1
Q
what are the ovaries?
A
- female gonads
- responsible for producing haploid gametes
- attached to wall of uterus
- suspended from side of uterus by ovarian ligament and mesovarium ligament to keep ovaries in correct position
2
Q
what is the fallopian tube?
A
- oviduct is an open cavity that starts the fallopian tube
- finger-like projections called fimbriae form a cup over the ovary to collect the ova and project it down the fallopian tube
- infundibulum is the first section of the tube
- ampulla is the curving section of the tube
- isthmus connects fallopian tube to uterus
3
Q
what is the uterus?
A
- thick-walled structure with cavity in centre
- fertilised ovum is implanted here to the embryo can develop
4
Q
what are the functions of the female reproductive system?
A
- produce haploid gametes: ova
- facilitate fertilisation of ova by sperm
- provide a site of implantation of the fertilised egg
- provide physical and nutritional needs throughout gestation period
- nurture the neonate after birth by producing milk
5
Q
what are the structures of the ovaries?
A
cortex: outer zone with germinal epithelial layer containing oocytes
inner medulla: blood vessels and lymph
- supporting tissue for developing oocytes
follicle: where oocytes are enclosed
- as follicle matures, it forms other structures in a continuous process
follicular cells: secrete steroid hormones
6
Q
what are the two types of follicular cells and what hormones do they secrete?
A
- granulosa cells: secrete 17-beta-oestradiol (oestrogen)
- theca cells: secrete progesterone
hormones have endocrine and paracrine function ova development, uterus, breasts and bone
7
Q
what is the role of the fallopian tubes?
A
- transport egg from ovary to uterus
- infundibulum with fimbriae help capture egg as it is released from ovary
- smooth muscles: inner circular muscle layer and outer longitudinal muscle layer for peristalsis
- highly folded mucosa which is ciliated and contains secretory cells for helping movement of ova
8
Q
what are the 3 walls of the uterus?
A
- perimetrium: external serosa
- myometrium: thick inner muscle layer
- endometrium: changes over course of menstrual cycle
9
Q
what are the components of the endometrial wall of the uterus?
A
- simple columnar epithelium
- compound tubular glands which are highly branched
- spiral arteries which move between glands and connective tissue of the lamina propria
- supporting tissue contains leukocytes and macrophages to form the stroma
- basal layer zona basalis: static layer
10
Q
what is the functional layer of the uterus?
A
- endometrial layer can vary along cycle
- sheds during menses and builds thicker again
- when thick layer, fertilised egg is implanted
- if no fertilised egg is implanted, the thick layer sheds
11
Q
what is the cervix?
A
- cervical canal connects uterus to vagina
- interior os and exterior os at its margins
- cervical glands secrete mucus to prevent microbes from reaching uterus
12
Q
what is the vagina?
A
- birth canal (8-10cm)
- thin distensible wall with 3 layers:
- adventitia on outside
- muscularis: thick muscular layer
- mucosa: inner layer of stratified squamous epithelium rich in glycogen
- glycogen is fermented by bacteria to lactic acid to produce pH 3.5-4 which inhibits pathogens
- contains antigen-presenting dendritic cells
13
Q
what are the two female cycles?
A
- ovarian
2. endometrial (menstrual)
14
Q
what is the neuroendocrine control of the female cycles?
A
- hypothalamic-pituitary-gonadal axis drives menstrual cycle
- hypothalamic neurons release gonadotropin-releasing hormone (GnRH) once per hour
- hypophyseal portal system connects hypothalamus to anterior pituitary
- metabotropic GnRH receptor increases IP3, DAG, Ca2+ and exocytosis of FSH and LH
15
Q
what is the hypothalamic-pituitary-gonadal axis?
A
- neurons in hypothalamus release GnRH
- GnRH binds to receptors in gonadotrophs within the anterior pituitary
- pituitary secrets FSH and LH to stimulate the ovary
16
Q
what are the actions of FSH and LH on the ovary?
A
- theca release progesterone
- feedback to pituitary and hypothalamus
- positive/negative feedback - granulosa release oestrogen
- feedback to pituitary and hypothalamus
- positive/negative feedback
- inhibin negatively feeds back at anterior pituitary
- activin positively feeds back to antierior pituitary
17
Q
how are the ovarian hormones produced?
