reproductive system. mammary glands present in both sexes, but only function in females modified...
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Reproductive System
Mammary Glands
Present in both sexes, but only function in females
Modified sweat glands
Function is to produce milk
Stimulated by sex hormones (mostly estrogens) to increase in size
Skin (cut)
Pectoralis major muscleConnective tissuesuspensory ligamentAdipose tissueLobeAreolaNipple
Opening oflactiferous ductLactiferous sinusLactiferous ductLobule containingalveoli Hypodermis
(superficial fascia)Intercostal muscles
First rib
(a) (b)
Reproductive System Function
Endocrine system plays a large role
2 hormones:
Follicle Stimulating hormone – helps produce sperm and oocyte (egg)
Luteinizing hormone – helps produce testosterone and induce ovulation
Male Reproductive FunctionsChief role – to produce sperm and testosterone
Spermatogenesis
Sperm production
Begins during puberty and continues throughout life
Only one sperm fertilizes an egg but a man make millions everyday
Involves meiosis – special nuclear division that halves the chromosomes
This process produces 4 functional sperm
Sperm pack light – the sperm head contains compacted DNA (nucleus)
Anterior to the nucleus is the helmet like acrosome
When sperm comes into contact with a oocyte the membrane of the acrosome breaks down the follicle (outside) cells of the egg
(a)
(b)
Plasma membrane
Tail
Axial filamentof tail
Mitochondria
Proximal centriole
NucleusAcrosomeDistal
centriole
Midpiece
NeckHead
Testosterone Production
Produced by the interstitial tissue of the testes but also released by the pituitary gland
Starts in puberty (in response to LH) and produced continuously (more or less) throughout life
Rising levels stimulate adolescent growth spurt, prompts reproductive organs to develop, underlies sex drive, and causes secondary sex characteristics
Secondary Sex characteristics
Deepening of voice
Increased hair growth
Enlargement of skeletal muscles
Increased bone growth and density
Female Reproductive Functions and Cycles
Ovarian Cycle
The total supply of eggs are present at birth
Ability to release eggs begins at puberty
Reproductive ability ends at menopause
Ovarian cycle
Cycle of how a egg undergoes change from an oocyte in the ovary, to an oocyte that is expelled for ovulation
This is triggered by LH and FSH
FSH starts the change
LH expels it from the ovary
(b) Ovarian cycle: Structural changes inthe ovarian follicles during the ovarian cycleare correlated with (d) changes in theendometrium of the uterus during theuterine cycle.
Primaryfollicle
Secondaryfollicle
Vesicularfollicle
Corpusluteum
Ovulation Degeneratingcorpus luteum
Lutealphase
Ovulation(Day 14)
Follicularphase
After expulsion from the ovary the oocyte travels down the fallopian tube
If fertilized, produces an ovum which combines with the 23 chromosomes of the sperm to form a fertilized egg (46 chromosomes)
Meiosis here only produces one functional egg and 3 polar bodies (non functional)
If not penetrated by a sperm it simply breaks apart
(d) The three phases of the uterine cycle:•Menstrual: Shedding of the functionallayer of the endometrium.•Proliferative: Rebuilding of thefunctional layer of the endometrium.•Secretory: Begins immediately afterovulation. Enrichment of the bloodsupply and glandular secretion ofnutrients prepare the endometrium toreceive an embryo.
The menstrual and proliferative phases occurbefore ovulation, and together correspond tothe follicular phase of the ovarian cycle. Thesecretory phase corresponds in time to theluteal phase of the ovarian cycle.
Menstrualflow
Basal la
yer Fu
ncti
on
al la
yer Endometrial
glands
Menstrualphase
Proliferativephase
Secretoryphase
1 105 2515 20
Blood vessels
28 Days
Uterine (Menstrual) Cycle
The window for implantation is only for a very short period each month
Occurs approx. 7 days after implantation
Menstrual cycle – cyclic changes that the endometrium goes through month after month, responding to changes in the levels of ovarian hormones in the blood
Progesterone and Estrogen (produced in ovaries) is regulated by FSH and LH
Estrogen produced in response to FSH
Progesterone in response to LH
Generally both female cycles occur in 28 days
Ovulation typically occurs midway in the cycles (day 14)
Days 1-5
Endometrial layer is sloughing off
Accompanied by bleeding for 3-5 days
Day 6-14
Proliferative phase
Stimulated by a rise in estrogen levels produced by growing follicles of the ovaries
Endometrium starts to regenerate and blood supply increases
Ovulation occurs in the end of this stage in response to the sudden surge of LH in the blood
Day 15-28
Rising levels of progesterone act on the estrogen primed endometrium and increase its blood supply even more
It is the uterus preparing for fertilization and implantation
If fertilization does not occur ovarian hormones decrease which causes the blood supply in the endometrium to go into spasms and kink. Endometrial cells begin to die and sets the stage for menses to begin again on day 28
Secondary sex characteristics
Enlargement of accessory organs
Development of breasts
Appearance of axillary and pubic hair
Increased deposits of fat beneath the skin in general, particularly the hips and breasts
Widening and lightening of pelvis
Onset of menses