Endocrine System Flashcards
What are the 4 similarities/differences between the Nervous System & Endocrine System?
Nervous System
- Action potentials along axons triggering neurotransmitters at synapses
-Fast process, brief duration, specific targets
- EX: Muscle Movement
Endocrine System
- Release hormones into blood throughout body
- Slow process, longer duration, widespread
BOTH WORK TO MAINTAIN HOMEOSTASIS
3 Main Functions of Hormones
1) Helps regulate physiological functions
2) Growth & Development
3) Reproduction
What do hormones help regulate? (6)
1) Extracellular fluid (Hydration)
2) Metabolism (energy use)
3) Biological clock
4) Contraction of cardiac & smooth muscle
5) Glandular secretion
6) Some immune functions
Exocrine vs Endocrine glands
Exocrine glands
-secrete into ducts & empty into body cavities or surface
-sweat, sebaceous, mucous, & digestive glands
Endocrine glands
-secrete hormones into bloodstream
Which organs release hormones as their primary function (endocrine glands)? (5)
Adrenal Gland
Parathyroid
Pituitary Gland
Pineal Gland
Thyroid
Which organs release hormones as their secondary function? (9)
Heart
Hypothalamus
Kidneys
Pancreas
Ovaries
Testes
Thymus
Stomach
Small Intestine
Target Cells…
- Any cell with a receptor that “listens” for a hormone
- Most receptors on cell surface (some inside cell ex: fat soluable hormones such as estrogen & testosterone)
-Variety in receptors causes many effects from 1 hormone - Receptors constantly synthesized & broken down
Receptor Down-regulation vs. Up-regulation
Down-regulation
- Decreased # of receptors due to excess hormone
- Receptors undergo endocytosis & are degraded
- Decreases sensitivity to hormone
-EX: Types II Diabetes (make too much insulin so body decreases # of receptors so not so sensitive to hormone)
Up-regulation
- Increased # of receptors due to lack of hormone
- Increases sensitivity to hormone
Circulating vs. Local Hormones
What are the 2 types of Local Hormones?
Circulating- secreted into blood & spread throughout body
Local- Histamine
- Paracrine- Act on neighboring cells
- Autocrine- Act on same cell secreting hormone
- DO NOT ENTER BLOODSTREAM
What are the 2 Chemical Classes of hormones?
Lipid Soluble Hormones (BIG)
-Steroids
-Thyroid hormone
- Nitric Oxide
-Eicosanoids
- ALL “-ONE” or “-GEN”/sex related hormones
Water Soluble Hormones (SMALL)
- Amines
- Protein
-Peptides
Lipid Soluble Characteristics (5)
- “Love” lipids (fats) & “hates” water (Hydrophobic)
- Non-polar molecule
- Diffuses through cell membrane
- Receptor WITHIN cell
- No 2nd messenger (hormone directs actions)
Water Soluble Characteristics (5)
- “Love” water & “hates” lipids (fats) (Hydrophilic)
- Polar molecules
- Can’t diffuse through cell membrane (since cell membrane is made of lipids)
- Receptor ON cell surface
- Needs 2nd messenger (another molecule delivers message for hormone)
What kinds of changes within the cell can occur from hormones? (3)
1) Cause cells to make things (synthesize new molecules)
2) Change permeability of membrane (to allow more molecules in, EX: Insulin causes receptors to allow more glucose in to decrease amount of sugar in blood)
3) Alter rates of reactions
Lipid Soluble Hormone Action Sequence (5)
Always turn on or off gene expression by regulating transcription
1) Diffusion through membrane
2) Binds to receptors
3) DNA transcribed into mRNA
4) mRNA –> protein synthesis at ribosomes
5) new protein alters cell physiology
Water Soluble Hormone Action Sequence (7)
Doorbell Method
1) Hormone binds to receptor
2) Receptor stimulates G protein inside cell
3) That activates Adenylate cyclase
4) Adenylate cyclase converts ATP into cyclic AMP (cAMP) aka 2nd messenger
5) cAMP activates protein kinases (enzymes)
6) Protein Kinases triggers physiological response
7) Phosphodiesterase inactives cAMP
