topic 5: PNS overview 3 Flashcards
(21 cards)
What is the role of the Peripheral Nervous System (PNS)?
Obtains info about body/environment and sends info to CNS for processing
Afferent neurons carry sensory information to the CNS, while efferent neurons carry responses from the CNS to organs.
What does the Sensory Nervous System do?
Relay info to CNS about internal/external environment
Information is carried via afferent neurons.
What is the function of the Somatic Nervous System?
Control of skeletal muscles via action of motor neurons
This system is voluntary and skeletal muscles will not contract without neuronal activation.
What is the role of the Autonomic Nervous System?
Regulates smooth muscle/gland function
It controls involuntary functions such as heart rate and digestion.
What is a neuromuscular junction?
Region where motoneuron synapses at skeletal muscle
It consists of axon terminals and motor end plates.
What type of receptors are found on skeletal muscle at the neuromuscular junction?
Cholinergic receptors
The neurotransmitter that activates them is acetylcholine (ACh).
What happens when ACh binds to nicotinic receptors on muscle fibers?
Opens ion channels allowing Na+ to flow into muscle fiber
Overall response is excitatory, leading to muscle contraction.
What enzyme breaks down acetylcholine after its release?
Acetylcholinesterase (AChE)
It breaks ACh down into acetyl and choline.
What is the primary response of the Sympathetic Nervous System?
Fright, fight, flight response
It prepares the body for intense physical activity during emergencies.
What type of neuron is the sympathetic preganglionic neuron?
Cholinergic neuron
It always releases acetylcholine (ACh).
What neurotransmitter is released by sympathetic postganglionic neurons?
Noradrenaline (norepinephrine)
It binds to adrenergic receptors on target cells.
What are the two types of adrenergic receptors?
Alpha and beta adrenergic receptors
These receptors are G-protein coupled receptors that mediate various physiological effects.
What effect does activation of alpha 1 adrenoceptors have?
Causes contraction of smooth muscle
This leads to narrowing of blood vessels.
What is the function of beta 1 adrenoceptors?
Increase heart rate
Beta 1 receptors are always found in the heart.
What is the structure of the parasympathetic nervous system in terms of neuron length?
Long preganglionic neuron and short postganglionic neuron
These neurons are often located close to or within the organ they innervate.
What neurotransmitter do parasympathetic preganglionic neurons release?
Acetylcholine (ACh)
This neuron is also cholinergic.
What type of receptors do parasympathetic postganglionic neurons activate?
Muscarinic cholinergic receptors
These are G-protein coupled receptors.
What is the overall effect of muscarinic receptor activation?
Triggers biological effects like muscle contraction/relaxation
This includes effects on various organs such as the heart.
Fill in the blank: The __________ nervous system is more dominant during basic metabolic demands.
Parasympathetic
True or False: The sympathetic nervous system is responsible for involuntary muscle control.
False
The sympathetic nervous system primarily prepares the body for action and is associated with voluntary responses.
What physiological changes occur due to sympathetic activation?
Increased heart rate and contraction force
This occurs through the activation of beta 1 adrenoceptors.
