M1 L2 Flashcards
1
Q
What are endocrine hormones?
A
Regulatory molecules produced in specific cells and transported by the bloodstream to influence distal targets
2
Q
Endocrine hormones:
* how far travel?
* how delivered?
* what type of processes does it regulate? Examples?
A
- travel long distances
- delivered via bloodstream
- regulates processes that require duration not speed SUCH AS reproduction, metabolism, growth, etc
3
Q
What are exocrine hormones?
* ex:
A
Signaling that uses ducts instead of circulation
* Salivary glands, pancreas
4
Q
What are paracrine hormones?
A
Hormones that act locally and are released into interstitial space & act on adjacent cells
5
Q
What are autocrine hormones?
A
Self signaling hormones cell that releases a hormone or signal and responds to it itself
6
Q
What are synaptic hormones?
A
messengers released in very close proximity to targets. They cross a tiny gap (synapse) to target cells
7
Q
Which hormone communication corresponds to this picture?
A
Synaptocrine
8
Q
Which hormone communication corresponds to this picture?
A
Paracrine
9
Q
Which hormone communication corresponds to this picture?
A
Endocrine
10
Q
Which hormone communication corresponds to this picture?
A
Autocrine
11
Q
Which hormone communication corresponds to this picture?
A
Exocrine
12
Q
What does the endocrine system coordinate?
A
Neuroendocrinoloy, growth/metabolism, salt/water balance, reproduction, stress
13
Q
What is homeostasis?
A
A relatively stable equilibrium maintained by physiological processes.
14
Q
What is homeostasis maintained with?
A
negative feedback
15
Q
How does negative feedback maintain homeostasis?
A
Negative feedback maintains homeostasis by detecting a change in the body and triggering a response that reverses that change, bringing the system back to its normal state (set point).
16
Q
How do endocrine systems maintain homeostasis?
A
Endocrine systems maintain homeostasis by releasing hormones that regulate body functions like metabolism, growth, and fluid balance, adjusting these processes in response to internal changes.
17
Q
Homeostasis - blood glucose after meal
* how is it before?
* what increases glucose
* what decreases glucose
A
- glucose low before meal
- Glucagon will increase glucose (esp after eating a meal)
- glucose too high - insulin decreases it in the blood
18
Q
How is glucose & insulin an example of negative feedback?
A
If glucose too high - send insulin to lower
If glucose too low - send glucagon to inc it
19
Q
What happens if beta cells are damaged?
A
If no beta cells then there will be no insulin produced.
This means a rise in glucagon won’t be stopped bc insulin not working. HYPERGLYCEMIA
20
Q
What happens with compromised glucagon production?
A
Not enough glucagon means not enough glucose release. This means insulin keeps coming in but nothing to balance it so it gets too low. HYPOGLYCEMIA
21
Q
What are sensors? Ex
A
Detects changes in variable being regulated
* temperature sensors in hand
22
Q
What are processors? Ex
A
compares level of variable to set point established in body ideal
* brain
23
Q
What are effectors? Ex
A
adjusts/corrects output of variable to bring it to ideal set point range
* shiver, put on coat, etc
24
Q
What role does the hypothalamus play in homeostasis?
A
sensor, processor, effector
* regulates many homeostatic functions
25
What role does the pituitary play in homeostasis?
sensor and effector
* senses hormones from hypothalamus, circulation, peripheral tissue
26
What are the two ways the hypothalamus can regulate the pituitary gland?
The hypothalamus regulates the pituitary gland in two different ways, depending on whether it's the anterior or posterior part of the pituitary.
27
What is the anterior (front half) pituitary?
* what controlled by/how communicate?
* is it innervated?
Makes and releases its own hormones
* Controlled by hormones from the hypothalamus that arrive via blood vessels (the hypophyseal portal system)
* NOT innervated by the hypothalamus
28
What hormones does the anterior pituitary release?
FSH, LH, ACTH, TSH, GH, PRL
29
How does the hypothalamus communicate with the anterior pituitary?
Through the hypophyseal portal system which is a special set of blood vessels that connects the hypothalamus to the anterior pituitary
* hypothalamus releases hormones (GnRH, TRH, CRH, etc) that travel through the portal to signal to the anterior pituitary to make and release its own hormones into the bloodstream.
30
Another name for anterior pituitary?
Pars Distalis
31
Another name for posterior pituitary?
pars nervosa
32
What is the posterior (back half) pituitary?
* how communicate? / is it innervated?
does NOT make its own hormones. Stores and releases hormones made by the hypothalamus (like oxytocin and vasopressin)
* it IS indeed innervated by the hypothalamus so the neurons in the hypothalamus that send their axons (nerve fibers) directly into the posterior pituitary.
33
What hormones does the posterior pituitary release?
Oxytocin and Vasopressin
34
What does the posterior pituitary do with the hormones it receives?
