Reproductive system Flashcards
(122 cards)
1
Q
whats are the steps of spermatogenesis
A
- proliferation
- meiosis 1 &2
- Differentiation
2
Q
Proliferation of spermatogenesis: where and what?
A
- happens at the germinal epithelium
- forms spermatogonia, then primary spermatocytes- continues til death
3
Q
explain Meiosis I and II of spermatogenesis
A
- Increases DNA heterogeneity, (crossing over)
- haploid spermatids produced
4
Q
explain where and what happens at the differentiation stage of spermatogenesis
A
- Forms mature spermatozoa capable of fertilising
- occurs in epididymus
5
Q
function of leydig cells
A
between tubules, secrete testosterone
6
Q
function of Sertoli cells
A
provide norishment to developing gametes
7
Q
Whats the function of FSH in spermatogenesis
A
- acts on sertoli cells
- stimulates spermatogenesis
8
Q
Whats the function of LH in spermatogenesis
A
- acts on leydig cells
- stimulates testosterone production
9
Q
Whats the function of testosterone hormone in spermatogenesis
A
- required for spermatogenesis
- inhibits release of FSH/LH
10
Q
Whats the function of inhibit hormone in spermatogenesis
A
regulates degree of spermatogenesis
11
Q
What is the steps of oogenesis
A
- Proliferation (mitosis)
- Maturations
- Meiosis I and II
12
Q
Describe proliferation in oogenesis
A
- Proliferation (mitosis)
- formation of the primary oocyte during gestation
- completed by birth
- stop is in 1st meiosis
13
Q
Describe maturation in oogenesis
A
- Maturations
- requires a supporting follicle
- cyclical pattern (waves) of growth/development of follicles initiated by puberty
14
Q
describe Meiosis I and II in oogenesis
A
- Meiosis I and II
- Meiosis I is resumed at ovulation following puberty
- meiosis II is completed at fertilisation
15
Q
describe how a polar body is formed
A
after first meiotic division and second meiotic division, 1 oocyte gets more cytoplasm than the other so it becomes polar bod so only 1 egg cell produced
16
Q
describe folliculogenesis
A
- oocyte is supported in a follicle
- Folliculogenesis (the growth and development of a follicle) occurs around a primary oocyte- oocyte arrested in prophase I
- Primary oocyte completes Meiosis I at puberty (ovulation)
- Expulsion from Ovulatory/Antral/Graafian follicle
17
Q
what is the primordial follicle
A
- primary oocyte surrounded by single layer of flattened pre granulosa cells
- forms “pool” of dormat follicles
- at puberty, waves of follicles resume growth (15-20 follicles)
18
Q
what is the primary follicle
A
- cells become cuboidal- granulosa cell
- glycoprotein layer secreted called Zona Pellucida
- granulosa cells proliferate (increase in number)
19
Q
how does follicle develop to secondary and preantral
A
increasing layers of granulosa cells
20
Q
describe antral and Graafian follicles
A
- Fluid-filled spaces appear between granulosa cells - antrum
- Nutrient/growth factors for oocyte
- Expulsion during ovulation
- Cumulus cells – involved in oocyte maturation
- Development of theca cells
21
Q
describe the steps to ovulation
A
- Lutenising hormone (LH)- syimulates preovulatory growth
- meiosis I complete triggered by LH surge
- 2 daughter cells with varying cytoplasm
- Secondary oocyte- arrests in meioisis I
- first polar body - extruded
- secondary oocyte ovulated- surrounded by cumulus
22
Q
what is the pathway of sperm to oviduct
A
Pathway:
- Traverse vagina
- Transverse the cervix
- Movement to the oviduct
- Flagella
- Female tract contractions
- Storage in oviduct
- Further maturation “capacitation”
- Loss of glycoprotein coat – allows acrosome reaction
- Hyperactivation
23
Q
what is normal vaginal ph and how does the prostate gland protect sperm
A
- Normal vaginal PH between 3.8-5.0 (acidic)
- Protects vaginal mucosa fro pathogenic organisms but is harmful to sperm
- Sprem is protected by prostate gland, which secretes alkaline solution
24
Q
describe passage of sperm through the cervix and how its prevented (structure)
A
- Cervix is muscular and tunnel like- connects the uterus and vagina
- COWS- Folds can prtect from damaged sperm or bacterial infection
- SOW has interdigitating pads to lock penis (species specificity- screw like penis)
- Transversion is also prevented by
- Cervix closed- but open fpr a few days during ovulation
- Mucus trapping sperm
- IgA, IgM antibodies agglutinationg sperm
25
describe the movement of sperm to the oviduct + prevention
