Chapter 12- The central nervous system Flashcards
What are the 4 regions of the brain in adults?
- Cerebral hemispheres
- Diencephalon
- Brain stem
- Cerebellum
Gray matter
Short, nonmyelinated neurons and neuron cell bodies. Contains dendrites, cell bodies, and axon terminals. Gray matter is peripheral in the brain
Gray matter function
Function- all synapses are found in gray matter- motor controls, sensory perception, decision making, etc
White matter
Myelinated axons, mostly in fiber tracts (bundles of axons that save space). White matter is central in the brain.
White matter function
Function- passes “messages” between different areas of gray matter
Cortex
The outer layer of gray matter in the brain
How are gray and white matter distributed in the brain stem?
Scattered gray matter is found within white matter
How are gray and white matter distributed in the spinal cord?
Gray matter surrounds a central cavity with white matter external to it- similar to the brain
Ventricles
Hollow chambers found in the brain that are filled with cerebrospinal fluid (CSF) and lined with ependymal cells (produce, secrete, and circulate CSF). CSF circulates between all ventricles freely- all ventricles don’t produce their own personal CSF
Where are the ventricles located?
- 2 lateral ventricles- one in each cerebral hemisphere
- Third ventricle- found in diencephalon
- Fourth ventricle- found in the hindbrain, continuous with the central canal of the spinal cord.
All 4 chambers are continuous with one another
Cerebral aqueduct
How the fourth ventricle connects to the third ventricle
Cerebral hemispheres
Form the most superior portion of the brain, make up most of the brain by mass
Regions of the cerebral hemispheres (3)
- Gray matter (cerebral cortex)
- White matter
- Basal nuclei
Gyri
Characteristic ridges of the cerebral hemispheres
Sulci
Characteristic shallow grooves of the cerebral cortex, divides the cerebral hemispheres into lobes. Almost all lobes are named after the bones they are found under (except for the insula).
Longitudinal fissure
Fissure that separates the left and right hemispheres
Transverse cerebral fissure
Fissure that separates the cerebral hemisphere from the cerebellum
Central sulcus
Separates the frontal lobe and the parietal lobe
Parieto-occipital sulcus
Separates the occipital lobe from the parietal lobe
Lateral sulcus
Separates the temporal lobe from the frontal and parietal lobes
Where is the insular lobe located in the brain?
Insula are buried in the lateral sulcus, must cut into the brain to find the insular lobe
Cerebral cortex/gray matter functions (6)
The portion of the brain where the conscious mind is found
Function- provides self awareness, sensation, communication, memory, understanding/learning, initiation of voluntary movement
Functional areas of the cerebral cortex (3)
- Motor areas- control voluntary movement
- Sensory areas- conscious awareness of sensations
- Association areas- integrate diverse information
Contralateral
Describes the cerebral hemispheres- the right hemisphere is concerned with the sensory and motor functions of the left side of the body and vice versa (opposite side of the body from the brain structure).
Are the cerebral hemispheres completely equal in function?
Hemispheres are not completely equal in function- one hemisphere may have structure/function that the other side does not. Ex- Broca’s area (speech) is usually found in the left hemisphere but not the right
How do both sides of the cortex work together?
No functional area of the cortex works alone- conscious behavior involves the entire cortex. The left and right hemispheres interact and send information constantly, some functions require different parts of the brain to work simultaneously.
Motor areas of the cerebral cortex- location and function
Location- frontal lobe, function- controls voluntary movement
Motor areas of the cerebral cortex (4)
- Primary motor cortex
- Premotor cortex
- Broca’s area
- Frontal eye field
Primary motor cortex (motor area)
Function- allows for conscious control of skilled/precise voluntary movements. Two notable components include pyramidal cells and the motor homunculus.
Pyramidal cells
Pyramidal cells are large neurons typically found in primary motor cortex. Axons of these neurons project to the spinal cord, are bundled together to form corticospinal tracts. Neurons directly synapse with and stimulate motor neurons (responsible for motor responses)- help with voluntary movement
Motor homunculus
The body is represented spatially in the primary motor cortex of each hemisphere. The larger the body part, the more precise the movement and more neurons dedicated to that area.
Motor innervation of the body is
Contralateral
Premotor cortex (motor area) functions (3)
- Helps plan movements by selecting and sequencing basic motor movements into more complex tasks
- Controls voluntary actions that depend on sensory feedback
- Sends activating impulses to primary motor cortex to coordinate the movement of several muscle groups
Damage to the premotor cortex can result in (2)
- People with damage to this area might have trouble understanding the physical actions of other people (why they’re moving a certain way)
- Trouble with learning how to do/planning a physical task
Broca’s area (motor area) functions (2)
- Specialized motor speech area that directs muscles involved in speech production
- Becomes active as we prepare to speak (plans speech) or as we plan other voluntary motor activities
Where is Broca’s area found in the brain?
In usually found on one side of the brain only (left side usually)
Damage to Broca’s area can result in (4)
- Being unable to produce speech
- Speech is halting (paused randomly)
- Repetitive speech (repeating the same entire words or sentences multiple times) 4. Disordered sentence structure (all the right words to say something, but the words are spoken in the wrong order)
Frontal area (motor area)
Function- controls voluntary movement of the eyes, important for allowing people to follow movement of objects
Damage to the frontal area causes
Damage= unable or less able to follow a moving object
Sensory area of the cerebral cortex general function
General function (of any area)- allows for conscious awareness of sensation
Parts of the sensory area of the cerebral cortex (8)
- Primary somatosensory cortex
- Somatosensory association cortex
- Visual areas (sight)
- Auditory areas (hearing)
- Vestibular cortex (balance/orientation)
- Olfactory cortex (smell)
- Gustatory cortex (taste)
- Visceral sensory area (sensations of internal organs)
Primary somatosensory cortex location
Parietal lobe
Primary somatosensory cortex function
Function- receive information from the general sensory receptors in skin, form proprioceptors- allows spatial discrimination (you can tell which part of the body is being stimulated). The more sensitive the body region, the bigger it is on the somatosensory homunculus.
