Anatomy and Phys Endocrine and NS Quiz Flashcards
Describe the homostatic control mechanism of the NS
- stimulus
- receptor detects vis sensory skin cells
- input of info (afferent pathway) to the control center
- info sent to efferent pathway and to an effector
- response of body is to return to homeostasis
describe the difference between the afferent and efferent pathway
SAME DAVE
afferent: signals delivered to CNS
efferent: signals delivered away from CNS
what are the 2 sub-categories of the peripheral NS
- sensory (afferent): sensory organs
- motor (efferent): combines voluntary and involuntary actions
what are the 2 sub-categories of the motor (efferent) pathway
- somatic (voluntary)
- autonomic (involuntary): parasympathetic (relax) and sympathetic (excite)
there are 2 main cells of the NS, what are they?
Neurons and neuroglia
neurons send and receive signals while neuroglia support this process.
name the Three General Types of Neurons
- Sensory Neurons: Transmit sensory information from receptors to the CNS.
- Interneurons: Process and relay signals within the spinal cord of the CNS.
- Motor Neurons: Carry signals from the CNS to effectors like muscles or glands.
what are the 3 properties of all neurons?
- excitable (receive signals)
- conductive (send signals)
- secretory (release NT)
define a nerve
a bundle of nerve fibers (axons) bound together by tissues
the bundle protects the axons when traveling long distances
describe how a signal travels down a neuron
Dendritic input and integration of incoming signals.
Action potential initiation if threshold is reached.
Rapid depolarization as sodium ions enter the neuron.
Propagation of the action potential along the axon.
Repolarization as potassium ions exit the neuron.
Refractory period to prevent immediate firing.
Propagation to axon terminals.
NT release into the synaptic cleft.
NTs bind to receptors of postsynaptic neurons.
Postsynaptic response: excitatory or inhibitory.
Integration of postsynaptic signals.
describe SAME DAVE
sensory - afferent
motor - efferent
dorsal- afferent
ventral- efferent
what is a ganglion
collection of neuronal cell bodies of the PNS. found in the dorsal root
(called nuclei in the CNS)
what are the 3 layers of the CONNECTIVE TISSUE SHEATHS OF PERIPHERAL NERVES
On the outside of each peripheral nerve, there is collagenous tissue: epineurium. Surrounding every fascicle within the nerve is the perineurium. Individual nerve fibers within the fascicles are embedded in endoneurium, which fills the space bound by the perineurium.
which voltage gates are slow and which are fast?
slow: Na+ inactivation and K+ activation
fast: Na+ activation
what is the toxin that prevents action potentials?
tetrodotoxin; found in fugu sushi. blocks NS cell signaling and can lead to flaccid paralysis
describe the signaling path through the peripheral nervous system.
Sensory Receptors detect stimuli.
Sensory Neurons Transmit signals to the CNS.
CNS interneuron processes information
Motor Neurons send signals to effectors
muscles/glands respond
describe a membrane potential, how it is maintained, and why it is important.
Membrane Potential: Voltage difference across a cell’s membrane.
Maintenance: Achieved through selective ion permeability, ion pumps, and leak channels.
Importance:
Essential for nerve and muscle function
Drives cell signaling (action potentials)
Maintains ion balance
describe the CNS vs the PNS
CNS: brain and spinal cord
PNS: all neurons sending signals to and from the body
explain how voltage-gated channels operate during an action potential.
Sodium Channels (Na+):
- Open: During depolarization (rising phase).
- Close: Shortly after opening (inactivation) and remain closed during repolarization.
Potassium Channels (K+):
- Open: During repolarization (falling phase).
- Close: Once the membrane potential returns to its resting state.
explain the concept of a threshold stimulus and the three phases of an action potential
- Depolarization: Membrane becomes positive. Na+ flows in
- Repolarization: Returns to resting state. Na+ gate closes, K+ finally opens and lets out K+
- Hyperpolarization: Briefly more negative than resting state.
*Return to resting potential (-70) until threshold (-55) is reached again
define what a myelinated neuron is and explain how myelination affects the transmission of an action potential
Myelinated neuron: a protective sheath called myelin around nerve fibers (axons) in the nervous system.
is composed of lipids (fats)
acts as an insulator and enhances the speed and efficiency of nerve impulses
helps neurons transmit signals more quickly and with less energy expenditure.
define tetanus
Prolonged, continuous muscle contraction without relaxation due to rapid and repetitive stimulation.
what are the different origins of the nerves in the parasympathetic NS vs the sympathetic NS
para: caudal end of the spinal cord by the brainstem (pons)
symp: many areas of the spinal cord
what are the different ganglia positions in the parasympathetic NS vs the sympathetic NS
para: close to where nerve originates in the spinal cord (more general)
symp: more distal and close to the organs that they innervate (more targeted)
what are the 5 mechanisms of cell signaling?
