9/20b Integrating Autonomic & Volitional Control (Biomedical Sciences) Flashcards
• Basics of neuro • How systems function together • Divisions • Neural circuits • Neurotransmitters • How ANS helps in maintaining function • What happens when people have dysfunction
Global Nervous System
- Brain, cerebellum, spinal cord
- Forebrain (cerebral cortex, basal ganglia, white matter)
- Diancephalon (deep inside cerebrum)
- Thalamus
- Brainstem (midbrain, pons, medulla)
- Spinal cord (cross sectional area smaller than a penny, caude equina)
Autonomic NS divisions***
primarily communicates with internal organs and determines their function
- sympathetic NS: has to go through a stressful/challenging situation. Increases arousal and expending energy, fight or flight
- Parasympathetic NS: maintain normal HR, breathing, allows you to relax and conserve energy, rest and digest
- Enteric**: works closely with ANS, but doesn’t rely on them, responds to SNS and PNS
when is diastolic pressure higher?
hardened artery
Decondititoned patients with orthostatic hypotension
bedridden, brain or spinal cord injuries, not a lot of time in upright sitting, complain of sweating and feeling flushed, light headedness and palor
Big picture of ANS
- need to get patients back into ADL we need muscles, heart, respiratory system, energy systems
- all of the above are controlled by nervous system
Somatic NS and CNS
control muscles
autonomic NS and CNS
cardio-respiratory system and ATP system in the body that controls metabolism
Functions and effects of PNS and SNS on different organs
almost all of the organs are not under your direct volitional control
–we don’t have full volitional control over our heart rate, or adrenal medulla
ANS Neural Circuitry
all organs involuntary functions receive inputs from SNS and PNS and can be done in 2 ways:
- Reduce SNS flow and increase PNS flow
- Increase SNS flow and decrease PNS flow
what section of the spinal cord does the SNS innervation come from?
thoracolumbar outflow section of the spinal cord: t1-l2/3
- exit spinal cord and supply/synapse pre/para vertebral chain of ganglia
- Axons of the neurons form ganglia exit and supply organs
what section of the spinal cord does the PNS innervation come from?
brainstem nuclei and sacral section of your spinal cord (craniosacral outflow - brasinstem nuclei are in the sacrum): S2-S4
- neurons send axons to parasympathetic ganglia where there is another neuron
- neuron from the parasympathetic ganglia exits ang goes to the organs
Somatic motor system vs autonomic motor system
Efferent Somatic - skeletal muscle and a neuron sitting in spinal cord (anterior horn cell) axons come out from the ventral root
Efferent autonomic - neuron in CNS (pre-ganglion), exits CNS, synapses on the autonomic ganglion (post ganglion neurons) then the axons (post ganglionic fibers) of the ganglion supply the organ
Location of the Pre ganglionic neuron in SNS/PNS
sits in the spinal cord
Location of the Post-ganglion neuron in SNS/PNS
sitting in either the pre or paravertebral chains
Preganglionic neurons release what?
in SNS and PNS always secrete Ach as neurotransmitters. Axons of the pregang are the Post ganglion nerves and produce effects on the end organ
what are the horns of the grey matter?
- posterior
- anterior: axons of the pregang neurons leave from the anterior/ventral roots and supply/innervate the autonomic ganglia (in pre or paravertebral chains)
- lateral: pregang neurons are in the lateral horn
Autonomic ganglia locations
either in prevertebral OR paravertebral chains
Paravertebral ganglionic chains
bilateral chains from cervical to sacral part of the spine. on either side of the spinal cord and house the post-ganglionic neurons
- superior cervical
- medial cervical
- inferior cervical (stellate)
- 11 thoracic
- 4-5 sacral
Prevertebral ganglionic chain
in front of the spinal cord, midline, get names from nearby arteries
- celiac
- superior mesenteric
- inferior mesenteric
Simplest route, Trajectory 1 of the preganglionic neuron (sympathetic)
- preganglionic neuron leaves from the anterior nerve root (efferent)
- Goes to the same level of the paravertebral ganglia and innervates the paravertebral ganglion
- Paravertebral neuron leaves and innervates the target organ
Trajectory 2 of the preganglionic neuron (sympathetic)
- preganglionic neuron leaves from the anterior nerve root (efferent)
- Descends up or down the sympathetic chain
- Synapses at a different level of the sympathetic chain(paravertebral chain)
- Paravertebral neuron leaves and innervates the target organ
