BIOL 273 - Unit 2.5 Flashcards
the two efferent branches of the peripheral nervous system
- Autonomic division
- Somatic division
What does the autonomic division consist of
- 2 neuron chain
- goes to innervate smooth and cardiac muscle , glands, adipose tissue
- involuntary division
What does the somatic division consist of
- innervates skeletal muscle
- voluntary division
2 branches of the autonomic division and what are their functions
- Sympathetic (prepares the body physical activity and stress) “fight or flight”
- Parasympathetic “rest and digest”
Describe the similarities between the sympathetic and parasympathetic branches
- same structure : two neuron chain between CNS and effector
- synapse between neurons is in cell clusters aka autonomic ganglia
What are the cells leading from the central nervous system to the ganglion called
preganglionic
What are the cells leading from the ganglion to the effector called
postganglionic
What are the two primary neurotransmiitters of the autonomic system
- Acetylcholine (ACh)
- Norepinephrine
What is the neurotransmitter acetylcholine (ACh) released by and where does it release to
released by ALL pre-ganglionic neurons (sympathetic+parasympathetic) onto nicotinic receptors
What post ganglionic neuron does Acetylcholine release from and where does it release to
post ganglionic parasympathetic neurons releases onto cholinergic muscarinic receptors
Where does neurotransmitter Norepinephrine release from and where is it released onto
released by most post-ganglionic sympathetic neurons onto adrenergic receptors
What does the autonomic pathway innervate (3)
- smooth and cardiac muscle
- Exocrine and endocrine glands
- adipose tissue
Varicosity function
allows for a less directed form of communication than that which occurs between a somatic motor neuron and a skeletal muscle
- diffuse release means that a single postganglionic neuron can affect a garge area of target tissue
How does the synapse structure differ from model synapse
axon ends with swollen areas at distal ends called a varicosity
What does varicosity contain
- vesicles with neurotransmitter to be released into interstitial fluid
What does the varicosity encounter
a receptor on the effector cell
How does neurotransmitter action terminate on varicosity
terminated by diffusion, metabolism or actively transported back into cells near synapse
What are the two types of receptors
- Adrenergic receptors
- Cholinergic receptors
What kind of neurotransmitters do adrenergic receptors respond to
epinephrine and noreponephrine
Describe alpha 1 receptors of adrenergic receptors , where is it found and what receptors does it best respond to
- found on most tissues
- respond best to norepinephrine
Describe beta 1 receptors of adregenic receptors , where is it found and what does it respond to
- found in heart muscle and kidney
- responds to norepinephrine and epinephrine equally
Describe beta 2 receptors of adregenic receptors, where is it found and what does it respond to
- found in blood vessels, smooth muscle
- responds to epinephrine more than norepinephrine
What assists in the neurotransmitter retrieval of adrenergic receptors
G proteins
What can beta 1 and beta 2 receptors of adrenergic receptors stimulate production of what
cAMP production
What can alpha 1 receptors of adrenergic receptors do
increases calcium ion levels in the cytoplasm
What are the two major classes of cholinergic receptors
- nicotinic
- muscarinic
What are nicotinic receptors of cholinergic receptors stimulated by
ACh and nicotine
What are muscarinic rceptors of cholinergic receptors stimulated by
ACh and muscarine
Where are nicotinic receptors found (2)
- on motor end plates on skeletal muscle
- sympathetic and parasympathetic ganglia
Where are muscarinic receptor of cholinergic receptors found
on target tissues of the parasympathetic system
How do nicotinic receptors of cholinergic receptors act
act via ion channels (Na+ goes into cell)
*always excitatory
How do muscarinic receptors of cholinergic receptors act
act via G proteins
*may be excitatory or inhibitory
What are the two parts of the adrenal gland
- Adrenal cortex
- Adrenal medulla
Function of adrenal cortex of the adrenal gland
secretes steroid hormones
Function of adrenal medulla of the adrenal gland
associated with the sympathetic division
- modified sympathetic ganglion
How many neurons carrying information from CNS to effector in the somatic division
a single neuron , causing muscle excitation , cannot inhibit function
Describe the neuromuscular junction
the synapse between a somatic motor neuron and a skeletal muscle fiber
What 2 two strucutres are involved in neuromuscular junction
Schwann cells around the terminal boutons at the synapse
What are the three components of the neuromuscular junction
- Pre-synaptic axon terminal
- filled with neurotransmitter - Synaptic cleft
- Post-synaptic membrane
- motor end plate, nicotinic ACh receptor channels
