SUGER Flashcards
What are the two parts of the pituitary?
anterior and posterior
How many hormones does the anterior and posterior pituitary secrete?
anterior- 7
posterior- 2
What hormones does the anterior pituitary secrete?
FSH- follicle stimulating hormone) LH- luteinising hormone ACTH- adrenocorticotropic hormone GH- growth hormone TSH- thyroid stimulating hormone MSH- melanocyte stimulating hormone Prolactin
What hormones are secreted by the posterior pituitary?
ADH- antidiuretic hormone / vasopressin
Oxytocin
What does LH and FSH do in women?
LH: stimulates ovulation, ovarian follicle maturation and corpus luteum formation
FSH: regulates development and growth of ovarian follicle
What does LH and FSH do in males?
LH: testosterone formation
FSH: stimulates production of androgen-binding protein (ABP) and spermatogenesis
What type of hormones are FSH and LH?
gonadotrophins
How does oestrogen levels affect FSH and LH?
MODERATE levels of oestrogen present experts NEGATIVE feedback on FSH and LH
HIGH oestrogen (with low progesterone) exerts POSITIVE feedback on LH and FSH
Oestrogen in PRESENCE OF PROGESTERONE exerts NEGATIVE feedback on FSH and LH
What is ACTH?
adrenocorticotrophic hormone
Where is ACTH produced?
corticotrophs
What does ACTH do?
produce cortisol
What are the functions of cortisol?
gluconeogenesis carbohydrate metabolism reduction of inflammation proteolysis and lipolysis reduction of bone formation (can lead to osteoporosis over time)
What is GH produced?
somatotrophs
What is the function of GH?
skeletal growth and bone density muscle strength protein synthesis glycogenolysis lipolysis
Where is TSH produced?
thyrotrophins
What does TSH do?
increases metabolism
Where is prolactin produced?
lactotrophs
What inhibits release of prolactin?
dopamine
How is prolactin release initiated?
suckling
What is the function of prolactin?
initiates milk production in breasts
maintain milk production once It has been established
What are the two main groups of anterior pituitary hormones and what do they do?
hypophysiotropic hormones- control secretion of anterior pituitary
peptide hormones- control secretion of other endocrine glands
What is GnRH and what does it do?
gonadotrophin-releasing hormone, stimulates release of FSH and LH
What is CRH and what does it do?
corticotrophin-releasing hormone, stimulates release of ACTH
What is GHRH and what does it do?
growth hormone releasing hormone, stimulates release of GH
What is TRH and what does it do?
thyrotrophin-releasing hormone, stimulates release of TSH
What is the affect of dopamine on the anterior pituitary?
inhibits release of prolactin
What is the affect of somatostatin on the anterior pituitary?
inhibits secretion of GHRH
Where is oxytocin made?
paraventricular nucleus of hypothalamus
What is the function of oxytocin?
acts on breasts to allow milk to flow from lactiferous ducts and out of nipple
acts on uterus to cause uterine contractions during labour
exerts positive feedback on itself
Where is ADH made?
supraoptic nucleus oh hypothalamus
Describe the action of ADH?
osmoreceptors in hypothalamus detect change
ADH binds to V2 receptors on collecting ducts
mobilisation of aquaporin 2 (AQP2) and insertion into cell membranes
allows passage of water from collecting ducts into blood to reduce plasma osmolality
increased water reabsorption
How is blood pressure maintained under action of ADH?
maintains blood pressure by acting on smooth muscle cells, causing vasoconstriction and increasing blood pressure
What bodily factors cause ADH release?
low blood volume/ blood loss
low blood oxygen
high blood carbon dioxide
high oncotic pressure of blood
Where are the islets of langerhans found and what is their general function?
pancreas
manufacture and release peptide hormones
What cells are found in the islets of langerhans and what do each secrete?
alpha cells- secretes glucagon
beta cells- secretes insulin
delta cells- somatostatin
What is the function of glucagon?
mobilises glucose, free fatty acids and triglycerides from stores
stimulates breakdown of fat and muscle into glucose
What does insulin do?