A
- theca cells synthesise and secrete progesterone from cholesterol
- LH induces synthesis of progesterone - androstenedione diffuses from theca to granulosa cells
- granulosa cells convert testosterone to oestrogen via enzyme aromatase
- FSH and LH both stimulate this pathway
18
Q
what are the actions of oestrogen and progesterone?
A
- develops ovum
- maintains corpus luteum which is derived from follicles which surround the ovum
- maintains pregnancy
19
Q
what does the hypothalamic-pituitary axis control depend on?
A
- it is controlled by positive or negative feedback depending on the phase
20
Q
how is the hypothalamic-pituitary axis controlled in the follicular phase?
A
- hypothalamus releases GnRH
- GnRH stimulates anterior pituitary to release FSH and LH which have positive effect on ovary
- oestrogen is released which has negative feedback on anterior pituitary and hypothalamus
21
Q
how is the hypothalamic-pituitary axis controlled in the midcycle phase?
A
- feedback of oestrogen to hypothalamus is negative throughout cycle, except prior to ovulation when it is positive
- oestrogen now has a positive feedback on anterior pituitary and hypothalamus during ovulation
22
Q
how is the hypothalamic-pituitary axis controlled in the luteal phase?
A
- progesterone secreted from ovary becomes major hormone of negative feedback to the anterior pituitary and hypothalamus
23
Q
how do the ovarian and endometrial cycles overlap?
A
- during the follicular phase of ovarian cycle, the endometrial cycle is in the proliferative phase as the endometrial lining thickens
- after ovulation, endometrial cycle transitions to secretory phase
- in follicular phase, ovum is contained in a developing follicle
- during ovulation when the egg is released, the follicle is termed the corpus luteum and enters the luteal phase
24
Q
how do hormones change across the ovarian and endometrial cycles?
A
- ovarian cycle is governed by FSH which peaks in day 12 and causes proliferation of theca and granulosa cells
- surge of oestrogen and progesterone after follicular stimulation
- critical level of oestrogen causes a switch to positive feedback in H-P axis which upregulates LH secretion from pituitary, leading into the secretory phase
25
what do oestrogen and progesterone control in the uterus?
- endometrium thickening
- feedback regulation of FSH and LH from anterior pituitary
- follicular phase: oestrogen causes cervical mucus to become copious, water and elastic to form channels in the follicular phase for sperm to be propelled through
- secretory phase: progesterone decreases and mucus thickens
26
what does oestrogen stimulate in the proliferative phase of the endometrial cycle?
- secretion of oestrogen is dominant in this phase
| - stimulates growth of endometrium, glands, stroma and elongation of spiral arteries
27
what does progesterone stimulate in the secretory phase of the endometrial cycle?
- following ovulation, the secretory phase is dominated by progesterone
- endometrial proliferation slows and thickness decreases
- glands accumulate with glycogen vacuoles and increase in mucus secretion
- stroma becomes swollen
- spiral arteries elongate and coil
- if there hasn't been fertilisation, cycle ends in menses
28
what is menses?
- when the endometrial wall breaks down
| - period
29
what are the different kinds of hormonal contraceptives?
oral contraceptive pill with different combinations:
- oestrogen and progesterone
- progesterone-only minipill
- monophasic or fixed-combination
- multiphasic or varying-dose
30
how do hormonal contraceptives work?
- feedback directly to hypothalamus to decrease stimulation of GnRH
- negative feedback on anterior pituitary to inhibit FSH/LH release and prevent ovulation
- low FSH is insufficient to stimulate folliculogenesis
- lack of LH surge inhibits ovulation
- progestin increases thickness of cervical mucus to prevent sperm entering fallopian tube
31
how does the morning after pill work?
1. alters endometrium
- prevents the womb lining from preparing to receive an egg
- even if an egg has been released, it cannot embed itself into the lining
2. influences cervical fluid
- thickens cervical mucus to prevent sperm from reaching the uterus
3. stops ovulation
- prevents release of an egg from the ovaries by making the body think it has already occured
32
how can the morning after pill be used?
- higher dose inhibits ovulation and interferes with implantation
- can be used as postcoital contraceptive
33
what are the steps in fertilisation?
