Lecture 2 Flashcards
What happen within our bodies when we are asleep?
- Airways still allow oxygen into the body
- Blood still reaches various organs
- Food and drink is still digested
- Sweat
What comprises the sensory part of the PNS?
somatic nervous system and visceral nerves
What comprises the motor part of the PNS?
somatic nervous system (voluntary), ANS (involuntary)
What are the two divisions of the ANS?
Sympathetic and parasympathetic
What is the sympathetic system involved in?
Fight or flight
What are the 4Es?
Excercise, excitement, emergency and embarrassment
What part of the body is coordinated by the sympathetic system?
Whole body
What is the parasympathetic system involved in?
Rest and relaxation
What are the 3Ds?
Digestion, defecation, diuresis
Why is there increased heart rate, cardiac contractility and blood pressure in sympathetic stimulation?
The cardiac output increases to pump more oxygen out (especially to the skeletal muscles)
What must occur to redirect blood to the skeletal and cardiac muscles?
Vasoconstriction in viscera, vasodilation in skeletal and cardiac muscle
Why is there increased ventilation and bronchodilation in sympathetic stimulation?
More oxygen per breath
What does pupillary dilation contribute to?
Increased awareness
How does the parasympathetic system facilitate digestion and absorption of nutrients?
Promotes secretion (including salivation), increases mobility (including swallowing) or the GI tract
Though sympathetic and parasympathetic stimulations usually have antagonistic control over an organ, what is an exception to this rule?
Cooperation in male sexual function:
Parasympathetic stimulation is responsible for erection
Sympathetic for ejaculation
What are some examples of functions almost only stimulated by the sympathetic system?
Sweat glands, hair follicles, blood vessel smooth muscle and adrenal medulla
What do preganglionic neurons release?
ACh
What are structural features of preganglionic neurons?
Myelinated, cholinergic fibers, has ligand gated ion channels
What is a receptor subtype of nicotinic ACh receptors on the post synaptic cell?
N2 receptor
In general, what neurotransmitter does the postganglionic fiber release in the sympathetic system?
Norepinephrine (noradrenaline)
Preganglionic neurons (sympathetic); long or short?
short
Postganglionic neurons (sympathetic); long or short?
long
What kind of receptors does the target tissue express?
alpha and beta adrenergic receptors (G protein coupled receptors)
Where do the preganglionic neurons in the sympathetic system originate?
T1-L3
How do the preganglionic neurons in the synapse with postganglionic neurons?
- prevertebral ganglia (in sympathetic chain)
2. postvertebral ganglia
What are the arteries that prevertebral ganglia are associated with?
celiac ganglion, superior mesenteric ganglion, right aorticorenal ganglion, inferior mesenteric ganglion
What structure is an exception in the sympathetic system?
Adrenal medulla
What neurotransmitters does the adrenal medulla release?
80% adrenaline, 20% noradrenaline
How is the adrenal medulla an exception in the sympathetic system?
Chromaffin cells function similar to postganglionic neurons but release mainly adrenaline, adrenaline travels to multiple tissues
What is an exception to the neurotransmitter rule?
Sweat glands
Why are sweat glands an exception to the neutransmitter rule?
Postganglionic neurons release ACh
Any structural differences between sweat glands and other sympathetic system neurons?
The target tissue expresses muscarinic ACh receptors
What does the postganglionic neuron (parasympathetic) release?
ACh
What receptor is expressed in the target tissue for the parasympathetic system?
Muscarinic ACh receptor
Preganglionic neuron (parasympathetic); long or short?
Long
Postganglionic neuron (parasympathetic); long or short?
Short
Where do preganglionic neurons (para) originate?
Brainstem, S2-S4
The Vagus nerve carries how much of parasympathetic outflow?
80%
Other than ACh and adrenaline, what is another example? of neurotransmitters
Non-adrenergic Non-cholinergic (NANC) transmitters
What are examples of NANC transmitters?
Substance P, nitric oxide, ATP, vasoactive intestinal peptide (VIP)
What do NANC transmitters participate in?
Cotransmission and modulates the synaptic response
What area of the brain controls emotional inputs in the ANS?
limbic lobe
What part of the brain integrates and coordinates ANS function?
hypothalamus
What is an example of brainstem nuclei and what does it do?
Nucleus tractus solitarii, mediate autonomic reflexes
What does the spinal cord do in the ANS?
Mediates autonomic reflexes
What cortical processes regulate autonomic output?
Descending cortical inputs
What can emotional stress and painful stimuli lead to?
Vasodilation and hypotension, then fainting
What can chronic stress cause?
Increased gastric acid secretion
What can nervousness lead to?
diarrhea
Which takes priority in regulation of the ANS; sensory input from visceral afferent neurons or cortical functions?
Sensory input - nothing else seems to matter as much!!
What are examples of sensory input from visceral afferent neurons?
hunger, nausea, bladder and bowel distension, hypothermia/hyperthermia, visceral pain
