Chapter 15 part 1 (sympathetic nervous system)

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ANS is a set of ___ pathways from the CNS that innervates
smooth muscle, cardiac muscle, glands
- also called visceral ___ system

efferent,
motor

Visceral Reflexes

Unconscious, automatic responses to stimulation of glands, cardiac or smooth muscle

1. Receptors- detect internal stimuli --> stretch, blood chemicals, etc.
2. Afferent neurons connect to interneurons in the CNS (processing)
3. ___ neurons
-carry motor signals to effectors
-____ is the efferent neurons of these reflex arcs
4. Effectors -glands, smooth or cardiac muscle

ANS modifes effector activity

Efferent ,
ANS

1. HBP detected by arterial stretch receptors called ___ 2. an afferent neuron in the ____ nerve (9), carries the signal to the medulla (CNS)
3. ____ nerve (9) (efferent) transmits inhibitory signals to the heart
4. heart slows, reducing BP

baroreceptors,
glossopharyngeal,
vagus

In autonomic pathways the signal must travel across ___ neurons to get to the target organ, and it must cross a synapse where these two neurons meet in an ___ ganglion

two,
autonomic

prev slide cont.

-The first neuron, called the ___neuron has a soma in the brainstem or spinal cord
>Its axon terminates in the ganglion
- The first neuron synapses with the ___ neuron whose axon extends the rest of the way to the target cells.

preganglionic,
postganglionic

Sympathetic division

prepares body for physical activity "fight or flight"
increases heart rate, BP, pulmonary airflow, blood glucose levels, blood flow to cardiac and skeletal muscle
While ____ blood flow to skin and digestive tract

reducing

____ division
calms many body functions and assists in bodily maintenance "rest and digest" - digestion and waste elimination

Parasympathetic

3rd division of ANS = ___ nervous system--> resides within the GI tract

enteric

Autonomic ___ is the background rate of activity of the ANS
-It is the balance between the sympathetic and parasympathetic tone
-___ tone maintains smooth muscle tone in the intestines and holds the resting heart rate down to about 70-80 beats/minute

tone,
Parasympathetic

If the _____ vagus nerves to the heart are cut, the heart beats at its own intrinsic rate of about 100 beats/min.
-____ tone keeps most blood vessels partially constricted and thus maintains blood pressure.
Loss of sympathetic tone can cause such a rapid ___ in blood pressure that a person goes into shock.

parasympathetic (vagus slows),
Sympathetic,
drop

___ between neurons are made in autonomic ganglia
-Sympathetic ganglia are located in the paravertebral (along the side) chain or prevertebral (in the front)
- ___ ganglia are located in or near the effector organ

Synapses,
Parasympathetic

Sympathetic Nervous System

Presynaptic (___) neurons have their cell bodies in the lateral horns of spinal cord (___) thoracolumbar

preganglionic,
T1-L2

Sympthetic NS cont.


Sympathetic chain ganglia (___)
- cervical, thoracic, lumbar, sacral and coccygeal ganglia
-white and gray communicating ___ suspend ganglia from spinal nerve

-pathways of preganglionic fibers:
-enter ganglia and ___ on postganglionic cell
-travel to higher or lower ganglia and synapse
-pass through chain without synapsing to reach collateral ganglia via splanchnic nerves

paravertebral
rami,
synapse

sympthetic nervous system

The neuronal cell bodies of the ___ cell column ___ axons leave the spinal cord via the ventral roots. They are the sympathetic preganglion neurons and they use ACh when they synapse in ganglia.

intermediolateral,
T1-L2

The ANS uses 2 neurons from CNS to effectors
a.) presynaptic neuron (preganglionic) cell body in CNS
b.) postsynaptic neuron (postganglionic) cell body in ___ganglion

peripheral

As axons leave the ___ cell column and enter the sympathetic chain, they may do one of four things. (next 3 slides)

1. They may ascend in the chain and synapse in more superior ___.

intermediolateral,
ganglia

2. They may descend in the chain and synapse in more ___ ganglia.

caudal

3. They may pass through the chain ___ synapsing and go to a ___ ganglion.

without ,
prevertebral

4. They may synapse in the ganglion at the ___ spinal level from which they arose.

same

Neuronal ___ is present in sympathetic system
- each preganglionic cell branches and synapses on multiple (10-20 postganglionic cells
-produces widespread effects on __ organs

divergence ,
multiple

Neuronal ___is also present in sympathetic ns.
Each postganglionic may receive synapses from multiple preganglionic neurons

convergence

Adrenal Glands

-Sympathoadrenal system is the closely related functioning __ __ and symphathetic nervous system
- Adrenal (suprarenal) glands sit on ___ pole of each kidney
-Adrenal ___ secretes steroid hormones and androgens - endocrine gland

adrenal medulla ,
superior
Cortex

Adrenal Glands cont.

Adrenal Medulla (inner core)
- Is a modified sympathetic ___
-stimulated by preganglionic sympathetic neurons that send fibers that penetrate the cortex of the gland and terminate on the ___ cells of the adrenal medulla
- Chromaffin cells of the adrenal medulla secrete ___(hormones) into blood:
>____ (85% ___, 15% norepinephrine, and a trace of dopamine)

ganglion ,
chromaffin,
neurotransmitters ,
catecholamines
epinephrine

Notice that all of the ___ sympathetic neurons arise from the thoracolumbar (T1-L2) spinal cord segments

preganglionic

Sympathetic does not have any ganglia in the head, the neurons hitch a ride on ___ ___.

blood vessels

Effectors in body wall (sweat glands, blood vessels, erector pili m. ) are innervated by sympathetic ___ that travel in spinal ____.

fibers,
nerves

Effectors in head and thoracic cavity are innervated by fibers in sympathetic ___ that for the most part travel with ___ ___ to reach their targets

nerves
blood vessels

Effectors in abdominal cavity are innervated by sympathetic fibers in ___ nerves
>celiac, superior and inferior mesenteric ganglion

splanchnic

When one preganglionic neuron fires it can excite multiple (up to 17) postganglionc fibers leading to different target organs. Thus the sympathetic division tends to have ___ effects.

widespread

Preganglionic neurons:

-in the spinal cord lateral horn from T1-L2
-Some synapse in paravertebral ganglia
-Others travel via __ nerves to prevertebral ganglia, or directly to the adrenal ___
Cholinergic (____)

splanchnic ,
medulla,
acetycholine

Postganglionic neurons:

- in paravertebral (sympathetic chain) or some prevertebral (collateral) ganglia
- Most are ___ (epinephrine or norepinephrine)
>Exception: ___ glands use ACh

adrenergic,
sweat (apocrine, merocrine)

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