- Sperm movement by swimming facilitated by flagella (5mm per min)
- Contractions of the femal uterine wall (myometrium)- pulls sperm upwards
- movement of sperm is stopped at the entrance of the oviduct by -
- Immunological defences of the female
- nuetrophils phagocytes sperm
26
describe storage of the sperm at the oviduct
- there is a pause in sperm movement at the Isthmus
- Proteins on the surface of the acrosome (sperm head) binds to the. receptors on the Isthmus Mucosa
- sperm reservoir waiting for ovulation
27
describe final maturation, capacitation and hyperactivation
- sperm let go of the epithelium of Isthmus and progress to Ampulla - final maturation of sperm occur here
- capacitation: changing of glycoprotein on surface- removal allows the acrosome to be readied for acrosome reaction
- Hyperactivation: Changes in flagellar beating - increases amplitude.
- Important as mucus gets thicker
- **correlation with hyperactivation and penetrating ZP**
28
what happens in the ovary before fertilisation
- high conc of Oestrogen- stimulates pituatory to release LH
- LH surge induces ovulation – the LH causes the follicle to have a growth spurt
- The oocyte inside detaches from the wall of the follicle. As the fluid increases, pressure increases until the follicle ruptures
- The fimbriae of the oviduct literally reposition – coming closer to the ovary so that when ovulation occurs, they catch the follicle
29
what happens in fertilisation during ovulation
- Follicular wall bursts
- Oocyte expelled by force of follicular/antral fluid
- Oocyte captured by fimbriae
- Cells (cumulus) surrounding oocyte are sticky & adhere to epithelium of oviduct
30
what are the steps to fertilisation
1. The sperm pushes through the follicular cells of the corona radiata and binds to the zona pellucida.
2. The acrosome releases digestive enzymes which soften the glycoprotein matrix of zona pellucida
3. The sperm then pushes its way through the softened layer and binds to exposed docking proteins on the egg membrane (species-specific receptors)
4. The membrane of the egg and sperm then fuse and the sperm nucleus enters the cell
31
what happens after fertilisation (cortisol reaction)
- Cortical granules within the egg’s cytoplasm release enzymes (via exocytosis) into the zona pellucida (jelly coat)
- These enzymes destroy sperm binding sites and thicken and harden the glycoprotein matrix of the jelly coat
- This prevents other sperm from being able to penetrate the egg (**polyspermy**), ensuring the zygote formed is diploid
32
define sexual reproduction
- 2 parents
- involves gametes: eggs and sperm
- Gamete formed by meiosis- haploid
- fusion of gametes to form a diploid embryo
- genetically different offspring
- variation- random assortment of chromosomes/ random fertilisation
- can lead to new species
33
advantages to sexual reproduction
- Greater variety in population
- Species can adapt more quickly to changes in environment
- Produces a new organism that results from a combo of traits from 2 parents
34
disadvantages rto sexual reproduction
finding a mate can use up valuable energy
slower process
good characteristic in a parent may not be passed onto offspring
35
define asexual reproduction
- One parent- non sexual
- no gametes
- New offspring by mitiosis
- clones- genetically identical
- commin in prokaryotes, fungi plants
- binary fission in bacteria
36
advantage of asexual reproduction
- allows single parent to produce - many offspring quickly- colonising
- no gamete wastage
- allows colonisation, exploiting favourable habitats
- offspring will have qualities of parent- genetically identical
37
define reproduction
production of new individuals by sexual or asexual means
37
disadvantages of asexual reproduction
- no genetic variaton- population could be wipoed out of conditions change
- overcrowding so not enough resources- exhaustion
- wasteful sometimes- spores produces but cant find a suitable environment
38
define life cycle
time from the beginning of an organism’s life until it reproduces
39
describe male gametes
- small and motile
- need to move efficiently to fertilise egg before rival
40
describe female gametes
large and stationary- stored food reserves
41
define fertilisation
process by which male and female haploid gametes fuse together initiating the development of diploid embryo
42
describe fertilisation in aquatic animals
- release egg and sperm into the water.
