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Brain.
Exam 6 - Lecture 2
Question | Answer |
---|---|
Gyri (Gyrus) | Ridges on the surface of the brain |
Sulci (Sulcus) | Shallow grooves on the surface of the brain |
Fissures | Deep grooves on the surface of the brain |
What is the largest part of the brain? | Cerebrum |
Cerebrum | Largest part of the brain; Controls higher mental functions; Divided into left and right hemispheres |
Longitudinal Fissure | Separates Cerebral hemispheres |
Neural Cortex of Brain | Surface layer of gray matter |
Nuclei of Brain | Deeper masses of gray matter |
Tracts | Bundles of Axons (white matter) |
Rostral | Toward Forehead |
Caudal | Toward Spinal Cord |
Brain weighs ___ to ___ lbs | 3 to 3.5 lbs |
Gray Matter is composed of: | Neuron cell bodies, Dendrites, and Synapses |
Where is Gray Matter in the Brain? | Forms Cortex over Cerebrum and Cerebellum; Forms Nuclei deep within brain |
White Matter is composed of: | Bundles of axons |
Where is White Matter in the Brain? | Forms Tracts that connect parts of the Brain; Connects gray matter |
Brainstem is made up of: | Midbrain, Medulla Oblongata, Pons |
What is the origin of the brain? | Neural Tube |
Primary Brain Vesicles | Prosencephalon (Forebrain), Mesencephalon (Midbrain), Rhombencephalon (Hindbrain) |
Prosencephalon (Forebrain) is composed of: | Telencephalon and Diencephalon |
Mesencephalon (Midbrain) is composed of: | Mesencephalon |
Rhombencephalon (Hindbrain) is composed of: | Metencephalon and Myelencephalon |
Telencephalon becomes: | Cerebrum |
Metencephalon becomes: | Cerebellum and Pons |
Myelencephalon becomes: | Medulla Oblongata |
Diencephalon becomes: | Thalamus and Hypothalamus |
Physical Brain Protection | 1. Bones of the cranium 2. Cranial meninges 3. Cerebrospinal fluid 4. Biochemical isolation (blood brain barrier) |
How does the skull protect the brain? | The bone absorbs most of the impact |
How do cranial meninges protects the brain? | Membranes anchor brain in place |
How does CSF protect the brain? | Fluid absorbs and disperses shock |
Are cranial meninges continual with spinal cord meninges? | Yes |
Outer membrane of Cranial Meninges | Dura Mater (endosteal layer) and Dura Mater (meningeal layer) |
Dural Sinus | Venous blood; Venous sinus is between the endosteal and meningeal layers of the Dura Mater |
Middle Membrane of Cranial Meninges | Arachnoid Mater |
Subarachnoid Space | Space underneath Arachnoid Mater; Contains CSF |
Inner Membrane of Cranial Meninges | Pia Mater; Entirely covers brain surface; Goes into brain grooves |
Meningitis | Inflammation of the meninges; caused by bacteria or virus |
Dural Folds | Folded inner layer of Dura Mater that extends into cranial cavity: 1. Falx Cerebri 2. Tentorium Cerebelli 3. Falx Cerebelli |
Falx Cerebri | Dural fold that contains Superior and Inferior Sagittal Sinuses |
Tentorium Cerebri | Dural fold that separates the Cerebellum and Cerebrum; Contains Transverse Sinus |
Falx Cerebelli | Divides Cerebellar hemispheres |
Functions of Dural Folds | Stabilize and support the brain; Contain collecting veins (Dural Sinuses) |
The 2 of the 3 Dural Folds that contain large venous sinuses that drain CSF and CNS blood into jugular veins are: | 1. Falx Cerebri (Superios and Inferior Sinuses) 2. Tentorium Cerebelli (Transverse Sinus) |
Ventricles | Lateral Ventricles, Third Ventricle, and Fourth Ventricle |
Lateral Ventricles | Each Cerebral hemisphere contains one large lateral ventricle; separated by a thin partition called the Septum Pellucidum |
Septum Pellucidum | Thin partition that separates the Lateral Ventricles in the Cerebrum |
Largest Ventricle | Lateral Ventricles in Cerebrum |
Third Ventricle | Located within Diencephalon (Thalami on either side) |
Interventricular Foramina (Foramen of Monroe) | Joins the Lateral Ventricles with the Third Ventricle |
