CNS Brain Flashcards
What makes up the CNS?
- Brain and spinal cord make up the CNS
How is the brain studied?
- Historically
- Study humans with brain damage
- Humans during brain surgery
- “Volunteers”
- Today, since 1990, we can learn about the brain less invasively
- fMRI = functional MRI
– Looks at increased blood flow (oxygen) to areas of brain - PET scan
– Looks at glucose utilization (high metabolic areas)
Facts about the brain?
- The brain weighs about 3.3 lbs
- Has a consistency of cold oatmeal
- Approx. 100 billion neurons
What is the Connective Tissues around Brain?
Connective Tissues around Brain
* Under the skull, there are 3 connective tissues surrounding the brain
(they surround the spinal cord as well)
* Dura mater (most superficial)
* Arachnoid mater
* Pia mater
What are the Meninges around Skull - Dura Mater?
Dura mater = “tough mother”
* Two layers of dense irregular CT, outermost layer
- Periosteal layer attached to skull (= periosteum)
- Meningeal layer = true external covering of brain
* Blood sinus (dural sinus) contained between layers
* Two layers are fused where there is no sinus
What is Arachnoid mater?
- Arachnoid mater = “spider mother”
- Just deep to dura mater
- Reticular CT
- Web-like extensions attach it to underlying pia mater; extensive blood supply
What is Pia mater?
- Pia mater = “soft mother”
- Deep to arachnoid mater
- Very thin, loose areolar CT
- Clings to surface of brain, into
indentations as well - Richly vascularized (small blood vessels)
What are the Spaces Between Meningeal Layers?
- Subdural space
- Subarachnoid space
What is Subdural space?
Subdural space
* Space between dura mater and
arachnoid mater
* Often referred to as potential space
* Can fill with fluid with disease or trauma
* Normally, contains only thin film of fluid
What is Subarachnoid space
Subarachnoid space
* Space between arachnoid mater and pia mater
* Contains cerebrospinal fluid (CSF)
What is Cerebrospinal Fluid (CSF)?
- Located in subarachnoid space and hollow cavities of
brain and spinal cord - Floats and cushions CNS, thereby preventing injury
- Provides nutrients, removes wastes from CNS
- Is similar to blood plasma, circulates within and around the CNS
- Continuously produced by ependymal cells of the capillary-rich choroid plexus
- Filtrate moves through ependymal cells, into ventricles
- Usually only 100-160 ml (1/2 cup) at any one time
What is CSF and the Choroid Plexus?
- Produced by filtration of plasma from blood capillaries in pia mater
- Filtrate moves through ependymal cells, into ventricles
- CSF continuously produced by filtration of blood plasma
CSF-Filled Structures of the Brain?
CSF-filled structures of the brain:
* Lateral ventricles (2)
* Third ventricle (1)
* Cerebral aqueduct (1)
* Fourth ventricle (1)
* Central canal (1, spinal cord)
What is the purpose of the ventricles in the brain?
Ventricles are connected, fluid-containing spaces within the brain
* After produced, CSF flows freely through ventricles
* Some CSF enters central canal (spinal cord)
* Most CSF enters subarachnoid space, bathing brain and spinal cord surfaces
What are Arachnoid Granulations?
Arachnoid granulations
* Portions of arachnoid mater that extend though dura mater into dural sinuses
* This is where CSF is returned to the blood after circulating through CNS
What is CSF movement?
CSF movement is in a pulsatile fashion
* Matches pulse of blood flow (from heart)
What is Hydrocephalus?
Hydrocephalus
* CSF is overproduced and/or not removed properly
* Increased intracranial pressure causes brain damage
* Treatment
- Insert shunt that delivers excess CSF to abdominal cavity
What is Meningitis?
- Inflammation of meninges, often by
infection (viral or bacterial) - The infection can spread to the
nervous tissue of brain- Swelling results
- Death can result
- Viral: most common; often resolves
within a few weeks - Bacterial: most dangerous; can be
treated with antibiotics
What is Blood Brain Barrier?
Capillaries of brain
* Are specialized continuous capillaries
* Endothelial cells are tightly packed; lacking in
intercellular clefts
* Many tight junctions formed by foots of
astrocytes
* Restricts what can enter the brain
- Lipid soluble substances more readily cross
- Can be issue with chemotherapy
What is White Matter?
White matter
* Made of myelinated axons
* Form fiber tracts
What is gray matter?
Gray matter composed of
* Dendrites
* Cell bodies
* Glial cells
* Unmyelinated axons
Gray and white matter
Brain
* Outer gray matter = cerebral cortex
* Inner gray matter = nuclei
Spinal cord
* Outer white matter = fiber tracts
* Inner gray matter
What is Cerebrum?
Cerebrum
* Makes up 83% of total brain mass (human)
* Two hemispheres (right and left)
* Has complex neural networks
* Originally part of the telencephalon
What is gray matter of cerebrum?
Gray matter
* Cerebral cortex
* Internal nuclei
What is the white matter of the cerebrum?
White matter
* Fiber tracts
* Example: corpus callosum
What is the Corpus Callosum?
Corpus Callosum
* Largest fiber tract that connects left and right sides of the brain (~200 million axons)
What are the types of processing in the cerebral cortex?
- Cerebral cortex = the executive suite
- The cerebral cortex has 3 primary types of processing areas
1. Sensory areas (interpret sensory information coming into brain)
2. Motor areas (dictate motor responses)
3. Association areas (receive and integrate info from multiple areas; stores
memories, assist with coordinated responses)
NOTE: There is much overlap in function and assistance from multiple
regions of the brain
What are the indentiations of Cerebral Cortex?
- Sulci (= furrow)
- Small indentations
- Gyri (= twister)
- Ridges - Fissures
- Deep indentations
What are the structures of Cerebral Cortex?
