hormones + sexual development Flashcards
lecture 2
1
Q
in the nervous system, what are passed directly between cells in a closed circuit
A
electro-chemical signals
2
Q
in the endocrine system, what is broadcasted around the body via bloodstream and picked up in multiple places
A
chemical messages
3
Q
endocrine system
A
uses hormones, synthesised by endocrine glands, useful for coorrdinating long lasting changes in body
4
Q
endocrine glands structure
A
Hormones -> extracellular fluid -> bloodstream -> target hormones
5
Q
3 types of hormones
A
amine hormones, peptide + protein hormones, steroid hormones
6
Q
define amine hormones
A
synthesised from one amino acid
7
Q
examples of amine hormones
A
adrenaline, noradrenaline, thyroxine
8
Q
define peptide and protein hormones
A
made from multiple amino acids
9
Q
example of peptide and protein hormone
A
insulin
10
Q
deinfe steroid hormones
A
made from cholesterol
11
Q
example of steroid hormones
A
sex hormones
12
Q
peptide hormones synthesis
A
Synthesised as prohormones, requiring further processing (e.g. cleavage) to activate
13
Q
peptide hormone storage
A
Stored in vesicles (regulatory secretion)
14
Q
peptide hormone solubility
A
Most are polar and water soluble, can travel freely in the blood
15
Q
peptide hormone receptors
A
Bind receptors on cell membrane and transducer signal via the use of second messenger systems
16
Q
peptide hormone effects
A
Often fast onset transient changes in protein activity, through gene expression changes can occur
17
Q
steroid hormones synthesis
A
Synthesised in a series of reactions from cholesterol
18
Q
steroid hormones storage
A
Released immediately (constitutive secretion)
19
Q
steriod hormones solubility
A
Generally non-polar and require carrier proteins to travel in blood
20
Q
steroid hormones receptors
A
Bind to intracellular receptors to change gene expression directly
21
Q
steriod hormones effects
A
Alterations in gene expression; slower onset but longer duration than peptide hormones
22
Q
amino acid derivative hormone synthesis
A
Synthesised from the amino acid tyrosine
23
Q
amino acid derivative hormone storage
A
Stored before release (storage mechanism varies)
24
Q
amino acid derivative hormone solubility
A
Some are polar (adrenaline), others must be protein-bound
25
amino acid derivative hormone receptors
Adrenaline acts on membrane receptors, while thyroid hormones act directly on nuclear receptors
26
amino acid derivative hormone effects
Adrenaline functions like peptides, thyroid hormones function in a similar manner to steroids
27
what does the pineal gland release
melatonin
28
functions of pineal gland
increases sleepiness, influences sleep/wale cycle, role in onset of puberty
29
what does the hypothalamus influence
release of hormones by the pituitary gland
30
what does the thyroid gland release
thyroid hormones (thyroxine + triiodothyronine)
31
functions of the thyroid gland
Primarily responsible for regulation of metabolism (turning food into energy)
Help regulate growth and maturation
32
what does the parathyroid gland release
parathyroid hormones
33
functions of the parathyroid gland
Regulates calcium levels within the blood and bones
34
define calcium
element that allows the normal conduction of electrical currents among nerves, also the primary element which causes muscles to contract
35
what does the thymus gland release
thymosin
36
functions of the thymus gland
Supports the body’s immune responses
Particularly active in children, helping develop the lymphoid system – defence against disease
37
what is the adrenal glands
Triangular-shaped endocrine glands that sit on top of the kidneys
38
2 parts that adrenal glands are divided into
adrenal cortex + adrenal medulla
39
where is the adrenal cortex located
outer part of the adrenal gland
40
what does the adrenal cortex release
mineralocorticoids (Aldosterone – reduces the secretion of salts by the kidneys thus controlling blood volume and regulating blood pressure) and glucocorticoids (Cortisol – stimulates the liver to increase blood sugar, and increases the metabolism of proteins and fats; releases resources for energy)
41
where is the adrenal medulla located
core of the adrenal gland
42
what does the adrenal medulla release
adrenaline and noreadrenaline
43
function of the adrenal medulla
prepares the body for vigorous action - especially flight or fight
44
what does the pancreas release
insulin and glucagon
45
what does insulin do
helps glucose move from the blood to cells where it’s used for energy
46
what does glucagon do
tells the liver to release glucose, stored in the liver as glycogen into the bloodstream
47
function of the pancreas
maintains blood sugar levels (glucose)
48
what does the ovaries release
oestrogen and progesterone
49
function of oestrogen
promotes female sexual characteristics
50
function of progesterone
helps prepare the uterus for/and maintain pregnancy
51
what does testes release
androgens
52
define androgens
male sex hormones
53
function of testes
promotes sperm production, growth of pubic hair, male sexual characteristics
54
2 glands in the pituitary gland
anterior pituitary and posterior pituitary
55
anterioir pituarity
glandular tissue - same embryonic tissue which formed the roof of the mouth; during development, it pinched off and migrated upward to sit beside the posterior pituitary
56
what is the anterior pituitary controlled by
blood borne factors released by the hypothalamus
57
posterior pituitary
neural tissue
58
what is the posterior pituitary originated from
outgrowth of hypothalamic tissue on the end of the pituitary gland
59
what is the posterior pituitary controlled by
nerves originating from the hypothalamus
60
master gland
See the neurons extending from the hypothalamus to the posterior pituitary
Produces a lot of hormones
61
