Chapter1 Flashcards
How does the endocrine system’s cells communicate?
Uses chemical messengers to relay information and instructions btwn cells
Difference btwn nervous system and endocrine system
NS: uses electricity and chemicals to send a fast message
Has a specific effector organ
ES: uses hormones
Effects many effector organs (high to all muscles)
Is slower and longer lasting
Difference btwn neurotransmitters and hormones
NT: are released by neurons
Talk to effector organs (i.e ACh)
Only work if there is a receptor in cell inhibitor =GABA
Hormones: are released by endocrine glands
Released in blood
Need receptors for it to affects the cell
How does negative feedback play a role in hormones?
Responses to changed body condition
If high or low from normal level
Signal tells body to make changes that will bring body back to normal level
Once body goes back, the signal is turned off
3 types of intercellular communication
Direct, parachute, endocrine
Direct communication
Exchange of ions and molecules btwn gap jxns
2 cells of the same type
Cardiac cells
Paracrine communication
Uses chemicals signals to transfer info
Within single tissue
Most common form
Endocrine communication
Release chemicals (hormones) into bloodstream Needs a receptor
3 types of hormones
Amino acid derivatives
Peptide hormones
Lipid derivatives
Free hormones
Remain functional for less than 1 hour
Diffuse out of blood stream and bind to receptors on target cells
Thyroid and steroid hormones
Remain in circulation much longer
Enter bloodstream
Lipid soluble hormones
Glucocorticoids Estrogens Androgens Thyroid hormone (T3) Calcitriol
Diffuse across the plasma membrane to reach receptor proteins
Hormones that aren’t lipid soluble
Prolactin ACTH Growth hormone ADH Peptide hormones ANP ANF Insulin Leptin Unable to penetrate plasma membrane
Hormone receptor
Protein molecule to which particular molecule binds strongly different tissues have different combinations of receptors
Hormones and plasma membrane receptors
Bind to receptor in plasma membrane
Cannot have direct effect on activities inside target cell
Use intracellular intermediary to exert effects
Second messengers
Cyclic-AMP --> derivative of ATP Cyclic-GMP --> derivative of GTP Calcium ions
Amplification
Takes something small and makes it bigger
Binding of a small number of hormone molecules to membrane receptors
Leads to many second messengers in cells
Magnifies effect of hormone on target cell
Down regulation
Presence of hormone trigger decrease in number of hormone receptors
Less sensitive and receptors are all filled up
Up-regulation
Absence of a hormone triggers increase in number of hormone receptors
More sensitive dreams
Receptors are available
What hormones do extra cellular receptors bind to?
No lipid soluble protein hormones
What hormones does intracellular receptors bind to?
Lipid soluble
Mechanisms of hormone action
Bind to DNA and make messenger RNA
Endocrine reflexes
Fxnal counterparts of neural reflexes
Mostly negative feeback
What riggers endocrine reflexes? Explain each
Humoral stimuli: changes in compositions for extracellular fluid
Hormonal stimuli: arrival or removal of specific hormone
Neural stimuli: arrival of NT at neuroglandular jxn