Chapter 14 - Nervous System Functions Flashcards
What is sensation?
Concious awareness of the effects of stimuli, received by sensory receptors. The brain perceives info about body and environment via senses.
What are the steps to sensation?
- Stimuli originates either inside or outside the body. And is detected by the sensory receptors.
- Stimuli is converted into action potentials which are carried to the CNS.
- Within the CNS nerve tracts convey action potentials to the cerebral cortex and other areas of CNS.
What are general senses and what are they?
They are distrubuted over large parts of the body. These general senses are somatic (info about body and environment) examples are touch, pressure, temp, pain. And Visceral primarily pain and pressure in the internal organs.
What are special senes and what are they?
They are found in special locations within the body and have specialized nerve endings. They include sight, smell, taste, hearing and balance.
What are the 5 types of sensory receptors according to the categorized by the type of stimulus?
Mechanoreceptors: Respond to manual stimulus tickle, touch, vibration.
Chemoreceptors: Respond to different chemicals. Smell and taste.
Thermoreceptors: Respond to change in temperature.
Photoreceptors: Respond to light. Sense of vision.
Nociceptors (pain receptors): Extreme mechanical, chemical or thermal stimuli. Causes sense of pain.
What are the 3 types of receptors catergorized by location?
Exteroreceptors: Associated with skin
Visceroreceptors: associated with organs.
Proprioceptors: Associated with joints and tendons.
Describe Free Nerve Endings
Simplest and most common sensory receptor
Scattered through body
Include: cold and warm receptors, pain receptors
What are merkel cells?
More complex than free nerve endings.
Located in basal layer of epidermis.
Responds to light touch and superficial pressure.
What are hair follicle receptors?
Respond to slight bending of hair.
Wraps around the hair follicle.
What are Pacinian Corpuscles?
Complex receptors, resembling an onion.
Located in deep dermis or hypodermis.
Detects deep cutaneous pressure + vibration
What is meissner corpsucles?
Detect fine touch (two-point discrimination)
Located in the dermal papilla.
What is the Ruffini End Organ?
Responds to continuous touch or pressure
Found in dermis, mostly fingers.
What are muscle spindles?
Provides information about length of muscles.
Involved in stretch reflex.
What is the difference between primary receptors and secondary receptors?
Primary Receptors: Transmit action potentials toward the central nervous system.
Secondary Receptors: release neuro-transmitters and form action potential.
What is adaption/accomodation?
Decresed sensitivity due to a continued stimulus
What are the types of Adaption Receptors?
Tonic receptors: slowly adapting receptors; accommodate very slowly.
Phasic receptors: rapidly adapting receptors; accommodate rapidly.
Describe Antero-lateral System?
Conveys pain, temperature, light touch, pressure, tickle, and itch.
Action potential reach primary neuron –> Synapses with second neuron in spinal cord –> Second neuron ascends to thalumus and synapses w. tertiary neurons and projects to Sensory Cortex.
Describe Dorsal-Column/Medial-Lemniscal System?
Carries sensations of two-point discrimination, proprioception, pressure, vibration to cerebrum, and cerebellum
Action potential reach primary neuron –> ascend through spinal cord to medulla oblongata –> Synapse with second neuron —> Ascend to thalamus and projects to sensory cortex.
What is referred pain?
Pain in one region of body that is not source of stimulus. Ex: feeling pain in the arm when having a heart attack.
Caused when both the organ and that region of the skin input to the same spinal segment
What is phantom pain?
occurs in people who have appendage amputated or structure removed
What is chronic pain?
Cerebrum and thalamus may malfunction and misinterpret discomfort as pain.
What does the motor system do?
Maintains posture and balance; moves limbs, trunk, head, eyes; facial expression, speech
What are reflexes?
movements that occur without conscious thought
Describe the two neurons: upper and lower
Upper motor neurons: directly connect to lower neurons
Lower motor neurons: axons leave the CNS, extend through PNS to skeletal muscles.
What are the three steps to voluntary movements?
- Stimulation of upper motor neurons.
- They stimulate lower motor neurons
- which stimulate skeletal muscles to contract.
What are the three motor areas of the Cerebral Cortex?
Precentral gyrus
Premotor area: Motor functions organized before initiation
Prefrontal area: motivation, foresight to plan and initiate movements, emotional behavior, mood
What are Direct Pathways and what are their two tracts?
Control fine, skilled movements in the face and distal limbs
Corticospinal: direct control of movements below the head
Corticobulbar: direct control of movements in head and neck
Describe the basal nuclei
Important in planning, organizing, coordinating movements and posture
Disease related to disfunction in basal nuclei: Parkinson’s Disease
What is the function of the cerebellum?
control balance during movement. Corrects discrepancies between intended movements and actual movements;
Capable of “learning” complex motor activities;
What are the three major parts of the cerebellum and their roles?
Vestibulo-cerebellum – balance and eye movements;
Spino-cerebellum – controls the discrepancies between intended and actual movements;
Cerebro-cerebellum – capable of “learning “ highly specific complex motor activities
What are the functions of the brain stem?
All ascending and descending pathways pass through the brainstem
Many vital reflexes important for survival are located here: respiration, coughing, heart rate, blood pressure, swallowing
What area of the brain affects speech?
Left cerebral Cortex
What are the two areas of the Left Cerebral Cortex that affect speech?
Wernicke’s area: sensory speech- understanding what is heard and thinking of what one will say.
Broca’s area: motor speech- sending messages to the appropriate muscles to actually make the sounds.
What is Aphasia?
absent or defective speech or language comprehension. Caused by lesion somewhere in the auditory/speech pathway.
Describe the differences between the left and right brain hemispheres.
Right: receives sensory information from left side of body. recognition of faces, artistic/musical ability
Left: receives sensory information from right side of body. mathematics and speech
What is the record of the brain’s electrical activity?
Electroencephalogram (EEG)
What are the 4 brain waive patterns?
Alpha: Resting state with eyes closed
Beta: During intense mental activity
Theta: Occur in children but also in adults experiencing frustration or brain disorders
Delta: Occur in deep sleep, infancy, and severe brain disorders
What are the three types of memory?
Sensory: very short-term retention of sensory input
Short-term: information retained for few seconds to minutes
Long-term: memory for longer than a few minutes.
What are the two types of long term memory?
explicit:
Retention of facts for months and years
implicit memory: development of skills such as riding a bicycle
What is the function of the limbic system?
Influences emotions,motivation, mood, sensations of pain and pleasure, Basic survival instincts, release of pheromones.
What are the effects of aging on the nervous system?
Gradual decline in sensory and motor function
Reflexes slow
Size and weight of brain decrease
Decreased short-term memory in most people
Long-term memory unaffected or improved
Changes in sleep patterns
What are the 2 layers of the epidermis and the 1 layer that is beneath these two?
Epidermis - Superficial layer of epithelial tissue
Dermis - Deep layer of connective tissue
Hypodermis - has loose connective tissue and adipose tissue
