Suger 2 Flashcards
(151 cards)
1
Q
What is the purpose of the endocrine system?
A
Allows for integration of whole body physiology & rapid adaptive changes
Allows communication between the different cells & tissues
Long term maintenance of metabolic environment
2
Q
What are the 8 main endocrine organs?
A
Pituitary gland Thyroid gland Breast Adrenal gland Kidneys Ovaries Uterus Testes
3
Q
What are the 2 main types of hormone?
A
Peptide
Steroid
4
Q
How are peptides synthesised?
A
Preprohormone made at ribosomes
Cleaved to form pro hormone by proteolytic enzymes in RER
Stored in vesicles
5
Q
Where are the receptors for peptide hormones found?
A
Cell surface membrane of target cell
6
Q
How do peptide hormones work?
A
Initiating other reactions in the cell’s cytoplasm
7
Q
Where are steroids produced?
A
Adrenal cortex
Gonads
8
Q
What are the steroid hormones derived from?
A
Cholesterol
9
Q
Where are the receptors for steroid hormones found?
A
Intracellular
10
Q
How do steroid hormones work?
A
Alter target cell’s gene expression & protein synthesis to change function & secretion of the cell
11
Q
How are each of the main hormones found in the blood plasma?
A
Peptides - unbound, fast acting
Steroid - bound to proteins, slow acting
12
Q
What are amines a derivative of?
A
Amino acid tyrosine
13
Q
What are some examples of an amine?
A
Thyroid hormones
Adrenaline
Noradrenaline
Dopamine
14
Q
What is the posterior pituitary gland made up of?
A
Neural tissue - axons of neutrons & their supporting glia
Connected to hypothalamus by pituitary stalk
15
Q
What 2 substances does the posterior pituitary release & where are they made?
A
Vasopressin - supraoptic nuclei of hypothalamus
Oxytocin - paraventricular nuclei
16
Q
What is the role of vasopressin/ADH?
A
Reabsorption of water from CD of kidneys by stimulating insertion of AQP2 aquaporin channels into the luminal membrane of the epithelial cells
17
Q
What is the role of oxytocin?
A
Expression of milk from glands of breasts to nipples & promotes onset of labour
18
Q
What is the anterior pituitary gland made up of?
A
Glandular epithelial tissue
19
Q
What are hypophysiotrophic hormones?
A
Hormones that control the secretion of anterior pituitary hormones (which control the secretion of a hormone from another endocrine gland)
Sequence of 3 hormones
20
Q
Where does the anterior pituitary gland recieve its blood supply from?
A
Portal venous system from hypothalamus
21
Q
What are the 6 main hormones that are secreted from the anterior pituitary?
A
FSH, follicle stimulating hormone LH, lutenising hormone GH, growth hormone, somatotrophin TSH, thyroid stimulating hormone, thyrotropin Prolactin ACTH, adrenocorticotrophin hormone
22
Q
What are FSH & LH stimulated to be excreted by?
A
GnRH, gonadotrophin releasing hormone
23
Q
What do FSH & LH do?
A
Stimulate gonads to release sex hormones
24
Q
What is GH stimulated to be excreted by?
A
GHRH, growth hormone releasing hormone
25
What does GH do?
Stimulates release of a growth-promoting peptide hormone, insulin-like growth factor 1
26
What is TSH stimulated to be excreted by?
TRH from hypothalamus
27
What does TSH do?
Stimulates thyroid to secrete thyroxine & triiodothyronine
28
What is prolactin stimulated to be excreted by?
Naturally inhibited by dopamine
| Levels of dopamine drop, secretion increases
29
What does prolactin do?
Stimulates milk production
| Stimulates development of mammary glands
30
What is ACTH stimulated to be excreted by?
CRH, corticotrophin releasing hormone
31
What does ACTH do?
Stimulates adrenal cortex & its secretion of cortisol
32
What are the 2 lobes of the thyroid gland connected by & which cartilages do they sit in front of?
Isthmus
| Tracheal cartilages 2-4
33
What is the blood supply to the thyroid gland?
Superior & inferior thyroid arteries
34
Why does the thyroid gland need a rich blood supply?