Fourth Ventricle | Located in the Pons and upper Medulla Oblongata; it is connected to and continuous with the Subarachnoid Space of the spinal cord by the Lateral Apertures and Medial Aperture (Foramen of Luschka and Magendie) |
Cerebral Aqueduct (of Sylvius) | Connects Third Ventricle to Fourth Ventricle |
Lateral Apertures (Foramina of Luschka) | Connect the Fourth Ventricle to the Subarachnoid Space of the Spinal Cord (on either side of the Medial Aperture) |
Medial Aperture (Foramen of Magendie) | Connects the Fourth Ventricle to the Subarachnoid Space of the Spinal Cord (between the two Lateral Apertures) |
Functions of CSF | Cushions and supports the Brain |
How much Cerebrospinal Fluid is in the human body? | 140 mLs |
How many times per day is CFS replaced? | About 4 times per day |
Choroid Plexus | Areas of Brain where CSF is made |
Ependymal Cells in the Choroid Plexus | Glial cells connected by tight junctions are in close contact with permeable capillaries; Transport/exchange nutrients, chemicals, and waste |
Functions of Ependymal Cells | Secrete CSF, Remove waste, Adjust composition of CSF |
CSF has _____ protein than blood | Less |
Does CSF have a difference in ions/amino acids/lipids/waste products than blood? | Yes |
Flow of CSF: | Choroid Plexus to Lateral Ventricles; Interventricular Foramen to 3rd Ventricle (more CSF); Central Aqueduct to 4th Ventricle (more CSF); Out of Lateral & Median Apertures; Fills Subarachnoid Space; Reabsorbed by Arachnoid Villi to blood of Venous sinuses |
In the flow of CSF, where is more CSF added? | Choroid Plexus in Third Ventricle and Fourth Ventricle |
CSF in Subarachnoid Space is absorved into Venous blood vis: | Arachnoid Villi |
Arachnoid Villi | Extensions of Subarachnoid Space; Extend through Dura Mater to Superior Sagittal Sinus |
Arachnoid Granulations | Large clusters of villi that absorb CSF into Venous circulation |
Blood-CSF Barrier | Formed by special Ependymal Cells; Surrounds capillaries of Choroid Plexus; Limits movement of compounds |
Blood-Brain Barrier | Isolates CNS neural tissue from general circulation; Formed by a network of tight junctions between endothelial cells lining the CNS capillaries; Astrocytes have foot processes that influence capillary permeability |
Before something can leave the capillary and enter the brain, it must go through: | Endothelial cells lining CNS capillaries with tight junctions between them, the basement membrane, and then foot processes of Astrocytes |
Lipid-soluble substances pass through the Blood-Brain Barrier by: | Diffusion (O2, CO2, steroids, nicotine, ethanol, heroin) |
Water-soluble substances pass through the Blood-Brain Barrier by: | Mediated Transport (amino acids, glucose) |
Exceptions to Blood-Brain Barrier | 3rd and 4th ventricles have breaks in BBB where blood has direct access – can monitor glucose, pH, osmolarity (this is the place where HIV can enter the brain) |
Where are the two places that blood has direct access to the brain? | The third and fourth ventricles |
Hydrocephaly | Too much CSF (or decreased removal of CSF) can result in extra fluid which compresses and distorts the brain and causes ventricle to expand which puts pressure on surrounding neural tissue |
In infants, the cranial sutures have not fused so the skull ___________ to accommodate excess fluid, which is called Hydrocephalus | Enlarges |
Hydrocephalus can cause: | Mental retardation |
Hydrocephaly can result from: | Blockage of aqueduct or subarachnoid spaces |
Treatments of Hydrocephaly | Shunts to drain excess CSF or Acetazolamide which decreases CSF production |
___% of all O2 goes to the brain | 20% |
Why does 20% of all O2 go to the brain? | Because it has no oxygen reserves or energy reserves – a steady supply of glucose is needed |