decrease glucose output by liver
increase storage of glucose, free fatty acids and triglycerides
stops breakdown of fat and muscle
What does somatostatin do?
inhibits GHRH release
Describe the action of insulin?
insulin binds to insulin receptors on muscle and fat cells
triggers intercellular signalling cascade
this mobilises intracellular GLUT4 vesicles to cell membrane
GLUT4 vesicle integrates into cell membrane, which:
1. increases number of glucose transports
2. increases rate of glucose facilitated diffusion
3. decreases blood glucose levels
What happens as glucose levels rise in the blood?
insulin is released and glucagon release is inhibited
increased glycogenesis in liver and muscles
glyconeogenesis is inhibited
this reduces blood glucose level
What happens as blood glucose levels fall?
glucagon is released and insulin release is inhibited
glycogenolysis occurs to release glucose from liver and muscles into blood
gluconeogenesis occurs
blood glucose level is increased
What does the thyroid gland produce?
triiodothyronine (T3) and thyroxine (T4)
Describe the anatomy of the thyroid.
butterfly shaped gland
2 lobes: left and right
4 parathyroid gland on posterior surface
Describe the location of the thyroid.
anterior neck between C5-T1
wraps around cricoid cartilage + superior tracheal rings
Describe the blood supply to the thyroid.
supplied by superior and inferior arteries
superior: branch of external carotid
supplies superior and anterior portion of gland
inferior: branch of subclavian
supplies posterior and inferior portion of gland
How is T3 and T4 produced?
mnemonic- ATE ICE
A: (secondary) active transport of iodide via Na/I symporter
T: thyroglobulin is produced in the follicular cells
E: exocytosis of thyroglobulin into follicular lumen
I: iodination of tyrosine residues on thyroglobulin to form monoiodothyronine (MIT) and diiodothyrine (DIT)
C: coupling of MIT and DIT (T3) and DIT and MIT (T4)
E: endocytosis of T3 and T4 into follicular cells. Proteolysis occurs to free T3 and T4 from thyroglobulin
What is the general action of T3 and T4?
increase BMR, important for brain maturation
What is the role of T3 in brain maturation?
in fetus: formation of axon terminal production of synapses growth of dendrites and dendritic extensions formation of myelin
in adult:
provides proper nerve-muscle reflex and normal cognition
What are the layers of the skin from outermost to innermost?
epidermis, dermis, subcutaneous layer
What are the 5 layers of epidermis from outermost to innermost?
stratum corneum stratum licidim stratum granulosum stratum spinosum stratum basale
What provides cell-cell adhesion for the skin?
primary adherens junctions
desmosomes (striatum spinosum)
tight-junctions
What do tight junctions in the skin do?
make it waterproof
What do corneodesmosomes do?
keep corneocytes together
What is filaggrin and what does it do?
natural moisturising factor (NMF)
allows skin to remain hydrated and maintains slightly acidic pH of skin
Why is the skin slightly acidic?
prevents protease activity to stop breakdown of corneodesmosomes
What is the affect of increased pH on the skin?
proteases no longer inhibited by low pH so they break down corneodesmosomes
impairs formation of lipid lamellae
this allows skin cells to move apart
this reduces water retention in skin
allergens can then penetrate
What is the affect of allergens on the skin?
allergens penetrate skin and attract lymphocytes which release inflammatory cytokines giving an inflammatory response
gives:
red skin/ erythema- dilation of vessels to bring more lymphocytes to area
itchy skin- stimulation of proprioceptors by release of histamine (from mast cells)
dry skin- skin cells leak water
What secretes sebum?
sebaceous glands
How does acne occur?
hair follicle gets blocked with sebum, skin cells and bacteria
inflammation and attraction of neutrophils
pus formation
Describe the nerve supply of the bladder.