Uses iodine to make hormones
35
What is the thyroid gland histologically made up of?
Numerous follicles
Walls - follicular cells
Lumen - contains colloid, protein rich material
36
What does the thyroid gland produce?
Thyroxine, T4
| Triiodothyronine, T3
37
What hormone does the thyroid gland respond to?
TSH from the anterior pituitary
38
How is iodine transported into a follicular cell?
* Large negatively charged iodine ions circulating in blood co-transported from interstitial fluid into cytoplasm of follicular cells with Na+
* Too large to diffuse out (iodine trapping), so diffuse down concentration gradient to luminal surface of follicular cell
39
How are the thyroid hormones initially formed?
* large amount of enzyme thyroglobulin in colloid
* iodine ions rapidly oxidised by enzyme thyroid peroxidase to form free iodine radicals
* attached to tyrosine, an amino acid in the structure of the thyroglobulin enzyme
* tyrosine & 1 iodine = moniodotyrosine (MIT)
* tyrosine & 2 iodines = diiodotyrosine (DIT)
40
What are T4 & T3 formed from?
```
T4 = DIT + DIT
T3 = DIT + MIT
```
41
How are the hormones transported from the colloid?
Portions of luminal membrane of follicular cells engulf the thyroglobulin structures by endocytosis
Proteolytic enzymes in lysosomes release T3 & T4
42
What does enzyme deiodinase do in the target cells?
Converts T4 to T3
| thyroid makes more T4 then T3
43
What are some of the things that thyroid hormones regulate?
```
Breathing
HR
Central & peripheral NS
Body weight
Muscle strength
Menstrual cycles
Body temperature
Cholesterol levels
...
```
44
Do receptors have a higher affinity for T3 or T4?
T3
45
What are the 3 main cell types of the islets of Langerhans?
Beta cells
Alpha cells
Delta cells
46
What do beta cells secrete & in response to what?
Insulin
| High blood glucose levels
47
What do alpha cells secrete & in response to what?
Glucagon
| Low blood glucose levels
48
What do delta cells secrete & what does it do?
Pancreatic somatostatin
| Inhibitory effect on release of insulin & glucagon
49
What is GH release inhibited by?
Somatostatin from hypothalamus
50
What does glucagon do? (3)
Increases blood glucose by:
- increasing hepatic output of glucose by increasing gluconeogenesis & glycogenolysis
- reducing peripheral uptake of glucose from the bloodstream
- stimulation of peripheral release of gluconeogenic precursors (e.g. glycerol, amino acids) through stimulation of lipolysis & muscle breakdown
51
What are the 2 phases of insulin release?
First - rapid, from vesicles
| Second - slower, release as made
52
What are the 8 steps of insulin release?
1) increase in amount of glucose transported into beta cells through GLUT2 glucose transporter protein when increased glucose levels in blood
2) enters glycolytic pathway & ATP moves into cell
3) extra ATP binds to K+ channels on cell surface membrane of beta cell, closing channels
4) K+ stops flowing out of cell, membrane potential altered
5) voltage-gated Ca2+ channels open
6) Ca2+ flows in
7) causes conformational changes to SNARE proteins on membranes of vesicles that contain insulin
8) vesicles can now bind with cell surface membrane & release insulin into interstitial fluid
53
What are incretins?
Hormones released from the gut that stimulate the release of insulin
54
Why is insulin greater following oral consumption of glucose compared to intravenous glucose?
Incretins stimulate the release of insulin
55
What does insulin do? (3)
Decreases blood glucose by:
- suppression of hepatic glucose output, decreasing gluconeogenesis & glycogenolysis
- increase glucose upstake by insulin-sensitive tissues for glycogen & protein & fatty acid synthesis
- suppression of lipolysis & breakdown of muscle
56
How is insulin uptaken by cells? (4 steps)
1) binds to insulin receptors on cell surface membrane (as peptide hormone)
2) intracellular signalling cascades take place
3) vesicles in cytoplasm that store GLUT4 glucose channels are mobilised to the cell surface membrane
4) increased GLUT4 results in more glucose being taken up by the cells
57
What are the 2 phases of the menstrual cycle?