Where does all that happen - 2 placss
The hypothalamus makes the hormones in special neurons that extend down to the pituitary. The pituitary stores them in nerve endings. When it’s time to release them, those nerve endings release the hormones at neurovascular junctions → straight into the blood.
35
EXAMPLE OF ALL:
* Processor:
* Sesnsor:
* Effector:
Processor: Hypothalamus
Sensors: Hypothalamus and Pituitary
Effectors: Hypothalamus, Pituitary, Testes
36
What is the Hypothalamus-Pituitary-Gonad (HPG) Axis
a hormonal system that regulates the production of sex hormones, like testosterone, in the male reproductive system.
37
What is GnRH? What do
GnRH is a hormone made by special neurons in the hypothalamus. It acts as the starter signal for the entire reproductive hormone system.
GnRH is released in pulses into the hypophyseal portal system
38
Where does GnRH travel to based on this picture? What happens then?
To the anterior pituitary via the hypophyseal portal system. The anterior pituitary responds to GnRH by releasing LH and FSH into the bloodstream.
39
Once the anterior pituitary releases LH and FSH, where does it go?
These two hormones go on to stimulate the testes (or ovaries in females) to make sex hormones like testosterone, estrogen, and progesterone.
40
What kind of feedback loop does the HPG axis follow?
primarily works through negative feedback:
When testosterone (or estrogen/progesterone in females) levels are high, they send a signal/feedback back to the:
Hypothalamus → to reduce GnRH THEN to the Pituitary → to reduce LH and FSH
41
What are gonadotropins?
LH and FSH
called gonadotropins because they act on the gonads (ovaries in this diagram).
42
Once LH and FSH travel through the bloodstream to the ovaries what do they stimulate the ovaries to do?
Grow and mature follicles (those small circles in the ovary part of the diagram).
Produce estradiol (a type of estrogen) and progesterone.
43
Explain rq how the HPG axis works
hypothalamus releases GnRH which travels through hypophyseal portal to anterior pituitary. Then LH/FSH are released to gonads. Gonads respond by releasing their respective hormones. The primary hormone sends negative feedback back to hypothalamus to decrease GnRH.
44
Primary hormone for ovaries & testes?
Ovaries: estradiol
Testes: testosterone
45
What happens if you remove the ovaries?
When you remove the ovaries (oophorectomy), estrogen and progesterone drop. These hormones normally suppress LH and FSH through negative feedback.
So without them, the brain thinks there's not enough, and LH and FSH levels rise.
46
What happens if you replace ovarian steroids?
If you replace ovarian steroids (like estrogen/progesterone), LH and FSH go back down because the brain senses the hormones again and negative feedback is restored.
47
What are steroid hormones?
* what type of solubility?
* can it be converted? ex?
a type of hormone made from cholesterol
* lipophilic so they can pass through LIPID membranes
* can be converted into other steroids (testosterone convert to estrogen)
48
What does production depend on?
Depends on the enzymes present in the gland (like the ovaries or testes) bc they control the process of turning cholesterol into the specific hormone needed.
49
What are peptide/glycoprotein hormones
* how long live for
* what regulates its release
Hormones made of amino acids (the building blocks of proteins). basically short chains of proteins that act as chemical messengers in the body.
* short half life - break down quickly
* hypothalamus regulates release
50
What does production of peptides depend on?
The body makes them by expressing specific genes that code for the hormone. If the gene isn’t turned on (expressed), the hormone isn’t made.
ex:
* if need to make GnRH - the GnRH gene needs to be turned on in the hypothalamus then cell reads this and builds GnRH peptide
51
Ex of peptides vs steroids
steroids:
* made from cholesterol: estrogen, testosterone, progesterone
peptides:
* made up of amino acids: GnRH, LH, FSH
52
What are progestins? key hormone?
steroid hormones that help prepare and maintain the uterus for pregnancy. (C21)
Progesterone
53
What are Androgens? key hormone?
steroid hormones that control the development of male traits and are also precursors to estrogens (C19)
Testosterone
54
What are Estrogens? key hormone?
steroid hormones that promote the development and regulation of the female reproductive system and secondary sex characteristics (C18)
Estradiol
55
Whats the order in which Testosterone is produced?
Begin with Cholesterol which gets converted to progestins (progesterone) which then goes through more conversions to get to androstenedione where testosterone can be produced.
56
Whats the order in which estradiol is produced?
Begin with Cholesterol which gets converted to progestins (progesterone) which then goes through more conversions to get to androstenedione where testosterone can be produced.
FROM HERE the aromatase enzyme converts testosterone into estrogens such as estradiol
57
What is the purpose of aromatase?
This enzyme is responsible for converting androgens like testosterone (C19) into estrogens (C18). It essentially removes a carbon and aromatizes the A ring. This step is irreversible.
Amount of aromatase in gonads
determine whether more androgens or estrogens are produced
58
What converts one steroid into another?
