Ch9 ANS 2 Flashcards
Preganglionic fibers that ascend from the upper thoracic cord supply
cervical paravertebral ganglia
cervical ganglia consist of
- superior ganglia
- middle ganglia
- cervicothoracic ganglia
How is the cervicothoracic ganglion formed?
fusion of the inferior cervical and first thoracic ganglion
postganglionic fibers of the superior and stellate ganglia innervate
- arteries of the face
- dilate pupil
- elevate upper eyelid
postganglionic fibers from lower lumbar and parasacral paravertebral ganglia innervate
blood vessels in the lower limb
Where do preganglionic fibers travel?
splanchnic nerves
Sympathetic signals to the gastrointestinal tract do this
- stop peristalsis
- reduce glandular secretions
- constrict sphincters of the digestive system
primary function of the sympathetic nervous system
maintain optimal blood supply in the organs
Moderate activity of the sympathetic system stimulates:
- smooth muscle in blood vessel walls
- maintaining some contraction of vessel walls
What happens in the ANS with increasing sympathetic activity?
vasoconstriction
What happens with decreasing sympathetic activity?
vasodilation
What happens when someone feels threatened?
- sympathetic prepares for vigorous muscle activity (fight or flight)
- vasoconstriction in skin and gut increases blood flow to active muscles
- BP/HR increase
- blood glucose increases
- bronchi and coronary vessels dilate
- activity of digestive system reduced
What are two things that cause body temp regulation?
- effects on metabolism
- effectors in skin
Where is epinephrine released?
adrenal medulla
What does epinephrine do (temperature)?
increases metabolic rate
sympathetic signals in body temp control
control
- diameter of blood vessels
- secretion of sweat glands
- erection of hairs on skin
regulation of blood flow: capacitance vessels
skeletal muscle veins and venules
regulation of blood flow: What can happen if blood pooling in LE and abdomen isn’t prevented?
drop in BP
- deprives brain of blood supply
- causes syncope
arterial walls of skeletal muscle contain
α-adrenergic receptors
What acts on α-adrenergic receptors to cause vasoconstriction?
norepinephrine
In addition to norepinephrine, what else can affect arteriole diameter?
local blood chemistry
sympathetic control in the head: blood flow, sweating, erection of hair cells
compared to rest of the body
identical to sympathetic actions in remainder of the body
sympathetic control in the head: control of the eye
sympathetic signals dilate the pupil and assist in elevating upper eyelid