- fertilisation occurs externally.
43
describe fertilisation in land animals
- use internal fertilisation in an environment suitable for transport of male gametes.
- this mostly involves the introduction of the male gametes into the female’s reproductive tract. – safer than external fertilisation
44
name the parts of the male urogenital system
- penis
- scrotum
- testes
- Acessory sex glands
45
Describe sperm in the male urogenital system
- male gamete is spermatozoon
- produced in seminiferous tubules
- production starts at puberty and continues throughout life
- sertoli cells nourish developing sperm cells through stages of spermatogenesis
- storage and maturation in epididymis
46
whats the structure of the testes
- located in scrotum
- covered by layer of peritoneum
- leydig cells- produce sex hormones
- seminiferous tubules produce spermatozooa
- different orientation in different species
e.g. Bull, ram, humans – vertical orientation, dog and stallion – horizontal orientation
47
why do the testes descend from the abdomen (name the muscle which causes descent)
- Optimum temperature for sperm production is between 2-6 ºC below core body temperature – descends to keep cool.
- Primarily ‘Cremaster’ skeletal muscle contracts to bring the testes closer to the body when the ambient temperature is low
48
describe the role of epididymis in the male urogenital system
- highly coiled tube- 60m in stallion
- Function: storage of sperm and maturation –acquire motility, acrosome changes shape, sperm concentrate, fertility acquired. Takes approx.’ 12 days!
49
Describe the role of the accessory sex glands in the amle urogeneital system
- Secrete fluid that mixes with sperm -Creates semen
- Functions:
- nourish (fructose)
- Transport sperm
- Activate sperm (flagella)
- Keep urethra clean
- Coagulation of sperm following ejaculation
49
describe the spermatic duct in the male urogenital
- forms the *Pampiniform plexus* –
The network of testicular veins surrounding the testicular artery provides the testes with a countercurrent heat exchanger.
- Blood travelling to the testes via the arteries loses heat to the testicular veins and is cooled to help keep the testes cooler.
- Cremastor muscle surrounds the spermatic cord pulling the testes up.
50
name the glands and tehir functions found in the male urogenital
- The **ampullar** glands- secretions that reduce chemical compounds, and fructose, a sugar and nutrient.
- The **vesicular** glands (seminal vesicles) - Promotes motility and also provides fructose as an energy source.
- The **prostate** gland produces secretions added to sperm to promote the motility and coagulation of sperm
- The **bulbourethral** glands secrete an alkaline mucuslike fluid. This fluid neutralizes the acidity of the urine residue in the urethra
51
Name the internal and external parts of the female urogenital system
**Internal**:
- Ovaries
- Oviducts
- Uterus
- Cervix
- Vagina
**External**:
- Vulva
- Clitoris
- Labia
52
describe the ovaries in the female urogenital system
- female gonads
- produce egg cells (oocytes)
- produce sex hormones
- Oocyte production begins during gestation
- most mammals born with thwir total no of oocytes
- mature in supportive sturtures in ovaries called follicles
53
describe role of oviduct in female urogenital system
- oocyte enters oviduct from the ovary
- Fimbria and infundibulum form funnel shape to receive oocyte
- facilitates transport of spermatozoa from uterus
- Lined with ciliated epithelia and smooth muscle to aid in the movement of spermatozoa and oocyte
- fertilisation occurs in ampulla- egg remains there for 2-5 days
- egg then transported to uterus
54
describe the function of Uterus in female urogenital system
- Transport of spermatozoa
- Supply foetus with nutrients and remove waste products
- Protect foetus
- Transport foetus at birth
55
describe the structure of Uterus in female urogenital system
3 walls:
- Endometrium – involved in Nourishing embryo
- Inner Uterine lining
- Glandular / secretory
- Responds to oestrogen and progesterone to thicken and develop.
