The Sympathetic NS Flashcards
What is the somatic system responsible for?
voluntary movement e.g. writing, running, walking and talking
What is the autonomic system responsible for?
controlling organs in the body (involuntary)
What is the autonomic NS divided into?
sympathetic and parasympathetic nervous systems
Give examples of systems under autonomic control
visceral reactions e.g. food digestion and eye dilation
Where is the hypothalamus located?
at the bottom of the diencephalon
What does the hypothalamus do?
- secrete hormones from the pituitary gland that act on the endocrine glands of the body
- send projections down the spinal cord to control the sympathetic and (in part) parasympathetic nervous systems
What is the hypothalamus sensitive to?
the blood flowing through it
What 3 tissue types does the ANS stimulate?
- cardiac muscle
- smooth muscle
- glands
How is the balance between the parasympathetic and sympathetic nervous systems maintained?
by increasing the amount of stimulation in one part of the system or decreasing the amount of discharge in the other
When does the sympathetic NS dominate?
when a person is in a stressful situation; the body reacts by preparing for ‘fight or flight’
What happens to the body under stress due to the sympathetic NS?
- muscles work harder and need more oxygen and energy
- one breathes faster and the bronchi and bronchioles open up for greater and quicker passage of air
- the heart beats stronger and faster
- the arteries to the heart and voluntary muscle dilate to increase blood flow
- the arteries to the skin and other peripheral areas constrict
- the liver secretes glycogen for quick supply of energy and the GI tract slows down
- pupils dilate
- one sweats to reduce elevated body temperature
What is cardiac output?
the amount of blood pumped by the heart per minute
What is the outflow of the sympathetic NS based on?
a two-neuron motor pathway consisting of preganglionic and postganglionic neurons
Where are the preganglionic neuron cell bodies located?
in the intermediolateral horn of T1 to L2 spinal segments; the thoracolumbar outflow
How do the preganglionic axons leave the spinal cord?
via the ventral roots into the sympathetic (chain) trunk