Extra SUGER PHYS Flashcards
(133 cards)
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
What effect does vasoconstriction of the afferent arteriole have on GFR?
A
GFR will decrease as the HPgc decreases.
3
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.
4
Q
Define renal clearance.
A
VOLUME of PLASMA from which a SUBSTANCE is completely REMOVED by the KIDNEY per unit time.
5
Q
What ion is pumped out of the ascending limb into the medullary interstitium?
A
Na+. This increases the medullary osmolarity.
6
Q
Briefly describe ADH action.
A
- Osmoreceptors in the hypothalamus detect an increase in plasma osmolality.
- The posterior pituitary is signalled to release ADH.
- ADH acts on the collecting ducts and increases insertion of aquaporin 2 channels, permeability to H2O increases, more H2O is retained.
7
Q
List the 3 main triggers for the release of Renin.
A
- Sympathetic stimulation.
- Low BP detected by afferent arteriole.
- Low Na+ detected by macula densa cells.
8
Q
Where is aldosterone synthesised?
A
In the adrenal cortex by glomerulosa cells.
it is a Mineralocorticoid
9
Q
Where does aldosterone act?
A
On the principal cells in the nephron collecting duct.
10
Q
What is the function of atrial natriuretic peptide (ANP)?
A
ANP is a renal vasodilator. It inhibits aldosterone release induced by Angiotensin 2 and it closes ENaC channels.
11
Q
What is the role of the Kidneys in Vitamin D activation?
A
Converts Calciol from the Liver into Calcitriol , in the Presence of PTH
(Enzyme: 1-hydroxylase)
12
Q
What layer of the trilaminar disc are the kidneys derived?
A
Intermediate mesoderm.
13
Q
What part of the trilaminar disc are the bladder and urethra formed?
A
The endoderm.
14
Q
What layer of the trilaminar disc forms the male and female genitalia?
A
Intermediate mesoderm.
15
Q
What is the indifferent stage?
A
When the Wolffian and Müllerian ducts are both present. It is impossible to tell the sex of the embryo.
Untill teh 6ht week
16
Q
What cells are responsible for secreting testosterone?
A
Interstitial cells of Leydig.
17
Q
When do leydig cells start producing testosterone?
A
Week 8.
18
Q
What does testosterone stimulate?
A
Differentiation of the Wolffian duct.
19
Q
Why does the Müllerian duct degenerate?
A
Due to Anti Mullerian Hormone, Being secreted from the Sertoli cells which causes a regression of the Mullerian System
20
Q
What layer of the trilaminar disc is the upper 2/3 of the anal canal derived from?
A
Endoderm.
21
Q
What layer of the trilaminar disc is the lower 1/3 of the anal canal derived from?
A
Ectoderm.
22
Q
Spermatogenesis: what do type B cells differentiate into?
A
They differentiate into primary spermatocytes that will then go onto meiosis.
23
Q
Spermatogenesis: what is the function of type A cells?
A
They replicate by mitosis to ensure a constant supply of spermatogonia to fuel spermatogenesis.
24
Q
Spermatogenesis: what does meiosis 1 produce?
A
2 secondary spermatocytes.
25
Spermatogenesis: what does meiosis 2 produce?
4 spermatids.
26
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.
27
What is the affect of LH on the testes?
Stimulates Leydig cells to produce testosterone.
28
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.
29
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.
30
What cells does FSH act on in females?
Granulosa cells.
31
What is the function of sertoli cells?
They release MIF, inhibin and activins (regulate FSH secretion), and androgen binding protein (increases testosterone concentration).
32
What is the function of granulosa cells?
They convert androgens into oestrogen using aromatase enzyme.
33
What are the characteristics of the endometrium in the proliferative phase?
Straight glands, no secretions. Stromal and epithelial mitoses.
34
What is the decidua basalis?
A part of the endometrium invaded by trophoblast.
35
What is the decidua capsularis?
A part of the endometrium overlying the blastocyst.
36
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.
37
What is the role of the cytotrophoblast?
Forms solid masses covered by syncytiotrophoblast - primary chorionic villi.
These masses become filled with stroma, forming secondary chorionic villi. Capillaries appear in the stroma – tertiary chorionic villi.
Anchor the growing fetus to the maternal uterine tissue.
38
Name 6 hormones produced by the anterior pituitary gland.
1. FSH.
2. LH.
3. GH.
4. ACTH.
5. TSH.
6. Prolaction.
39
Name 2 hormones produced by the posterior pituitary gland.
. ADH.
| 2. Oxytocin.
40
How does the anterior pituitary gland receive its blood supply?
Via a portal venous circulation from the hypothalamus.
41
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.
42
Briefly describe the mechanism of prolactin.
Hypothalamus -> dopamine -> anterior pituitary -> prolactin -> mammary glands -> milk production -> positive feedback on dopamine.