- Myometrium
- Muscular – involved in expulsion of the foetus at child birth
- Perimetrium
- Serous membrane – strong outer layer. secretes a lubricating fluid that helps to reduce friction
56
How does the uterus differ in different species
Size and length of the horns and corpus differs due to site of implatation and number of embrys implanting
57
describe the function and structure of cervix in female urogenital system
- Forms connection between uterus and vagina
- Thick wall of collagen and elastic fibres
- Contains mucus glands which produce a thick mucus in many species outside of their oestress/season to prevent anything getting in and help prevent entry of pathogens etc.
- Forms barrier protecting the uterus from the external environment during pregnancy – mucus plug, seals preventing pathogens entry and stops embryo exiting the uterus
- Role in sexual receptivity
58
whats the structure of the vagina
- Stratified squamous epithelium gives protection
- May become keratinised in some species during oestrus.
59
describe vestibulum, labia and clitoris
**Vestibulum** – surrounds the opening of the vagina
**Labia** – folds of skin
**Clitoris** **–** lots of nerve endings
60
describe the avian reproductive tract
- Oviparous (lays eggs)
- Internal fertilisation
- slightly different mechanism-
- sperm deposition in inverted cloaca of female from cloaca of male
(cloaca - a single exit and entrance for sperm, eggs, and waste).
- sperm brought back into the body to fertilise the oocytes
61
what are hormones and how are they secreted
- chemical signals that affect the activity of other glandsand tissues
- homones control development, growth , puberty and reproduction
- secreted in ductless glands
- all glands in the endocrine system are ductkless- released straight into blood
62
where is Gonadotrophin-releasing hormone (GnRH) secreted from
hypothalamus
63
What is secreted from the anterior/posterior pituitary land
- **Anterior Pituitary-** Follicle stimulating hormone, luteinising hormone, prolactin
- **Posterior Pituitary-** Oxytocin
64
What hormones do the gonads secrete
- **Ovary (including CL)-** Oestrogens, progesterone, oxytocin, inhibin, Relaxin
- **Testis-** Testosterone, oestrogen
65
what hormones does the placenta release
- Progesterone, oestrogens
- Prostaglandin
66
Describe the hormonal control of the female reproductive cycle
1. GnRH is released by the hypothalamus and acts on the anterior pituitary.
2. LH and FSH is released in response to GnRH
3. FSH is required for oogenesis while LH stimulates theca cells Oestrogen
4. Maturing follicles secrete increasing amounts of oestrogen and this surge results in s sure of LH via a positive feedback loop
5. At low oestrogen levels, GnRH, LH and FSH are regulated via a negative feedback loop.
6. Corpus luteus produces progesterone and oxytocin.
7. Progesterone also a has a negative feedback effect on the secretion of GnRH
8. Oxytocin stimulates the uterus to secrete prostaglandins
9. Prostaglandins are involved in luteolysis, CL is broken down and progesterone levels fall (if not preganant) and cycle begins again.
10. if pregnant HcG stimulates CL to produce progesterone until it can produce enough itself.
67
Describe the hormonal contol of the male reproductive system
1. GnRH stumulates the secretion of FSH and LH
2. FSH stimulates spermatogenesis in sertoli cells of seminiferous tubules
3. LH secretes testosterone
4. Testosterone is regulated via a neative feedback loop to prevent too much testosterone
68
what can too much testosterone lead to
low sperm count
69
What is oestrogen secreted by and what is its action
Secreted by placenta/ granulosa cells
repairs and thickens the endometrium, negative feeback
70
what is progesterone secreted by and its action
CL
negative feedback, maintains the endometrium lining
71
what is oxytocin secreted by and its action
corpus luteum, posterior pituitary
stimulates uterus to secrete prostaglandin, uterine contractions
72
what is prostaglandin secreted by and its action
uterus, placenta
luteolysis and affects the menstrual cycle
73
what is testosterone secreted by and its action
leydig cells in testis
spermatogenesis, negative feedback to slow down release of LH and FSH
74
what is Relaxin secreted by and its action
ovaries, placenta,
loosens and relaxes muscles, joints and ligaments during pregnancy and prep for birth
75
what is prolaxin secreted by and its action
Anterior pituitary
lactation, certain breast tissue development and milk production.