1. gametes transported to ampulla of oviduct
2. sperm move into the oviduct
3. sperm acrosomal reaction
4. oocyte activation
34
how are gametes transported to the ampulla of the oviduct during fertilisation?
- oocyte is surrounded by granulosa cells and is helped to be moved by cilia/smooth muscles
35
how do sperm enter the oviduct during fertilisation?
- sperm move via flagellum, contraction of smooth muscle in uterus, fallopian tube contractions and cervical mucus channels which enable propelling
- only 50-100 sperm reach the ampulla of the oviduct
36
what is the sperm acrosomal reaction during fertilisation?
- penetration of granulosa to reach the glycoprotein layer
- sperm attach to layer ZP3 binding proteins on zona pellucida
- acrosome secretes hydrolysing enzymes to penetrate zone pellucida and move in
37
how are oocytes activated in fertilisation?
cortical reaction:
- increase in intracellular Ca2+ in oocyte triggers second meiotic division
- 2 polar bodies are formed, one from first division and once from second
- cortical granules contain enzymes and fuse with membrane
- exocytosis of enzymes act on zona pellucida to harden layer and destroy ZP receptors to prevent entry of other sperm: prevents polyploidy
38
what completes fertilisation?
- fusion of haploid pronuclei to form diploid zygote
39
what is pre-implantation?
- zygote undergoes cleavages until after 3 days it forms a Morella, a solid mass of cells kept in oviduct by contraction of isthmus until uterus is ready
- when uterus is ready for implantation, cilia in oviduct transport Morella to uterus
- when free-floating in uterus, Morella becomes a blastocyst,
40
what is a blastocyst?
- a hollow ball of cells with a fluid-filled cavity
- lined with a trophectoderm layer which transforms to a yolk sac
- contains an inner mass cell accumulating on one side which later forms the embryo (6 days)
41
what occurs during implantation?
- endometrium reception of blastocyst during secretory phase (high progesterone levels)
- blastocyst invasion promotes stromal cells to trigger predecidualisation
- decidual cells spread across surface of endometrium to form zona compactum
- contains an underlying zona spongiosa
42
what are the steps in the invasion of the endometrium (implantation)?
1. Hatching: zona pellucida layer degenerates
2. apposition: zona pellucida has completely cleared
- formation of a more compact zone of cells with underlying spongy cells
- blastocyst contains trophoblast layer and inner cell mast
3. adhesion: mediated by intracellular integrins
4. invasion: blastocyst invades endometrial layer
43
what are blastocyst trophoblastic cells?
- contains inner cytotrophoblast
| - contains outer syncytiotrophoblast
44
what is the placenta?
- life support system of embryo
- provides oxygen and nutrients
- collects waste material
- dominant mode of transport from 9 weeks after fertilisation
- 120 spiral arteries bring pulsatile blood
- intervillous space reduce force and velocity to allow time for exchange
45
how is the placenta formed?
- syncytiotrophoblast lacunae merge/fuse and fill with maternal blood
- cytotrophoblast and syncytiotrophoblast form villi/microvilli projecting into maternal blood
46
what separates foetal and maternal blood in the placenta?
- foetal capillary endothelium
- mesenchyme: additional cells within structure
- cytotrophoblasts
- syncytiotrophoblast
47
what substances are transported from maternal blood to foetal blood?
- glucose: facilitated diffusion
- amino acids: secondary active transport via cotransport with another molecule
- vitamins: active transport as vitamins are needed in high concentrations
- large molecules are transported by receptor-mediated endocytosis: LDL, hormones and antibodies
48
what substances are transported from foetal blood to maternal blood?
- waste urea
- creatinine
- both via diffusion
49
how is oxygen transport from maternal to foetal blood facilitated?
- oxygen exchange is facilitated by higher affinity of foetal Hb for O2
- foetal Hb has a gamma-globin chain to replace one of the beta-globin chains, causing higher affinity for O2
- at same partial pressure, foetal Hb has 45% affinity, adult Hb has 20%
50
how do hormones change in trimester 1?
- placental HCG is released from trophoblast which has similar effect as LH and restores corpus luteum
- corpus luteum secretes oestrogen and progesterone to support the endometrium and prevent menses
51
how do hormones change in trimester 2-3?
