancreatic cells stimulus
Hyperglycaemia
433
What stimulates alpha pancreatic cells
Hypoglycaemia
Sympathetic nervous system
434
What does the exocrine portion of the pancreas have
Acini 99%
435
Where are insulin contained in the beta cell of the pancreas
Vesicles
C peptide is also within the vesicles
436
How is insulin produced
You have proinsulin undergoes cleaving processes in the RER modifications resulting in them being packaged in vesicles
Hyperglycaemia means that glucose enters through beta cells and gets broken down into ATP
Causes Vesicles to exocytose
437
What is C peptide
A good way to monitor insulin levels
438
What does insulin do?
The liver:
Promotes glycogenesis (Decrease glucose) and minor effect on protein synthesis
Increase amino acid uptake
Adipose tissue:
Stimulated lipogenesis
Increase glucose uptake via GLUT 4 = decrease blood glucose
Muscle:
Increase glucose uptake via Glut 4. A minor effect is glycogenesis
Increase amino acid uptake + protein synthesis
439
What does the endocrine portion of the pancreas have
Islets of Langerhans 1%
440
What does pancreatic alpha cell secrete
Glucagon
441
What does glucagon do?
In liver:
gluconeogenesis & glycogenolysis + to increase blood glucose levels
In adipose tissue:
Lipolysis
442
What is oogonium
Stem cells (dipolid)
443
What happens prepuberty
oogonium ⇢ primordial follicle (2n) stuck in prophase 1
444
Primary oocyte is…
Primordial follicle → Late secondary oocyte
445
What phase is graffian cells stuck in
Metaphase 2
446
What cells is primordial follicle stuck in
Prophase 1
447
Follicular phase
Primordial follicle → graffian cell
448
Follicular phase products
Mitosis
Oestrogen is produced
Follicular fluid
primary oocyte → secondary oocyte
449
What days does the follicular phase take place
1-14 days
450
What day of ovulation is peak oestrogen levels
day 14 (end of the follicular phase)
There is also a high amount of oestrogen in the mid follicular phase. This inhibits FSH and stimulates LH.
451
What happens at end of the follicular phase
Oestrogen stimulates GnRH to secrete LH and inhibits FSH (LH surge)
452
What does LH surge do?
increase follicular fluid (blood flow to antrum)
Stimulates graffian cells to release secondary oocyte- ovulation day 14-15
The secondary oocyte is caught by fimbriae and stays in the ampulla
453
What is the ovulatory phase
LH surge
454
How is the corpus luteum formed?
LH stimulates Remaining granulosa cells from ovulation to specialise
LH stimulates the corpus luteum to produce progesterone
455
What arteries are there within endometrium
Stratum functionalis: Spiral and Coil arteries
Stratum Basalis : Striaght arteries
456
Why is there blood during the menstruation phase
As the stratum Functionalis is being shed the spiral and straight arteries are also being shed.
457
Proliferation phase of menstrual cycle
regenration of stratum functionalis
regenerate spiral and coiled arteries
makes uterine glands
thin cervical mucous production
oestrogen is the primary hormone
Days 6-14
458
Secretory phase
The main hormone is progesterone
Angiogenesis
Secretion of uterine glands
Thickening cervical plug
Day 15-28
459
Where is spermatogenisis occuring
Seminiferous tubu`les
460
Where is spermatogenisis occuring
Seminiferous tubu`les
461
What cells make up seminiferous tubes
Sertoli cells
they are connected to one another via tight junctions/adherens junctions
462
What is the importance of tight junctions within seminiferous tubules
Splits into two compartments the basal compartment and the ad lumen compartment
Creates a barrier from preventing sperm antigens from entering bloodstream and therefore immune response- called the blood testes barrier
463
What does a spermatogonium split into? (2n)
Undergoes mitosis to become type A cell and type B cell
They type A cell continues to become reused is the next spermatogonium
Type B cell goes to ad luminal compartment (tight junctions open up)
464
When does a type B cell become a spermatocyte
When it gets past tight junctions and goes from basal lumen to ad luminal compartment
465
How are secondary spermatocyte made?