Follicular - first 14 days
| Luteal - 14 days after ovulation
58
What does the rise of FSH cause?
Primordial follicles in the ovaries to begin to develop
59
What occurs as the follicles begin to develop?
Their granulosa cells begin to secrete oestrogen
60
What are the effects of oestrogen during the cycle? (2)
Negative feedback effect on anterior pituitary when low levels in first 10 days
Positive feedback effect on release of LH when levels increase
61
What does the LH surge cause?
Ovulation
Oocyte expelled from dominant follicle in ovary
Corpus luteum remains
62
What does the corpus luteum produce?
Oestrogen
| Progesterone
63
What is the effect of progesterone?
Negative feedback effect on hypothalamus
Inhibits secretion of GnRH
Thus inhibits secretion of FSH & LH
64
How does the cycle restart?
Corpus luteum degenerates
| Less -ve feedback on hypothalamus
65
What does an oocyte begin as?
Primordial follicle
| One primary oocyte surrounded by a single layer of granulosa cells
66
When does the primordial follicle develop into the primary follicle?
When oocyte develops & becomes fully grown
| Granulose cells begin to proliferate & become multilayered
67
What separates the oocyte from the innermost later of granulosa cells?
Zona pellucida
68
How does the oocyte maintain its meiotic arrest?
Granulosa cells inner layer delivers nutrients
| Cytoplasmic processes transverse the ZP & form gap junctions with oocyte
69
What is the theca of the follicle?
Differentiated layers around outside
| Involved in oestrogen secretion from granulosa cells
70
What is the antrum & why does it develop?
Fluid filled space in midst of granulosa cells
Secretions of granulosa cells cause it to develop
Follicle from pre-antral to early antral
71
How many antral follicles become the dominant follicle that continues to develop?
1
72
What causes the dominant follicle's growth? (2)
Expansion of antrum due to increase in fluid
| Granulose cells closest to oocyte form mound like structure, cumulus oophorus
73
What happens to the oocyte as ovulation occurs?
Undergoes first meiotic division
| Cumulus oophorus separates it from granulosa cells so can float freely in antrum
74
How is the oocyte released from the follicle?
Digestive enzymes break down granulosa cells, leaving ZP & cumulus oophorus
75
What do trophoblasts of the developing structure secrete?
Human chorionic gonadotrophin, hCG
| glycoprotein
76
What are the roles of hCG? (3)
Prevents degeneration of corpus luteum
Strongly stimulates secretion of steroid hormones from CL
Allows continued secretion of oestrogen & progesterone from corpus luteum until placenta developed enough to take over
77
What is progesterone's role in pregnancy? (2)
Inhibits uterine contraction (to prevent premature birth)
| Continues to have negative feedback effect on GnRH
78
What are the 2 reasons for preventing a menstrual cycle during pregnancy?
Prevents miscarriage
| Builds up endometrium of uterus in preparation for development of placenta
79
What is oestrogen's role in pregnancy? (3)
Stimulates development of uterine muscle (myometrium)
Regulates levels of progesterone
Prepares breasts for lactation
80
Why does the placenta need to get androgens from the mother's ovaries & adrenal glands?
Androgens precursor for oestrogen
| Placenta does not have enzymes for synthesis
81
Where else does the placenta get androgens from?
Foetus's adrenal glands & liver
82
What is the role of relaxin in pregnancy?
Limits uterine contractions
| Softens cervix
83
What is the role of oxytocin in pregnancy?
Stimulates contraction of smooth muscle of myometrium
In turn stimulates further secretion of oxytocin
Positive feedback loop
84
What are prostaglandins involved in in pregnancy?
Initiation of labour
85
What are some of the physiological changes to the CV system in pregnancy?
```
CO increase
TPR decreases
BP decreases overall
Heart displaced & becomes larger
Blood flow to uterus increases
Risk of varicose veins increases
Blood volume increases
Erythrocyte count increases
Physiological anaemia of pregnancy (erythrocyte count doesn't increase as much as volume)
```
86
What are some of the non-CVS physiological changes in pregnancy?