Notable structures:
* Central sulcus
- divides frontal and parietal lobes
* Longitudinal fissure
- separates both cerebral hemispheres
* Transverse cerebral fissure
- Separates the cerebellum from cerebral hemispheres
What are the Lobes of the Cerebral Cortex?
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
- Insula
Which side of the brain controls the left side of the body?
- The right hemisphere controls/receives info the left side of the body and vice versa
What is the purpose of the frontal lobe?
- Voluntary motor control
- Most anterior region: higher order cognitive functions (thinking, planning, decision making, working memory, executive functions)
What is the primary motor cotex?
Primary motor cortex
* Conscious control of skeletal muscles
* Damage →loss of voluntary motor control
What is the Motor Homunculus?
- Map of body’s motor control on brain
What is the prefrontal cortex?
Prefrontal cortex
* Most complicated cortical region
* Association area
* Processes emotions related to personal and social interactions
- Personality
* Working memory for object recall tasks
- Cognition
* Solving complex, multitask problems
- Intellect
* Damage: mental and personality
disorders
What are Frontal Lobe Lobotomies?
Used to correct behavioral issues and/or mental illness
What are the structures of the frontal lob?
- Primary motor cortex
- prefrontal cortex
- Brocas area
What is the Parietal Lobe?
Input and interpretation of sensory information coming from somatic senses (touch, temperature, pain, pressure, etc.)
what are the Structural and Functional Areas of Parietal Lobe?
- Parietal lobe (somatic sensation)
- Primary somatosensory cortex
- Receives input from somatic sensory receptors of body (touch, pressure, vibration, pain, temperature)
- Damage
- Inability to identify an object by touch
- Can still identify by sight (processed in different part of the brain)
What is the Sensory Homunculus?
Map of body’s sensory input on brain
What is the Temporal Lobe?
- Receives and interprets sound and sensory information from inner ear
- Receives and interprets smell from nasal cavity
What are the Structural and Functional Areas of Temporal Lobe?
- Primary auditory cortex
- Auditory association area
- Primary olfactory cortex
What is the Primary auditory cortex?
Primary auditory cortex
* Conscious awareness of sound
* Inner ear excites
What is the Auditory association area?
Auditory association area
* Evaluation of sound
- Ex. Screech, music, thunder
* Wernicke’s area
- Recognition of spoken words
What is the Primary olfactory cortex?
Primary olfactory cortex
* Conscious awareness of smells
* Sensory input from olfactory nerves
Temporal lobe and recognition of smells?
Association area allows for
recognition of smells
* Part of the limbic system
- Involved with emotions
Purpose of Occipital Lobe?
Occipital Lobe
* Receives and interprets stimuli from retina of eye
What are the Structural Areas of Occipital Lobe?
- Primary visual cortex
What is the Primary visual cortex?
Primary visual cortex
* Receives information coming from
receptors in retina
What is Insula?
- “New” lobe of cerebrum
- Functions: diverse (still researching)
- Visceral sensory cortex here
– Receives sensory input (pain, pressure,
hunger, etc.) from thoracic and abdominal
organs - Involved with the processing of
emotions - Self-recognition (and interoception =
awareness of the inner self)
What is the gustatory cortex?
Insula has a gustatory cortex
* Taste receives and interprets sensory information from taste receptors of oral cavity and throat
What is Parkinson’s Disease?
Two cardinal features with Parkinson’s:
* Loss of dopamine-producing cells of substantia nigra, and
* Clustering of a protein (alpha synuclein) in tight deposits called Lewy bodies
What is the purpose of the Limbic System?
- Limbic system structures are found in the cerebrum and diencephalon
- Considered the emotional brain
What are the structures of the limbic system?
Structures deep within temporal lobe:
* Amygdaloid body: memory of fears, regulates anger, proper responses to social clues; involved in PTSD
* Hippocampus: conversion of short-term memories to long-term memories
The limbic system interacts with many other parts of the brain, including
* The olfactory cortex
- Reason why smells can evoke emotions
* Hypothalamus
- Reason why emotional stress can cause high blood pressure and heart burn
What are the structures of Diencephalon?
Structures
* Thalamus
* Epithalamus
* Hypothalamus
What is the thalamus?
- Makes up 80% diencephalon
- Paired egg-shaped structures (one in both hemispheres)
- Information going to cerebral cortex must first go through thalamus (except olfactory input)
- Relay center for most sensory information to cerebral cortex
- Exception: olfaction
What is the epithalamus?
- Pineal gland
- Secretes melatonin
- Sleep hormone
What is the Hypothalamus?
Visceral control center made of many different nuclei
* Hunger and thirst
- Monitors concentration of salts and nutrients in blood
* Body temperature
- Initiates sweating and shivering in response to temperature changes in blood
* Controls smooth muscle cardiac muscle, glands
- Blood pressure
- Digestion
- Respiration
- Limbic center control center
Regulates the release of hormones from pituitary gland (endocrine)
What is the Cerebellum?
- Smooths and coordinates muscle movements by:
- Processing information from the motor cortex on planned movements
- Processing information from inner ear on head position and from proprioceptors throughout body on its position in space
- Involved with balance, fine motor
control, and motor memory - Originates from metencephalon
What are the components of the brain stem?
The brain stem components:
* Medulla oblongata
* Pons
* Midbrain
What is the Myelencephalon: Medulla Oblongata?
- Important nuclei involved in basic life support functions
- Cardiac center (heart rate and force of contraction
- Vasomotor center (regulates blood pressure)
- Respiratory center (rhythm and rate of breathing)
What is a stroke?
STROKE: Interruption of blood flow to a region of
the brain resulting in neuronal cell death
