Lecture 5 / Endocrine / Reproduction Flashcards
Hormones regulate…
Growth, reproduction and metabolism
Glands and tissues of the endocrine system secrete hormones which travel in the blood to “target cells” which are…
What happens when hormones reach target cells?
Target cells are simply cells with the appropriate receptor
Hormone binds to receptor and changes the cells activity
Receptors are proteins that can be in two places, they are
A) on cell membrane
B) intercellular ( on nuclear membrane )
What do water soluble hormones include?
Peptides, proteins, catecholamines ( nor / epinephrine / adrenergic )
Aka : 1st messenger
After a 1st messenger hormone such as a ligand binds to a receptor protein does it enter the cell?
Once binded what happens ?
Does not enter cell.
The hormone binding to receptor initiates “hormone receptor complex” and activates membrane proteins
Such as G protein
Once the G protein has been activated by the hormone receptor complex what does it do?
G proteins activate 2nd messenger eg cAMP and Ca2+
What are the function of 2nd messengers?
Example with cAMP
Activate other enzymes or ion channels
Eg
Cyclic AMP activates protein kinase enzymes
After cAMP activates protein kinase what does protein kinase go on to do?
Acts on other proteins (phosphorylates) to alter their activity
Simplify the fast response of cyclic AMP second messenger system of water soluble hormones
1) 1st messenger hormone binds to receptor
2) receptor activates G protein >GTP
3) G protein activates adenylate cyclase
4) adenylate cyclase converts ATP to cAMP (2nd messenger)
5) cAMP activates protein kinase
6) protein kinase phosphorylates proteins to alter their activity
Adenylate cyclase converts _____ to cAMP
ATP
Describe how epinephrine reacts on the liver cells
Epinephrine binds to receptor protein which then activates G protein
Which activates adenylate cyclase which produces 2nd messenger cAMP
cAMP activates protein kinase
Why do we want to use 2nd messenger systems?
A) because hormone is water soluable it cannot enter cell
B) rapid acting enzymes already present and just need to be activated
c)1 hormone molecule activates many - multiplies the effect of a single molecule
D)limited, messenger is broken down or removed
Give an example of a messenger being broken down or removed with respect to 2nd messengers
cAMP broken down by phosphodiesterase in cell
How is hormone secretion into blood regulated ?
My stimuli acting on endocrine gland
What may the stimuli producing homone into blood be? (3)
1) a non hormone substance in the blood
2) the nervous system
3) a hormone
Describe how a non hormone substance in the blood may stimulate hormone production via endocrine gland or tissue (example)
Eg) high glucose in blood triggers beta cells of the islets of langerhans to secrete insulin, insulin then opens the door to body cells reducing the blood glucose concentration
What’s another name for a non hormone stimulus acting on an endocrine gland / tissue
HUMORAL STIMULUS
Give and example of how calcium could be a HUMORAL stimulus
Low calcium in the blood stimulates parathyroid gland to release parathyroid hormone
PTH raises blood calcium levels by decreasing osteoblasts activity
Increases osteoclast activity
NEGATIVE FEEDBACK
Explain how the nervous system can stimulate endocrine tissue to release hormone
With example
Subject is sitting with resting heart rate ***SURPRISE*** Adrenal medulla activated Releases epinephrine (adrenergic) Increased heart rate (SNS)
Explain with an example how a hormone may stimulate the release of another hormone on an endocrine tissue / gland
Low metabolism triggers TRH from hypothalamus (thyrotropin releasing hormone)
Which stimulates the anterior pituitary to release TSH
TsH stimulates thyroid gland to release t4
T4 converts to T3 in target tissue or liver —> increased metabolism
Simplify low metabolism to high metabolism via hormones
Low met triggers TRH from hypothal TSH from ant pituitary T4 from thyroid To T3 on target tissue or liver
Explain what stress is
What it triggers
And what part of the body coordinates it
Extreme internal or external stimulus
Triggers general adaptation syndrome
Coordinated directly or indirectly by the hypothalamus
Describe lipid soluable hormones
Steroids and Thyroid hormone Hydrophobic Enter cell bind to intracellular receptors Activate genes Triggers protein synthesis It is slow but has lasting responses
Explain the process of lipid soluble hormone action
Hormone binds to receptor in cytosol or nucleus
Hormone receptor complex binds to specific region
Messenger RNA –> ribosomes –> proteins
Explain what stress is
What it triggers
And what part of the body coordinates it
Extreme internal or external stimulus
Triggers general adaptation syndrome
Coordinated directly or indirectly by the hypothalamus
Describe lipid soluable hormones
Steroids and Thyroid hormone Hydrophobic Enter cell bind to intracellular receptors Activate genes Triggers protein synthesis It is slow but has lasting responses
Explain the process of lipid soluble hormone action
Hormone binds to receptor in cytosol or nucleus
Hormone receptor complex binds to specific region
Messenger RNA –> ribosomes –> proteins
Describe an alarm reaction ( fight or flight response) which is apart of the general adaptation system
>immediate nervous system
CNS ( Sensory input detects change )
To Hypothalamus to > RAS (activates alertness)
SNS activates a) organs and b) adrenal medulla to release epinephrine (fight or flight)
Which things are associated with the general adaptation syndrome in response to stress
Alarm reaction ( fight or flight ) Resistance reaction
What are the effects of an alarm reaction (fight or flight response) on blood sugar
Increase blood glucose because SNS inhibits insulin release (glycogen, through adrenergic hormones turned into glucose from liver stores)
What are the effects of an alarm reaction on heart rate, respiratory rate and blood flow to skin / abdominal viscera
Increased HR
Increased respiration
Decreased blood flow to skin and abdominal viscera
During an alert or fight or flight reaction why do you think less blood is delivered to the skin and abdominal viscera?
