D3:1 Biology SL/HL

This is for IBDP Biology SL/HL students

Which hormones are produced in the ovaries?

Estrogen and progesterone

What does estrogen and progresterone do?

Stimulates the development of female genitalia before birth and at puberty. Responsible for development of female secondary sexual characteristics

What hormones are produced in the pituitary gland?

LH and FSH

What are the two phases of the menstrual cycle called?

Follicular phase and luteal phase

What happens during the follicular phase?

In each follicle an egg is stimulated to grow and at the same time the endometrium is repaired and starts to thicken. An egg is then released into the oviduct

What happens during the luteal phase?

The wall of the follicle that released an egg becomes the corpus luteum and the endometrium continues developing preparing for fertilization. If fertilization does not happend the corpus luteum and endometrium breaks down

FSH in the menstrual cycle

Rises to a peak at the end of the follicular phase. Stimulates development of follicles and estrogen production

Estrogen in the menstrual cycle

Rises to a peak at the end of the follicular phase. Stimulates repair and thickening of endometrium

LH in the menstrual cycle

Rises to sudden and sharp peak in the end of follicular phase. Stimulates completion of meiosis and partial digestion of follicle wall

Progesterone in the menstrual cycle

rises at the start of luteal phase, reaches a peak, and then drops back to low level. Inhibits FSH and LH secretion by the pituitary gland

What is oogenesis?

Production of egg cells in the ovaries

What is the process of oogenesis?

Primordial germinal cells divide to form oogonia, oogonia divide to form primary oocytes, primary oocytes undergo meiosis and freeze (primary follicles), when puberty hits, primary oocytes continue meiosis I and become secondary oocytes and polar bodies. After fertilization, meiosis II commences to develop ovum and second polar body

What is spermatogenesis?

Production of sperm

What is the process of spermatogenesis?

Germinal epithelium cells divide to produce spermatogonium, they grow and become primary spermatocytes, divides by meiosis I to produce secondary spermatocytes, undergoes meiosis II to produce haploid spermatids, sertoli cells help spermatids differentiate into sperm, sperm exits testis by fluid in seminiferous tubules

What is the hypothalamus?

Section of brain that links to the nervous and endocrine systems to maintain homeostasis

What is the pituitary gland?

Lies adjacent to the hypothalamus and is in direct contact. Receives instructions from hypothalamus and consists of anterior and posterior lobe

What happens in the anterior lobe?

releasing factors from hypothalamus cause endocrine cells to release specific hormones in bloodstream

What happens in the posterior lobe?

releases hormones into bloodstream produced by hypothalamus itself via neurosecretory cells

What is the process of fertilization?

Acrosome reaction (sperm binds to zona pellucida. Acrosomes have digestive enzymes), penetration of egg membrane (sperm nucleus enters egg), cortical reaction (cortical granules are reles by the egg and cause the digestion of binding proteins → no more sperm enter)

What happens during pregnancy?

Embryo produces hCG causing corpus luteum to secrete progresterone and estrogen to maintain endometrium. Placenta secretes estrogen and progresterone. Secretion of progresterone inhibits the secretion of oxytocin. More oxytocin = more contractions = more secretion of oxytocin