Chapter 15 & 16 - ANS & Sensory, Motor & Integrative Systems Flashcards
(2) divisions of ANS
sympathetic
parasympathetic
Structure of the Sympathetic Division
thorocolumbar (sympathetic) division- Preganglionic neurons originate from thoracic & lumbar levels of spinal cord (T1-L2).
**Sympathetic ganglia - **site of synapse between sympathetic pre & postganglionic
(2) types - sympathetic trunk & prevertebral (collateral) ganglia
Preganglionic & postganglionic neurons
**preganglionic - **cell body in CNS, exits as cranial/spinal nerve
axon = type B fiber (small, myelinated)
**postganglionic - **in PNS (outside CNS), cell body & dendrites in **autonomic ganglia **
axon = small, unmyelinated type C fiber
Sympathetic division
**sympathetic ganglia (2) **
**Sympathetic trunk (vertebral chain) ganglia. - **innervate organs above diaphragm
Prevertebral (collateral) ganglia: celiac, superior mesenteric, inferior mesenteric,
aorticorenal and renal.
innervate organs below diaphragm
Once axons of sympathetic preganglionic neurons pass to **sympathetic trunk ganglia, **they may connect with postganglionic neurons in the following ways (4)
1) synapse with neurons in nearest gangliaon
2) axons ascend/descend to higher/lower ganglion, **sympathetic chains **
3) through sympathetic trunk ganglion to synapse with neurons in prevertebral ganglion
4) through **sympathetic trunk & prevertebral **to chromaffin cells of adrenal medulla
A single sympathetic preganglionic fiber has many axon _______________ and may synapse with 20 or more postganglionic neurons.
branches (collaterals)
sympathetic postganglionic axons typically terminate in several
visceral effectors
therefore effects are more widespread than parasympathetic stimulation
Structure of the Parasympathetic Division
craniosacral divison - Preganglionic neurons originate from cranial
nerves III, VII, IX, X & sacral spinal nerves S2-S4
**parasympathetic ganglia - **preganglionic synapse with postganglionic in **terminal (intramural) ganglia **.
Parasympathetic Presynaptic neuron usually synapses with 4-5 postsynaptic neurons all of which supply ?
a single visceral effector
Autonomic Plexuses in Thorax, Abdomen & Pelvis
network of sympathetic & parasympathetic neurons
**thorax plexus - **heart
**pulmonary plexus - **bronchial tree
**celiac (solar) **plexus - largest. stomach, spleen, pancreas, liver, gallbladder & adrenal medulla
Sympathetic response
fight or flight
↑ ATP, heart rate, BP, blood supply to skeletel/cardiac muscles, liver & fat, blood glucose
dilation of pupils, constriction of blood vessels
breakdown of glycogen & lipids
Parasympathetic Responses
rest & digest
**conserve & restore energy **
↑ digestive & urinary function
↓ body functions supporting physical activity
Sensation
conscious & subconscious awareness of changes in environment
components of sensation
Stimulation of sensory receptor → transduction of stimulus → nerve impulses → integration of sensory input.
Classification of Sensory Receptors
General senses
Special Senses
- General senses
- Special senses
1) somatic & visceral
a. **somatic - **tactile, thermal, pain &proprioceptive sensations
b. Visceral- provide info about conditions within internal organs.
2) smell, taste, vision, hearing, equilibrium/balance
Types of Sensory Receptors
free nerve endings
encapsulted nerve endings
seperate cells
free nerve endings
pain & thermoreceptors
encapsulated nerve endings
dendrites enclosed in CT capsule
pacinian corpuscles
seperate cells
hair cells, photoreceptors & gustatory receptor cells
Generator Potential and Receptor Potential
Generator potential: produced by free nerve, encapsulated **nerve **endings, and olfactory receptors. When it reaches threshold, triggers 1+ nerve impulses in axon of ** first-order sensory neuron. **
Receptor potential triggers release of neurotransmitters→ **postsynaptic potential → action potential. **
Classification of Sensory Receptors Based on the Location
o Exteroceptors: external surface
o **Interoceptors: **internal environment (vessels, organs & muscles & NS)
o **Proprioceptors: **muscles, tendons, joints & nner ear
Classification of Sensory Receptors based on the type of Stimulus
**mechanoreceptors - **mechanical stimuli (touch, proprioception)
thermoreceptors
**nociceptors - **pain
**photoreceptors - **light
**chemoreceptors - **chemicals in mouth, nose & body fluids
**Osmoreceptors **
Adaptation of Sensory Receptors
**rapidly adapting receptors: ** detect pressure, touch and smell.
**slowly adapting receptors: **detect pain, body position & blood chemical composition
**Somatic Sensations **
(4) modalities
sensory receptors in skin, muscles, tendons, joints & inner ear
**1) tactile **
2) thermal
3) pain
**4) proprioceptive **
**
Tactile Sensations **include?
touch
pressure
vibration
itch
tickle
Tactile receptors in skin
Meissner corpuscles
hair root plexuses
Merkel discs
Ruffini corpuscles
pacinian corpuscles
free nerve endings.
