02 Endocrine Flashcards
What is the CNS comprised of?
brain and spinal cord
What is the PNS comprised of?
cranial nerves, spinal nerves, ganglia, peripheral nerves
What are the two types of neurons that connect the periphery with the CNS?
- motor (efferent) neruons
- sensory (afferent) neurons
What are the two divisions of motor (efferent) neurons?
- somatic - voluntary
- autonomic - involuntary - (divided into sympathetic and parasympathetic NS)
What forms myelin in the peripheral nervous system?
schwann cells
Describe how an AP travels down a presynaptic neuron and the response it elicits in the postsynaptic neuron
- AP arrives at presynaptic axon terminal
- voltage gated Ca+ channels open resulting in Ca2+ influx into the presynaptic membrane
- synaptic vessels fuse to presynaptic membrane and expel neurotransmitter (NT) into synaptic cleft
- NT diffuses across synaptic cleft
- NT binds to receptors on postsynaptic membrane
- ligand gated ion channels open resulting Na+ influx
- Postsynaptic potential depolarizes to threshold triggering an AP
What is the sensory input for autonomic and somatic systems?
- Autonomic - interoreceptors
- Somatic - special senses and somatic senses
What neurotransmitters are present in the autonomic vs somatic system?
- autonomic - acetylcholine and norepinephrine
- somatic - acetylcholine
Where is ACh released in the autonomic system?
- preganglionic axons
- postganglionic parasympathetic
- postganglionic sympathetic to sweat glands
Where is norepinephrine released in the sympathetic system?
postganglionic sympathetic fibres other than to sweat glands
The motor neuron pathway of the somatic vs autonomic system consist of a _____# neuron pathway
- somatic - one neuron
- autonomic - two neuron
What are the effectors in the somatic system?
skeletal muscle
What are the effectors in the autonomic system?
cardiac muscle, smooth muscle, and glands
Describe the neuron pathway and the neurotransmitter involved in the somatic NS
One neuron pathway, myelinated, releases ACh, effector is skeletal muscle
Describe the neuron pathway and the neurotransmitters involved in the parasympathetic NS
two neurons pathway, preganglionic neuron is myelinated, synapses in the autonomic ganglion, releases ACh, 2 neuron (postganglionic neuron) is unmyelinated and releases ACh
What is ganglion and where is it found?
neuronal bodies found in the somatic and autonomic branches of the PNS
What is the function of the hypothalamus?
- controls internal organs via the autonomic nervous system and pituitary gland
- regulates behavioral patterns, circadian rhythm, body temperature and eating/drinking behaviour
What three glands influence other glands?
hypothalamus, pituitary and adrenal glands
Describe the order of actions lipid soluble hormones take to act on target cells
- transported in blood bound to transport proteins
- diffuse directly through cell plasma membrane
- bind to receptors within nucleus or cytosol of a target cell to alter gene expression
- mRNA direct synthesis of new proteins (usually enzymes)
- physiological responses/cell activity altered response to the hormone
Describe the order of actions water soluble hormones take to act on target cells
- binds to receptors on target cell membrane
- activates G protein which activates adenylate cyclase
- ATP converted to cAMP.
- cAMP activates protein kinases
- phosphorylation of enzymes within the cell
With respect to size and myelination of cell axons, the velocity of nerve impulse conduction is greatest in what size and myelinated or non myelinated fibres?
large diameter, heavily myelinated fibres
Endocrine hormones act on ____ cells
distant target
Paracrine hormones act on ____ cells
local target
Autocrine hormones act on ________
- the cell that produced the hormone