Because more blood delivered to skeletal muscles heart and brain
During an alarm reaction what happens to digestion and urine production ?
Decreased digestion and urine production
A resistance reaction is apart of general adaptation syndrome what does it do
Why does it happen
It is long term production of endocrine
Initiated by the hypothalamic regulating hormones
Happens by recovery from 1) tissue damage
2)response to long term stress like starvation
During resistance reaction , which is part of general adaptation syndrome a product is cortisol( gluco corticoid) how does this happen?
Hypothalamus releases GHRH AND CRH (corticotropin releasing hormone) to anterior pituitary
The anterior pituitary then releases
GH and ACTH (adrenal corticotropin hormone)
The ACTH signals the adrenal cortex p release cortisol
Cortisol is released 30 seconds after an alert reaction but it’s effects are only seen hours after .. Why?
Because cortisol is a steroid, it is a lipid soluble hormone and acts at nuclear receptors…
Cortisol inhibits
Insulin release
What is a result of resistance reaction or cortisol production
Increased blood glucose
Liver stimulated to produce new glucose from fats and later proteins
Little insulin available so glucose is not taken up well by skeletal muscle at rest and adipose tissue
When a resistance reaction has been happening and cortisol has been produces the blood glucose level is high because the liver is stimulated to do so and there is little insulin … What is glucose spared for use by
Nervous system
When resistance reaction is occurring due to stress / alarm glucose is spared for use by the NS. Where is the metabolism directed to for non nervous tissue ?
Fats for energy
Result of GH and cortisol
If stress continues cortisol inhibits ______ and then proteins are used. Also an increase in _______ and amino acids in blood:
Growth hormone
Fatty acids
After a resistance response can cause inhibition of important things like
Immune responses (t and b lymphocytes)
Bone formation
Formation of CT / wound healing
As a result of a resistance reaction the body will release aldosterone and antidiuretic hormone (ADH) which
Reduces salt and water loss at kidney to maintain blood volume and increase blood pressure
Long term effects of resistance reaction are
Decreased weight Increased blood pressure Increased heart rate Immune suppression (cortisol) Loss of bone density Increased risk of type 2 diabetes
Exhaustion can occur as an end step of General adaptation syndrome, it results from depleted body resources like
Lipid reserves , glucocorticoids, loss of k+ ( due to the adosterone secretion ) damage to organs, heart kidney and liver
During the exhaustion phase there is a loss of _______ due to aldosterone release
K+
Aldosterone regulates the salt and water balance in the body
Comes from adrenal cortex (mineralcorticoid) - cortisol also comes from adrenal cortex
Anterior pituitary releases ACTH which stimulates the ______ to release cortisol
Adrenal cortex
After puberty in the male reproductive system the hypothalamus , anterior pituitary and gonads release important hormones for spermatogenisis what are they ?
Hypo : gonadotropin releasing hormone
Anterior pituitary : leutinizing hormone / follicle stimulating hormone
Gonads : testosterone (leydig)
Where does spermatogenisis occur? Which hormones directly influence it?
Sertoli Cells
Testosterone and FSH
Which male sex hormones are released from the anterior pituitary to the testes ?
FSH and LH
Functions of testosterone with regard to development
Male reproductive tract organs
Secondary sex characteristics (hair, deep voice)
Stimulates bone growth and epiphysial plate
Testosterone functions in protein anabolism or catabolism?
Anabolism
Testosterone directly effects production of being sexy or spermatogenisis ?
