11 Anatomy of the Autonomic Nervous System Flashcards
Q: What are the 3 nervous systems?
A: central, peripheral, autonomic
Q: Define viscera.
A: the internal organs in the main cavities of the body, especially those in the abdomen
Q: What is the autonomic system responsible for? Where do the different components of the ANS arise?
A: involuntary control of viscera
different parts of the CNS
Q: What are the divisions of the autonomic system? What is the largest component of the ANS?
A: -sympathetic **
-parasympathetic
=> 2 main ones
-enteric= gut system (particularly involved in bowel movements
Q: How are the physiological outcomes of the ANS mainly split? What are these groups called? Energy consumption?
A: parasympathetic
- localised
- conserves body energy (low demand)
sympathetic
- mass responses
- requires lots of NRG
- mobilises multiple body systems at one time
Q: In what situation is the sympathetic NS needed? why?
A: fight or flight response as whole body needs to be activated
Q: Draw a simple diagram explaining central autonomic control. Describe. (6)
A: 2 things initiate:
- higher brain centres: memories and past experiences may modify response
- homeostatic changes: internal monitoring (MAIN)
- > hypothalamus: core of control
- > medulla
2 outcomes:
- sympathetic
- parasympathetic
Q: What is the basic structure for all autonomic pathways? (3)
A: 1. preganglionic neuron which has cell body in CNS
- synapses with ganglion cells in ganglion = accumulation of cell bodies in peripheral system
- post ganglionic fibre goes into body and innervates organs
Q: How do the sympathetic and parasympathetic systems differ in terms of ganglia? (2,1)
A: sympathetic:
- found in sympathetic trunk
- structure is closer to spinal cord that the organ/viscera being innervated
parasympathetic:
-Found close to or even in the organ/viscera they innervate (hence more localised action)
Q: Define afferent nerves and afferent nerves.
A: Afferent nerves carry sensory impulses from all parts of the body to the CNS -> SENSORY
Efferent nerves - “messages” are conducted from the CNS to the muscles and the organs of the body -> MOTOR
Q: In the sympathetic NS, where do the pre-ganglionic efferent fibres arise from? (2) Appearance? Called?
A: Thoracic (spinal) nerves Upper Lumbar (spinal) nerves (L1-3) -> end point varies person to person
in these vertebrae, cross section shows extra grey matter in between curves of butterfly
due to origins: Thoracolumbar outflow
Q: Why do you get sympathetic outflow at some levels but distribution to body from all levels? (4)
A: -due to sympathetic chain= chain of ganglia (close to spinal cord)
-structure allows a number of ways for sympathetic fibres to emerge from T1 to L2/3 and distribute in the body
- easiest way is to just go out spinal cord at that level
- others pass up/down through chain and then distribute with other spinal nerves
Q: Describe the sympathetic pathway (adaption of the basic one for autonomic pathways). (4)
A: 1. Preganglionic neurons in the lateral column grey matter of spinal cord T1 to L2/3
- Emerge from the spinal cord via the ventral root of the spinal nerve
- Pass through ventral ramus to white rami communicantes to ganglion
- Postganglionic fibres distributed to effector organ via grey rami communicantes
Q: Once the sympathetic fibres reach the ganglion, what are the different paths it can take? (3)
A: -immediately synapse within ganglion cell in ganglion at that level
- go through ganglion without synapsing and go up and down to other ganglia
- go through ganglion without synapsing and go to more peripheral subsidiary ganglion
Q: Where does the sympathetic trunk extend from and to? How many ganglia are there in the:
cervical region? importance?
thoracic region?
lumbar region?
pelvis?
A: base of skull to coccyx= base of vertebral column
3 -> important ganglia for head and neck
11 or 12
4 or 5
4 or 5