review Flashcards
Describe in general terms how steroid hormones exert their effects from their release to their physiological response
Lipophilic hormones, such as steroids, are poorly soluble in water, and therefore require carriers to be transported throughout the body.
Steroids are selectively produced based on what enzymes are present, and they are immediately released from where they are produced (not stored).
In order for them to exert their effects, they need to be unbound from their carrier. Then, they can pass through the membranes of their target cell (as they are lipophilic) to interact with their receptor.
Describe the hormonal regulation of testosterone synthesis and spermatogenesis. Make sure to include the entire hormone regulatory pathway and the specific testicular cells involved
Leydig cells in the seminiferous tubules (testes) are stimulated by LH to secrete testosterone. LH is released by the anterior pituitary gland in response to the hypothalamus.
Testosterone can enter the bloodstream and circulate to distant target cells.
However, most of the testosterone enters the lumen of the seminiferous tubules where it supports spermatogenesis
During exercise, alveolar ventilation can increase up to 20-fold. Since there is no change in arterial PO2 or PCO2 and the concentration of H+ in the cerebral extracellular fluid remains relatively constant, what causes the increaseinventilation?
many factors…
reflexes originating from body movements:
- muscle mechanoreceptors excited during muscle contraction reflexly stimulate the respiratory center to increase ventilation
epinephrine release:
- (from adrenal medulla) stimulates ventilation
increased body temperature:
sweating alone cannot counter the heat generated during exercise so body temperature rises slightly. (increases ventilation)
impulses from cerebral cortex:
- during exercise, motor areas of the cerebral cortex simultaneously stimulate the medullary respiratory neurons and activate the motor neurons of exercising muscles. this is feedforward mechanism that can occur before any homeostatic factors could occur
Describe Wolffian and Mullerian ducts, and how each develop/which one gives male or female internal/external reproductive system
hCG is released by the placenta
- if testes are present, hCG will stimulate them to produce and secrete testosterone
- testosterone will stimulate wolffian ducts to grow into the male reproductive system
- testosterone is also converted to DHT, which develops the male external genitalia
- testes secrete Mullerian-inhibiting factor, which causes the degradation of the Mullerian ducts
however, if there is no testes present, the wolffian ducts will degrade and the mullerian ducts develop into the female reproductive tract and external genitalia
Which hormone causes changes in the uterine lining to prepare for potential implantation of an embryo to establish a pregnancy?
Progesterone
Which hormone is important it the production of estrogen which is secreted in increasing quantities by the secondary follicles?
LH
Which hormone exerts a positive feedback action to cause a surge in LH secretion?
Estrogen
Which hormone is important for stimulating early follicular development and formation of the secondary follicle?
FSH
What does the hormone inhibin do?
Inhibits the production of LH and FSH by the pituitary gland
absorptive vs post absorptive
absorptive:
- anabolism dominates as ingested food is digested and absorbed into circulation
- ingested simple carbohydrates are converted in the liver to glucose, which is then released to be available as fuel, or it is stored as glycogen
- ingested fats and proteins are also immediately stored or used
- insulin plays a key role in anabolism, regulating blood sugar with effects on fats and proteins as well
post-absorptive:
- several hours after ingesting food, catabolism dominates
- glycogen stores in the liver and skeletal muscle becomes the primary energy source
- if the post-absorptive stage persist, glycogen alone cannot meet the body’s energy needs to lipolysis occurs to break down triglycerides
- glucagon plays a key role in decreased blood glucose levels, producing glucose among other things
compare and contrast spermatogenesis and oogenesis
- spermatogonia located in outermost layer of the seminiferous tubule
- they divide and create a constant supply of new germ cells
- they continue to migrate further through the Sertoli cells of the tubules towards the lumen
in the lumen, Leydig cells are stimulated by LH from the anterior pituitary gland to secrete testosterone. Testosterone helps support the spermatogenesis. - each spermatogonia produces 16 spermatids
- they can then be packaged into spermatozoa, stripped down of non-essential components and ready to leave
vs
- undifferentiated primordial germ cells in the ovaries undergo mitotic division during fetal life
- by the fifth month of gestation, there are millions of primary oocytes
- they are all surrounded by a single layer of granulosa cells (primordial follicle)
- immediately, the number of primary oocytes starts to decay
- follicles start to develop (primary follicle) and release an ova (secondary oocyte), or decay
- it can be fertilized by a sperm where its 23 single stranded chromosomes combine with the 23 single stranded chromosomes from the sperm
- hormones in follicular phase of the ovarian cycle support the growth and preparation of the mature egg
so a major difference is that in female all the primary oocytes are produced BEFORE the female is born (during fetal development)
The lung wants to collapse. Explain the forces preventing it
Each alveoli is connected to other alveoli
when the alveoli starts to collapse, the surrounding alveoli are stretched, making them recoil and pull outward on the collapsing alveolus.
pulmonary surfactant, a complex mixture of lipids and proteins secreted by type II alveolar cells, helps disperse water molecules on the surface of the alveoli. this makes water attractions decreased, which causes a decrease in surface tension which will also prevent collapsation
collapsing pressure is determined by 2T (surface tension) / r (alveolar radius), so thus by changing surface tension to be less, we will get a smaller collapsing pressure as well
describe insulin and glucagon
glucagon is majorly involved in the postabsorptive stage. the secretion of glucagon is triggered by the decrease in blood glucose
- its major site of action is the liver
- secreted by alpha cells of the pancreas
- it increases hepatic glucose production by decreasing glycogen synthesis (enhances glycogenolysis and gluconeogenesis)
- promotes lipolysis and inhibits fat storage and enhances formation of ketone bodies
- promotes protein catabolism in the liver
insulin is produced by the beta cells of the pancreatic islets
- dominant in absorptive state (anabolism)
- regulates blood sugar
- increases glucose uptake through GLUT-4 channels
- inhibits glycogenolysis and gluconeogenesis in the liver
- promotes storage of glucose as glycogen in liver and skeletal muscle
- lowers blood free fatty acid and promotes its storage as triglycerides
- enhances protein synthesis
compare and contrast spermatogenesis and oogenesis
Comparison:
Both spermatogenesis and oogenesis involve the development and maturation of germ cells.
Both processes involve hormonal regulation for their progression (testosterone in spermatogenesis and ovarian hormones in oogenesis).
Both produce gametes necessary for sexual reproduction.
Contrast:
- Spermatogenesis occurs continuously and throughout a male’s reproductive life, while oogenesis is a finite process that begins before birth and ends at menopause.
- Spermatogenesis results in the formation of spermatozoa, while oogenesis results in the production of ovum (eggs).
- The number of spermatozoa produced from each spermatogonium is much higher compared to the number of ovum produced from each primary oocyte.