Proprioceptors
inform the brain about the body’s position in space
Damage to the primary somatosensory cortex causes
Damage= difficulty perceiving touch in general or on the correct part of the body, have difficulty identifying objects by touch. Also have trouble recognizing parts of their own body
Somatosensory association cortex location
Parietal lobe
Somatosensory association cortex function
Function- integrates sensory input relayed to it via the primary somatosensory cortex- produces understanding of what is being felt (size, texture, relationship of its parts). Example- reaching into your purse and being able to tell your phone from your keys, etc.
Primary visual cortex
Largest cortical sensory area, located in the occipital lobe. Function- receives visual information that originates on the retina in the eye. Originally the image is upside down and backwards- the cortex fixes it
Visual association area
Location- occipital lobe. Function- uses past visual experiences to interpret visual stimuli- allows us to reorganize things
Visual areas of the cerebral cortex (2)
- Primary visual cortex
2. Visual association area
Auditory areas of the cerebral cortex (2)
- Primary auditory cortex
2. Auditory association area
Primary auditory cortex
Location- temporal lobe. Function- interpretation of sound from the inner ear as pitch, loudness, and location of sound in space
Auditory association area
Location- temporal lobe. Function- permits perception of sound stimulus and stores memories of sounds for reference. This is why you can remember songs or recognize people’s voices without seeing them
Vestibular cortex
Location- insula and adjacent parietal cortex (this is where it is believed to be- location is unclear). Function- allows for conscious awareness of balance/orientation
Olfactory cortex
Primary olfactory cortex is the main area. Location- temporal lobe. Function- conscious awareness of different odors, storage of memory so we can remember smells
Gustatory cortex
Location- insula. Function- perception of taste stimuli
Visceral sensory area
Location- insula. Function- allows conscious perception of visceral sensations. For example, you can feel a full stomach or bladder
Lateralization
The division of labor that exists between the two cerebral hemispheres.
Cerebral dominance
One hemisphere “dominates” a particular task- does most of the work, but the other hemisphere will have involvement. This is usually in reference to language. For a small amount of people, the cerebral dominance is flip flopped- this is usually left handed people. For some people, there is no cerebral dominance- usually ambidextrous
Which functions are typically associated with the left side of the brain?
Language abilities, math, logic. Example- the left side of the brain is dominant while speaking publicly, memorizing information
Which functions are typically associated with the right side of the brain?
Visual-spatial skills, insightfulness, creativity. Example- the right side of the brain is dominant for new ideas, art, poetry, etc
Which structures allow both hemispheres to communicate?
Fiber tracts connect the left and right side of the brain- can share information almost instantaneously and allows complete functional integration
Cerebral white matter function
Communication in the CNS. Mostly consists of myelinated fibers bundled into tracts
How is cerebral white matter classified? (3)
- Association of fibers
- Commissural fibers
- Projection fibers
Association of fibers function
Connect different areas of the same hemisphere
Commissural fibers
Connect corresponding areas of different hemispheres. Benefit- allows hemispheres to function as a coordinated “team”
Projection fibers
Allow sensory information to reach cortex motor output to leave the cortex
Basal nuclei/ganglia location
Deep to the white matter in each hemisphere
Basal nuclei/ganglia function (2)
Functions- filters out incorrect or inappropriate responses relating to:
- Muscle movement- the basal nuclei ensures that your muscle movement is coordinated and more precise
- Emotions and cognition- ensures that you don’t react inappropriately as a result of that emotion.
Diencephalon structures (3)
- Thalamus
- Hypothalamus
- Epithalamus
Diencephalon location
Around third ventricle of the brain
Thalamus functions (6)
- Relays sensory information coming into the cerebral cortex
- Information is “edited” here- impulses with similar functions are grouped together and relayed to appropriate part of the cortex
- Motor activities
- Cortical arousal (sleep/wake cycles)
- Learning
- Memory
How does the thalamus relay sensory information that comes into the cerebral cortex?
Your body is constantly sending a stream of sensory information to the cortex- the thalamus sends relevant information to the correct part of the cortex. Like a mail person- the thalamus is not responsible for interpreting or integrating information- just sends it to the right place. Gives a general feeling of “I like this” or “I don’t like this” in response to the stimulus.
Hypothalamus general functions (7)
Main visceral control center in the body:
- Controls autonomic nervous system
- Initiates physical response to emotion
- Regulates body temperature- the body “thermostat”
- Regulates food intake
- Regulates water balance and thirst
- Regulates sleep-wake cycles
- Controls endocrine system function
Which autonomic nervous system functions does the hypothalamus control?
Things that occur without you thinking about them- blood pressure, rate and force of heartbeat, digestive tract mobility, pupil size of the eye, etc. The harder your heart beats, the higher your blood pressure will be. Digestive tract can contract to move things through or can be at rest.
How does the hypothalamus initiate a physical response to emotion?
Involves the limbic system. Involved in perception of pleasure, fear, rage, sex drive, sleep. Ex- pounding heartbeat, sweating, etc.
How does the hypothalamus regulate body temperature?
Monitors the body temperature and initiates cooling down or heat generating processes. The hypothalamus is in close contact to the blood supply- blood temperature indicates internal body temperature
How does the hypothalamus regulate food intake?
Monitors blood nutrient levels (glucose and amino acids, some hormones)