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Sl Bio > 6.6 > Flashcards

6.6 Flashcards

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Biology 101 flashcards
1
Q

key endocrine glands

A
  1. pineal gland
  2. pituitary gland
  3. thyroid gland
  4. thymus
  5. adrenal gland
  6. pancreas
  7. ovary
  8. testes
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2
Q

endocrine glands (definition)

A
  • glands which produce and secrete hormones directly into the blood, carried to the target tissues
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3
Q

What hormones regulate blood glucose levels?

A

pancreas hormones:
- insulin
- glucagon

secreted directly into the blood from: islets of Lagerhans

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4
Q

blood glucose set point

A

~ 5mmol/L

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5
Q

If glucose lvls drop:

A
  • pancreas detects drop
  • α cells secrete glucagon hormone
  • stimulates liver to convert glycogen into glucose and its release into the blood
  • blood glucose increases to normal
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6
Q

If glucose lvls rise:

A
  • pancreas detects rise
  • β cells secrete insulin hormone
  • liver is stimulated to convert glucose into glycogen
  • stimulates uptake of glucose by skeletal and muscle tissues
  • blood glucose drops to normal
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7
Q

diabetes definition

A
  • consistency elevated blood glucose levels
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8
Q

symptoms of diabetes

A
  • constant urination
  • constant thirst
  • tired
  • craves sugar
  • glucose in urine
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9
Q

complications of diabetes

A
  • damages tissues and their proteins
  • prevents water reabsorption in kidneys –> increase in volume of urine and body dehydration
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10
Q

type 1 diabetes (early onset) (deinfition/cause)

A
  • cannot produce enough insulin
  • autoimmune disease (body’s natural defence system cannot tell the difference between own cells and foreign cells)
  • destruction of β cells by immune system
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11
Q

type 1 diabetes (early onset) treatment

A
  • testing blood glucose levels regularly and injecting insulin when too high
  • implant devices to release insulin
  • stem cell treatment to create new β cells
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12
Q

type 2 diabetes (late onset) (definition/causes)

A
  • cannot respond to insulin
  • lack of insulin receptors or glucose transporters on target cells
  • can be caused by sugary or fatty diets, prolonged obesity, genetic factors that affect metabolism
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13
Q

type 2 diabetes (late onset) treatment

A
  • adjusting diet
  • frequent, smaller meals
  • avoid sugary foods
  • eat foods with low glycemic index (foods which are digested more slowly and less likely to increase blood sugar lvls)
  • high fibre foods
  • exercise
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14
Q

more hormones produced by endocrine glands

A
  • thyroxin (produced by thyroid gland)
  • leptin (produced by adipose cells)
  • melatonin (produced by pineal gland in the darkness)
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15
Q

thyroxin

A
  • targets most body cells (liver, muscle, brain)
  • increases metabolic rate/rate of protein synthesis
  • increases heat production when body temp. is low

deficiency results in:
- tired/lack of energy
- forgetfulness
- depression
- decrease appetite and weight gain (less glucose/fat broken down by cell resp.)
- feel cold
- constipation
- impaired brain development

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16
Q

leptin

A
  • targets appetite control centre of the hypothalamus (bind to receptors in cell membranes)
  • increase in adipose tissue increases leptin secretions into blood
  • appetite inhibition (feelings of satiety, reduced food intake)
  • experiment: mice with (two –>) ob/ob recessive allele injected with insulin showed decline in appetite
17
Q

melatonin

A
  • targets pituitary gland and other glands
  • affects synchronization of circadian rhythms (24-hr cycle)
  • circadian rhythms are controlled by two groups of cells in the hypothalamus
  • melatonin increases at night, decreases at dawn
  • at night drops body temp and possibly reduces urine production
  • light detected by retina helps set circadian rhythm
  • body’s circadian rhythm mostly maintained even w/o light cues
18
Q

types of chromosomes (humans have 23)

A
  • 22 pairs are autosomes (homologous pairs)
  • 1 pair is sex chromosomes (determines sex) XX = female XY = male
19
Q

testosterone in development

A
  • testes develop from embryonic gonads when the embryo is becoming a fetus (in presence of testosterone)
  • develops testosterone secreting cells

during puberty:
- testosterone secretion increases
- causes primary sexual characteristic of sperm production in testes

