UNIT 2 – THE UNIT 2 – THE CONTINUATION OF LIFECONTINUATION OF LIFE

Chapter 15 – Sex Organs & Chapter 15 – Sex Organs & Hormonal ControlHormonal Control

TestesTestes Site of sperm & testosterone productionSite of sperm & testosterone production SpermSperm made in the made in the seminferous tubulesseminferous tubules

(connected to sperm duct)(connected to sperm duct) TestosteroneTestosterone produced by produced by insterstitialinsterstitial

cellscells Sperm need energy & a liquid medium Sperm need energy & a liquid medium

(semen) to move(semen) to move Seminal vesiclesSeminal vesicles secrete liquid: secrete liquid: - - FructoseFructose - for energy- for energy - - ProstaglandinsProstaglandins - stimulate female contractions- stimulate female contractions Prostate glandProstate gland – secretes enzymes – secretes enzymes - maintains - maintains semensemen viscosity viscosity The seminal vesicles & prostate are The seminal vesicles & prostate are

accessory glandsaccessory glands

OvariesOvaries Site of egg productionSite of egg production Eggs contained in Eggs contained in

Graafian follicleGraafian follicle - secretes - secretes oestrogenoestrogen After ovulation, follicle After ovulation, follicle

develops into develops into corpus corpus luteumluteum

- secretes - secretes progesteroneprogesterone

Hormonal ControlHormonal Control Hormones – chemical messengersHormones – chemical messengers Secreted by endocrine glands into Secreted by endocrine glands into

bloodstreambloodstream Specific responses from target Specific responses from target

tissuestissues Pituitary:Pituitary: Secretes gonadotrophic hormonesSecretes gonadotrophic hormones e.g e.g FSH (follicle stimulating FSH (follicle stimulating

hormone), hormone), ICSH (Interstitial cell stimulating ICSH (Interstitial cell stimulating

hormone)hormone) LH (lutenising hormone)LH (lutenising hormone)

Influence of hormones - Influence of hormones - malesmales

FSH promotes sperm FSH promotes sperm productionproduction

ICSH (LH) stimulates ICSH (LH) stimulates testosterone productiontestosterone production

Testosterone:Testosterone: Stimulates sperm production Stimulates sperm production Also activates prostate & Also activates prostate &

seminal vesiclesseminal vesicles Testosterone self-regulatesTestosterone self-regulates - high conc. inhibits FSH & - high conc. inhibits FSH &

ICSH secretionICSH secretion - low conc. FSH & ICSH - low conc. FSH & ICSH

secreted againsecreted again - this is negative feedback- this is negative feedback

ICSH

Influence of hormones - Influence of hormones - ovariesovaries

FSH FSH stimulates stimulates Graafian Graafian follicle follicle development development

- & oestrogen - & oestrogen secretionsecretion

LH triggers LH triggers ovulationovulation

LH stimulates LH stimulates progesterone progesterone secretionsecretion

Influence of hormones – Influence of hormones – uterus/pituitaryuterus/pituitary

Oestrogen:Oestrogen: Stimulates proliferation of Stimulates proliferation of

uterus lining (endometrium)uterus lining (endometrium) Stimulates LH secretion by Stimulates LH secretion by

pituitarypituitary Progesterone:Progesterone: Promotes endometrium Promotes endometrium

thickeningthickening Inhibits FSH & LH secretionInhibits FSH & LH secretion

Menstrual CycleMenstrual Cycle Continuous cycle – 28 days Continuous cycle – 28 days

longlong Follicular PhaseFollicular Phase FSH stimulates Graafian FSH stimulates Graafian

folliclefollicle Endometrium proliferated ( Endometrium proliferated (

by Oestrogen production)by Oestrogen production) Day 14 – LH production Day 14 – LH production

surgesurge Graafian follicle ruptured Graafian follicle ruptured Egg into oviduct – 3 to 4 Egg into oviduct – 3 to 4

days for fertilisationdays for fertilisation

Menstrual CycleMenstrual Cycle Luteal Phase:Luteal Phase: Graafian follicle into corpus Graafian follicle into corpus

luteumluteum Progesterone rise = endometrial Progesterone rise = endometrial

developmentdevelopment Pituitary inhibited (-ve feedback) Pituitary inhibited (-ve feedback)

– FSH/LH levels drop (no more – FSH/LH levels drop (no more ovulation)ovulation)

Day 22 – corpus luteum Day 22 – corpus luteum degeneratesdegenerates

Progesterone & oestrogen levels Progesterone & oestrogen levels dropdrop

Day 28 – endometrium lost = Day 28 – endometrium lost = menstruationmenstruation

Menstrual CycleMenstrual Cycle

FertilisationFertilisation If fertilised – egg secretes If fertilised – egg secretes

HCG (similar to LH)HCG (similar to LH) Corpus Luteum maintainedCorpus Luteum maintained Progesterone secreted Progesterone secreted

continuously – endometrium continuously – endometrium thickenedthickened

Menstruation preventedMenstruation prevented - at 6 weeks placenta controls - at 6 weeks placenta controls

progesterone productionprogesterone production Pregnancy tests detect HCG Pregnancy tests detect HCG

in urinein urine

Role of cervixRole of cervix Cervix cells secrete mucus Cervix cells secrete mucus

– lubrication of the vagina– lubrication of the vagina Oestrogen stimulates Oestrogen stimulates

watery mucus secretionwatery mucus secretion – – easier sperm penetrationeasier sperm penetration Sperm directed by Sperm directed by

molecules in mucusmolecules in mucus Prostaglandins assist in Prostaglandins assist in

muscular contractionsmuscular contractions High levels of progesterone High levels of progesterone

thickens mucus thickens mucus – – protects fertilised egg protects fertilised egg

from infectionfrom infection

FertilityFertility In males – FSH/ICSH at a In males – FSH/ICSH at a

constant levelconstant level Constant production of Constant production of

testosterone & spermtestosterone & sperm Men are Men are continuously continuously

fertilefertile In females – hormone levels In females – hormone levels

alter greatlyalter greatly Cyclical fertility – Cyclical fertility – (3-4 (3-4

days after ovulation)days after ovulation) Signs – temp increase Signs – temp increase

(0.5(0.5ooC) & watery mucusC) & watery mucus