A steady supply of _________ is needed in the brain because it has no energy reserves | Glucose |
Arterial blood supply to brain comes from: | Vertebral arteries and Internal carotid arteries |
Venous blood supple leaves brain via: | Jugular veins (dural sinuses drain into these) |
Dural sinuses drain into ___________, which take venous blood away from the brain | Jugular veins |
No oxygen to the brain for 5 minutes results in: | Loss of consciousness |
No oxygen to the brain for 9 minutes results in: | Permanent brain damage |
Brain Dead | Apparent and irreversible loss of function |
Cerebrovascular Disease | Disorders that interfere with blood circulation to the brain (Stroke or Cerebrovascular Accident [CVS]) – these are events that shut off blood to a portion of the brain causing neurons to die |
Exampes of Cerebrovascular Disease disorders: | Stroke or Cerebrovascular Accidents (CVAs) |
Function of the Brainstem (“Stalk of the brain”) | Relays messages between the spinal cord and the brain |
General Anatomy of the Medulla Oblongata | Most inferior part of the brainstem; 3cm extension of spinal cord, Pyramids and olives are visible on the surface, Ascending and descending nerve tracts, Nuclei of sensory and motor CNS (VIII, IX, X, XI, XII) |
What is the most inferior part of the brainstem? | Medulla Oblongata |
The Medulla Oblongata is a ___cm extension of the spinal cord | 3 cm |
________ and _________ are visible on the surface of the Medulla Oblongata | Pyramids and olives |
Medulla Oblongata contains ________ and ________ nerve tracts | Ascending and Descending |
Medulla Oblongata contains the nuclei of sensory and motor CNS – which Cranial Nerves? | VIII, IX, X, XI, XII (8, 9, 10, 11, 12) |
Functions of Medulla Oblongata | 1. Allows brain and spinal cord to communicate 2. Coordinates complex autonomic reflexes 3. Coordinates visceral functions (heart rate, vasoconstriction/dilation, breathing) 4. Non-vital reflexes (coughing, sneezing, swallowing, vomiting) |
Medulla Oblongata allows _______ and ________ to communicate | Brain and Spinal Cord |
Which part of the brainstem coordinates complex autonomic reflexes? | Medulla Oblongata |
Which part of the brainstem controls visceral functions such as heart rate, vasoconstriction/dilation, and breathing? | Medulla Oblongata |
Which part of the brainstem controls non-vital reflexes such as coughing, sneezing, swallowing, and vomiting? | Medulla Oblongata |
What are the three groups of nuclei in the Medulla Oblongata? | 1. Autonomic nuclei that control visceral activities 2. Sensory and motor nuclei of the cranial nerves 3. Relat stations along sensory and motor pathways |
Autonomic Nuclei are located in the: | Medulla Oblongata |
Autonomic Nuclei are made up of: | Gray matter |
Three centers in the Autonomic Nuclei | ’Vital’ Centers (monitor CO2 levels and make appropriate adjustments) 2. Cardiovascular Center (responsible for Cardiac [heart] and Vasomotor [vessels]) 3. Respiratory Rhythmicity Center (sets pace as per input from Pons) |
Function of Vital Centers of the Autonomic Nuclei: | Monitor CO2 levels and make appropriate adjustments |
Cardiovascular Center of Autonomic Nuclei is responsible for: | Cardiac (heart) and Vasomotor (vessel) |
Function of Respiratory Rhythmicity Center of Autonomic Nuclei: | Setting ‘pace’ as per input from Pons |
Reticular Formation is composed of: | Cardiovascular Center and Respiratory Rhythmicity Center of the Autonomic Nuclei in the Medulla Oblongata |
How do the Autonomic Nuclei work? | Receive input (ascending/sensory) from Cranial Nerves → Cerebrum and Brain Stem → Output (descending/motor) to regulate activity of peripheral systems (via tracts of white matter) |
Relay Stations for sensory and motor contain: | Nucleus Gracilis and Nucleus Cuneatus – they pass somatosensory information to the Thalamus. Tracts leaving this area cross over (decussate) to opposite sides of the spinal cord (this area is called the Pyramid) |
