6.6 - Hormones, Homeostasis, and Reproduction Flashcards
Control of blood glucose levels
Pancreas made of exocrine tissue secreting digestive enzymes and islets of Langerhans, endocrine tissue made of alpha and beta cells that secrete insulin and glucagon
insulin:
- hormone released when blood glucose concentration is too high
- synthesized and secreted by beta cells into blood stream
- binds to receptors on tissue cells to stimulate cells to take up glucose
- stimulates storage of glucose as glycogen in liver
- lowers concentration
glucagon:
- hormone released when blood glucose concentration is too low
- synthesized and secreted by alpha cells into blood stream
- stimulates breakdown of glycogen in liver to glucose released into blood stream
- increases concentration
Thyroxin
hormone made of iodine secrete by thyroid to regulate metabolic activity and body temperature
- thyroxin secretion is triggered by low body temperatures which increase metabolic activity and generates heat
Leptin
Hormone secreted by adipose tissue (fat storage cells) that binds to hypothalamus to suppress appetite
- secretion of leptin increases with adipose tissue -> increase in leptin blood concentration -> inhibits appetite -> less food intake
- > less adipose tissue -> less leptin
- negative feedback
Melatonin
hormone secreted by the pineal gland and controlled by suprachiasmatic nuclei (SCN cells in the hypothalamus) to regulate circadian rhythm (internal 24h behavioural cycle)
- secretion is high at night, promoting sleep, lowering body temperature and urine production
- secretion is lowers at dawn and melatonin is removed from the blood by the liver
ganglion cells in the retina stimulate SCN cells to adjust secretion of melatonin based on daylight
Sex determination of embryonic gonads
Embryonic gonads develop into ovaries
develop into testis in the presence of SRY gene on the Y chromosome
- SRY gene codes for testes determining factor (TDF) protein that stimulates the development of testis
Testosterone
hormone secreted by the testes
- during pregnancy stimulates prenatal development of male genitalia
- during puberty stimulates development of male secondary sexual characteristics (pubic hair, penis enlargement, enlargement of larynx)
Estrogen and progesterone
hormone always present
- during pregnancy secreted by placenta and ovaries of mother to stimulate prenatal development of female reproductive organs
- during puberty secretion increases (absence of testosterone) to stimulate female secondary sexual characteristics (enlargement of breasts, pubic hair, arm hair)
Menstrual cycle
cycle in women controlled by negative and positive feedback mechanisms of ovarian and pituitary hormones giving the chance of pregnancy from puberty to menopause (except during pregnancy)
follicular phase:
- Follicle-stimulating hormone secreted from pituitary gland (FSH was at its peak at the end of cycle)
- stimulates development of group of follicles
- stimulates secretion of estrogen from follicle wall
- estrogen secreted from follicle wall:
- stimulates thickening of uterus endometrium wall
- stimulates follicle reception of FSH stimulating more
estrogen
(positive feedback until peak)
- inhibits reception of FSH at high levels
- stimulates secretion of LH from pituitary gland
- Luteal hormone from pituitary gland (peaks)
- stimulates release of egg from most developed follicle
(collected by oviduct)
- stimulates degenraton of other follicles
Luteal Phase:
- LH
- stimulates development of corpus lumen from follicle
which secretes progesterone and estrogen
progesterone (peaks):
- stimulates maintenance/thickening of endometrium (prep
for embryo implantation)
- inhibits secretion of FSH and LH inhibiting its own
secretion (negative feedback)
FSH: (peaks from decrease in progesterone)
- stimulates start of new cycle
If no fertilization occurs, endometrium is shed and corpus lumen breaks down
Type I diabetes (causes and treatments)
elevated blood glucose level causing tissue damage due to insufficient production of insulin due to destruction of beta cells by immune system
cause: - autoimmune disease treatment: - insulin injections before eating - regular blood glucose level testing - stem cells to replace beta cells - device implants releasing insulin when necessary
type ii diabetes
elevated glucose levels due to inability to respond to insulin from insulin receptor or glucose channel deficiency in target cells
causes:
- genetics
- high sugar diet
- obesity
treatments:
- adjusting diet (avoiding high sugar foods, more high fibre foods)
- small frequent meals
- exercise and weightloss
In vitro fertilization (IVF)
- drug taken for down-regulation to stop secretion of FSH and
LH, stopping estrogen and progesterone secretion to stop
mentrual cycle (better control) - drug with high FSH and LH taken for superovulation development of multiple follicles
- drug with HCG to stimulate maturation of follicles
- eggs are extracted from follicles
- fertilization by mixing eggs and sperm
- successful embryos are implanted into uterus
- drug with progesterone taken to maintain thick endometrium
- normal pregnancy
Male reproductive system diagram
- testis: produce sperm and testosterone
- scrotum: holds testis at low temp
- epididymis: stores sperm
- seminal duct: transfers sperm during ejaculation
- seminal vesicle: secretes fluid with fuctose, alkalis, proteins to
make semen with sperm - prostate gland: secretes fluid for semen
- urethra: transfers urine during urination and semen during
ejaculation - penis: penetrates vagina for ejaculation near cervix
female reproductive system diagram
- ovaries: produce eggs, progesterone, estrogen
- oviduct: collects eggs during ovulation, site for fertilization, transfers embryo to uterus
- uterus: provides resources for embryo and fetus during
pregnancy - cervix: protects fetus, birth canal
- vagina: stimulates penis, birth canal
- vulva: protects reproductive system