- placenta becomes primary hormone source of HCG
- human placental lactogen (HPL) coordinates fuel economy: converts glucose to fatty acids for energy, stores ketone and develops mammary glands
- progesterone is synthesised from circulating cholesterol
- oestrogen is involved in placenta-foetal synthesis
52
how is progesterone secreted into maternal system and to the foetus?
- cholesterol derived from maternal system crosses into placenta to form pregnenedione
- pregnenedione diffuses back into maternal system and foetus
53
how is estriol secreted into the maternal system?
- cholesterol comes from maternal system and crosses into placenta to form pregnenedione
- pregnenedione crosses into foetus which contains enzymes to synthesis intermediatory steps
- pregnenedione crosses back into the placenta and is converted into estriol which crosses back into maternal system
54
what is parturition stage 0?
- quiescence: insensitive to hormones which trigger contraction
- prelude to birth from contraception to intitation of parturition
- makes up 95% of gestation (32+ weeks)
- uterus is relaxed and insensitive to uterotonic hormones
- myometrium grows and leads to distension which can cause Braxton-Hicks contractions in preparation for birth
- progesterone suppresses myometrial contractions
55
what is parturition stage 1?
- preparation for birth (prior to labour)
- foetal H-P adrenal axis causes increase in cortisol, which causes increase to oestrogen:progesterone ratio
- oestrogen increases contractility and stimulates prostaglandin (PG) release
- PG promotes formation of gap junctions to increase communication between muscle cells
- PG causes thinning and dilation of cervix
- gene expression: contraction-associated proteins (CAPs) e.g. oxytocin and PG
- cervical gene expression: enzymes to hydrolyse collagen matrix
56
what is parturition stage 2?
process of birth:
- increase PG and OT levels for myometrial contraction and cervical dilation
- increased myometrial connectivity
- PG and OT increase myometrial connectivity
- positive feedback: Ferguson reflex by neuroendocrine regulation of OT and uterine contraction stimulating more PG
57
what are the stages of labour and delivery?
1. dilation: placental relaxation
2. expulsion
3. placental: separation from decidua
58
what is parturition stage 3?
recovery from birth: involution
- haemostasis: vasoconstriction of spiral arteries by OT contracting the myometrium, so less chance of haemorrhage
- pre-pregnancy hormone levels
- decrease in placental oestrogen
- myometrial atrophy and regression of uterine vasculature
- cervix remodelling
- re-establishment of fertility and endometrial cycle in 3-5 months
59
what is the secretory unit of the breast in lactation?
alveoli:
| - contain contractile myoepithelial cells to aid milk expulsion and adipose tissue
60
what is first milk?
colostrum:
- high fat and protein but low volume
- antibodies for within the GI tract
61
what are the components of milk lactation?
- fat emulsion in aqeuous solution
- lactose
- protein: lactalbumin and casein
- cations and anions
62
how is lactation controlled by hormones during pregnancy?
- oestrogen and progesterone stimulate breast growth
- oestrogen stimulates prolactin (PRL): major milk production hormone
- PRL stimulates breast development and lactogenesis
- in pregnancy oestrogen and progesterone inhibit PRL action on the breast
63
what is the postpartum hormone action on lactation?
- mammogenic: promotion of cell proliferation by oestrogen
- lactogenic: promote milk production by PRL
- galactokinetic: promote myoepithelial contraction by OT
- galactopoietic: maintain milk production by PRL and cortisol
64
how do neuronal and hormonal systems interact to enable lactation?
suckling is the most powerful stimulus:
- inhibits dopamine release from hypothalamus
- PRL is released from anterior pituitary to produce milk
- OT is released from posterior pituitary to release milk
- downregulates GnRH release to inhibit ovarian cycle
Physiology and Pharmacology
flashcards
Decks in class (13)
# Cards
-
Pharmacology80
-
The Autonomic Nervous System and Pharmacology52
-
The Endocrine System26
-
Epithelia and the Integumentary System66
-
Muscle62
-
The Cardiovascular System89
-
Blood and Clotting44
-
Respiration104
-
Renal Anatomy and Disease91
-
Body Fluids (vasopressin)32
-
Gastrointestinal System73
-
Regulation of glucose33
-
Female Reproductive System64