Steroidogenic enzymes
59
Why do lipophilic steroids need to be carried through blood?
Lipophilic (fat-loving) steroids like testosterone do not dissolve easily in blood, which is mostly water. So, they must be carried/stabilized by carrier proteins in the blood.
60
What does bioavailable testosterone mean?
The portion of testosterone that your body can actually use to do stuff and bind to receptors because they are either free or loosely bound
There are 3 forms of testosterone: 1 - Free/unbound, 2 - loosely bound to albumin, 3 - SHBG bound (tight bound bc high affinity for steroids)
61
What does it mean if more testosterone is SHBG (sex hormone binding globulin) bound?
You have less bioavailable testosterone because it is tighly bound and is not free to do its job.
Women have more SHBG bound testosterone bc they dont need it
62
What does labile mean?
It is albumin-bound testosterone (so loosely bound and is bioavailable)
63
How are lipophilic steroids carried through the blood?
Lipophilic steroids like testosterone are carried in the blood by binding to carrier proteins, mainly SHBG and albumin (generic carrier protein).
64
What superfamily do steroid hormone receptors belong to?
The nuclear receptor superfamily. These proteins live inside cells and directly affect gene expression.
Each receptor has different domains (sections) with specialized roles:
65
What happens after a steroid hormone binds to its receptor?
The receptor-hormone complex moves into the nucleus, binds to DNA, and regulates gene expression.
66
What is the function of the DNA Binding Domain (DBD)?
DBD binds to specific DNA sequences to regulate gene expression of that hormone AND THEN cause changes within cell
* specificity for DNA targets
* This part recognizes and attaches to specific DNA sequences in the nucleus. It guides the receptor to the right spot on the DNA to regulate gene expression.
67
What are DNA target sites called?
Hormone response element
* ex: androgen response element
68
What is the function of the Ligand Binding Domain (LBD)? ex?
LBD binds the steroid hormone (ligand) to its receptor— this activates the receptor.
* androgen receptor binds to androgen (not so much estrogen/progesterone)
69
How do DBD and LDB work together?
The ligand binds to the ligand-binding domain which activates the protein, then the DNA-binding domain moves to the nucleus, attaches to specific DNA, and changes gene expression.
* If the ligand only binds to androgen, then the DNA site only binds the hormone response element specific to androgen too
70
What does it mean that steroid receptors are nuclear receptor transcription factors
—they help turn certain genes on or off.
71
Steps of steroid receptors functioning as nuclear receptor transcription factors?
* speed of process?
1) The hormone or ligand enters the cell (cytosol)
2) Inside the cytosol, the hormone encounters its specific receptor and binds to it
3) Once bound, the ligand/receptor complex is formed. This complex may then move into the nucleus. Translocation to nucleus can't happen until hormone is bound
4) Ligand-receptor complex allows DNA binding domain on receptor to attach to DNA to causes changes in cell
* slow process
72
What domain allows the receptor to bind the hormone?
The ligand-binding domain.
73
What domain allows the receptor complex to bind DNA?
The DNA-binding domain
74
What does GnRH do?
* made up of how many amino acid and synthesized where?
Controls release of gonadotropins (LH and FSH) from the anterior pituitary
* 10 amino acids, synthesized in the hypothalamus by GnRH neurons
75
How is GnRH released?
in pulsatile matter
76
What does LH do? (2 things)
* Stimulates testes and ovaries
to make progestins and androgens
* Stimulates ovulation
77
what does FSH do
- Stimulates ovaries to make estradiol
- Stimulates testes to make factors that support spermatogenesis
78
what does HCG do?
- Produced in pregnancy by embryo and placenta
- Stimulates the corpus luteum to produce progesterone early in pregnancy
79
What do beta subunits do for hormones?
Even though some hormones share the same alpha subunit, the beta subunit is what makes them act differently in the body.
80
How does G-Protein Coupled Receptors (GPCRs) work for peptide and glycoprotein hormones?
1) The receptor (GPCR) located on the cell membrane binds to hormones (like LH, FSH, TSH) outside the cell.
2) The G-protein located on the inside of the membrane gets activates when hormone/ligand binds to receptor. Alpha separates and causes signaling cascade.
3) The effector is the target that the activated G protein interacts with. It triggers the production of 2nd messengers to cause change.
RAPID SIGNALING
81
Cellular effects of G-protein coupled receptor signaling?
GPCRs help cells respond quickly or slowly to signals like hormones by producing second messengers that trigger a chain reaction inside the cell and alter intraceculler signaling.
82
Steroid hormones
* response speed
* how diffuse?
* how make hormone
* how converted
* slow response
* diffuse freely
* hormone metabolized from another chemical
* converted by enzyme
83
Peptide hormones
* response speed
* how diffuse?
* how make hormone
* fast response
* needs a transporter
* hormone is encoded by a gene (DNA sequence)