Trajectory 3 of the preganglionic neuron (sympathetic)
- preganglionic neuron leaves from the anterior nerve root (efferent)
- Descends up or down the sympathetic chain
- Does not synapse at a different level of the sympathetic chain(paravertebral chain)
- Moves to the prevertebral chain and synapses then leaces to innervate the target organ
Parasympathetic division and trajectory***
- 75% of the PNS fibers come from CN X (vagus nerve)
- Preganglionic neurons are on the vagus nerve, CN 3, and CN 7 and 9 and in the Sacral column
- postganglionic neurons are on the ciliary, pterygopalatine, submax
- the organ specific ganglia are very close to the organ
Central autonomic network
BRAIN
- controls craniosacral and thoracolumbar output
- get afferent info from periphery, process, and provide either syp or parasymp back to the organ
- Need to know the pathway of the HYPOTHALAMUS
Hypothalamus Role
- important for homeostasis, ability to maintain balance o the system
- Major Roles 5Fs and 1S:
1. Food: hunger/feeding behavior - glucocorticoids, growth hormone, TSH)
2. Furnace: thermoregulatory behavior, hormone secretion
3. Fight
4. Flight
5. Fuck
6. Sleep - small structure and medially supports the pituitary
ANS Neurotransmitter mechanisms
Neurotransmitters: chemical messengers that are received by one axon and received by another neuron to transmit information
- EPI (also humoral)
- NE (also humoral)
- Ach (pregang acting on post gang releases ach)
Cholinergic neurons
release Ach - preganglionic neurons
- Nicotinic: autonomic ganglia
- Muscarinic: heart, smooth muscle, glands
Adrenergic Neurotransmitters
Don’t need to know the details of this, just know that they are EPI and NE
Alpha 1 receptor - smooth muscle
Beta 1 receptor - heart
Receptors and Neurotransmitters of SNS**
- Pregang synapse and release Ach-> postgang nicotinic receptors take the Ach -> post gang synapses to the organ terminal (sweat glands, blood vessels) on muscarinic receptors and also releases Ach
- Pregang -> synapse and release Ach-> postgang nicotinic receptors take the Ach -> post gang synapses to the organ terminal (heart, blood vessels) on adrenergic receptors and also releases Norepi/epi
- Pregang -> synapse and release Ach on adrenergic receptors in adrenal medulla -> adrenal medulla secretes epinepherine that circulates in the blood stream and acts on the heart and blood vessels
**Receptors and Neurotransmitters of PNS*
Pregang synapse and release Ach-> postgang nicotinic receptors take the Ach -> post gang synapses to the organ terminal (glands, smooth muscle, heart) on muscarinic receptors and also releases Ach
process of homeostasis
- imbalance triggers a change in variable
- the change is detected by a receptor
- the receptor inputs information along an afferent pathway to the control center
- the control center changes its response and sends the output of PNS or SNS or both to the effector
- the effector responds and feeds back to influence magnitude of stimulus and returns variable to homeostasis
Negative or Positive Feedback Loop
responding to a stimulus
Feedforward Loop
- when you exercise, HR automatically increases before exercise to prepare
- responding to cold weather by shivering
Autonomic reflexes
Baroreceptors Micturition (bladder) Pupillary Peristalsis Respiratory
Negative feedback loop
imbalance is the perturbation, receptor senses it and effector changes it
Reflex arc
- sensory receptor
- afferent nerve fiber
- synapse(s) efferent nerve fiber
- effectors
-can be simple or more complex
does homeostasis include feedforward or feedback loops more?
Feedback loops
Simple reflex arc
TTR - somatic reflex
simple stretch reflex with the tendon tap that gives stretch to your afferent fibers that synapse on efferent neuron that causes the reflex
ANS reflex arcs
COMPLEX reflexes afferent pathways (input) > integration/central processing > efferent ways (output) > Back to afferent pathways (input)
-influenced in may ways
sensory receptors of the ANS
- Mechanoreceptors: (respond to mechanical stimuli) aortic baroreceptors, carotid sinuses, lungs; bladder, veins, intestines
- Chemoreceptors: (sense pH, or concentration levels) carotid/aortic bodies, medulla, hypothalamus; stomach, taste buds, olfactory bulbs
- Nociceptors: attached to viscera, arterial walls
- Thermoreceptors: hypothalamus; cutaneous
Dysfunction of the ANS
typically long standing dysfunctions
- orthostatic hypotension
- neurogenic bladder changes (spastic bladder)
- stress
- anxiety
- syncope
- autonomic dysreflexia
- dysautonomia
- Spinal Shock
- Horner’s Syndrome