43
Briefly describe the mechanism of ACTH.
Hypothalamus -> CRH (Corticotropin-releasing hormone) -> anterior pituitary -> ACTH (adrenocorticotropic hormone ) -> adrenal glands -> cortisol release -> negative feedback on hypothalamus and pituitary.
ACTH also has negative feedback on Hypothalamus (short loop)
44
How would you describe growth hormone secretion from the anterior pituitary?
It is secreted in a pulsatile fashion and increases during deep sleep.
45
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.
46
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.
47
What are the 4 cells to make up the islets of langerhans?
What do they secrete?
1. Beta cells: insulin. (70%)
2. Alpha cells: glucagon. (20%)
3. Delta cells: somatostatin. (8%)
4. Pancreatic polypeptide secreting cells. (2%)
48
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 breakdow
49
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.
50
Describe the mechanism of insulin secretion from beta cells.
Glucose binds to beta cells (GLUT 2) -> glucose is converted into glucose-6-phosphate, Glycolysis, Krebs and OP happens -> ADP is converted to ATP -> ATP inactivates K+ channels, so they close close -> membrane depolarisation -> Ca2+ channels open -> Ca2+ influx -> Ca2+ binds to insulin secretory granules --> insulin release.
51
What is glucose converted into when it enters a beta cell?
Glucose-6-phosphate.
52
What substance can tell you if high insulin levels are due to endogenous insulin production?
How does it work?
The presence of C peptide. It connects alpha and beta chains to make PROINSULIN
when it is cleaved - insulin will become active, and it circulate in the blood.
So high blood active insulin = high C peptide
53
What is the long term response to low blood glucose?
Gluconeogensis.
54
Name 3 places where glucose sensors are located.
1. Pancreatic islets.
2. Medulla.
3. Hypothalamus.
55
What hormones from the hypothalamus stimulate the anterior pituitary to release GH?
Growth hormone-releasing hormone (GHRH) – stimulates release of growth hormone (GH or somatotropin ) from anterior pituitary ===> growth and protein synthesis
Somatostatin (SST) inhibits release of GHRH
Growth hormone is secreted in a pulsatile fashion during deep sleep
56
What hormone from the hypothalamus stimulates the anterior pituitary to release ACTH?
CRH.
Corticotrophin - Releasing Hormone
(Due to Stress, Hypoglycaemia) etc
57
What hormone from the hypothalamus stimulates the anterior pituitary to release TSH (thyroid-stimulating hormone )?
Thyrotropin-releasing hormone (TRH)
58
What hormone from the hypothalamus stimulates the anterior pituitary to release prolactin?
Dopamine.
59
How much of the total cardiac output does each kidney receive?
10%.
60
Why does blood pressure decrease in pregnancy?
There is mass vasodilation which reduces the TPR and so BP decreases. (BP=TPRxCO).
61
What does the adrenal cortex produce?
Steroid hormones.
62
What does the adrenal medulla produce?
Adrenaline and noradrenaline (catecholamines).
63
What does the zona glomerulosa produce?
Mineralocorticoids e.g. aldosterone.
64
What does the zona fasciculata produce?
Glucocorticoids e.g. cortisol.
65
What does the zona reticularis produce?
Androgens e.g. DHEA.
66
Why do steroid hormones bind to CBG proteins?
They are H2O insoluble and so need to bind to CBG for transport through the blood.
eg Transcortin
67
What regulates cortisol synthesis?
ACTH!
68
What happens to adrenal glands if there isn't enough ACTH?
They will shrink.
69
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.
70
Name the 2 hypothalamic nuclei whose axons extend into the posterior pituitary gland via the pituitary stalk
1. Paraventricular nuclei.
| 2. Supraoptic nuclei.
71
Where does the posterior pituitary gland originate from?
Originates from neuronal tissue.
72
What hypothalamic nucleus contains cells responsible for
a ADH?
b Oxytocin
a Supraoptic nucleus
| b Paraventricular nucleus
73
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. Vasoconstriction through adrenaline
3. Suppresses inflammatory and immune responses.
4. Inhibition of non-essential functions e.g. growth and reproduction.
74
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
75
What does the vagina develop from?
Upper 1/3 - mullerian duct. Lower 2/3 - urogenital sinus.
76
What line marks the junction between the upper 2/3 and lower 1/3 of the anal canal?
The pectinate line.
77
What is the epithelium of the anal canal above the pectinate line?
Simple columnar.
78
What is the epithelium of the anal canal below the pectinate line?
Stratified squamous.
79
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.
80
What forms the blood testes barrier?
Tight junctions between sertoli cells.
81
Describe oogenesis.
