11.4 Flashcards
What is needed for sexual reproduction to occur?
A male gamete and a female gamete
Define spermatogenesis
It is the production of male gamete by meiosis
Where does spermatogenesis occur?
It occurs in the testes in a structure called the seminiferous tubule
Why are the testes located in the scrotum, which is located outside the body?
Sperm production requires a lower temperature than the internal temperature of the body
What kind of cells undergoes meiosis?
Germinal cells; which are the cells that have the ability to produce gametes aka sex cells
What is the name of the male germinal cell?
Spermatogonia
Why do spermatogonia undergo both mitosis and meiosis?
Meiosis
- For the production of gametes (sperm)
Mitosis
- To replenish the number of spermatogonia
What does diploid cells (2n) mean?
It contains 1 chromosome from mom and 1 from the dad
Homologous pair
What does haploid cells (n) mean?
It contains 1 chromosome from mom or 1 from the dad
Describe the production of semen (6)
- Sperm is a type of germinal cell, which is produced by meiosis
- They are found in the seminiferous tubule which is located in the testes
- There are 3 main parts of the male reproductive system that takes part in the production of semen, this includes…
1. Epididymis - This is where the sperm is matured and develops its capacity to swim
- Also where sperm is stored
2. Seminal vesicle - The vesicle secretes nutrients (e.g. Fructose)
- The nutrients provides the sperms energy to swim
3. Prostate gland - This gland realises alkaline fluids
- The alkaline fluid helps neutralises the acidic environment of the vagina when semen is ejaculated into the vagina
Explain the structure and function of the placenta (8)
Functions
- It is the life support system for the foetus
- Facilitates the exchange of materials between the mother and the foetus
- Secretes hormones, oestrogen and progesterone to maintain the pregnancy after the corpus lutetium degenerates
Structure
- It has a disc shaped structure which helps nourishes the developing foetus
- It is lined with chorionic villi which increases the surface area for the exchange of materials between the mother and the foetus
- The exchanged material is transported from the villi to the foetus of the umbilical cord
- The umbilical cord connects the foetus to the placenta
- Upon birth, the placenta is expelled from the uterus with the infant
- The placenta will then be separated from the infant by the cutting of the umbilical cord
Outline the hormonal control of birth (4)
- Near the end of pregnancy, the progesterone level decreases which removes inhibition of oxytocin secretion
- Oxytocin is released from the posterior pituitary gland
- Oxytocin stimulates uterus contraction which means that the cervix dilates
- Increase in oxytocin increases the rate and intensity of contractions
- This is one of the positive feedbacks
Outline the function of the proximal convoluted tubule (1)
It’s function is to selectively reabsorb glucose, minerals, amino acids, water and other useful substances
Explain the role of the medulla and the collecting duct of the kidney in the maintenance of the water balance in blood (3)
- The collecting duct is permeable to water since it has aquaporins (water channels)
- The medulla is hypertonic, meaning that there is a high solute concentration
- The medulla helps with the reabsorption of water, which allows excretion of concentrate urine
- The secretion of ADH increases the permeability of collecting duct to water
Describe the process of fertilisation in humans (6)
- Sperm breaks through the
