Ch 14/15 Flashcards
Define sensation
Conscious awareness of stimuli received by sensory receptors
Explain the steps to sensation
- Stimuli in/out of the body must be detected by sensory receptors and converted into action potential, which are multiplied to the CNS by nerves
- In the CNS, nerve tracts guide action potentials to the cerebral cortex and to other areas of CNS
- Action potentials reaching cerebral cortex must translated so the person can be aware of stimulus
Explain ‘ general’ type of sense
- distributed over large part of body
- receptor generates an action potential called a Generator Potential that travels to the brain called Primary Receptors
Explain the ‘special senses’
Receptor produces a receptor potential and the receptor then releases a neurotransmitter that binds to receptors on the membrane of neuron which then travels to the brain. Called “ Secondary receptor “
What are the 5 types of sensory receptors?
- Mechanoreceptors: compression, bending, stretching of cells. Touch, pressure, balance, & hearing.
- Chemoreceptors: chemicals become attached to receptors on their membranes. Smell & taste
- Thermoreceptors: respond to changes in temperature
- Photoreceptors: responds to light
- Nociceptors: extreme mechanical, chemical, or thermal stimuli. Pain
What are the types of receptors based on location
Exteroreceptors: associated with skin
Visceroreceptors: associated with organs
Proprioreceptors: associated with joints and tendons
Explain free nerve endings
- simplest, most common sensory receptors
- scattered throughout most of body
Hair follicle receptors
Sensation not very localized, yet very sensitive
Pacinian corpuscles
- responds to pressure and vibration
- when associated with joints, involved in proprioception
Golgi tendon organs
- respond to increased tension on tendon
Muscle spindles
- involved in stretch reflex
What are the responses of sensory receptors?
- Accommodation (adaptation): decreased sensitivity to a continued stimulus
- Proprioceptors: provide info about the precise position and the rate of movement of various body parts, the weight of an object being held and the range of movement of a joint.
- two types of proprioceptors provide info:
- tonic receptors( slowly adapting receptors) generate action potentials as long as stimulus is applied. Ex allow us to know where our little finger is at all times without actually looking for it.
- phasic receptors ( rapidly adapting receptors ) adapt rapidly and are most sensitive to changes in stimuli. Ex allows us to know where our pinky finger is while moving it, thus we can control its movement through space and predict where it will be the next movement
What is spinocerebellar system ?
- carries proprioceptive info to cerebellum
- actual movements monitored and compared to cerebral info representing intended movement
What is spinoolivary?
- contribute to coordination of movement associated with balance
What is spinotectal?
Involved in reflexes that turn the eyes and the head towards point of cutaneous stimulation
What is referred pain ?
- sensation in one region of body that is not source of stimulus
What is phantom pain?
Occurs in people who have appendage amputated or structure removed such as a tooth. It feels as though the pain is coming from a body part that is no longer there.
What is chronic pain
Misinterpret discomfort as pain
What are voluntary movements
Consciously activated to achieve a specific goal
What are the 2 neurons?
Upper motor neurons: directly or through interneurons connect to lower
Lower motor neurons: Axons leave the CNS, extend through PNS to skeletal muscles
What are the 3 areas of the cerebral cortex?
- Pre central gyrus: primary motor cortex
- Pre motor area: anterior to primary motor cortex
- Prefrontal area: motivation, emotional behaviour, mood.
What are the functions of the Brainstem?
Heart rate, blood pressure, respiration, sleep, swallowing, vomiting, coughing and sneezing
Explain the speech function of the brain?
Wernickes area: sensory speech- understanding what is heard and thinking of what one will say
Broca’s area: motor speech- sending messages to appropriate muscles to make the sounds
Aphasia: absent or defected speech comprehension caused by lesion somewhere in the auditory/ speech pathway
Explain the right / left cerebral cortex
Right :
Controls muscular activity in and receives sensory info from left side of body
- three dimensional or spatial perception. Recognition of faces, musical ability
Left: controls muscular activity in and receives sensory info from right side of body
- mathematics and speech
