KIN 103 (Chp: 22) Flashcards
What are the two main functions of the endocrine system?
MAINTAIN homeostasis
INTEGRATE nervous and immune system with most bodily systems
Problem with endocrine system (Hypersecretion of hormone)
Hypersecretion of hormone (tumours, exogenous source/drugs)
Problem with endocrine system (Hyposecretion of hormones)
Hyposecretion (atrophy or problem with secreting gland)
Problem with endocrine system (receptor defects)
Receptor or 2nd messenger defect (down-regulation of receptor, problems with 2nd messenger system)
Insulin (What does it do?)
- Insulin promotes glucose uptake and inhibits fat breakdown
- Insulin facilitates the opening of channels to let glucose in
What does glucose do in adipose tissue?
- In adipose tissue glucose comes in and becomes pyruvate
In muscle tissue what does glucose do?
- In muscle tissue glucose comes in and becomes pyruvate that gets used for energy
Glycemic index (GI) (What is it?)
Glycemic index (GI)
- higher number foods are better for sporting events
- Only useful if you eat the food in question alone
- (combining foods this does not work)
What do hormones control?
Hormones control:
- Growth and development
- Metabolism
- Regulate internal environment
○ H20, ions, electrolytes, temperature
- Reproduction
Hormones act on cells by controlling what?
Hormones act on target cells by controlling:
- Rate of enzymatic reactions
- Transport of ions or molecules across cell membranes
- Gene expression and protein synthesis
Why is solubility important in Hormones?
Why is solubility important?
- Receptor location (inside or out)
- Transport through plasma (free or bound)
- Length or action (long or short)
Hormone messengers (3 kinds)
Hormone messangers
- Peptides and proteins
○ Lipid soluble
- Steroid
○ Lipid soluble
- Amines
○ Lipid soluble (thyroid hormones)
○ Lipid insoluble (catecolamines)
Peptides and AMINE (characteristics)
- Made in advance stored in secretory vesicle
- Gets dissolved in plasma
- Half life is short
- Receptors on cell membrane
- Works in second messengers
- E.g.: insulin
Steroid (Characteristics)
- Synthesized on demand
- Bound to carrier
- Half life is long
- Receptors in cytoplasm/nucleus
- Works in gene synthesis
- androgen, estrogen, cortisol
How does transcription and translation work in hormone synthesis?
- Enzymes in the Endoplasmic reticulum (ER) chop off the signal sequence creating an inactive prohormone. The prohormone passes from the ER through the Golgi complex
- Enzymes chop off the active reportions of the now active hormone and it remains in the secretory vesicle with other fragments ready for secretion
What do peptides do when they reach their receptor?
This occurs through amplification (the upping in size of second messengers
Steroids (where are they synthesized)
Glands like the adrenal cortex, gonads, placenta
Aromatase (what does it do?)
It is used to convert testosterone to estradiol
5a-reductase (What does it do?)
It is important for development of secondary sex characteristics
Is cholesterol a hormone?
no it is not in itself
Steroid hormones in synthesis (step 1-3)
- hydrophobic steroids are bound to plasma protein carriers. Only unbound hormones can diffuse into the target cell
- Steroid hormone receptors are in the cytoplasm or nucleus
2a. some steroids also bind elsewhere to create rapid cellular responses - the receptor hormone complex binds to DNA and activates or represses one or more genes
Single amino acids (What are they made from?)
- Made from either tryptophan or tyrosine
○ (tyrosine leads to catecholamines)
○ Epinepherine from adrenal gland
○ Norepinepherine from neurons
§ These are both part of the stress response
Neurohormones (What are they?)
- Neurohormones (secreted by neuron into blood)
○ Catacholamines from adrenal medulla
○ Posterior pituitary hormones (like vasopressin/ADH and oxytoxin)
○ Hypothalamic neurohormones (most are trophic)
Long loop feedback (what is it?)
- Peripheral endocrine gland produces hormone that suppresses secretion of anterior pituitary and hypothalamic trophic hormones
- Most dominant feedback mechanism
Short loop feedback
- Pituitary hormone suppresses hypothalamic trophic hormone
- Secondary feedback mechanism
Posterior pituitary
- The posterior pituitary stores and releases two neurohormones
○ Neural tissue
○ Stores hormones produced in the hypothalamus
○ When hypothalamus is stimulated, posterior pituitary secretes two neurohormones: vasopressin, ADH, and oxytocin
Vasopressin (Where is it secreted by?)
By the posterior pituitary
- increases water conservation
- alters permeability of the collecting duct cells
Anterior pituitary
The anterior pituitary secretes six hormones
- Adrenocorticotrophic (ACTH), prolactin (PRL) etc
- Regulated by hypothalamic hormones
○ Somatostatin (SS) = growth hormone inhibiting hormone
Trophic hormones (What are they?)
- Trophic hormones stimulate secretion of other hormones
Corticotropin-releasing hormone (What does it do?)
- Corticotropin-releasing hormone causes the release of ATCH from the anterior pituitary. This causes the release of cortisol from the adrenal cortex (this results in long loop negative feedback