Endrocrinology physiology Flashcards
1
Q
Pituitary gland position
A
Hanging off hypothalamus connected to the infundibulum
2
Q
Nuclei found in the posterior pituitary gland
A
Supraoptic nucleus
Paraventricular nucleus
3
Q
What does the supraoptic nucleus secrete?
A
ADH/ Vasopressin
4
Q
What stimulates the supraoptic nucleus in the hypothalamus
A
low blood volume
low blood pressure
high plasma osmolality
pain
5
Q
What effect does alcohol have on the supraoptic nucleus
A
Inhibitory
6
Q
What does the paraventricular nucleus secrete in the posterior pituitary gland
A
Oxytocin
7
Q
What stimulates the paraventricular nucleus in the posterior hypothalmus
A
Birthing process
Suckling
Ejaculation
8
Q
What is the hypophyseal portal system
A
2 capillary beds (primary & secondary capillary plexuses)
Connected in series through an intermediate portal vein
this is the anterior pituitary connection
9
Q
The paraventricular nucleus secretes what in the anterior compartment of the pituitary gland
A
CRH: Corticotropin-releasing hormone
TRH: Thyrotropin-releasing hormone
10
Q
Action of CRH
A
Stimulates genes in corticotrope.
Proopiomelanocortin gets broken down into Alpha Milano stimulating hormone (alpha MSH) and adrenocorticotropic hormone (ACTH)
11
Q
Action of TRH
A
Stimulates thyrotrope to release TSH
12
Q
What does the arcuate nucleus secrete
A
Growth Hormone releasing hormone
PIH or dopamine
13
Q
The action of Growth Hormone releasing hormone
A
Causes stimulation of somatotrope to secrete growth hormone
14
Q
The action of PIH or dopamine
A
Stimulates lactotrope to secrete Prolactin
15
Q
Ganado tropen releasing hormone action
A
Stimulates Gonadotrope to secrete FSH LH
Depending on the frequency of GnRH: High frequency is LH, lower frequency is FSH
Somatostatin inhibits this
16
Q
Nucleus present in anterior pituitary gland
A
Paraventricular nucleus
Arcuate nucleus
Preoptic nucleus
17
Q
What does oxytocin bind to in the uterus?
A
smooth muscle of the myometrium
causing it to contract and therefore help during birthing process
18
Q
Oxytocins involvement in lactation
A
Binds to the mammillary bodies of breasts send signals to the hypothalamus
Results in milk ejection during lactation
Stimulated by suckling
19
Q
Oxytocin has a ____ half life
A
short
so regulated frequnetly
20
Q
What receptor does ADH bind to the principal cell of the collecting tube
What receptor does ADH bind to in blood vessels
A
Vasopressin type 2 receptor
Vasopressin type 1 receptor
21
Q
Steps of ADH activation
A
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
22
Q
Effects of stimulation of ADH
A
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
23
Q
Hormones of the anterior pituitary gland
A
FLAT PIG
FSH
LH
ACTH
TSH
Prolactin
GH
24
Q
What nucleus secrete growth hormone
A
Arcuate nucleus
25
What inhibits/ stimulates prolactin
inhibits PIH or dopamine (arcuate nucleus)
stimulates: thyrotropin-releasing hormone (paraventricular nucleus)
Stimulates: oestrogen + breastfeeding
26
How does iodide enter from the blood into follicles of the thyroid gland
secondary active transport
27
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
28
What is it called when a tyrosine amino acid has:
one iodide group
two iodide group
Monoiodotyrosine
Diiodotyrosine
29
What makes up the thyroid hormone?
T4 thyroxine +
T3 triiodothyronine
30
How is T3 + T4 made from tyrosine molecule
Tyrosine is broken down into T3 + T4 components via lysozyme enzymes
31
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
32
How does T3 act
Inducing gene transcription and protein synthesis
33
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
34
What cell is stimulated by low calcium levels
Chief cells
35
What does it mean when there is low blood calcium
Stimulates the parathyroid to secrete parathyroid hormone
36
How does the Parathyroid hormone affect kidneys
Increases calcium reabsorption decreasing Ca2+ excretion
Excreting phosphates as well
37
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
38
What makes up the adrenal cortex
Zona glomerulosa
Zona Fasiculata
Zona Reticularis
39
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 ….
40
What is aldosterone derived from and what type of hormone is it?
Cholesterol
Steroid hormone
41
What inhibits Zona glomerulosa
Atrial natriuretic peptide
42
What hormones are corticosteroids
steroid hormones produced in the adrenal cortex
Cholesterol is the Precursor
43
What does aldosterone do?
Increase Na+ absorption
Decrease K+
Increase H2O absorption
44
Where is aldosterone produced
Zona glomerulosa
45
Where is cortisol secreted
Zona fasciculata
46
What stimulates Cortisol secretion
ACTH
undergoes same action as with aldosterone
47
What is cortisol derived from?
