Integrating Autonomic & Volitional Control (9/20b) [Biomedical Sciences 1] Flashcards
What does the BP tell you?
Tells you the pressure in your arteries when the heart is relaxing/contracting
What does systolic BP tell you?
tells you about contractility of the heart
What does diastolic BP tell you?
tells you how much pressure the blood applies against the walls of the arteries and how much peripheral resistance is in the arteries
What does the HR tell you?
It tells you how fast the heart is pumping blood
How is BP and HR controlled?
Sympathetic and parasympathetic control
How do we move?
Nervous system - brain coordinates the systems
Musculoskeletal (somatic)- muscles to do the work
Cardiorespiratory (autonomic)- lungs to supply oxygen
Metabolic (autonomic) - energy to do the movement
Parts of the CNS
Forebrain Midbrain Brain Stem Hindbrain Spinal cord
Parts of the Forebrain
Cerebral cortex + white matter
Basal ganglia
Diencephalon (thalamus + hypothalamus)
Parts of the Brain Stem
Midbrain
Pons
Medulla oblongata
Parts of the Hindbrain
Brain stem
Cerebellum
Parts of the Spinal Cord
Cervical
Thoracic
Lumbar
Sacral
Autonomic Nervous System (ANS)
part of the CNS
communicates with internal organs and glands
Sympathetic and Parasympathetic divisions (and enteric NS)
Sympathetic vs Parasympathetic Nervous Systems
Sympathetic (SyNS)- arousing, fight or flight, uses energy
Parasympathetic (PsNS)- calming, rest and digest, conserves energy
Sympathetic ganglia
lie close to the spinal column and supply virtually every tissue in the body
some tissues (EX: skeletal muscle) are regulated only indirectly through their arterial blood supply
Parasympathetic ganglia
found in close approximation with their targets, which don’t include skin or skeletal muscle
Basic organization of SyNS
Preganglionic Neurons = spinal cord: T1-L2/L3, mostly from lateral horn gray matter → thoracolumbar outflow
Synapse in pre/paravertebral chain of ganglia (sympathetic)
Organ
Basic organization of PsNS
Preganglionic Neurons = brainstem nuclei (CNs 3, 7, 9, 10), spinal cord S2-S4 → craniosacral outflow
Synapse on parasympathetic ganglia
Organ
Circuitry - Somatic Motor System (volitional)
somatic motor neuron in the spinal cord, axons leave the ventral route and innervate skeletal muscle
Circuitry - Autonomic Motor System
preganglionic neuron in spinal cord, synapses on autonomic ganglion, axons of postganglionic neuron supply the organ
Ganglia controlled by preganglionic nerves
Preganglionic nerve cell bodies located in spinal cord and brainstem
- Release Acetylcholine (Ach) onto postganglionic nerves in ganglia
Axons of the ganglionic cells produce effects on the end organs (postganglionic nerves)
SyNS: Paravertebral sympathetic ganglia (trunk/chain)
Paravertebral = next to each other
- Bilateral chains (cervical to sacral)
- Found on both sides of spinal cord
Host postganglionic neurons
GANGLIONS:
- Superior Cervical Ganglion
- Middle Cervical Ganglion
- 3 Inferior Cervical Ganglia (Stellate – fused inferior cervical and first thoracic)
- 11 Thoracic
- 4 Lumbar
- 4 or 5 Sacral
SyNS: Prevertebral (collateral) sympathetic ganglia
Midline, anterior to spinal cord, near arteries of same names
- Celiac ganglion
- Superior mesenteric ganglion
- Inferior mesenteric ganglion
Basic trajectory of 1st preganglionic neuron within sympathetic trunk
Preganglionic nerve →
ventral root →
rami communicans →
postganglionic nerve in paravertebral or prevertebral ganglia
3 route options in sympathetic trunk
Option 1: Leaves ventral (anterior nerve) route of spinal cord (efferent), goes to the same level of paravertebral ganglion, synapses at postganglionic neuron
Option 2: Leaves ventral route, goes up or down paravertebral chain, then synapses at a different level postganglionic neuron
Option 3: Leaves ventral route, goes up/down paravertebral chain and supplies the preganglionic ganglion
Parasympathetic ganglia
PNS Ganglia located close to target organs (separated unlike those in the SNS)
75% of PNS fibers via CN X (vagus nerve)
GANGLIA
- Ciliary ganglion
- Pterygopalatine ganglion
- Submaxillary (submandibular) ganglion
- Otic Ganglion
- Multiple organ specific ganglia for thoracoabdominal and pelvic viscera
Central Autonomic Network
Higher up control
Get afferent info from periphery, process it, produces sympathetic or parasympathetic response
Afferent and efferent pathways
Main goal of hypothalamus
integrating autonomic, behavioral (somatic) and neuroendocrine responses to maintain homeostasis
6 Roles of Hypothalamus (5 F’s and 1 S)
- Food metabolism
- Furnace (body temp)
- Fight response
- Flight response
- F*ck (sexual/parental behavior)
- Sleep/wake cycles
ANS Neurotransmitters
chemical messengers that are released by an axon and placed on a neuron to transmit a response
COMMON:
- Norepinephrine (NE)
- Epinephrine (E)
- Acetylcholine (Ach)
OTHERS:
- Serotonin (5-HT), Dopamine, Histamine
- Adenosine, ATP, Substance P
- Nitric Oxide, Neuropeptide Y, Vasoactive Intestinal Peptide
Autonomic receptors and NT effects
2 groups of cholinergic (Ach)
- Nicotinic: autonomic ganglia
- Muscarinic: heart, smooth muscle, glands
Adrenergic (NE/Epi) –
- Alpha 1: Smooth muscle
- Beta 1: Heart
SyNS receptors/NT
Preganglionic neuron → postganglionic neuron → organ
ACh (nicotinic) → ACh (muscarinic) at sweat glands/blood vessels
ACh (nicotinic) → NE (adregenic) at heart/blood vessels
ACh (nicotinic) → E (adregenic) at heart/blood vessels
PsNS receptors/NT
Preganglionic neuron → postganglionic neuron → organ
ACh (nicotinic) → ACh (muscarinic) at glands/smooth muscle/heart
Homeostasis - Overview
Maintenance of an internal balance by adjusting physiological processes
Hypothalamus plays critical role
Usually feedback loop, some situations can involve feedforward control (EX: an athlete’s body may begin to prepare for exercise by increasing HR, RR, etc.)
Homeostasis - Steps
Stimulus → produces change in variable
Change detected by receptor
Input → info sent along afferent pathway to control center
Output → info sent along efferent pathway to effector
Response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis
Autonomic Reflexes to Maintain Homeostasis - Examples
Baroreceptor (negative feedback)
micturition (bladder)
pupillary
peristalsis
respiratory
Reflex Arc
Autonomic reflexes parallel organization of somatic reflexes
Involves
- Sensory Receptor
- Afferent Nerve Fiber
- Synapse(s) Efferent Nerve Fiber
- Effectors
Can be simple OR more complex
Simple vs Complex Reflexes
In ANS, not many simple reflexes → most are more complex
SIMPLE
EX somatic reflex: simple stretch reflex
COMPLEX Afferent pathways (input) → integration/processing → efferent pathways (output) → loops back to afferent pathways
Sensory Receptors
Mechanoreceptors
- EX: baroreceptor, lungs, bladder
Chemoreceptors
- EX: hypothalamus, stomach
Nociceptors
- EX: throughout viscera, arterial walls
Thermoreceptors
- EX: hypothalamus, cutaneous
Examples of ANS Dysfunction
Stress
Anxiety
Hypertension
Orthostatic hypotension
