IB Biology: Hormones

19 flashcards · Other · by Gabrielle Wong

  1. Horomone

    Protein responsible for the maintenance of body characteristics within certain ranges (regulatory substance)

  2. Homeostasis

    Ensuring the internal envrionment of the body remains relatively constant within a range through negative feedback loops

  3. Thyroxin hormone secreted by thyroid gland (found in the neck) regulates metabolism and body temperature by increasing mRNA production, which eventually increases metabolism At lower tempetrautes: increased thyroxin secretion, arterioles narrow, restrict warm blood to skin, decrease in sweat, increase in shivering for heat At higher temperatures: decreased thyroxin secretion, arterioles widen, blood moves away from skin, more sweat, muscle relaxation

  4. Leptin secreted by adipose fat tissue controlled by the tissue and food intake targets the hypothalamus, binds to receptors to reduce appetite

    Obese people have highe rlevels of letpin, possible due to resistance (decrease in sensitivity to leptin), leptin may increase appetite with low fat reserves, but won't suppress appetite when reserves are higher

  5. Melatonin's Effects: increases in the evening to induce drowsiness decreases in the morning rapidly absorbed by the liver for quck onset of effects helps control circadian rhythms - a 24 hour cycle that controls sleepiness; secretion is controlled by suprachiasmatic nuclei

    Jet lag occurs becuase a person has altered their exposure to light and disrupted normal sleep schedule; melatonin supplements can be taken to induce sleepiness until circadian rhythm naturally resets

  6. Glucagon: secreted by alpha cells when blood sugar falls below a set point Breaks down and releases glycogen to increase blood sugar levels

    Works in tandem with insulin to maintain blood sugar levels

  7. Insulin: secreted by beta cells when blood sugar rises above a set point Uptakes glucose to store as glycogen

  8. Comparing Type 1 and Type II Diabetes

  9. IVF: stands for in-vitro fertilization eggs are harvested from ovaries this requires hormone therapy for one month: at 2 weeks: drug to suspend normal hormones 12 days after: FSH injections and HCG to promote maturation of follicles, leading to superovulation Man ejaculates into container, sperm is collected Semen may be checked to ensure sperm is healthy harvested eggs are mixed with the sperm 1-3 of the embryos found are implanted into the uterus after incubation in a petri dish pregnancy tes…

    Example of when this may be used: when couples have fertility issues (ex. male has low sperm count, impotency, woman has inability to ovulate normally, blocked Fallopian tubes)

  10. Soil and seed theory: theory that states the male was the seed and soil was menstruation blood, and that was what led to reproduction

    Disproved in part by William Harvey, who studied female deer, looked at the sexual organs, and found no embryo until 6-7 weeks after impregnation, but wasn't able to fully solve since microscopes hadn't been invented yet

  11. Role of SRY: a gene located on the Y-chromosome that led to the production of TDF (testes-determining factor), which causes the development of the male genitals, sperm production, and primary sexual charactersitiscs in puberty (ex. englargement of penis, deepnding of voice, growth of pubic hair)

    Without the SRY: embyronic glands become ovaries, estrogen and progresterone are present; in puberty, breast enlargement, growth of pubic hair, and start of menstruation occurs

  12. Reproductive system: females

  13. Reproductive system: males

  14. Gonadropin releasing hormone

    Stimulates the production of FSH and LH by the pituary gland

  15. Follicle stimulating hormone:

    Increases the produciton of estrogen, forming a positive feedback loop Aids in production of follices Spike leads to ovulation

  16. Lutenizing hormone

    Increases production of estrogen, forming a positive feeback loop Aids in develop of Graafian follice after ovulation Spike leads to ovulation

  17. Estrogen

    Increases production of FSH and LH until high levels, where it then inhibits Increases the density of endometrium

  18. Progesterone

    Proudction by corpeus leueum for 10-12 days after ovulation Inhibits FSH and LH production Maintains vascular endometrium Decrease leads to shedding of lining, leading to period

  19. Diagram of the menstrual cycle