- Oogonia/Primitive Germ cells undergo meiotic divisions in utero
- Develop into Primary Oocytes, and begin Meiotic division, They stop in Prophase of Meiosis 1 - Meiotic Arrest
Resumption occurs after puberty - only the eggs destined for OVULATION will complete meiosis 1
- Each daughter cell has 23 chromosones, each with 2 chromatids
- However, the SECONDARY OOCYTE HAS ALL THE CYTOPLASM
- Meiosis 2 occurs and means that the secondary oocyte becomes an ovum
Meiosis 2 is also ARRESTED at metaphase 2 until FERTILISATION
Meiosis 2 is only completed in the fallopian tube AFTER FERTILISATION (penetrated by sperm)
82
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.
83
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.
84
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.
85
Menstrual cycle: why do LH and FSH levels decrease after ovulation?
They are inhibited by the high progesterone and oestrogen concentrations.
86
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.
87
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.
88
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.
89
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.
90
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.
91
What is the full name of T3?
Triiodothyronine.
92
How many iodine molecules does thyroxine contain?
4.
93
How may iodine molecules does triiodothyronine contain?
3.
94
What cells in the thyroid actively take up iodine in the form of iodide?
Follicular cells.
95
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.
96
What process needs to occur before T3 and T4 can be released into the blood stream?
Proteolysis.
97
Is more T4 or T3 produced in the thyroid?
| What is active?
T4 (thyroxine).
| T3 (triiodothyronine) is more active
98
Briefly describe thyroid hormone synthesis.
Follicular cells take up iodide. Iodide diffuses to colloid which contains thyroglobulin.
Iodide is oxidised to iodine. (THYROID OXIDASE)
Iodine binds to TYROSINE RESIDUES on Thyroglobulin molecules ==> due to enzyme THYROID PEROXIDASE, resulting in either a 1 iodine molecule (Monoiodotyrosine) or a 2 iodine molecule (Diiodotyrosine) (just iodotyrosine )
thyroid is STIMULATED to produce thyroid hormone, the T1 and T2 molecules are cleaved from their tyrosine backbone (but are still attached to
the thyroglobulin) and join to create T3 (T1 + T2) or T4 (T2 + T2)
Engulfed by Colloid side membrane and taken into follicular cell by ENDOCYTOSIS
PROTEOLYSIS of the thyroglobulin results in the release of T3 & T4 Which diffuses into the blood
99
What enzyme stimulates T3 and T4 formation in the thyroid
Thyroid peroxidase.
100
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.
101
Give 3 histological characteristics of the secretory phase.
1. Spiral arteries.
2. Decidualised stroma.
3. Secretions.
4. Torturous glands.
102
What cells in the parathyroid detect Ca2+ levels?
Chief cells.
103
What does ANP inhibit the release of?
Renin.
| ANP is a vasodilator and acts to decrease blood pressure.
104
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.
105
What are the histological characteristics of the endometrium in the late-secretory phase?
Prominent spiral arteries and decidualised stroma. More secretions and elongated glands.
106
What are C-cells also known as?
Parafollicular cells.
They Secrete calcitonin, found in the thyroid gland!
107
What 2 hormones are secreted in the kidney?
EPO and renin.
108
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.
109
What is the parasympathetic innervation to the bladder? What does it do?
the PELVIC NERVE (S2-S4) - increased signals from this nerve causes contraction of the detrusor muscles - thereby stimulating micturition
110
What is the sympathetic innervation to the bladder? What does it do?
hypogastric nerve (T12 – L2). It causes relaxation of the detrusor muscle, promoting urine retention.
111
What is the somatic nervous supply to the pelvis?
pudendal nerve (S2-4). It innervates the external urethral sphincter, providing voluntary control over micturition.
112
Where are sesnory afferent nerves in the bladder found? What do they do?
there are sensory (afferent) nerves that report to the brain. They are found in the bladder wall and signal the need to urinate when the bladder becomes full.
113
Outline the bladders stretch reflex
The reflex arc:
Bladder fills with urine, and the bladder walls stretch. Sensory nerves detect stretch and transmit this information to the spinal cord.
Interneurons within the spinal cord relay the signal to the parasympathetic efferents (the pelvic nerve).
The pelvic nerve acts to contract the detrusor muscle, and stimulate micturition.
It is overridden by higher centres in the brain, this is learnt in toilet training
114
Outline negative feedback on Thyroxine produciton
T3 v T4 : what is there more of in the blood? What is the more active form?