The primary spermatocyte undergoes meiosis 1 to become 2 secondary spermatocyte
This further undergoes meiosis 2 to become spermatids
466
Spermatids become _____ via \_\_\_\_\_
Spermatozoa via spermiogenesis
467
Spermatogenesis
468
What cell do LH act on for spermatogenesis on the actions does it do
Leydig cells they convert cholesterol into testosterone
469
What cell do FSH act on for spermatogenesis on the actions does it do
Acts on Sertoli cells to produce Androgen Bonding protein (ABG)
470
What two molecules are needed for spermatogenesis
testosterone and Androgen Bonding protein (ABG)
471
What is the role of androgen bonding protein
Helps keep testosterone very soluble and highly concentrated
472
What process do Sertoli cells primarily help with
Spermiogenesis
473
What kind of feedback system does a high testosterone levels initiate
Negative feedback system
474
What hormone is secreted by Sertoli cells when sperm levels are too high
Inhibin causes a negative feedback system with hypothalamus and anterior pituitary
475
Summary of the path of sperm to outside
S-Seminiferous tubules
R- Rete testis
E- Efferent duct
E- Epipdyms
V- Vas deferens
E- Ejaculatory duct
N- Nothing
U-Urethra
P- Penile Urethra
SREEVEN UP
476
Seminal vesicles
Accounts for 60-70% of seminal fluid
Fructose
Prostaglandin
Coagulase
477
Prostate gland
Accounts for 30% of seminal fluid
Citrate
Fibrinolysis
PSA
478
Role of prostaglandin in fertilisation
binds to the smooth muscle of the uterus and causes it to contract- retropulsion
479
Role of coagulase in fertilisation
Allows for sperm to bind to vagina wall
480
Stages of fertilisation
1. Capacitation: cleaning of the sperm head. by the end it only has modified glycoproteins on its head. Increases mobility of sperm
2. Acrosomal reaction: sperm binds with the ZP3 receptor. Calcium rushes in and activates the acrosome releasing its contents. Digests zona pellucida
3. Fast block to polyspermy: sperm touches oocyte membrane beta unit of protein allows sodium in inhibiting other sperms from attaching
4. Slow Block to Polyspermy: Alpha unit of protein causes the smooth endoplasmic reticulum releases Ca++ and activates lysozyme to fuse with the oocyte membrane. ZP3 degrades and hardens the zona pellucida. Sperm can no longer bind to the ZP3 receptor.
5. Secondary oocyte undergoes meiosis Pronucleus of male and female fuse together
481
How many phases can the menstrual cycle be subdivided into?
Follicular phase (0-14)
Luteal Phase (14-28)
482
What happens in the follicular phase of the menstrual cycle
FSH will enter the ovaries and stimulate follicle maturation of primary follicles and mature follicles into a secondary follicle.
Oestrogen is produced during this phase
As oestrogen levels are rising to have positive feedback from LH. More LH is is secreted (LH surge= ovulation)
Oocyte is released
483
What kind of feedback does oestrogen have on the pituitary gland 10 days before the menstrual cycle begins
Negative and therefore inhibiting LH
484
In low concentration oestrogen inhibits …
LH secretion
485
When is FSH released? What is it in response to?
Low oestrogen conc
486
Roles of oestrogen
Stimulate bone and growth
Muscle growth
Stimulation of endometrial growth
Maintain female secondary characteristics
487
In high concentrations oestrogen stimulates
LH
488
Why is there an FSH surge alongside an LH surge
As a side effect of LH
489
What hormones does the corpus luteum secrete
Oestrogen
Inhibin
Progesterone
490
Luteal phase
Days 15-28
Progesterone is increasing
Oestrogen is still detectable, just in smaller amounts.
This suppresses GnRH release
Inhibin is increasing
Progesterone (+ oestrogen) stimulate endometrium growth
491
What feedback system does inhibin have
As the corpus luteum develops inhibin suppresses GnRH secretion
492
What happens to the corpus luteum during the luteal phase
The corpus luteum will degrade and therefore the hormones it secretes will decrease alongside it. It allows for other oocytes to mature.
493
Ovulation graph
494
Spermatogenesis vs spermiogenesis
Spermiogenesis: spermatid → spermatozoon. The maturation of a spermatid leads to the formation of a Sperm cell (spermatozoon). This takes place within Sertoli cells
Spermatogenis: Fomration of spermatozoa. Spermatogonium → 4 spermatozoa