Both
What are the hormones released by the hypothalamus, anterior pituitary, and overies
Hypothal > GnRH
Anterior pit> LH and FSL
Ovaries > estrogens via primary / secondary follicles
Which hormone directly influences the primary and secondary development of follicles
FSH
Stimulates primary to become secondary
Which hormone plays a big role in ovulation
LH
When progesterone is high what is probably low ?
FSH, because FSH is inhibited by P
Also conversely
What stimulates estrogen production
From where ?
LH
Theca and granulosa cells of follicle
A surge in LH stimulates ovulation and formation
Of corpus luteum
Recap the hormones that come into play from primary follicle to corpus luteum
FSH primary to secondary
LH formation of corpus luteum
A positive feedback mechanism occurs when the follicle in “follicular phase” explain
Estrogen is released from the secondary follicle for a few days
This stimulates LH (via GnRH)
Which stimulates the follicle to increase estrogen
Come up with a mnemonic device to remember which anterior pituitary hormone does what
FSH > f for follicle
LH > lovely ovulation
Horrible estrogen / test
In luteal phase progesterone inhibits
LH release
Luteal for LH
Functions of estrogen other than ovulation
Stimulates growth of and maintains endetrium
Develops secondary sex characteristic (breast and fat distribution)
Bone growth and closure of epiphysis
Where is progesterone secreted from
What is it’s function
Corpus luteum
Preps uterus for pregnancy
Ovarian cycle is 28 days
The follicular phase is also called the pre ovulation phase how long is it
Days 1 - 14
In the pre ovulatory or follicular phase what happens in the ovary?
Progesterone is low
LH and FSH secreted
Some primary follicles develop to secondary (due to FSH)
Follicles also secrete estrogen and there is a surge in estrogen levels
What happens late in follicular phase
One secondary follicle will develop into a graffian follicle
At the level of the uterus days 1-5 are the menstrual phase what happens
Stratum functionalis is shed
Bleeding
Blood secretions and cells = 50 - 150 mL
At the level of the uterus days 6-14 are the proliferative phase what happens
Estrogen causes repair and proliferation of stratum functionalis
Mitosis in stratum basalis
Days 15 to 28 are called the luteal phase at the level of the ovary (post ovulatory) what happens
High progesterone from corpus luteum inhibits GnRH
Inhibition of FSH and LH
No follicles develop
Days 15 -28 at the level of the uterus is called the _______
What happens to the uterus wall
Secretory phase
Progesterone secreted from corpus luteum prepares uterus for implantation
It’s becomes vascular and thick and stores glycogen
f in the secretory phase at the level of he uterus progesterone inhibits _______ and does what to the cervix
Inhibits uterine contractions
Keeps cervix firm and inflexible from collagen fibers
If fertilization occurs the placenta releases human chorionic gomatotropin which
Maintains corpus luteum
And has similar structure to LH
If fertilization occurs the corpus luteum secretes progesterone and estrogen
For how long
After that what structure releases these hormones
First 6 weeks of pregnancy
The placenta
If fertilization does not occur corpus luteum becomes
Corpus albicans
No hCG
And lower LH
Since FSH and LH are inhibited after pregnancy and high levels of progesterone that means
No new follicles can develop
If fertilization doesn’t occur progesterone and estrone decrease so then which hormones increase
And what happens to the uterus
LH and FSH
Menstruation begins
Describe how oral contraceptives work
They can be high in estrogen and progesterone Inhibits GnRH in turn no FSH and LH Therefore no follicle maturation No ovulation A thickened mucus inhibits sperm
Describe how IU implants work
Similar as oral contraceptive but with progestin
Describe how morning after pill works
High E and P or just P
Functions to prevent implantation, ovulation, and fertilization
Can be taken w/in 5 days of unprotected sex. Better in 72 hrs
Usually 2 doses jn 12 hours apart
What happens as result of morning after pill
Higher instance of ectopic pregnancy
T or f Chinese women have higher rate of failure with morning after pill
T
How does mifepristone work?
Block progesterone receptors
In low doses it blocks ovulation
Alters endometrium so egg cannot implant
How does mifepristone elicit abortion
Safe and effective Not licenced Causes endometrium to slough off With embryo Taken with prostaglandins
Why is mifepristone taken with prostaglandins
Prostaglandins elicit uterine contractions which helps the body push out the endometrium
What is the placenta composed of
Chorion of fetus and endometrium of mom
Blood vessels of each in close proximity but do not mix
Functions of placenta
Exchange of materials between mom and fetus such as
Gasses nutrients hormones antibodies (passive immunity) wastes virus drugs etc
The placenta secrets estrogen and progesterone but also HCG what is it’s function
Maintains corpus luteum for 6 weeks
Peaks at 10 weeks and then drops
Detected by preg tests
Stimulates testosterone secretion by fetal testes
What is the function of human chorionic gomatotropin
Maintains corpus luteum
