Background info part 2 Flashcards
components that make up the ANS
- sensory (afferent) and motor (efferent)
- sympathetic and parasympathetic
-affects cardiac function, digestion, respiration, salivation, sweating, pupil diameter, urination, and sexual arousal
sympathetic nervous system
outflow comes from the thoraco-lumbar region
- fight or flight
the neurotransmitter at the postganglionic nerve endings of the sympathetic NS is ? Whats the exception?
norepinephrine; exceptions are that ACh is the neurotransmitter for sympathetic postganglionic innervation of sweat glands
sympathetic preganglionic neurons are found in the?
- lateral horn of the grey matter in the thoracic and lumbar regions of the spinal cord
parasympathetic nervous system
outflow comes from the cranial and sacral regions of the spinal cord
- relaxed state
postganglionic nerve endings of the PNS is?
acetylcholine (ACh)
the parasympathetic preganglionic neurons are found in the?
cranial and sacral regions
preganglionic nerve fibers are contained in?
some of the cranial nerves (III - oculomotor, VII - facial, IX - glossopharyngeal, and X - vagus), in the sacral region the fibers emerge from the cord as the sacral outflow and innervate the gut and sexual organs
the fibers of the parasympathetic preganglionic neurons generally synapse with their?
post-ganglionic neurons close to the organ innervated, the fibers are very short
the neurotransmitter released from both preganglionic and postganglionic nerves is?
acetylcholine
how is median nerve simulation impacted when measuring autonomic nervous system skin potentials
- stimulation can be on either side
- it is stimulation of afferent fibers that is important in establishing the sweating response reflex
function of ANS in the cardiovascular system
regulates blood pressure by affecting heart rate and peripheral resistance
function of ANS in the skin
the sympathetic system supplies the blood vessels of the skin; hence it is involved in thermoregulation, also supplies the sweat glands
function of ANS in the gastrointestinal system
regulates all aspects of gastrointestinal function
function of ANS in the urinary and reproductive systems
innervates the bladder and internal urethral sphincter, also supplies the erectile tissue
function of ANS in the eyes
- the parasympathetic system supplies the pupillary and ciliary muscles
- the sympathetic system supplies muscle in the eyelids
RR interval
- one cycle
- a function of intrinsic properties of the sinus node as well as autonomic influences
how is sweat production are used to assess autonomic nerve function?
- eccrine sweat glands are innervated by sympathetic nerves
- sympathetic activity causes an increase in sweat production, which is commonly assessed by measuring an increase in skin conductance
- an alternative that you will use here is to simply measure changes in potential across the hand and foot following peripheral nerve stimulation
how is heart rate variability, are used to assess autonomic nerve function?
- heart rate varies from beat to beat as a consequence of changes in parasympathetic and sympathetic nerve activity
- measurement of 20 to 40 consecutive RR intervals on an ECG during quiet breathing followed by a further 20 to 40 consecutive intervals during deep breathing provides a clear indication of the extent of the autonomic control of the heart
how postural changes are used to assess autonomic nerve function
- an abrupt change from a supine to an erect posture is associated with alterations in heart rate and blood pressure
- any decrease in blood pressure results in increased sympathetic activity with an increase in the heart rate and force of contraction
orthostatic hypotension
- people who experience a decrease of 20 mmHg systolic pressure or at least 10 mmHg diastolic pressure within three minutes of standing
- often associated with autonomic dysfunction, although there are a variety of other causes.
how are pupillary reflexes used to assess autonomic nerve function
- pupillary light reflex involves four neurons that convey information from the retina to the midbrain, and then back to the small muscles of the eye
pupillary reflexes (PNS)
parasympathetic motor nerve fibers innervate the circular muscles of the iris; they cause the iris to constrict, reducing the aperture (diameter) of the pupil
pupillary reflexes (SNS)
- sympathetic motor nerve fibers supply the radial muscles of the iris; contraction of the radial muscles leads to dilation of the pupil
- sympathetic fibers also innervate muscles in the eyelids, holding the upper eyelid open
- damage to the sympathetic supply can result in a drooping upper eyelid (ptosis) and in a constricted pupil (Horner’s syndrome).
various neuropathies that can potentially be encountered by people with diabetes
peripheral, autonomic, proximal or focal
change in potential in the hand that would follow peripheral nerve stimulation
You can explain the change in potential across the hand that follows peripheral nerve stimulation because when the peripheral nerves are stimulated it travels to the brain and activates the sympathetic nervous system which then activates the sweat glands and we see the hands sweat.
heart rate variability (breathing)
- quiet breathing: smaller/normal
- deep breathing: greater
RR interval (breathing)
- quiet breathing: smaller/normal
- deep breathing: greater
Valsalva maneuver
- take a deep breath in and then attempt to expire with the glottis closed, the mouth kept shut, and with the nose pinched closed
- used to assess the integrity of the autonomic nerves supplying the heart and blood vessels
purpose of an EMG
records electrical activity of the innervated muscle fibers
ways that an EMG can be measured
- intramuscular: needle electrodes inserted through the skin into the muscle
- surface: electrodes placed on the skin surface
coactivation among antagonistic muscle groups
- a phenomenon in which contraction of a muscle leads to minor activity in the antagonistic muscle
- helps to stabilize the joint during isotonic contractions
- consider the example of an isotonic contraction such as lifting a weight with your arm. The biceps muscle contracts to lift the weight, and the triceps also contract to help control this lifting movement
concentric contractions
the contraction of the biceps provides an example of concentric contraction; the muscle is shortening as the contraction proceeds
eccentric contractions
the controlled contraction of the triceps provides an example of eccentric contraction; here the muscle is lengthening even though it is contracting
conditions that may lead to muscle fatigue
- depletion of ATP stores
- changes in the “sense of effort”
- loss of the “central drive”
- failure of neuromuscular propagation
- reduction in Ca2+ release in excitation-contraction coupling
- metabolic changes in the muscle cell (such as build up of lactic acid which can make the skeletal muscle acidic, inhibiting any further anaerobic glycolysis)
- reduction in muscle blood flow owing to compression of blood vessels
three ways that ATP can be produced
aerobic glycolysis, anaerobic glycolysis, phosphocreatine