What two structures are located in the Pyramid in the Medulla Oblongata? | Nucleus Gracilis and Nucleus Cuneatus |
Decussate | Cross over |
What is the point in the Medulla Oblongata called where information crosses over? | The Pyramid |
Solitary Nucleus | Receives visceral sensory information (sneezing, coughing, swallowing centers) |
Olivary Nucleus | Involved in information from somatic motor commands to the cerebellar cortex |
The Pons connects the ___________ with the ___________, ____________, ___________, and ____________. | Connects Cerebellum with Mesencephalon, Diencephalon, Cerebrum, and Spinal Cord |
Three regions of Gray Matter in the Pons: | 1. Apneustic and Pneumotaxic Centers (respiratory center) 2. Sensory and Motor Nuclei (Cranial Nerves V-VII) 3. Relay Stations (senstory and motor pathways to cerebellum) |
Functions of the Apneustic and Pneumotoxic Centers of the Pons: | Regulates rate and depth of breathing; Adjusts respiratory rhythmicity centers of Medulla Oblongata |
Pons contains sensory and motor nuclei of which Cranial Nerves? | V, VI, VII (5-7) |
The Relay Stations of the Pons are in charge of sensory and motor pathways to the ________. | Cerebellum |
White Matter of the Pons contains: | Ascending, descending, and transverse tracts that connect the Gray Matter of the Pons with the opposite cerebellar hemisphere |
Midbrain (Mesencephalon) is located _______ to Pons | Superior |
Midbrain contains nuclei of which Cranial Nerves? | III and IV (3 & 4) Tectum |
Corpora Quadrigemina is separated into four ________ | Colliculi (two Superior Colliculi and two Inferior Colliculi) |
The Superior Colliculus are responsible for _______ input | Visual (turning from bright light) |
The Inferior Colliculus are responsible for _______ input | Auditory (turning toward sound) |
The Corpora Quadrigemina (on top of the Tectum) integrates _________ and __________ stimuli | Visual and Auditory |
The Midbrain connects the ______ and _______ with the ________. | Pons and Cerebellum with the Cerebrum |
Substantia Nigra | ”Black Substance,” Helps fine-tune voluntary motor activity (contains dopaminergic neurons) |
Reticular Activating System | Helps mainain consciousness |
Nucleus Ruber | ”Red Nucleus,” Involved in basal muscle tone |
Gray Matter of the Midbrain is composed of: | Superior Colliculi, Inferior Colliculi, Red Nucleus & Substantia Nigra, Reticular Formation (Reticular Activating System), and Motor Nuclei (Cranial Nerves 3 & 4) |
White Matter of the Midbrain is composed of: | Cerebral Peduncles (which are composed of motor tracts connecting the Midbrain and the Cerebrum) |
The Thalamus is the relay and processing center for _________ information | Sensory |
Gray Matter of the Thalamus | Oval Mass of Gray Matter – two lateral portions connected by an Intermediate Mass (These surround the Third Ventricle) |
The Gray Mass of the _________ surrounds the Third Ventricle | Thalamus |
Sensory information from the Spinal Cord synapse in the _________ before projecting into the Cerebrum | Thalamus |
Nearly all sensory information goes to the Thalamus before projecting into the __________ (except Olfaction) | Cerebrum |
Which sensory stimuli does not go through the Thalamus on its way to the Cerebrum? | Olfaction |
How many Nuclei are in the Thalamus? | 23 Nuclei – but only 3 are major players (Medial Geniculate Nucleus, Lateral Geniculate Nucleus, Ventral Posterior Nucleus) |
The three major nuclei in the Thalamus: | Medial Geniculate Nucleus (Auditory Information), Lateral Geniculate Nucleus (Visual Information), Ventral Posterior Nucleus (Most other types of sensory information) |
The Medial Geniculate Nucleus (in the Thalamus) relays _________ information | Auditory |
The Lateral Geniculate Nucleus (in the Thalamus) relays __________ information | Visual |