Enzyme that converts it
T3 - Triiodothyronine - NEGATIVE FEEDBACK ON ANTERIOR PITUITARY TO STOP RELEASEING THYROID STIMULATING HORMONE
T3 is the more active hormone, not T4
Theres a higher concenraion of T4, it is thought to be a resovoir for T3
T4 is generally converted into T3 by enzymes known as deiodinases in target cells
115
Describe Cortisol secretion and negative feedback
Hormone secretion
- Hypothalamus secretes Corticotrophin - Releasing Hormone CRH (Due to Stress, Hypoglycaemia)
- Reaches anterior pituitary and Stimulates release of Adrenocorticotrophin hormone, ACTH
- This stimulates Adrenal Cortex to secrete Cortisol and Androgens
THE SECRETION OF ACTH HAS A NEGATIVE FEEDBAKC ON THE HYPOTHALAMUS, SO IT SECRETES LESS CRH (CORTICOTROPHIN) - SHORT LOOP
CORTISOL HAS A NEGATIVE FEEDBACK ON THE ANTERIOR ITIUTIARY GLAND TO SECRETE ACTH (ADRENOCORTICOTROPHIN)
116
What are the 2 main types of cells in the collecting duct?
Principle - Respond to Aldosterone and ADH
Intercalated -
2 types, A and B cells
A cells deal with acidosis, involved in the excretion of H+ and absorption of bicarbonate
B cells deal with alkalosis involved in the excretion of bicarbonate and the excretion of H+ ions
117
Outline Vit D synthesis
- 7-dehydrocholesterol is made directly from ingested chloresterol
- 7-dehydroxcholesterol is converted into Vitamin D3, by UV radiation
- Vitamin D3 is converted into Calcidiol in the Liver via the cytochrome P450 system)
- Calcidiol is converted to Calcitriol (Vit D) (1-a hydroxylase) in the presence of PTH in the Kidneys
118
Skin - What is the uppermost layer?
What is it made up of?
Stratum Corneum Uppermost Layer, 20-30 layers of skin
Glycolipid is the cement, Dead keratinised cells are the bricks
The dead Keratinised cells secrete natural antibiotics
Made up of corneo-desmosomes
and desmosomes
- Corneo-desmosomes (known as adhesion molecules) keep the
corneocytes together
119
What are corneocytes?
Corneocytes are terminally differentiated keratinocytes and compose most of the stratum corneum, the outermost layer of the epidermis
120
What layer of the skin has Melanocytes? What do melanocytes do?
The Stratum Basale also contain Melanocytes , which secrete Melanin
- The melanin in the melaoncytes is stored In Melanosomes
121
What layer of the epidermis has immune cells?
Stratum Spinosum 8 - 10 cell layers thick,
| Has dendritic cells, that immune cells looking for invading microbes
122
What is the layer of the skin where keratinocytes flatten out and die?
Stratum Granulosum 3-5 cell layers thick
This is where Keratinocytes FLATTEN OUT AND DIE. Creates Epidermal Skin barrier, Glycolipids are secreted out and cement them together
123
What layer of skin is only found in the sole of feet and palms?
Next layer up is the Stratum Lucidum, 2-3 cell layers thick
Translucent, full of dead keratinocytes
Only found in thick skin, like palm and soles of feet
124
Name the hormones released by the Hypothalamus
Corticotropin-releasing hormone (CRH)
Growth hormone-releasing hormone (GHRH)
Thyrotropin-releasing hormone (TRH)
Dopamine (DA)
Gonadotropin-releasing hormone (GnRH)
125
What does insulin do at muscle cells?
Binds to GLUT-4 receptors, glucose enters the cell via glut 4
126
Describe how changes in the osmolality of the extracellular fluid are detected.
Detected by osmoreceptors (1)
| - In the hypothalamus (1)
127
outline the process of micturition again
As the bladder fills with urine, stretch receptors in the bladder wall are
stimulated by the increase in pressure (1)
- Afferent neurons from these receptors enter the spinal cord and stimulate the
parasympathetic pelvic splanchnic nerve causing the detrusor muscle to
contract (1)
- The afferent neurons also inhibit the sympathetic hypogastric nerve to the
internal urethral sphincter and the somatic pudendal nerve to the external
urethral sphincter causing it to relax (1)
- The opening of both sphincters and contraction of the detrusor muscle result
in urination (1)
128
What part of the nephron is found in the renal medulla? What is the purpose of the this part?
What would cysts here do?
loop of henle, responsible for generating an osmotic gradient in the medulla that
functions to reabsorb water
Cysts in the renal medulla, therefore, causes the patient to produce large
volumes of dilute urine because the loop of Henle is unable to reabsorb water
sufficiently
129
What is the equation for GFR
GFR = filtration coefficient (glomerular capillary hydrostatic pressure –
Bowman’s space hydrostatic pressure – osmotic pressure in glomerular
capillary)
130
What is the enzyme that converts calcidiol into active vitamin D in the kidneys?
1-alpha hydroxylase
that converts 25-hydroxyvitamin-D3 to
1,25-dihydroxyvitamin-D3.
131
the urogenital organs develop from which layer of the germ cells?
Intermediate mesoderm
132
Where does the renal artery come of the aorta
L2
133
What are the order of steps for catecholamine synthesis?
tyrosine -> l-dopa -> dopamine -> noradrenaline -> adrenaline