20
Q

estrogen and progesterone

A
  • female reproductive organs develop in absence of fetal testosterone and presence if maternal estrogen and progesterone (estrogen and progesterone are secreted by the mother’s ovaries and later her placenta)
  • ovaries develop from embryonic gonads

during puberty:
- primary sexual characteristic of egg release

21
Q

Menstrual cycle hormones

A

Produced from the pituitary:
- FSH: stimulates oocyte (and follicle) development, stimulates secretion of estrogen by follicle wall
- LH: matures oocyte and causes release (ovulation), promotes development of follicle wall into corpus luteum after ovulation (corpus luteum secretes estrogen and progesterone)

Produced from the ovaries:
- estrogen: develops endometrium, stimulates increase in FSH receptors, in high lvls will inhibit secretion of FSH and stimulate LH secretion
- progesterone: maintains endometrium, inhibits FSH and LH secretion by the pituitary gland

  • HCG: pregnancy hormone (keeps estrogen and progesterone high)
  • Oxytocin: birth hormone (contractions of uterus)
22
Q

follicular phase (what happens?)

A
  • follicles developing in ovary, growing egg in each follicle
  • lining of the uterus thickens
  • most developed follicle breaks open and egg is released into oviduct
  • other follicles degenerate
23
Q

luteal phase (what happens?)

A
  • follicle wall becomes corpus luteum (in ovary)
  • endometrium develops for implantation of embryo
  • if no fertilization: corpus luteum breaks down
  • endometrium shed during menstruation
24
Q

Stages of the menstrual cycle

A

(follicular phase)
Day 1-4:
- menstruation (endometrium is shed)
- FSH increases and stimulates follicle development
Day 5-14
- FSH and follicle stimulates estrogen release
- estrogen stimulates endometrium thickening
- estrogen stimulates LH
- peak in LH causes ovulation
(luteal phase)
Day 14-28
- fall in LH, corpus luteum forms from now empty follicle
- corpus luteum releases progesterone
- progesterone thickens endometrium and inhibits FSH and LH

If no fertilization, progesterone and estrogen drop, triggering menstruation and FSH release

25
Q

Causes of infertility

A

female:
- ova not maturing or being released
- abnormality in uterus (prevents implantation)
- antibodies in cervical mucus impair sperm
- blocked fallopian tubes
male:
- unable to achieve an erection or normal ejaculation
- low sperm count or sperm are abnormal w/low mobility
- blocked vas deferens

26
Q

IVF (what is it?)

A
  • In vitro fertilisation
  • often used to overcome infertility
  • fertilization that occurs outside the body
27
Q

IVF steps

A
  1. Suitability for IVF is determined
  2. down-regulation: shutting down of the menstrual cycle by stopping secretion of the pituitary and ovarian hormones for two weeks- allows better control of egg production
  3. FSH and LH are given to stimulate multiple egg releases, superovulation: collects multiple eggs from the woman, high doses of FSH are injected over ~10 day period to stimulate development of multiple follicles
  4. when follicles reach 15-20mm in diameter, an injection of HCG given to maturation process, 36 hours later under a general anesthetic, (8-12) follicles are collected from ovaries
  5. prepared eggs are combined with sperm in sterile conditions, successfully fertilized eggs are then incubated before implantation
  6. after incubation, viable blastocysts (cluster of dividing cells made by a fertilized egg) are selected and developed into embryos
  7. up to 3 can be selected and placed in the uterus after 48 hours for implantation (risk of multiple pregnancy)
  8. ~2 weeks before implantation, woman takes progesterone (suppository) to aid in implantation. treatment continued until pregnancy test, if positive, until 12 weeks of gestation
  9. after bedrest, pregnancy test administered, if positive, pregnancy continues as normal, if negative, a few months can be waited to attempt process again
28
Q

William Harvey’s investigation of sexual reproduction (seed and soil theory)

A
  • “seed and soil” theory stated that the male produces a seed which forms an egg when mixed with menstrual blood, egg then develops into a fetus inside the mother
  • Harvey studied animal reproduction in chickens and deer: dissected female deer after mating to find changes in sexual organs –> none was found
  • therefore Harvey found that menstrual blood did not contribute to the formation of a fetus
  • no microscopes: sperm, eggs and embryos were too small to observe

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