```
Weight gain
Breathing more shallow & frequent
Linea nigra
Striae gravidarum (stretch marks)
Darkening of skin around abdomen & areoli
Acid reflux more common
Lumber hyperlordosis
```
87
How does the uterus adapt for paturation?
Grows due to increased cell division & hypertrophy of individual myometrial cells
88
What is the disconnected arrangement of the myometrial cells maintained by?
Progesterone
89
What stimulates the synthesis of connexion proteins & thus gap junctions between myometrial cells?
Oestrogen
90
What stimulates the production of placental prostaglandins?
Oestrogen
91
What do placental prostaglandins act to do?
Act with oestrogen to stimulate the synthesis of enzymes that mediate the breakdown of collagen fibres that form the cervix (cervical ripening)
92
What stimulates the synthesis of receptors for the hormone oxytocin?
Oestrogen
93
What is foetal stress?
Foetal head pressing on the cervix
94
What does foetal stress stimulate?
Release of ACTH
| Cortisol thus secreted
95
What are cortisol's effects on the placenta?
Decrease in oestrogen secretion
Decrease in progesterone secretion
Increase in prostaglandin secretion
96
What does the increase in secretion of prostaglandins cause?
Uterine muscles to start to push the foetus down
Stretches cervix & stimulates nerve fibres
Stimulates production & secretion of oxytocin
97
What are the seminiferous tubules make up of?
Basement membrane (on which sit fibroblast cells)
Sertoli cells
Spermatogonia (sperm stem cells)
98
Where are Leydig cells found & what do they produce?
Interstitial space between tubules
| Testosterone
99
What are the 2 types of daughter cell produced from the mitosis of spermatogonia?
Type A
| Type B
100
What occurs to type A cells?
Remain outside BTB
| Continue to undergo mitosis to produce more spermatogonia
101
What occurs to type B cells?
Primary spermatocytes
Pass through BTB to move in towards lumen of seminiferous tubule
Will develop into spermatozoa
102
What 2 steps occur before spermiogenesis?
Primary spermatocytes undergo first stage of meiosis into secondary spermatocytes
Secondary spermatocytes undergo second stage of meiosis to form spermatids
103
What is spermiogenesis?
Process by which spermatids develop into immature spermatozoa
104
What steps of oogenesis occur before puberty?
Oogenia undergo mitosis until ~7 months
Develop into primary oocytes
Begin meiosis I
Meiotic arrest between prophase I & metaphase I
105
What does the first meiotic division produce?
Haploid secondary oocyte (ovulated)
| Smaller primary polar body (almost no cytoplasm)
106
What does the second meiotic division of the fertilised secondary oocyte produce?
Ovum
| Second polar body
107
What do the ovum & spermatozoa join to make?
Zygote
108
What causes puberty in males?
Increase in ACTH secretion
Androgens stimulated to be produced
Androgens stimulate early pubic & axillary hair growth
Act alongside GH & IGF-1 to cause growth spurts
109
What are the male secondary sex characteristics? (puberty)
Facial & body hair
Deepening of voice due to growth of larynx
Masculine pattern of fat distribution
Thickening of skin oil gland secretionns
110
How are puberty & the hypothalamic-anterior pituitary-gonadal axis related?
Increase in secretion of GnRH
Increase in secretion of LH & FSH
Seminiferous tubules stimulated to secrete testosterone & DHT
111
What causes puberty in females?
Increase in GnRH secretion
| Increase in pulsatility amplitude of secretion
112
Why does menopause occur?
Depletion of primordial follicles
113
What are the hormonal changes during menopause?
Ovaries essentially fail
Oestrogen levels fall
No regulation of GnRH/FSH/LH
114
What are some of the symptoms of the menopause?
* Atrophy of genital organs & breasts
* Thinning & dryness of vaginal epithelium
* Significant decrease in bone mass (osteoporosis risk)
* Hot flashes
* Increased risk of CV diseases (oestrogen has a protective effect)
* Physiological symptoms: irritability, lethargy, forgetfulness, less libido
115
What are the 2 types of receptor in the bladder wall (detrusor wall)?
Muscarinic M3
| Beta-adrenergic B3
116
What do muscarinic M3 receptors respond to?
ACh from parasympathetic NS
117
What do muscarinic M3 receptors receive innervation from?
