07 - The Autonomic Nervous System Flashcards
What is the branch of your nervous system that controls your glands and involuntary muscles?
Autonomic Nervous System (ANS)
What are the involuntary muscles?
Heart & smooth muscle
What is ANS also called?
Visceral motor nervous system
- Visceral - organs
What is the most important role of ANS?
To maintain homeostasis
Is there a sensory part to the ANS?
Yes
- There is also a sensory part of the system
- It is largely ignored except regarding referred pain and interoception
What are the 2 types of motor division?
- Somatic motor division
- Autonomic motor division
What are the 2 divisions in the autonomic motor division?
Sympathetic division
Parasympathetic division
What is the sympathetic division?
Flight, fight & fright
What is the parasympathetic division?
Rest, relaxation and rumination
What does the somatic motor division control?
Striated or voluntary muscles
What are the 2 nervous systems?
Central nervous system (brain & spinal cord)
Peripheral nervous system
What are the 2 sensory divisions that brings info to the peripheral nervous system?
Autonomic sensory division (mostly interoceptors)
Somatic sensory division
What’s the system? What motor nerve is it?
Voluntary control & one neuron from CNS to effector (no ganglia)
Somatic motor system
Somatic motor nerve
What’s the system? What motor nerve is it?
Involuntary control (autonomous) & two neurons between the CNS and effector
Autonomic motor system
Autonomic motor nerve
What are the 2 neurons between the CNS and effector of the autonomic motor system called?
First: preganglionic
Second: postganglionic
Where does the preganglionic and postganglionic neurons connect?
In areas called autonomic ganglia
What neurotransmitter is used in somatic motor systems?
Acetylcholine
- The only neurotransmitter used
What are the 2 inputs in the autonomic NS?
Sympathetic input
Parasympathetic input
How does the sympathetic input work in the heart?
Sympathetic input speeds up heart rate (tachycardia) and increases the force of contractions
- A positive inotropic effect)
- This is an appropriate response for preparing for fight and flight
How does the parasympathetic input work in the heart?
Parasympathetic input slows heart rate (bradycardia) and decreases the strength of contractions
- A negative inotropic effect
- This is an appropriate response for rest and relaxation
How does the sympathetic input work in the gastrointestinal tract?
Sympathetic input yields relaxation
How does the parasympathetic input work in the gastrointestinal tract?
Parasympathetic increase activity
What would happen if a sympathectomy were performed on the heart (i.e., all the sympathetic input was stopped)?
Decrease in heart rate and blood pressure
Are both types of input of the ANS the same in an organ?
No
- Input from one branch of the ANS is dominant in an organ
What input of the ANS is dominant in the heart?
Parasympathetic nervous system
- In the heart there are both branches of the ANS, but the sympathetic nervous system is dominated by the parasympathetic nervous system
What input of the ANS is dominant in the GI tract?
Parasympathetic nervous
- In the GI tract the parasympathetic nervous system dominates the sympathetic system for regulating gastrointestinal motility
If all autonomic input to the heart was stopped then what would happen to heart rate and force of contraction? Why?
Heart rate would increase, and the force of contractions would increase
- B/c the heart is dominated by the parasympathetic nervous system, thus if both inputs are stopped, more input from the parasympathetic nervous system is stopped, therefore, the heart rate would increase & force of contractions would increase
- The heart will not stop b/c it has pacemaker cells
Give some examples of organs with only ONE type of ANS input
Sweat glands have only sympathetic input
Visceral arterioles have almost only sympathetic input
The iris sphincter muscle has only parasympathetic inputs (it constricts the pupil)
The radial muscle of the iris has only sympathetic input (it dilates the pupil)
If all autonomic input to the peripheral blood vessels were to stop what would happen?
Blood vessels would dilate, and blood pressure would drop
What is the constriction of the pupil called?
Miosis
What is the relaxation of the pupil called?
Mydriasis
What does sympathetic stimulation cause in the eye (pupil)?
Causes radial muscles to contract
- Pupil enlarges
- B/c in a fight-flight situation, you want bigger pupils so you can see better (eg. when running away)