Flashcards in March 18, 2015 --> Nerves (121-136) Deck (45):
When a patient experiences unwanted moments, such as involuntary jerking movements of an arm or leg, which disorders might be implicated? Which part of the nervous system might be affected?
-Parkinson's disease and Huntington's disease
-Basal Ganglia is affected
The combination of what two things are often referred to as the lentiform nucleus
Putamen and globus pallidus
Which two parts of the nervous system are considered large collections of nuclei that modify movement on a minute-to-minute basis?
The cerebral cortex sends information to both the basal ganglia and cerebellum and they both send information back to the cortex via what structure? what two pathways are used to do this?
Via the thalamus
- Direct and Indirect pathway
The direct and indirect pathways for communication both use what neurotransmitter?
What affect does the neurotransmitter have on direct and indirect pathways respectively?
Direct: Dopamine is excitatory with an overall net excitatory role
Indirect: Dopamine is inhibitory
The output of the cerebellum is (inhibitory,excitatory) while the basal ganglia are (inhibitory, excitatory)
Basal ganglia: inhibitory
Basic function of cerebellum?
Function is to maintain equilibrium and muscle coordination
What are the major parts of the extrapyramidal system?
The subcortical nuclei
- This includes the caudate nucleus, putamen and globes pallidus
What is the classic neurotransmitter of autonomic ganglia
What are the two classes of acetylcholine receptors in autonomic ganglia
Nicotinic receptors are stimulated by what?
Ach and Nicotine
NOT by muscarine
Where are nicotinic receptors found and what do they produce?
-Found at ALL ganglionic synapses
-Also found at neuromuscular junctions and the adrenal medulla
Muscarinic receptors are stimulated by what?
ACh and muscarine
NOT by nicotine
Where are muscarinic receptors found?
Found at target organs when ACh is released by postganglionic neurons including heart, smooth muscle and glands
The fast EPSP (excitatory postsynaptic potentials) results from activation of what receptors?
Activation of nicotinic receptors, which cause ion channels to open
Muscarinic receptors are blocked by what?
Nicotinic receptors are blocked by what?
hexamethonium and curare
The slow EPSP is mediated by which receptors?
Muscarinic receptors that inhibit the M current, a current produced by conductance of potassium
Fibers that secrete acetylcholine are said to be what? Fibers that secrete norepinephrine are said to be what?
What are the cholinergic effects of PREGANGLIONIC autonomic neurons?
What are the cholinergic effects of POSTGANGLIONIC parasympathetic fibers?
Excitatory or inhibitory
Which neurons are cholinergic?
- All preganglionic nerons in both sympathetic and parasympathetic nervous systems
- Either all or almost all of the postganglionic neurons of the parasympathetic system
Which neurons are adrenergic?
Most of the postganglionic sympathetic neurons
- except for the postganglionic sympathetic nerve fibers to the sweat glands, to the piloerector muscles of the hairs and to a very few blood vessels which are cholinergic
What are the two main types of adrenergic receptors in the ANS?
Describe the locations of Alpha 1 and 2 receptors and the different effects they have on their targets
1: located on smooth muscle; produce excitation
2: located in presynaptic nerve terminals, platelets, fat cells, and walls of GI tract; Produce inhibition
Describe the locations of Beta 1 and 2 receptors and the different effects they have on their targets
1: Located in the heart; produces excitation (increased heart rate and contractility)
2: Located on smooth muscle; produces relaxation (dilation)
Which neurotransmitters stimulate alpha receptors? Which stimulate both alpha & beta receptors?
Alpha & Beta: Epinephrine
What are the two main types of cholinergic receptors?
Nicotinic and muscarinic
T or F, ACh is released at the terminal sympathetic fibers of the heart
False, NOT released. Cardiac muscle is inhibited by acetylcholine
What enzyme breaks down Acetylcholine
- Rapidly breaks down ACh into acetate and choline after its release from the presynaptic terminal onto the muscle end-plate. If it is inhibited, there is prolongation of the end-plate potential
The pyramidal tract is also called what?
The corticospinal tract
The corticospinal tract carries messages for what?
Voluntary motor movement
The autonomic nervous system is a motor system that controls what things?
- NOT skeletal muscle
2 classes of receptors based on the location of the stimuli in which the receptors respond:
1. Interoreceptors (viscerorecptors) - located in the body's internal environment
2. Exteroreceptors - receptors that respond to stimuli from body surface
Proprioreceptors are classified into which of the two receptor classes?
What are nocioceptors?
(and free nerve endings) are sensitive to pain
What is Adaptation in relation to nerves?
A property of certain receptors where the receptor becomes LESS RESPONSIVE or stops responding to repeated or continued stimuli of constant intensity. A decrease in the frequency of action potentials in an afferent neuron despite constant stimulus intensity
Which of the encapsulated nerve endings are considered touch and pressure receptors and which are stretch receptors?
Touch & Pressure
- Meissner's corpuscle
- Krause's corpuscle
- Ruffini's corpuscle
- Pacinian corpuscle
- Muscle spindles
- Golgi tendon receptors
Describe the location of each of the 4 touch and pressure receptors that are encapsulated
Meissner's: Exteroceptors; epidermis, hairless skin
Krause's : Mucous membrane
Ruffini's : Dermis of skin, exteroceptors
Pacinian : Dermis of skin, joint capsules
Describe the function of each of the 4 touch and pressure receptors that are encapsulated
Meissner's : Discriminative touch: low frequency vibration
Krause's: Touch; low-frequency vibration; cold
Ruffini's : Crude and persistent touch; heat
Pacinian : Deep pressure; high frequency vibration; stretch
The PNS is subdivided into what 3 things?
1. Somatic Nervous System
2. Autonomic Nervous system
3. Enteric nervous system
Describe the somatic nervous system
Includes all nerves controlling the muscular system and external sensory receptors. External sense organs are receptors. Muscle fibers and gland cells are effectors
Describe autonomic nervous system
The organs of our body such as the heart, stomach and intestines. Largely works unconsciously. Has two divisions: Sympathetic nervous system and Parasympathetic nervous system