76
What are the 2 types of reproductive cycles
2 types of reproductive cycles (oestrus vs menstrual)
77
Compare the oestrous and menstrual cycle
**Oestrous**
- occurs in non primates
- doesnt involve menstruation
- starts with signs of oestrus
**Menstrual**
- occur in primates
- involves menstruation
- starts with menstruation
78
describe the oestrous cycle
- Repetitive patterns of hormones and behaviour which lead to ovulation
- Discrete periods when female is receptive to mating
- Oestrous cycle is alternating follicular and luteal phases
79
what is the follicular and luteal phase
- Follicular phase: egg matures until ovulation occurs
- Luteal phase: ovulation until luteolysis.
80
whats the difference between oestrus and oestrous
Oestrus- noun (in heat)
Oestrous- adjective (oestrous cycle)
81
What are teh steps to the oestrous cycle
**Proestrus**
- Development of follicles, secretion of pheromones, male attraction but no mating
**Oestrus**
- Sexual receptivity and (usually) ovulation
**Metoestrus**
- Formation of the corpus luteum and beginning of progesterone secretion
**Dioestrus**
- Continued release of progesterone
82
Compare these between oestrous and menstrual cycle
- Follicular Phase
- Sexual Receptivity
- Ovulation
- Fertile Period
- Luteal Phase
- Endometrial sloughing
- Menopause
Follicular phase
- O: short (20% of cycle or less)
- M: Long (50% of cycle)
Sexual Receptivity
- O: Well-defined
- M: Relatively uniform through cycle
Ovulation
- O: At beginning of cycle
- M: Designated as being mid-cycle
Fertile Period
- O: Often short (25 hours) (except bitch)
- M: Up to 6 days before ovulation
Luteal Phase
- O: In most approx 16 days (except bitch)
- M: Approx 14 days
Endometrial sloughing
- O: none
- M: after luteolysis
Menopause
- O: Not reported
- M: Well defines as numer of follicles falls
83
whats the action of oestrogen in mating
- change in behaviour to allow mating]
- production of pheromones
- prepare external genitalia and vagina
- opens the cervix
- increased secretion from cerviox and vagina
- increase uterine contractions
- prepare uterine environment for sperm transport and implantation of fertilised egg
84
whats the action of oestrogen in prenancy and birth
- Helps in maternal regulation of pregnancy
- Contribute to growth and development of mammary tissue
- Prepares uterus for birth
85
whats the action of progesterone in prepaing for pregnancy
- Increases secretory activity from the uterus
- Closes cervix
- Reduces uterine contractions – “progesterone block”
86
whats the action of progesterone in parturition
Causes mammary gland enlargement and preparation for milk production
87
what are the three different types of oestrus cycles
- Polyoestrus
- Seasonally polyoestrus
- monoestrous
88
describe the polyoestrus cycle and give examples of species
- cows and pigs
- have many cycles and males remain sexually active throughout
- Repeated cycles unless interrupted by pregnancy
- Can become pregnant at any time of the year regardless of season
89
describe the seasonally polyoestrus cycle and give examples of species
- mares, ewes, queens
- exhibit more than one oestrous cycle within a season
- Repeated cycles are seen at particular times of the year
- At other times there is an absence of oestrous cyclicity (called anoestrus)
- Cyclicity is normally determined by day length – role of *melatonin*
- In some **increasing** day length stimulates activity e.g. the mare
- In others **decreasing** day length stimulates activity e.g. the ewe
90
describe the seasonally monoestrus cycle and give examples of species
- bears, dogs
- one annual cycle - well defined breeding season
- Have one oestrus followed by an obligatory period of anoestrus
- Often (standing) oestrus is prolonged allowing increased probability of mating
91
describe non pregnancy vs pregnancy in domestic ruminants (Corpus luteum maintenance)
Non pregnancy:
- CL forms; begins to produce oxytocin
- Oxytocin stimulates uterus to produce prostaglandin (PGF2a)
- PGF2a causes luteolysis
In pregnancy
- CL forms; begins to produce oxytoci
- Developing embryo produces Interferon tau (IFNt)
- IFNt blocks uterine oxytocin receptors → no PGF2a → CL remains for entire pregnancy
92
Describe non pregnancy vs pregnancy in mares (CL maintenance )
Non-Pregnant
- CL forms; produces progesterone
- P4 acts on brain - inhibits GnRH and LH release
- Reduced LH removes hormonal support for CL
- Luteolysis (breakdown of CL) – drop in P4 secretion
Pregnant
- CL forms; P4 causes reduction in LH
- Developing embryo produces eCG
- LH-like action
- eCG provides hormonal support to sustain CL and P4 production
93
Describe pregancy vs nonpreganacy in bitches- (CL maintenance)
- Bitches are monoestrous breeders with a prolonged dioestrous in every cycle
- Dioestrous = high progesterone levels
- Bitch experiences prolonged period of high P4 levels regardless of whether pregnant or not
- Therefore, no need for specific maternal recognition of pregnancy mechanism as Progesterone maintained.
