whore-mones Flashcards
1
Q
Oestrus cycle
A
set of recurring physiological changes induced by reproductive hormones
2
Q
Process of fertilisation and whatnot
A
- gametogenesis occurs (cell entering meiosis) in the testes and ovaries
- fertilisation is achieved through combing sperm cells with egg cell (in fallopian tubes)
- fertilised egg moves down the fallopian tube to the uterus, going through transitional stages
- zygote: DNA combines, giving the number of chromosomes (single celled still)
- blastocyst: cells undergo mitosis
- development of the utero lining for the blastocyte to implant
3
Q
Types of mammals
A
- monotremes: lay eggs (exposed to the environment and predation)
- marsupials: development of a pouch that allows for more protection
- placental: development and fertilisation occurs internally, providing increased protection from environmental stresses and allows a constant supply of nutrients via placenta (however this takes a lot of energy)
4
Q
Seasonal breeders
A
Hormones regulated fertility - limited to certain periods of time within the year (oestrus)
5
Q
Continuous breeders
A
female fertility occurs in a cycle that repeats throughout the year - typically higher order primates and some other mammals such as pigs, mice, rabbits
6
Q
Seasonal breeders adv
A
- young born when conditions are favourable (food resources, temperature) creating an increased chance of survival
- parents benefit from reduced time when mating(gestation and rearing young take place (most vulnerable to predators and energy drain)
7
Q
Continuous breeders adv
A
Can breed all year round (no restrictions therefore greater number of offspring)
8
Q
Types of hormones (categories)
A
Gonotrophic: acts on gonads (an organ that produces gametes)
Sex hormones: (produced by a sex gland)
9
Q
Types of gonotrophic hormones
A
FSH = follicle stimulating hormone LH = luteinising hormones
10
Q
FSH (female)
A
- causes an egg to mature in an ovary
- stimulates the ovaries to release oestrogen 14 days into cycle
11
Q
FSH (male)
A
- produced by pituitary gland
- stimulates production of a protein in Sertoli cells (testes) which maintains testosterone levels that achieve spermatogenesis
12
Q
LH (female)
A
- anterior pituitary gland sends a spike of LH to signal for the release of the egg (ovulation)
13
Q
LH (male)
A
- stimulates the production of testosterone in the testes (leydig cells)
14
Q
Types of sex hormones
A
Predominately female:
- progesterone
- oestrogen
(produced by the follicle and corpus luteum)
Predominately male
- testosterone (Leydig)
- inhibin (Sertoli cells)
15
Q
Role of progesterone
A
- maintains the lining of the uterus during pregnancy (if an egg is fertilised the body produces this to ensure the process is not restarted)
- blocks the release of FSH and LH so that further ovulation does not occur during pregnancy
16
Q
Role of Oestrogen
A
- prepares the lining of the uterus for implantation, role in feedback control
- Secondary sexual characteristics: enlarged breasts, pubic hair, widening of hips
17
Q
Role of testosterone
A
T is produced in response to LH
- has a regulatory affect as it inhibits the action of GnRH
18
Q
Role of Inhibin
A
- travels to pituitary gland
- inhibits production of LH and FSH
19
Q
GnRH
A
Gonadotrophic releasing hormone
- produced in hypothalamus, moves to anterior pituitary gland
- stimulates the production of LH and FSH
20
Q
Process of Female Oestrus cycle
A
- GnRH (gonadotrophic releasing hormone) produced in hypothalamus moves to anterior pituitary gland – stimulating the production of FSH and LH.
- FSH (follicle stimulating hormone) is secreted by the pituitary gland and begins the development of an egg in the ovary.
- The FSH stimulates the release of oestrogen from ovaries to prepare the lining of the uterus for implantation. Blocks the production of FSH and LH hormone.
- A spike in LH (luteinizing hormone) from the pituitary gland signals for the release of the egg from the ovaries (ovulation).
- The egg travels to the fallopian tubes and if fertilisation occurs, the body maintains pregnancy through the secretion of progesterone which maintains the lining, stopping menstruation from occurring through inhibiting production of FSH.
21
Q
Process: (fertilisation and implantation)
A
- The egg releases chemicals which attracts the sperm.
- The oviduct secretes a fluid that travels down the female reproductive tract. The sperm swim through the fluid (upstream = positive rheotaxis).
- Sperm that reach the oviduct (site of fertilisation) are held in storage and released in small batches.
- Presence of progesterone and alkaline pH causes sperm to mature so it can penetrate the egg. The sperm becomes hypermobile – the tail beats strongly so the sperm can propel into egg.
- The sperm physically push through the first outer membrane (corona radiata) which is made of protective cells and releases enzymes to assist penetration.
- Acrosome (protective cap) of sperm gets through to the next barrier – zone pellucida. The acrosome fuses with cell membrane and the tip of sperm releases more enzymes.
- Surface proteins allow one sperm to penetrate this barrier – triggering the release of enzymes by the egg that destroy the glycoproteins in the zona pellucida, causing electrical charges which prevent other sperm from entering.
- A zygote is produced embryo blastocyst foetus
22
Q
Process: male cycle
A
- GnRH (gonadotrophic releasing hormone) produced in hypothalamus moves to anterior PG, stimulating the production of FSH and LH.
- LH stimulates the production of testosterone in the testes (Leydig cells)
- FSH stimulates the production of a protein by Sertoli cells in the testes, maintains testosterone levels high enough to produce spermatogenesis.
- Testosterone inhibits the action of GnRH produced by hypothalamus and allow for spermatogenesis.
- Inhibin inhibits the production of LH and FSH in pituitary gland.
23
Q
PG
A
Prostaglandins
- Secreted by the wall of the uterus: stimulates uterus contractions by reducing progesterone
- Makes the tissue of the uterus more sensitive to OT
24
Q
OC
A
Oxytocin
- Stimulated by PG
- Triggers and maintains labour causing muscular contractions of uterus to increase as pressure of the baby’s head onto cervix increases
- Initiates labour: muscles in the uterus contact and tissue of cervix softens so the cervix can dilate (widen)
- causes placenta to release prostaglandins
- Positive feedback on PG and on pituitary to make more OT
25
Prolactin
- Stimulated by OT
- Secreted by pituitary gland
- Enlargement of mammary glands for milk production
26
Maternal thyroxin
- secreted by: mother's thyroid
- active period during pregnancy: from 12 weeks
- Carrier: maintains corpus luteum (maintains the endometrium )
- baby: low levels result in low birth weight and immature lungs
27
Insulin
Secreted by: foetal pancreas
Active period during pregnancy: from 10 weeks
No effect on carrier
Promotes foetal growth
28
hcG
Human chorionic gonadotropin
secreted by: developing embryo
active during: first trimester
Carrier: Maintain placental attachment
Baby: no effect
29
IGF
insulin like growth factors
secreted: uterine wall of mother
active: first trimester
Carrier: stimulates growth of placenta and regulates transport of nutrients
BabyL promotes growth of foetal tissue
30
Glucocorticoids
Cortisol and cortisone
Secreted: foetus
Active: increases in third trimester (w mother's stress)
Carrier: alcohol will stimulate glucocorticoids (low bbirth weight and affects organ development)
Baby: limits growth
31
relaxin
ovaries: helps dilate cervix to allow passage of foetus; widens pubic bones and relaxes pelvic ligaments
