Final: Animal Hormones Slides Flashcards
Endocrine system structure and function
Major communication system, consists of many glands located throughout body
What do glands do?
Release hormones that act as chemical messengers
How do hormones get to their target cell(s)?
Use the blood as a medium of transport (long distance travel)
Difference between major and mixed/secondary/accessory glands
Only function of major glands is to release hormones; mixed glands release hormones but have other functions
Name the major glands (8)
Hypothalamus, pineal, pituitary, thyroid, parathyroid, adrenal glands, pancreas, gonads
Name the minor glands (5)
Thymus, heart, stomach, kidneys, small intestine
What does a receiving cell need to respond to a hormone?
the right (matching) receptor
Main chemical (structural) difference between peptides and steroids
Peptides: amino acid sequences; large; cannot permeate into cell
Steroids: modified from cholesterol; can permeate into cell
Receptor location for peptides and steroids
Extracellular for peptides (on cell membrane), Intracellular for steroids (inside cell)
How are peptides and steroids synthesized?
Peptides made in rough ER, ribosomes, and Golgi
Steroids made in smooth ER and mitochondria
How are peptides and steroids secreted?
Peptides secreted by exocytosis
Steroids secreted by simple diffusion (they’re lipophilic so can cross the membrane)
Steps in peptide synthesis
- Start as preprohormones in ribosomes and RER
- Get converted to prohormones (packaged in Golgi as prohormones)
- Become actual active hormones once released
How do peptides and steroids travel in the blood?
Blood is mostly water: Peptides don’t need carrier protein but steroids do (bc lipids don’t mix with water)
What is the third class of hormones?
Amines, which are modified single amino acids
Mechanisms of steroid action on target cell(s)
Binds to receptor inside cell (could be in nucleus or cytoplasm) - hormone receptor complex binds to DNA on HRE - activates/deactivates genes - affects mRNA and then protein synthesis - physiological response
What is the hormone response element (HRE)?
Binding site for hormone receptor complex on DNA
Mechanisms of peptide action on target cell(s)
Bind to extracellular receptor - activate G protein - activate adenylyl cyclase and cAMP synthesis - start protein kinase cascade - brings about cellular response
Main difference in effect of steroids and peptides
Peptides are faster than steroids bc they mostly activate local responses in local proteins, but steroids cause major changes bc they mess with DNA
Mechanisms of hormonal secretion
Humoral, neural, hormonal
How does the humoral mechanism work? Give an example.
Measures some factor in the blood
Example: always need homeostatic level of Ca2+ - what if calcium levels are low?
-Receptor and control center: parathyroid gland
-Parathyroid gland releases parathyroid hormone (PTH) to restore calcium levels to normal (Ca2+ comes from bones)
How does the neural mechanism work? Give an example.
Controlled by nervous system
Example: Input from sympathetic NS causes release of epinephrine (amine) from adrenal medulla (in adrenal gland); has lots of target cells
How does the hormonal mechanism work?
Gland releases hormone A, which triggers release of hormone B, and so on until response achieved
Another name for the hypophysis
Pituitary gland
Importance of hypophysis
Produces 8 hormones that are essential to survival
Structure of hypophysis and what are parts made of
Anterior pituitary (adenohypophysis; in front, made of epithelial tissue) and posterior pituitary (neurohypophysis; in back, made of neurons)
Hormones released by neurohypophysis and their target(s) (2)
- Vasopressin/ADH (anti-diuretic hormone), targets kidney tubules
- Oxytocin, targets uterus and mammary glands
Function of neurohypophysis
Paraventricular nucleus and the supraoptic nucleus of the hypothalamus synthesize hormones that are stored int he terminals for later release
Function of ADH
Minimize water loss
Function of oxytocin
Released in females during labor (induces smooth muscle contraction) and lactation (release of milk); function in males not exactly known
Hormones released by adenohypophysis (6)
- Follicle stimulating hormone (FSH) and luteinizing hormone (LH)
- Thyroid stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Prolactin (PRL)
- Growth hormone (GH)
Function and targets of follicle stimulating hormone (FSH) and luteinizing hormone (LH)
FSH targets testes in males, LH targets ovaries in females; produce gametes and sex hormones
Function and target of prolactin (PRL)
Targets mammary glands; produces milk
Function and target of thyroid stimulating hormone (TSH)
Targets thyroid; increases rate of metabolism
Function and target of adrenocorticotropic hormone (ACTH)
Targets adrenal cortex; helps body cope with stress
Function and target of growth hormone (GH)
Targets muscles, liver bonds (almost everywhere); promotes growth
What controls the anterior pituitary and how?
Hypothalamus, by secreting hypophysiotropic hormones (releasing hormones)
Hormones released by hypothalamus (6)
- Dopamine (DA)
- Gonadotropin releasing hormone (GnRH)
- Thyrotropin releasing hormone (TRH)
- Corticotropin releasing hormone (CRH)
- Growth hormone releasing hormone (GHRH)
- Somatostatin (SS)
Which hypothalamus-released hormones are negative and which are positive controls?
Negative: dopamine (DA) and somatostatin (SS)
Positive: gonadotropin RH (GnRH), thyrotropin RH (TRH), corticotropin RH (CRH), growth hormone RH (GHRH)
Which hormone does dopamine (DA) regulate?
Prolactin (PRL); negative control
Which hormones does gonadotropin releasing hormone (GnRH) regulate?
Follicle stimulating hormone (FSH) and luteinizing hormone (LH); positive control
Which hormone does thyrotropin releasing hormone (TRH) regulate?
Thyroid stimulating hormone (TSH); positive control
Which hormone does corticotropin releasing hormone (CRH) regulate?
Adrenocorticotropic hormone (ACTH); positive control
Which hormone do growth hormone releasing hormone (GHRH) and somatostatin (SS) regulate?
Growth hormone (GH); GHRH is positive and SS is negative
Steps in hypothalamic-pituitary-adrenal axis when cortisol levels are low
- Hypothalamus secretes CRH
- Anterior pituitary releases ACTH
- Adrenal cortex releases cortisol
- Cortisol increases plasma concentration of glucose, fatty acids, amino acids
Functions of cortisol (7)
- Increase fuel (glucose) availability to brain (good)
- Gluconeogensis: convert amino/fatty acids to glucose (good)
- Lypolytic hormone: induces fat breakdown (good)
- Anti-inflammatory effects: suppresses immune system function (bad)
- Impedes memory function (bad)
- Proteolytic hormone: breaks down proteins (bad)
- Prevents growth (bad)
What is stress in the body?
Threat to homeostasis