AUTONOMIC:
sympathetic:
hypogastric nerves: relaxation of detrusor muscle (urine retention)
parasympathetic:
pelvic splanchnic: contraction of detrusor muscles (micturition stimulation)
SOMATIC:
pudendal nerves: innervated external urethral sphincter (contraction or relaxation)
What is micturition?
release of urine from bladder
Describe the bladder stretch reflex arc
bladder fills and stretches
activates stretch receptors
afferent sensory nerves transmit signal to brain
interneurons relay signal to parasympathetic efferent nerves (pelvic nerve)
contracts detrusor muscle
stimulations micturition
What is the name for emptying the bladder
voiding
Describe how the bladder voids
detrusor muscle contracts to increase pressure in the bladder
internal urethral sphincter relaxes
once its appropriate to void, external; urethral sphincter will be continuously relaxed to allow voiding
Where does the pelvic splanchnic nerve exit the spinal cord?
S2-S4
Where does the hypogastric nerve exit the spinal cord?
T12-L2
Where does the pudendal nerve exit the spinal cord?
S2-S4
What is the function of oestrogen in pregnancy?
regulates levels of progesterone
prepares uterus for baby
prepares breasts for lactation
induces synthesis of receptors for oxytocin
Where is oestrogen made during pregnancy?
first 2 months- corpus lute in ovaries, then placenta
What is the function of progesterone in pregnancy?
prevents miscarriage by building up endometrium for support of placenta
inhibits uterine contractility so gets is not expelled prematurely
What produces progesterone in first 2 months of pregnancy?
corpus luteum of ovaries
What is the function of hCG?
stimulates oestrogen/ progesterone production by ovary
What hormone gives a positive pregnancy test?
hCG- human chorionic gonadotrophin
When does hCG diminish?
when placenta is mature enough to take over oestrogen/ placenta production
What produces prolactin?
anterior pituitary
What is the function of prolactin?
increase cells that produce milk
prevent ovulation
What action stimulates prolactin release?
suckling
When is relaxin level highest?
in early pregnancy
What produces relaxin?
ovary and placenta
What is the function of relaxin?
softens cervix
helps limit uterine activity
cervical ripening for delivery
What is the function of oxytocin in pregnancy?
triggers ‘caring’ reproductive behaviour
uterine contractions during pregnancy and labour
What drug is used to induce labour?
oxytocin, synthetic prostaglandins
What is the function of prostaglandins?
tissue hormones- roles in initiation of labour
What is the main prostaglandin?
PGF2a
What changes can be seen in a pregnant woman vascular system?
increased CO decreased systemic BP decreased total peripheral resistance increased uterine blood flow increased blood volume increased plasma and blood cell mass varicose veins
What respiratory changes occur in a pregnant woman?
increased alveolar ventilation
What GI changes can be observed in a pregnant woman?
increased acid reflux
gastroparesis (delayed emptying)
What changes in the skin can be seen in pregnant women?
linea nigra
striae gravidarum
darkened areola
What is linea nigra?
hyperpigmentation in pregnant women- dark vertical line that runs down abdomen
What is the proper term for a ‘pregnancy line’?
linea nigra
What is the proper name for stretch marks?
striae gravidarum
What are some biochemical changes in pregnant women?
weight gain
increased protein and liid synthesis
insulin resistance
What type of women have less weight gain in pregnancy?
obese women, as they already have fat stores
What is a other term for labour?
parturition
When does labour occur?
40 weeks after the 1st day of last cycle
What is the term for softening of the cervix?
cervical ripening
How many stages are there in labour?
3
Why does cervical ripening need to occur before birth?
the allow dilation
How does cervical ripening occur?
occurs in response to oestrogen, relaxin and prostaglandins breaking down cervical connective tissue
What initiates uterine contractions?
oxytocin
What signals the first stage of labour and what occurs?
from beginning of labour until cervix is fully dilated (10cm)
2 phases:
latent phase: slow cervical dilation over several hours
active phase: faster dilation until 10cm
What happens in the 2nd and 3rd stage of labour?
second: from full dilation until baby is delivered
third: after delivery until placenta has been delivered
What are the layers of the uterus from outermost to innermost?
