1. 6.6 Hormones, homeostasis and reproduction
Essential idea: Hormones are used when signals need to be widely distributed.
Nature of science: Developments in scientific research follow improvements in apparatus—William Harvey was hampered in his observational research into reproduction by lack of equipment. The microscope was invented 17 years after his death. (1.8)

2. Understandings:
Insulin and glucagon are secreted by β and α cells of the pancreas respectively to control blood glucose concentration.
Thyroxin is secreted by the thyroid gland to regulate the metabolic rate and help control body temperature.
Leptin is secreted by cells in adipose tissue and acts on the hypothalamus of the brain to inhibit appetite.
Melatonin is secreted by the pineal gland to control circadian rhythms.
A gene on the Y chromosome causes embryonic gonads to develop as testes and secrete testosterone.
Testosterone causes pre-natal development of male genitalia and both sperm production and development of male secondary sexual characteristics during puberty.
Estrogen and progesterone cause pre-natal development of female reproductive organs and female secondary sexual characteristics during puberty.
The menstrual cycle is controlled by negative and positive feedback mechanisms involving ovarian and pituitary hormones.

3. Applications and skills:
Application: Causes and treatment of Type I and Type II diabetes.
Application: Testing of leptin on patients with clinical obesity and reasons for the failure to control the disease.
Application: Causes of jet lag and use of melatonin to alleviate it.
Application: The use in IVF of drugs to suspend the normal secretion of hormones, followed by the use of artificial doses of hormones to induce superovulation and establish a pregnancy.
Application: William Harvey’s investigation of sexual reproduction in deer.
Skill: Annotate diagrams of the male and female reproductive system to show names of structures and their functions.

4. Glucose Homeostasis

5. pubic bone urinary bladder ureter rectum seminal vesicle
prostate gland
urethra
penis
vas deferens
bulbourethral gland
epididymis
testis
urethral opening
scrotum 5

6. 6

7. A section through the testis
vas deferens
epididymis
uncoiled seminiferous tubule
testis
A section through the testis
spermatogonia
daughter cells
sperm
Sertoli cells
interstitial cell
Cross-section of a seminiferous tubule 7

8. occurs continuously starting at puberty
spermatogonium
primary spermatocyte
secondary spermatocytes
spermatids
sperm
Mitosis
Meiosis I
Meiosis II
Differentiation 8

9. interstitial cells Sertoli cells
hypothalamus
GnRH
anterior pituitary LH
FSH
testes
interstitial cells
Sertoli cells
testosterone
spermatogenesis
stimulates
inhibits
inhibin 9

10. myometrium uterus fimbria endometrium ovary uterine tube
urinary bladder
pubic bone
cervix
urethra
vagina
rectum
clitoris
anus
labia 10

11. 11

12. ovary uterine tube Ruptured follicle Ovulated secondary oocyte (egg)
Corpus luteum
Degenerating corpus luteum
Mature follicle with a secondary oocyte
ovary
ovulating egg
Developing follicles
ovary
Undeveloped follicles, each containing a primary oocyte 12

13. produced monthly beginning at puberty produced after fertilization
develops in the fetus
produced monthly beginning at puberty
produced after fertilization
egg
secondary oocyte (egg)
polar body
oogonium
primary oocyte
polar body
polar body
polar body
Mitosis
Meiosis I
Meiosis II 13

14. An ovulated secondary oocyte Sperm surrounding an oocyte
secondary oocyte (egg)
corona radiata
zona pellucida
An ovulated secondary oocyte
Sperm surrounding an oocyte 14

16. Vasectomy Tubal ligation
The uterine tube is severed and its ends are sealed
The vas deferens is severed and its ends are sealed
ovary
testis
uterus
scrotum
Vasectomy
Tubal ligation 16