Efferent fibres of pelvic splanchnic nerve - from sacral region
118
What do beta-adrenergic B3 receptors respond to?
Noradrenaline from sympathetic NS
119
What do beta-adrenergic B3 receptors receive innervation from?
Hypogastric nerve - from thoracolumbar region
120
What receptors does the internal urethral sphincter have in males?
Alpha-adrenergic A1 receptors (innervated by hypogastric nerve)
121
What receptors are in the external urethral sphincter?
Nicotonic
122
What do the receptors in the external urethral sphincter respond to?
ACh released from pudendal nerve
123
What detects it when the bladder is empty & where do these signal go?
```
Sensory afferent fibres of pelvic nerve
Carry slow impulses to sacral cord
Up spinal cord
Thoracolumbar region
Hypogastric nerve
```
124
What does the hypogastric nerve release & what does this do?
Noradrenaline release
* B3 receptors in detrusor - relax
* A1 receptors in internal urethral sphincter (M) - contract
125
How is the pontine micturition centre involved with the empty bladder? (3)
* Impulses sent down spinal cord to hypogastric nerve, adding to impulses
* Inhibits impulses to efferent fibres of pelvic splanchnic nerve so no activation of M3 receptors - no contraction
* Impulses sent along pudendal nerve - contraction of external urethral sphincter
126
What occurs when the bladder is full?
Detrusor muscle stretched
Stimulation of afferent fibres
More rapid impulses
127
How is the pontine micturition centre involved with the full bladder? (3)
* Inhibits impulses down hypogastric nerve - no relaxation of detrusor & no contraction of internal sphincter
* Stimulate efferent fibres of pelvic splanchnic nerves - contraction of detrusor
* Inhibition of pudendal nerve - no contraction of external sphincter
128
What does the hypogastric nerve do in micturition when stimulated?
Relaxes detrusor
| Contracts internal urethral sphincter
129
What does the pelvic splanchnic nerve do in micturition when stimulated?
Contraction of detrusor
130
What does the pudendal nerve do in micturition when stimulated?
Contraction of external urethral sphincter
131
What is the voiding reflex?
Voiding (emptying) of bladder continues uninterrupted until bladder is empty
132
How does the voiding reflex occur?
Afferent fibres continue to send impulses during urination
Stimulate interneuron within sacral segment
Impulse to efferent pelvic splanchnic nerve
Continued contraction of detrusor
133
What are the roles of progesterone with the endometrium in the menstrual cycle? (3)
* Maintains integrity during menstrual phase
* Causes cells to become more complex in preparation for implantation in secretatory phases (from corpus luteum)
* No pregnancy, levels fall so endometrium shed
134
What are the roles of oestrogen with the endometrium?
Stimulates endometrial growth in proliferative phase
135
What are the roles of progesterone with the cervix?
* cells secrete thick mucus in infertile phase
| * cervical os closed
136
What are the roles of oestrogen with the cervix?
* stimulates cervical cells to secrete fertile-type mucus
| * cervical os open
137
What is the epithelia of the tubuli recti?
Simple/stratified cuboidal
138
What is the epithelia of the recti testes?
Simple cuboidal
139
What is the epithelia of the efferent ductules?
Pseudostratified columnar
140
What is the epithelia of the epididymis?
Pseudostratified columnar with sterocilia
141
What is the epithelia of the vas deferens?
Pseudostratified columnar
142
What is the epithelia of the ejaculatory duct?
Simple columnar
143
What is the epithelia of the bulbourethral gland?
Simple columnar
144
What is the epithelia of the seminal vesicles?
Pseudostratified columnar
145
What is the epithelia of the ovaries?
Simple cuboidal
146
What is the epithelia of the fallopian tubes?
Simple columnar & ciliated
147
What is the epithelia of the vagina?
Stratified squamous & non-keratinised
148
What is the epithelia of the endometrium?
Simple columnar & ciliated
149
What is the epithelia of the labia majora/minora?
Stratified squamous keratinised (skin)
150
What is the epithelia of the endocervix?
Simple columnar
151
What is the epithelia of the ectocervix?
Stratified squamous & non-keratinised
