BIOLOGY 321 Lecture Notes - Lecture 13: Globulin, Follicular Phase, Lipophilicity

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26 Mar 2017
Department
Professor
Primate Sexuality 2/28/17
1. Hormone Transport
- Steroids are lipophilic, only sparingly water soluble
- Steroids bind to wataer soluble carrier proteins to travel in the blood
i. Ex. SHBG: sex hormone binding globulin
ii. Carrier proteins allow testosterone to stay in bloodstream without being broken down as
quickly
- Protein hormones are able to travel freely but bind to receptors on cell surface, steroid hormones
can pass directly into the cell
- [testosterone] freely floating means that it is in an “active” form—it has been released from its
carrier protein; this does not represent the majority of testosterone, which is generally bound
2. Metabolism, Degradation & Excretion
- Liver: primary site where they are broken down; filled with enzymes
i. Does this by creating a water soluble metabolite that can be excreted
ii. Small percentage is excreted in its regular form
- As a consequence, urine samples are tested for the metabolites of the desired hormone
i. Sweat and saliva samples: these have fatty components, which allows for easier testing
for steroid (bc they are lipophilic)
- During exercise, or flight or fight by extension, blood is directed away from internal organs
towards muscles, meaning hormones will be broken down more slowly causing an artificial
change in testosterone
3. Hormone Function
- Growth & Development
- Homeostasis
- Energy Balance regulation
- Reproduction*
Hormone Function: Reproduction
I. Periodicities
a. Sexual reproduction involves periodicities because
i. Period of recovery is required
1. Germ cell production (both sperm and eggs)
2. Behavioral adaptations ensuring insemination
3. arising from within the body
ii. Favorable environmental conditions are limited
1. May be a season when there is more rainfall, more food availablethis
corresponds with when it is more ideal to be raising your young
2. Arising from the outside world
b. Asexual vs. Sexual Reproduction
i. Asexual reproduction propogates all of ones genes to all the offspringgood for the
genes in this scenario
ii. Sexual reproduction allows for increased diversity
1. Protects against pathogen evolution
2. Greater diversity means people are more likely to have different fitness against
threats
3. Also, in asexual reproduction, harmful mutagens become spread
c. Pulsatile Secretion
i. Basal secretion of most hormones is pulsatile (surge followed by quiescence)
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ii. Pulses may be as quickly as 5-10 min
d. HPG Axis Negative Feedback Loop:
i. Hypothalmus GnRH posterior/anterior pituitary LH/FSH testes
testosterone
ii. Testosterone then acts via negative feedback to suppress hypothalamus and GnRH
e. Schedules of Secretion
i. Circhoral: episodes occur hourly
ii. Circadian: periodicity of about once every 24 hours (adult sleep wake pattern)
1. Endogenously generated, Regulated by light and dark
2. Upon waking, large spike in cortisol to increase blood pressure and blood
glucose
iii. Diurnal: occurring every day (12-hr portion of 24hr daily cycle)
1. Synchronized with day/night cycle
iv. Circannual: pattern that occurs on a yearly basis
1. Ex. Is seasonal breeders estradiol concentrations occur in the monthly cycles
only during the breeding season, the rest of the year there is a lower more
suppressed level
f. Age changes in periodicities: for example, LH periodicities in female from infant (quiescent
period) to puberty, and adulthood where it becomes the most regular
g. Ovarian Hormone Periodicities
i. Endocrine cycle: shown in slide
ii. Models of periodicity:
1. Short (weekly)
2. Mid (biweekly): 14-16 days, guinea pig
3. Long (monty): 28-32 days; ex. Rhesus, chimp, human
II. Hormonal Control of Ovarian Cycle
a. Ovarian cycle (accompanied by endocrine and endometrial cycles)
i. Follicular phase: when follicle
ii. Periovulatory phase: when the follicle releases the egg
iii. Luteal phase: when the corpus luteum starts to produce progesterone to prepare the body
for pregnancy in case it happens
iv. If no pregnancy, luteam degrades and endometrium is shed
b. Menstrual (Uterine) Cycle
i. External signs of periodity:
1. Strepshirrines have a vaginal cycle when the cells become cornified and it
generally becomes imperforate
2. Catarrhines have a ‘menstrual cycle’
ii. Phases
1. Menstrual: break down of endometrial lining, in graph day 0 is day of
menstruation
2. Proliferative: growth of spiral arteries to build up blood supply for endometrial
lining
3. Secretory: when glandular structures in endometrium are created to prepare the
lining for implantation
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