The Ventral Posterior Nucleus (in the Thalamus) relays __________ information | Most other types of sensory information (other than auditory and visual) |
The Thalamus projects information to what three cortices in the Cerebrum? | Gustatory, Auditory, and Visual |
Conscious awareness occurs in the: | Cortex |
The Thalamus coordinates the activities of ________, _________, and ________ by relaying information between them | Basal Nuclei (motor & learning), Limbic System (emotion & motivation), and Cerebral Cortex (thinking, memory, language) |
The Basal Nuclei are responsible for: | Motor and Learning |
The Limbic System is responsible for: | Emotion and Motivation |
The Cerebral Cortex is responsible for: | Thinking, Memory, and Language |
The Limbic System is a ___________ grouping, not an anatomical grouping | Functional |
Limbic System is made up of: | Hippocampus, Amygdala, Parts of Thalamus & Hypothalamus |
Fornix | Tract of White Matter that connects the Hippocampus with the Hypothalamus |
Functions of the Limbic System: | Processing of memories and creation of emotional states, drives, & associated behaviors |
The Limbic System is responsible for emotional states, memory storage & retrieval, and motivational drives. It receives input from many regions, including ________. | Olfactory |
Functions of Hypothalamus | Coordinates activities of nervous and endocrine systems |
Hypothalamus communicates with: | Posterior Pituitary, Anterior Pituitary, and Adrenal Medulla (hormones) |
The Hypothalamus has control of the autonomic functions such as heart rate, blood pressure, digestion, and respiration because it communicates with the ______ and _______. | Pons and Medulla Oblongata |
Hypothalamus controls: | Skeletal muscles (subconscious – facial expressions), body temp (through MO), Circadian rhythms, Hunger & thirst centers, Feeding reflexes (through mammiliary bodies – chewing, swallowing, licking), Coordination btwn voluntary & involuntary fnctns |
Cerebellum contains ___% of neurons in the Brain | 50% |
The Cerebellum is the _________ Center | Autonomic |
Gray Matter of the Cerebellum is made up of: | Purkinje Cells (largest in CNS – inhibitory input to 200,000 synapses) |
The largest cells in the CNS are: | Purkinje Cells |
Purkinje Cells send inhibitory input to _________ synapses | 200,000 |
White Matter of the Cerebellum is made up of: | Arbor Vitae |
The Cerebellum adjusts postural muscles of the body and learns/fine tunes conscious and subconscious movements, but does NOT: | Initiate movement or have conscious perception of sensation |
Functions of the Cerebellum: | Adjusts postural muscles (coordinates rapid, automatic adjustments to maintain balance & equilibrium) & Learning & fine tuning [conscious & subconscious] (compares motor commands w/ proprioceptive information & performs adjustment to make move smoother) |
The Cerebellum refines learned movement patterns by taking in information from ___________ and fine tunes the movement and makes it smoother with repetition | Proprioceptor/eyes/ears via brainstem |
Reticular Activating System | Group of Nuclei (Gray Matter) scattered throughout Brainstem |
Functions of Reticular Activating System: | Controls cyclic activites such as sleep-wake cycle (injury leads to irreversible coma), Regulates balance and posture, Relays information from eyes and ears to Cerebellum, Centers gaze and generates central pattern |
The Reticular Activating System includes ______ and _______ Centers | Cardiac and Vasomotor Centers |
What is responsible for relaying information from the eyes and ears to the Cerebellum? | Reticular Activating System |
What is responsible for centering gaze and generating central patterns? | Reticular Activating System |
Injury of the Reticular Activating System leads to: | Irreversible coma |