Hormones Flashcards
Learn function, target tissues and pathologies
Growth Hormone
Secreted from the pituitary
Somatotrophins
Production increases at night and during exercise
Function: stimulate cell growth and division
Target: almost every tissue except bone
Why is GH not effective on bone?
Bone does not have GH receptors.
GH acts on liver inducing elevated production of IGF - 1
IGF-1
Not produced by all cells - especially bone
Involved in protien synthesis and growth
IGF-2
Same family as IGF- 1
Unlike IGF-1: is produced in the fetus
Produced by the liver.
- can also be produced in ther CNS after birth - adult
Once born liver switches from producing IGF-2 to IGF 1
Types of Neurotrophins
1) Nerve Growth Factor
2) Brain Derived Neurotrophic Factor
NGF
Nerve Growth Factor
•utilizes tyrosine kinase system
•helps with nerve growth
• produced by muscle
Target = nerve cells
- anti apoptotic
- in cases of damage increased production allows for repair/ re-innervation of tissues
- NGF can also come from other Nerve cells and impact DNA
- required for initial growth and development of fetus
BDNF
• Produced in the brain the brain
• development of CNS in fetus
• similar fnxn as NGF
• Anti apoptotic
• involved in making new dendritic & axon connections
•production stimulated by aerobic activity
- i.e. exercise
Erythropoietin
Epo Tyrosine kinase system Synthesized in kidney Release is simulated by: 1) drop in red blood cell count 2) decrease in oxygen carrying capacity Function: - increase red blood cell synthesis - helps erythroblast maturation into erythrocytes Target: - bone marrow
Hormones involved in wound healing
PDF - platelet derived growth factor
EGF - epidermal growth factor
FGF - fibroblast growth factor
Angiogenin
Thyroid Hormone (TH)
• precurser:
- Thyronglobulin
TH = utilized by almost every cell in the body
- has 2 b modefied to T3 to be active
TRH from hypothalamus → Anterior Pituitary → TSH → Thyroid gland
↳ T4 & T3 released
• TH =modefied AA
• same Mechanism as steriod hormone
• TH does not create metabolism. It only increases or decreases metabolic function
• negative feedback loop
• TH also goes to mitochondria = increases ATP Synthesis
Effects of TH on other hormones
• GH
- allows for GH production
• N G F
- direct effect on NGFsynthesis
- effecton growth & synthesis of CNS during Week 1
- initial growth= dependent on maternal TH
- TH Synthesis = Iodine dependent
- prolactin
TH release
1) Circadian rhythm
↳ release of TH decreases at night & increases during the day
2) Ambient Temp.
a)warm/hot= decreases TH release
b) cold= increases TH release
3) Exercise :
= increases ATP ⇒ increases TH release
4) Diet
• big meal = increases TH release
↳ allows for utilization of nutrients
- diet/fasting = decrease in BMR
↳ conserve energy
↳ think starving fish exp.Pathophysiology of TH
Hypo secretion :
1) Hashimotos:
- developement of antibodies to thyroid cells
= Thyroid cell distruction
= most common in women age 20-40
Symptoms:
- lethargy
- constantly cold
- fluid pouches under eyes
• Treatment :
- Levothyroxin (T4)
↳ start dose low, increase slowly until feeling normal
Pathophysiology of TH
__ _ _ _ deficiency
- Lethargy
- weak
- tired
No negative feedback
> increase in TSH & TG
⇒ accumulation goiter
Iodine deficiency
Hyper thyroidism
Graves Disease = long Acting Thyroid Stimulation (LAT) ↳ Prevalent in women ↳ AB binds 2 TSH receptors = increase in TH secretion - increase in BMR ↳ Hot all the time/sweaty - usually very thin -exopthalmus = fat deposit Behind the eyes= eye bulging Treatment= Radio Active Iodine (RAI) ↳ accumulates in thyroid gland ↳ degredation of RAI = death of colloid follicles too much= thyroid gland distruction ⇒ use levethyroxin to rebuild/replace Thyroid Gland
Thyroid Cancer
Primarily in women ↳early to mid 30's - tumors accumulate Ca Treatment: thyroid gland removal -P laced on Levethyroxin 2 compensate 4 Lack of Thyroid Gland
Calcitonin
decreases blood Ca by putting it into bone
- Stimulates osteoblasts
- Can also stim (progenitors) clast → blast
- Source= thyroid - Clear cells
↳release= Stim when blood Ca increases
Calcium
- One of the MOST important minerals in the body
1) maintain membrain potential
↳ important in Nerve impulse ability
2) Blood Clotting cofactor
↳ cofactor for many enzymes
3) essential for membrane Structure & fusion
Osteoprogenitors
1) osteoblasts
2) osteoclasts
Osteoblasts
build Ca
- increase Ca deposition in the bone
- Can beconverted to osteoclasts
↳ osteoclasts cannot be converted back to osteoblast
Osteoclast
Cleave
- pull Ca out of bone & put it into blood
> increase blood Ca levels
Bone Remodeling
moving Ca from one part of bone to another - or into blood
- prevents bone from growing out (width)
↳ ensure bone grows length wise
