Ch.9: Endocrine (2/17) Flashcards
Electrical signals
-fast quick & short lives reponses (sec,msec - depends on type of hormone or AP) (eg. muscle movement
-generated by changes in cell membrane potential that triggers response
characteristics of chemical signals
-called hormones
-generated slowly, slower action, effects are long lasting (min,hrs,days)
-produced by endocrine glands
endocrine (word breakdown)
endo=internal
krinein=distinguish bw 2 things
hormones travel via
blood
neurotransmitters
chemical signals that allow for neutron to neutron communication
What ions are present inside the cell at rest?
Potassium (K+), phosphate, proteins, amino acids (all negatively charged)
What ions are present outside the cell at rest?
Sodium (Na+), Calcium (Ca2+), Chloride (Cl-) (positively charged).
What is the resting membrane potential of a cell?
-70 mV (cell is polarized, inside is negative).
What happens during depolarization of a cell?
-Sodium (Na+) enters the cell (ca2+ also)
-making the inside more positive (potential difference shifts from -70 mV to a more positive value).
What does the sign of the membrane potential represent?
The sign indicates the condition inside the cell (e.g., -70 mV means the inside is negative).
What is an action potential (AP)?
-Complete reversal of polarity; inside becomes positive relative to outside,
-self-propagating (once an action potential starts, it continues without needing additional stimulation)
-travels long distances without fading (signal stays strong as it moves along the neuron, without decreasing in strength)
What causes depolarization and the generation of an action potential?
Sodium (Na+) and/or Calcium (Ca2+) entering the cell.
How is repolarization achieved after depolarization?
Potassium (K+) exits the cell to return the membrane potential back to -70 mV.
What is hyperpolarization?
When the cell becomes more negative than the resting membrane potential (e.g., after excessive K+ exit or chloride (Cl-) entry).
graded potential
A change in membrane potential that does not fully depolarize the cell, can be depolarizing or hyperpolarizing, and fades with time and space.
difference between depolarizing and hyperpolarizing graded potentials?
Depolarizing: Makes the cell less negative (e.g., from -70 to -50 or -20 mV).
Hyperpolarizing: Makes the cell more negative (e.g., from -70 to -90 mV).
EPSPs (Excitatory Postsynaptic Potentials)?
Depolarizing signals that excite the cell, leading to muscle contraction or neuron activation.
IPSPs (Inhibitory Postsynaptic Potentials)?
Hyperpolarizing signals, preventing muscle contraction or neuron activation.
What is the role of glycine in the cell?
Glycine binds to chloride channels, causing chloride (Cl-) entry (hyperpolarizing) and inhibiting the cell.
role of GABA (Gamma-Aminobutyric Acid) in the cell?
GABA is an inhibitory neurotransmitter that helps hyperpolarize the cell by binding with chloride (Cl-) channels, opening them to allow chloride ions (Cl-) to enter the cell. This influx of Cl- makes the inside of the cell more negative, inhibiting further action.
GABA a not GABA b
function & type of hormones?
-Chemical signals released from ductless glands
-Bind to specific receptors on or inside target cells
-Trigger a cellular response
Growth hormone, insulin, calcitonin, parathyroid hormone, androgens, estrogens.
neurohormones
-chemicals secreted by neurons synthesized by hypothalamus, GI tract, or nerves
-Released into the bloodstream in pituitary gland
-Travel to target organs
role of Antidiuretic Hormone (ADH)?
-neurohormone
-Regulates water balance and reabsorption in kidneys
-Prevents DIURESIS (water loss through urine)
ADH Present: Concentrated urine, less volume
ADH Absent: Diluted urine, large volume (Diabetes Insipidus)
What is the role of Oxytocin?
-neurohormone
-Stimulates uterine contractions (when giving labor)
-Stimulates milk letdown/ejection during breastfeeding