so CL is maintained
94
how dies zygote become blastocyst in the first 11 days
- after zygote formation, cell division happens every 24 hours
- Day 1- 6- cell divides every 24 hours- 2/4/ 8/16/32 cells
- By day 7/8- 64 cells (blastocyst)
- By day 10-11, 256 cells
- the mass of cells hatches out
- zona pellucida decomposes
95
outline the blastocyst structure
- Blastocyst
- Fluid in the middle- blastocele
- inner cell mass = embryo
- outer cells = placenta (trophoblast)
- protected by zona pellicuda
96
what happens as the embryo develops
- the inner cell mass forms foetal membranes
- yolk sac
- amnion
- allantois
- the outer cells form
- chorion
97
whats the role of the yolk sac
- surrounds yolk in reptile and bird eggs,
- important in haematopoiesis
- important in providing food for embryos when the placenta is developing
98
whats te role of amnion and allantois
- Amnion
- innermost fluid filled membrane
- protection of foetus
- Allantois
- Transports waste products
- Connection becomes umbilical cord
99
whats the role of the chorion
- outer membrane
- Forms the placenta (the foetal part)
100
where does implantation occuer
at the endometrial lining of the uterus
101
How does implantation occur (4 steps )
1. Hatching- blastocyst hatches out of zona pelicuda
2. Apposition- The trophoblast proteins form selctin. The uterine epithelium forms pinopods (bumps)- Progesterone is needed for formation
3. Adhesion- selectin binds to receptors
4. Invasion- trophoblastic cells produce enzymes that alllow invasion of endometrium
102
How is the placenta formed an how is it adapted
- The placenta is formed when foetal membranes become closely attached to the uterine wall
- adapted via:- surface are for exchange is increased via
- chorionic villi formation
- The maternal capillaries, found in the endometrium, grow/move towards the chorionic villi
103
what kind of placenta do horses and pigs have
- diffuse placenta
- Placenta occurs over the entire surface of the uterine luminal epithelium with the formation of folds/villi and is found in horses and pigs
- The chorionic villi form all around the chorionic sac in a **DIFFUSE** PATTERN
- they all connect up at the umbilical cord
104
What kind of placenta do ruminate have
- *cotyledonary placenta*
- these animals have numerous smaller placentae.
- **Cotyledon**: the fetal side of the placenta
- **Caruncle**: the maternal side of the placenta
- **Placentome**: a cotyledon and caruncle together
The chorionic villi are less diffuse. They are concentrated in little buttons called **cotyledons**
So this pattern of distribution is called **cotyledonary**
105
what kind of placenta do cats and dogs have
- Zonary placentas
- Chorion cappilaries organised like a belt surrounding the embryo
- Belt distribution
106
What is the role of the placenta.