Meissner Corpuscles or Corpuscles of Touch
egg-shaped mass of **dendrites **enclosed by capsule of CT
rapidly adapting
- *dermal papillae of hairless skin *
TOUCH & PRESSURE
Hair root plexuses
rapidly adapting- **touch **
in hairy skin
free nerve endings wrapped around hair follicles
detect movement on skin that disturbs hair
Merkel Discs or Tactile Discs
type I cutaneous mechanoreceptors
slowly adapting touch
fingertips, hands, lips, external genitals
Ruffini Corpuscles
type II cutaneous mechanoreceptors
elongated, encapsulated receptors
deep in dermis, ligaments & tendons
hands & soles
Pacinian or Lamellated Corpuscles
Large oval structure composed of a multilayered CT capsule that encloses a dendrite (encapsulated)
fast adapting - pressure
joints, tendons, muscles, peiosteum, mammary glands, external genitals, pancreas & urinary bladder
Thermal Sensations
thermoreceptors
**cold - **stratum basale: medium myelinated A fibers
**warm - **dermis: small unmyelinated C
Pain Sensations
protective
nociceptors
free nerve endings
**fast: **acute, sharp/pricking
**slow: **chronic, aching
Refered pain
Pain is felt in or just deep to the skin that overlies the stimulated organ or in a surface area far from the stimulated organ
Proprioceptive Sensations
proprioceptors
slow adaptation
weight discrimation
(3) types: **muscle spindles, tendon organs & joint kinesthetic receptors **
Proprioceptors: muscle spindles
parellel to & among skeletal muscle fibers
measure muscle length
consist of **intrafusal (inside) muscle fibers - **specialized with sensory nerve endings & gamma motor neurons
**extrafusal (outside) muscle fibers - **surround muscle fiber supplied by alpha motor neurons
Tendon Organs
at junction of tendon & muscle
protect tendons from damage due to xs tension
thin capsule of CT that encloses few tendon fascicles
Joint Kinesthetic Receptors
Found within or around articular capsules of synovial joints.
Free nerve endings & Ruffini corpuscles respond to pressure
**pacinian corpuscles **respond to accel/deceleration of joints during movement
Somatic Sensory Pathways
- first order neurons
- second order neuron
- third order neuron
- (somatic receptor →** brain stem/spinal cord**
- brain stem/spinal cord → thalamus
- thalamus → primary somatosensory area
Major Somatic sensory pathways
o The posterior column-medial lemniscus pathway.
o The anterolateral (spinothalamic) pathway.
o The trigeminothalamic pathway.
o The anterior and posterior spinocerebellar pathway.
The Posterior Column-Medial Lemniscus Pathway
impulses for touch, pressure, vibration, conscius proprioception from **limbs, trunk, neck, & posterior head **to cerebral cortex
The Anterolateral (spinothalamic) pathway
pain, cold , warmth, itch, & tickle from the limbs, trunk, neck, and posterior head to cerebral cortex.
Trigeminothalamic Pathway
most somatic sensations
from face, nasal/oral cavity & teeth to cerebral cortex
Somatic Motor Pathways
upper motor neurons → lower motor neurons →
skeletal muscles
Neural circuits involving basal ganglia and cerebellum regulate activity of
_______________ motor neurons.
upper
Organization of the Upper Motor Neuron Pathways
**direct motor pathway **
originates in cerebral cortex
Direct Motor pathways (2)
**corticospinal - **limbs & trunk
**corticobulbar - **skeletal muscles in head
Indirect motor pathway-
originates in brain stem
Indirect or Extrapyramidal Pathways (4)
Rubrospinal tract
- Tectospinal tract
- Vestibulospinal tract
- Reticulospinal tract
Modulation of Movement from the Cerebellum
coordinates and smoothes contractions of skeletal
muscles during skilled movements & helps maintain posture and balance.
Integrative Functions of the Cerebrum
wakefulness, sleep, learning, memory
o The role of Reticular Activating System (RAS) in Awakening
neuronal axons from **reticular formation **through **thalamus **to cerebral cortex
increased activity = awakening
Sleep
(2) components
state of altered consciousness
1) NREM
2) REM
4 stages of sleep
- relaxed
- light sleep
- moderately deep sleep
- deepest sleep (sleepwalking)
Learning
ability to acquire new info/skills through instruction/experience
Memory
process by which information acquired through **learning **is stored and retrieved.
Memory types (3)
immediate
short-term
long-term
