Somatosensory
What is the somatosensory system?
Detects touch, temperature, pain, vibration, pressure, hair movement, and proprioception (muscle/limb location)
What is a receptive field?
Part of the body/environment where a stimulus is applied that changes the activity of a neuron - excites or inhibits
What is the somatic motor system?
Part of the nervous system that generates voluntary movements of skeletal muscles (attached to bones)
What is the main goal of the autonomic nervous system?
Maintain homeostasis - balanced, stable, internal environment around a set point
What is referred pain?
Pain felt in one part of the body that is actually caused by pain or injury to another part of the body
What are the two types of somatosensory receptors?
Encapsulated and Free
What are the two ways somatosensory receptors adapt to stimuli and how do they work?
Rapidly - respond only at beginning and end of stimulus
Slowly - respond throughout stimulus application
What are Flexors vs Extensors?
Flexors - Decrease joint angles
Extensors - Increase joint angles
What are the two divisions of the autonomic nervous system and what do they do?
Parasympathetic - rest/digest
Sympathetic - fight/flight
What is myasthenia gravis, what does it interfere with, and how can it be treated?
Autoimmune disease where body's immune system attacks nicotinic ACh receptors
Interferes with normal muscle contraction and causes severe muscle weakness
Can be treated with AChE antagonists that block ACh breakdown
What are the two types of stimulus receptors respond to and what do they mean?
Stimulus Intensity - A.P. frequency
Stimulus Timing - Beginning and end of A.P.s
What are the three categories of somatosensory receptors and what do they detect?
Thermoreceptors - temperature
Mechanoreceptors - distortions of skin, muscles, or joints
Nociceptors - pain
What are the three types of movement in the somatic motor system?
Reflexes
Rhythmic Movements
Voluntary Movements
What is the autonomic nervous system controlled by?
Hypothalamus
What is cerebral palsy and when does damage occur?
Group of movement disorders caused by damage to parts of the brain that control movement
Weak or stiff muscles and tremors
Damage occurs during pregnancy or shortly after birth
What is a dermatome?
Area of skin supplied by primary somatosensory neuron axons of one spinal cord segment
How does the size and density of receptive fields vary across the body?
Largest receptive fields with low density - limbs/rest of body
What does the primary motor cortex receive input from?
Premotor Cortex
Broca's Area
Prefrontal Cortex (PFC)
What are the three types of enteroreceptors and what do each detect?
Nociceptors - pain/damage in visceral organs
Chemoreceptors - detect blood gases and chemicals
Mechanoreceptors - detect stretch of blood vessels (blood pressure)
What is muscular dystrophy, who does it impact the most, and what does it look like in the life span?
Genetic condition that causes severe muscle weakness
Almost always in males
Victims are usually wheelchair bound by age 12, death in early 30s
What do both the dorsal column pathway and the spinothalamic pathway have in common? (3 things)
Have 3 neurons in a series
Cross over
Terminate in cerebral cortex where homunculus is located
What is lateral inhibition?
Neurons with the most activity from stimuli inhibit neighboring neurons only slightly excited by stimuli
What are the two types of muscle fibers and what is different about them? What types of muscles are they in?
Dark/Slow Twitch - dark, resist fatigue, lots of mitochondria and myohemoglobin - standing and posture muscles
White/Fast Twitch - white, fatigue quickly, very little mitochondria and myohemoglobin - quick, strong muscles
What is the visceral sensory pathway from start to finish?
glossopharyngeal (IX) and Vagus (X)
NTS Medulla
Hypothalamus
Changes made depending on visceral sensory conditions
What is Amyotrophic Lateral Sclerosis (ALS)?
Lou Gehrig's disease
Loss of voluntary movement over 1-5 years
Death results from failure of diaphragm
Motor neurons in ventral horn die and muscles can no longer work