4.2 Sexual Reproduction in Humans Flashcards
Scrotum
Sac of skin where the temperature is lower than the temperature inside the body - optimum temperature for sperm development
Testes
Produce Spermatazoa and the male hormone testosterone
contained in scrotum
Epididymis
A long coiled tube outside testes. Sperm remain here for a short time while they become mature
Vas deferens
A tube that carries sperm out of testes to urethra
Seminal vesicle
Produces mucus secretions which aid sperm mobility. Mucus contains a mix of chemicals which include fructose used in respiration for movment
Prostrate gland
Secretes zinc-containing fluid
Urethra
tube that carries urine and semen out of body
Penis
An intromittent organ deliveling sperm copulation
Spermatogenesis
General Epithelium (2n)
(Mitosis)
Spermatogonium (2n)
(Mitosis)
Primary Spermatocyte (2n)
(Meiosis 1)
Secondary Spermatocyte (n)
(Meiosis 2)
Spermatids (n)
(Mature)
Spermatozoa
Ovary
Produce the female gametes and make female hormones
Oviduct
Mucular tube that contains the egg to the uterus
Uterus
Muscular organ wich functions to nourish and house the fertilized egg untill the unborn childed is ready to be delivered
Endometrium
the lining of the womb - where the embryo plants during pregnancy and shed duringn mensturation
Cervix
Ring of muscle between uterus and vagina
Vagina
closed muscular canal that extends from vulva to cervix
Oogenesis
General Epithelium (2n)
(Mitosis)
Oogonium (2n)
Mitosis
Primary oocytes (2n)
(Meiosis 1 - stops at prophase - before birth)
Secondary oocyte (n)
(Meiosis 2 - stops at metaphase - after puberty)
Ovum (n)
After fertilisation
What happens at day 14?
Ovulation
What does the corpus luteum secrete?
Progesterone
What is the corpus luteum?
After fertilization the remaining folicle develops into the corpus luteum
Clevage
sequence of mitotic divisions as the embryo moves down the oviduct
Morula
Solid ball of 16 cells which has formed within 3 days
Blastocyst
Hollow ball of cells which has formed by day 7. Moves from the oviduct to the uterus
Implantation Window
period when the endometrium is receptive to accept implantation of blastocyst
Trophoblastic Villi
Develops around day 9 - they penotrate endometrium and increase surface area for absorption of nutrience
Placenta
-Connects embryo to uterus wall
-Combination of mother and embryo tissues
Roles of placenta
- Endocrine gland - Produce hormones to support pregnancy
- Exchange of materials - Nutrience, waste product,respiratory gas exchanged between blood - counter current flow - maintains a high conc gradient
- No contact between blood to protect the fragile foetal capillaries from damage by H.B.P of mother
- Protection against mothers imune system
Events that lead to fertilisation
- Capacitation - Removal of cholestrol and glycoproteins from cell membrane over the acrosome in the sperm head. Membrane becomes fluid and more permeable to Ca2+
- Acrosome reaction - Protase released from acrosome to digest corona radiata
- Sperm head entry - cell membrane of secondary oocyte and sperm fuse and the sperm head sinks into the cytoplasm. Secondary oocyte is called Ovum
- Cortical reactioni - Production fertilisation membrane to provent polyspermy
What happens in the uterus when the follicle is maturing in the ovary?
Period - endometrium lining is shed
What happens in the uterus when mature Graafian follicle is formed?
Endometrium thickens
(rebuilds)
What happens in the uterus at ovulation?
Endometrium is at it’s thickest
What happens in the uterus when Corpus luteum forms?
Endometrium is maintained at its thickest
What hormone does the Hypothalamus produce to the Anterior gland?
Gonadotrophic releasing hormone
What 2 hormones does the anterior pituitary gland produce?
Follicle stimulating hormone (FSH)
Lutenising hormone (LH)
What does the Follicle Stimulating hormone do?
Stimulates the development of primary follicles
Produce Graafian follicle
Stimulates cells to produce oestrogen
What does the luteinising hormone do?
Reaches max conc just before ovulation
Induce ovulation
At day 14 concentration causes Graafian follicle to release the secondary oocyte
Positive feed effect on FSH
What does Oestrogen do?
Triggers the rebuilding of the endometrium
Inhibits FSH secretion by negative feedback
Stimulates LH production be positive feedback
What does Progesterone do?
Maintains the newly built endometrium
If there’s no implantation the falling conc of FSH and LH causes corpus luteum to degenerate so progesterone production declines
Main role of Follicle stimulating hormone
Follicle development
Main role Lutenising hormone
Ovulation
Main role of oestrogen
Rebuild endometrium
Main role of progesterone
Maintain endometrium
What is the amnion?
The membrane derived from the inner cell membrane from the inner cell mass of the blastocyst
Initially in contact with the embryo
What is amniotic fluid?
98% water, a solution of urea, salts a little protein and a trace of sugar
Contains some foetal cells that have sloughed off the foeutus
Functions of amniotic fluid?
- Maintains the foetus’s temperature
- Provides lubrication
- Contributes to lung development
- Allows movement so muscles and bones function before birth
- Acts as a shock absorber
How many trimesters are in a pregnancy?
3
How long is the first trimester?
0-3
What happens in the first trimester?
Includes conception, implantation and embryogenesis
All major organs are laid down
High risk of miscarriage
After 10 week embryo is describes as a foetus
How long is the second trimester?
4-6.5 months
What happens in the second trimester?
Development
Movements of foetus can be felt
What happens in the third trimester?
All major structures are complete
This is a period of growth
Fat is laid down
Length doubles and mass increases three-fold
Senses that such as hearing are developing
What does the human chroionic gonadotrophin hormone do?
It’s a glycoprotein
Maintains the corpus luteum in secretion of progesterone
When is human chorionic gonadotrophin produced?
About 6 days after fertilisation the blastocyst sectetes hCG
What does progesterone inhibits during pregnancy?
Inhibit Oxytocin so the myometrium and muscles in the milk ducts do not contract