- contact-dependent (physically connect)
- paracrine (hormone diffuses into the environment and is picked up by surrounding cells– not specific)
- synaptic (release of NT)
- endocrine (hormone release into the bloodstream and travels distance to target cell)
- autocrine (sends signals to itself)
what is the overarching purpose of the endocrine system?
synthesize and secrete hormones to control lifetime processes (like growth) and maintains homeostasis
what is the purpose of endocrine glands
they secrete hormones into the extra cellular fluid (bloodstream)
- are ductless
- have no specific tubes, just travel in the body
- are made of epithelial tissue
What are the major endocrine glands?
gonads
adrenal
thyroid
parathyroid
pituitary
hypothalamus
pineal
thymus
pancreas
what hormone does the hypothalamus secrete?
production of ADH, oxytocin, and regulatory hormones
what hormone does the pituitary gland secrete?
anterior pituitary: ACTH, TSH, GH, PRL, FSH, LH, and MSH
posterior pituitary: release of oxytocin and ADH
what hormone does the thyroid gland secrete?
T4, T3, and CT
(thyroxine, triiodothyronine, and calcitonin)
what hormone does the thymus secrete?
(this organ undergoes hypertrophy during adulthood)
hormone: thymosins
what hormone do the adrenal glands secrete?
each adrenal gland is subdivided into:
- adrenal medulla: Epinephrine (E) and norepinephrine (NE)
- adrenal cortex: cortisol (stress), corticosterone, cortisone, aldosterone, anrogens
what hormone does the pineal gland secrete?
melatonin (sleep/wake cycle)
what hormone do the parathyroid glands secrete?
(they are located on the posterior surface of the thyroid gland)
hormone: parathyroid hormone (PTH)
what hormone does the heart secrete?
atrial natriuretic peptide (ANP)
what hormone does the kidney secrete?
erythropoietin (EPO) and calcitriol
what hormone does the adipose tissue secrete?
leptin- suppresses appetite
resistin- insulin antagonist
what hormone do the gonads secrete?
Male: the testes secrete androgens (esp. testosterone) and inhibin
Female: the ovaries secrete estrogens, progestins, and inhibin
define a hormone
a chemical messenger secreted into the bloodstream by endocrine cells that cause an intended effect in a target cell
what are the 3 types of hormones? what are they derived from?
- proteins (peptide/amines): amino acid derived
- steroid: cholesterol/lipid/fat derived
- prostaglandins: fatty acid derived
Can steroid hormones cross the plasma membrane?
yes they can enter the cell.
- because steriods are lipid-derived, and the plasma membrane is composed of phospholipids
Explain the GH pathway.
the anabolic (meaning growth) hormone GH (growth hormone) is released from the anterior pituitary gland in the brain and travels throughout the body.
- in the body, it increases bone growth, organ size, fat and cab breakdown, metabolism, and lean skeletal muscle mass
- GH in the liver produces IGF (insulin G factor) which may affect aging
explain the GH pathway with regards to GHIH and GHRH
GHIH and GHRH are released from the hypothalamus to regulate hormone release in the anterior pituitary
- GHIH results in a negative feedback mechanism back to the hypothalamus to decrease GH release in the anterior pituitary
What is the second messenger system?
it is the result of a protein hormone binding to a receptor on the plasma membrane
- results in the system having many different cellular responses
What are the 3 endocrine pathologies?
it is bad if…
1. excess levels of hormones in the blood
2. deficiency of hormone levels in the blood
3. abnormal responsiveness of target tissue to the hormone
What is giantism
- over secretion of the GH hormone in childhood
- grow really tall quickly
what is acromegaly
- over secretion of GH later in life
- face and hands continue to grow when the rest of the body does not
what is pituitary dwarfism
- opposite of giantism
- deficient in GH hormone during childhood
- unresponsive target tissues
what is hGH
human growth hormone: genetically engineered pharmaceutical drug that must be injected to be effective
- great for people suffering from developmental problems from the GH pathway
- banned a lot by sports teams