what controls the master gland
Hypothalamic control of the anterior and posterior pituitary is fundamentally different
Based on their different origins
62
anterior pituitary hormones
growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, follicle stimulating hormone, luteinizing hormone, prolactin
63
growth hormone function
Stimulates growth in childhood and is important for maintaining a healthy body composition
In adults, it’s also important for maintaining muscle mass and bone mass
64
thyroid stimulating hormone function
Stimulates thyroid gland
65
Adrenocorticotropic hormone (ACTH) function
Increases secretion of steroid hormones by adrenal gland
66
Follicle stimulating hormone (FSH) function in females
increases production of oestrogen and promotes maturation of the ovum
67
Follicle stimulating hormone (FSH) function in males
promotes sperm production
68
Luteinizing hormone (LH) function in females
increases production of progesterone and stimulates ovulation
69
Luteinizing hormone (LH) function in males
increases production of testosterone
70
prolactin function
promotes milk production after childbirth, can affect sex hormone levels from the ovaries and testes
71
posterior pituitary hormones
oxytocin, vasopressin
72
oxytocin function
Milk release in nursing mothers
Controls uterine contractions
Some aspects of parental behaviour
Sexual pleasure
73
Vasopressin function
Constricts blood vessels and raises blood pressure
Decreases urine volume
74
hormone release in regulated by 1 of 3 different signals
Nervous system
Non-hormonal chemicals in the blood
Hormones – most are secreted in ‘pulses’
75
what is negative feedback
Hypothalamus and anterior pituitary sense when there’s enough of a particular hormone in blood circulation and stop releasing their tropic hormones
76
normal development of reproductive organs - week 0
Sex chromosomes – exist as X and Y
If a fertilised egg inherits 2 X chromosomes, it will become female (XX)
If a fertilised egg inherits a X and a Y chromosome, it will become male (XY)
77
normal development of reproductive organs - weeks 0-6
Males and females develop identically
Embryo contains the precursor tissue for making both types of gonads (ovaries and testes)
Embryo also has 2 complete sets of internal reproductive ducts
Wolffian system
Mullerian system
78
wolffian system - normal development of reproductive organs weeks 0-6
precursors of the male reproductive duct
- Seminal vesicles (store sperm)
- Vas deferens (duct from the testis to the penis)
79
mullerian system - normal development of reproductive organs weeks 0-6
precursors of the female reproductive ducts:
- Uterus
- Upper vagina
- Fallopian tubes – passage from the ovaries to the uterus
80
normal development of reproductive organs - week 6
SRY (sex determining region Y) gene – only found on the Y chromosome
Medulla of primordial gonads develop into testes
In the absence of the H-Y antigen, the cortical cells of the primordial gonads develop into ovaries
81
SRY (sex determining region Y) gene
Sets in motion a cascade of events which lead to sexual differentiation
Produces H-Y antigen which differentiates the foetal testis
82
normal development of reproductive organs - weeks 9 - 12
External genitalia develop from the same precursor tissue in both males and females
Androgens, particularly dihydrotestosterone, produced by the tests stimulates external genitalia to become male
Female external genitalia don’t need to be stimulated by female sex hormones to become female
83
normal development of reproductive organs - weeks 12
testes produce:
- Mullerian inhibiting substance - causes mullerian system to degenerate and the testes to descend into the scrotum
- Androgens – testosterone and dihydrotestosterone; stimulates development of Wolffian system
84
genetic issues - turners syndrome development - week 0
Instead of the normal pair of sex chromosomes, only 1 X chromosome is present and fully functional
85
genetic issues - turners syndrome development - week 40
No Y chromosomes – testes don’t develop
2 X chromosomes are required to produce ovaries, therefore ovaries don’t develop
No gonads – but develop normal female internal sex organs and external genitalia
Unable to have children – no ovaries
86
hormonal issue - androgen insensitivity development - week 9 onwards
Caused by a genetic mutation that prevents the formation of functioning androgen receptors
Takes a genetic male (XY)
Primordial gonads develop into testes
External genitalia are insensitive to action of androgens, including dihydrotestosterone
87
hormonal issue - androgen insensitivity development - week 12
Testes continue to secrete androgens and mullerian-inhibiting substance
Androgens fail to have their masculinising effect – male internal sex organs fail to develop
Mullerian-inhibiting substances does have its defeminising – female internal sex organs fail to develop 1
88
hormonal issue - androgen insensitivity development - week 40
Child born appears to be a girl – external genitalia are female
However, baby has no uterus or ovaries – at puberty, child develops a women's body shape but is unable to have children
89
hormonal issue - persistent mullerian duct syndrome - week 12
2 possible causes - failure to produce mullerian-inhibiting substance or absence of receptors for this hormone
90
what happens when persistent Müllerian duct syndrome week 12 development occurs in a genetic male
Androgens have their masculinising effect – male reproductive system develops normally
Mullerian inhibiting substance doesn’t have its defeminising effect – female internal sex organs develop normally
91
hormonal issue - persistent mullerian duct syndrome - week 40
Child is born with both sets of sex organs
Presence of the additional female sex organs may interfere with normal functioning of the male sex organs