cholesterol
48
Steroid hormones transported around blood
Steroid hormones need carrier proteins to travel within the blood
49
What does zona glomerulosa secrete
Mineral corticoids (Aldosterone)
50
What does zona fasiculata secrete
Glucocorticoids (Cortisol)
51
What does zona reticulosa secrete
Gonadocorticoids (Androgens)
52
What stimulates zona fasiculata
53
What does cortisol do
Protein catabolism
Suppresses immune system
Lipolysis
54
Gonadocorticoids are …
weak
55
Adrenogens act on
Weak and therefore act as precursor
Fmelaes to release oestrogen
Males release testosterone
Libido effect
56
What feedback system does cortisol induce
Negative feedback system
57
Primary stimulant for sympathetic nervous system
Short term acute stress
Fight or flight
58
What contains sympathetic nerve fibers
Ventral grey horn of the spinal cord
59
What do chromaffin cells of the adrenal cortex convert tyrosine into
Epinephrine (80%)
Norepinephrine (20%)
60
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
61
What is a heterocrine gland and given example
Has both endocrine and exocrine function
Pancreas
62
What cells do the endocrine portion of the pancreas have (Islets of Langerhans)
Alpha cell-glucagon
Beta cells-Insulin
63
What is beta pancreatic cells stimulus
Hyperglycaemia
64
What stimulates alpha pancreatic cells
Hypoglycaemia
Sympathetic nervous system
65
What does the exocrine portion of the pancreas have
Acini 99%
66
Where are insulin contained in the beta cell of the pancreas
Vesicles
C peptide is also within the vesicles
67
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
68
What is C peptide
A good way to monitor insulin levels
69
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
70
What does the endocrine portion of the pancreas have
Islets of Langerhans 1%
71
What does pancreatic alpha cell secrete
Glucagon
72
What does glucagon do?
In liver:
gluconeogenesis & glycogenolysis + to increase blood glucose levels
In adipose tissue:
Lipolysis
73
What is oogonium
Stem cells (dipolid)
74
What happens prepuberty
oogonium ⇢ primordial follicle (2n) stuck in prophase 1
75
Primary oocyte is…
Primordial follicle → Late secondary oocyte
76
What phase is graffian cells stuck in
Metaphase 2
77
What cells is primordial follicle stuck in
Prophase 1
78
Follicular phase
Primordial follicle → graffian cell
79
Follicular phase products
Mitosis
Oestrogen is produced
Follicular fluid
primary oocyte → secondary oocyte
80
What days does the follicular phase take place
1-14 days
81
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.
82
What happens at end of the follicular phase
Oestrogen stimulates GnRH to secrete LH and inhibits FSH (LH surge)
83
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
84
What is the ovulatory phase
LH surge
85
How is the corpus luteum formed?
LH stimulates Remaining granulosa cells from ovulation to specialise
LH stimulates the corpus luteum to produce progesterone
86
What arteries are there within endometrium
Stratum functionalis: Spiral and Coil arteries
Stratum Basalis : Striaght arteries
87
Why is there blood during the menstruation phase
As the stratum Functionalis is being shed the spiral and straight arteries are also being shed.
88
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
89
Secretory phase
The main hormone is progesterone
Angiogenesis
Secretion of uterine glands
Thickening cervical plug
Day 15-28
90
Where is spermatogenisis occuring
Seminiferous tubu`les
91
Where is spermatogenisis occuring
Seminiferous tubu`les
92
What cells make up seminiferous tubes
Sertoli cells
they are connected to one another via tight junctions/adherens junctions
93
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
94
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)
95
When does a type B cell become a spermatocyte
When it gets past tight junctions and goes from basal lumen to ad luminal compartment
96
How are secondary spermatocyte made?
The primary spermatocyte undergoes meiosis 1 to become 2 secondary spermatocyte
This further undergoes meiosis 2 to become spermatids
97
Spermatids become _____ via \_\_\_\_\_
Spermatozoa via spermiogenesis
98
Spermatogenesis
99
What cell do LH act on for spermatogenesis on the actions does it do
Leydig cells they convert cholesterol into testosterone
100
What cell do FSH act on for spermatogenesis on the actions does it do
Acts on Sertoli cells to produce Androgen Bonding protein (ABG)
101
What two molecules are needed for spermatogenesis
testosterone and Androgen Bonding protein (ABG)
102
What is the role of androgen bonding protein
Helps keep testosterone very soluble and highly concentrated
103
What process do Sertoli cells primarily help with
Spermiogenesis
104
What kind of feedback system does a high testosterone levels initiate
Negative feedback system
105
What hormone is secreted by Sertoli cells when sperm levels are too high
Inhibin causes a negative feedback system with hypothalamus and anterior pituitary
106
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
107
Seminal vesicles
Accounts for 60-70% of seminal fluid
Fructose
Prostaglandin
Coagulase
108
Prostate gland
Accounts for 30% of seminal fluid
Citrate
Fibrinolysis
PSA
109
Role of prostaglandin in fertilisation
binds to the smooth muscle of the uterus and causes it to contract- retropulsion
110
Role of coagulase in fertilisation
Allows for sperm to bind to vagina wall
111
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
112
How many phases can the menstrual cycle be subdivided into?
Follicular phase (0-14)
Luteal Phase (14-28)
113
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
114
What kind of feedback does oestrogen have on the pituitary gland 10 days before the menstrual cycle begins
Negative and therefore inhibiting LH
115
In low concentration oestrogen inhibits …
LH secretion
116
When is FSH released? What is it in response to?
Low oestrogen conc
117
Roles of oestrogen
Stimulate bone and growth
Muscle growth
Stimulation of endometrial growth
Maintain female secondary characteristics
118
In high concentrations oestrogen stimulates
LH
119
Why is there an FSH surge alongside an LH surge
As a side effect of LH
120
What hormones does the corpus luteum secrete
Oestrogen
Inhibin
Progesterone
121
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
122
What feedback system does inhibin have
As the corpus luteum develops inhibin suppresses GnRH secretion
123
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.
124
Ovulation graph
125
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