- Transfer of hormones
- Placental progesterone: sustains preganacy (corpus luteum)
- Placenatal Oestrogen- Maintains lining
- Delivery of O2 and removal of CO2 (passive diffusion)
- Delivery of nutrients – glucose (FD), amino acids (AT)
- Kidney removal of waste with example – urea/ions
107
what are the 3 stages of parturition
stage 1: onset of contractions and dilations
Stage 2: Expulsion of foetus
Stage 3: Expulsion of placenta
108
Describe the first stage of parturition
- Onset of contractions & dilatation
- Onset of coordinated myometrial contractions
- foetus assumes the position of expulsion
- uterine contractions cause the placental attachments to weaken
- dilation of the cervix
109
Describe the second stage of parturition
- Expulsion of the fetus
- Abdominal + myometrial contractions significantly increase uterine pressure
- The fetus delivered within the amnion or it ruptures during birth
- fetus becomes hypoxic in birth canal, promotes fetal movement and stimulates contractions
- fetal head reaches the vulva and the contractions of the uterine and abdominal muscles reach a climax of expulsive effort
110
Describe the thrid stage of parturition
- Expulsion of the placenta
- In polytomous species, the expulsion is interspersed between fetal births
- Lasts from an average of 1 hour in the mare to 6 hours in the cow.
- Except for the mare (and humans?), animals normally eat the placenta
111
what is the Ferguson's reflex and when does this happen
- 2nd stage
- contractions force feuts against cervix
- Neurohormonal reflex
- brain releases oxytocin
- causing myometrial contractions
112
what is the role of fetal cortisol
- FC causes progesterone levels to drop and oestrogen to increase (placental cells produce enzymes which convert progest to oestrogen )
- this is because progesterone usually inhibits oxytocin release and myometerium contractiosn
113
how odes oestrogen affect smooth muscle in prep for birth
- muscle mass increases
- number of gap junctions between cells increases
- number of Ca2+ channels increases
- number oxytocin receptors increases
114
outline the location of mammary glands in different species
- Pig, dog, cat: glands along the length of mammary ridges (thoracoabdominal)
- Primates, elephant: paired glands in thoracic region
- Cow, mare and goat: glands develop in the inguinal region (below the abdomen)
115
Describe the effect foetal cortisol has on the production of placental oestrogen and progesterone at stage 1 of parturition (5 marks)
- Foetal cortisol stress hormone – produced foetus increases in size/running out of space
- Switch placenta to produce oestrogen compare to progesterone
- Progesterone production is usually inhibiting oxytocin release and contraction of myometrium
Oestrogen
1. Increases muscle mass (throughout preg)
2. Increase gap junctions and Ca2+ channels
3. Increases number of oxytocin receptors
4. The posterior pit – produces oxytocin
5. Oxytocin stimulates contraction of myometrium
Prostaglandins
1. Placental prostaglandins
2. Increase myometrium contractions
3. Dilate the cervix
116
Describe the Ferguson reflex (4 marks)
- This is an example of positive feedback
- Define this – reinforce a change away from normal /As opposed to negative feedback during which is a mech to reverse a change away from normal
- The foetus pushes head against the opening of cevix
- Stretch receptors in the walls of cervix
- Sensory neurone send impulses to Paraventricular nucleus of hypothalamus
- Large neurosecretory cells are depolarised
- Action potential down to post pituitary
- Action causes the exocytosis of oxytocin into blood
- Travels in blood
- Binds to receptors
- On walls of uterus – endometrium expressing receptors
- This causes muscular contraction
- Back to beginning
117
During the process of parturition, Progesterone is important, describe the function and site of production (3 marks)
- CL/ovary/placenta
- preparation of uterus for implantation
- uterine conditions (growth and dev) for foetal development
- prevents follicular development and further ovulation
- growth of mammary tissue in preparation for milk production
- R milk production
118
During the process of parturition Prolactin is important, describe the function and site of production (2 marks)
- anterior) pituitary gland
- Production of milk
119
During the process of parturition Foetal cortisol is important, describe the function and site of production (3 marks)
- Adrenal (cortex) gland of foetus
- Initiates parturition
- Increase placental PG
- Increases oestrogens and decreases progesterone levels
120
Describe the stages of the milk let down reflex. (5 marks)
1. Suckling stimulus (pressure receptors on nipple)
2. Impulse sent to PVN of hypothalamus
3. AP generated
4. Posterior pituitary release oxytocin – hormone
5. In blood
6. To cells of alveoli/myo-epithelium that surround alveoli
7. Cells contract – pushes out milk from cistern