perimetrium
myometrium
endometrium
What happens to endometrium during menstrual cycle?
changes thickness
What layer of the uterus contains the smooth muscle?
myometrium
Describe the development of the placenta.
blastocyst implants on endometrium
this is a synctiotrophoblast
goes into the endometrium
forms fingerlike projections called chorionic villi
these contain fetal blood vessels
villi closest to connecting stalk of developing embryo are most vascular and contain mesoderm
this area is the chorion frondosum
cells in this area proliferate and become placenta
the connecting stalk becomes the umbilical cord
When is placental development usually complete?
by 10 weeks gestation
What is gestation?
time between conception and birth
What is hcS and what is its function?
somatotropin
stimulates mammary development
Describe follicular development
this is when granulose cells surround oocyte forming the follicle
primordial follicle small spidery follicle secondary (preantral) follicle pre-ovulatory (antral) then ovulation luteinization corpus luteum luteolysis/ regression of follicle
What are the phases of the menstrual cycle?
follicular phase
ovulation
luteal phase
How long is the follicular phase of menstruation?
start of menstruation to ovulation- 14 days
What occurs in the follicular stage of the menstrual cycle?
- when follicles reach secondary follicle stage they develop FSH receptors
- they then require FSH stimulation to develop further
- as follicles grow the granulose cells secrete more and more oestrogen, which has negative feedback on pituitary gland, leading to decreased LH and FSH
- increasing oestrogen also makes cervical mucus more permeable which allows sperm to penetrate
- one follicle develops further than others becoming dominant follicle
- LH spikes before ovulation causing dominance follicle to release ovum from ovary
- ovulation occurs 14 days before end of cycle
How long is the luteal phase of menstruation?`
from ovulation to start of menstruation- 14 days
What occurs in the luteal phase of the menstrual cycle?
- follicle which releases ovum collapses and becomes corpus luteum
- corpus luteum secretes high levels of progesterone to maintain endometrial lining and thicken cervical mucus
- corpus luteum also secretes small amount of oestrogen
- at fertilisation,, synchotrophoblast of embryo secrete hCG which maintains corpus luteum
- if no fertilisation, corpus luteum degenerates causing a fall in oestrogen and progesterone
- this causes endometrium to break down and menstruation to occur
- stromal cells of endometrium release prostaglandins which encourage breakdown of endometrium
-
On what day of the menstrual cycle does menstruation begin?
day 1
How does ceasing of negative feedback allow the menstrual cycle too restart?
negative feedback from oestrogen and progesterone on the hypothalamus and pituitary gland ceases, allowing LH and FSH levels to rise so the cycle restarts
Describe the steps of fertilisation
- around ovulation the primary oocyte undergoes meiosis leaving a haploid cell, the other 23 chromosomes become a polar body
- fertilisation occurs at ampulla of Fallopian tube
- sperm attempt to penetrate corona radiate and zone pellucida to fertilise egg
- usually only 1 sperm will get through before layers shut other sperm out
- when sperm enters the 23 chromosomes of egg multiple into 2 sets
- one set combines with 23 chromosomes from sperm and the other 23 create second polar body
Where does fertilisation occur?
ampulla of Fallopian tube
Describe the process of implantation.
- fertilised egg is called a zygote
- zygote divides rapidly to form the morula
- during this process the mass of cells travel along Fallopian tube towards uterus
- while travelling it becomes a blastocyst and loses the outer two layers
- by the time the blastocyst enters the uterus (8-10 days after ovulation) it contains 100-150 cells
- the cells of the trophoblast adhere to stroma of endometrium
- the synchtiotrophoblast forms projections into the stoma
- when implantation occurs, the synctiotrophoblast starts to produce hCG
- hCG helps maintain corpus luteum in ovary so that it continues to produce progesterone and oestrogen
What ducts are involved in embryology of a human?
mesonephric/ wolffian
paramesonephric/ mullerian
When does development of external genitalia begin?
3rd week
What is oogenesis and spermatogenesis?
processes of formation of female or male gametes
