Brain and Nervous System Flashcards
Where is the arbor vitae located and what is its function?
The arbor vitae lies in the center of the cerebellum and is critical in the coordination of the arms, legs and any actions requiring hand-eye coordination. The arbor vitae is made of white matter that transmits information throughout the brain.
What are the two major structure of the midbrain AKA mesencephalon?
Tectum and tegmentum.
The tectum contain the corpora quadrigemina.
The tegmentum contains the red nuclei, cerebral peduncles, and the substantia nigra.
List the primary functions of the cerebral cortex in each of the lobes in the cerebrum: frontal lobe, temporal lobe, parietal lobe, occipital lobe and the insula.
Frontal lobe: voluntary motor function, motivation, aggression, sense of smell, mood. Personality and decision making
Temporal lobe: receives input for smell/hearing, plays impt role in memory. Abstract thought and judgement.
Parietal lobe: receiving most sensory info (not smell, hearing, taste, and vision - so NOT the special senses).
Occipital lobe: receives visual input.
Insula: receives taste information.
What are the nuclei found in the pons. Describe their functions.
Pontine nuclei, which relay info from the cerebrum to the cerebellum.
Pons also has nuclei for cranial nerves 5 (trigeminal), 6 (abducens), 7 (facial) and 8 (vestibulocochlear).
What is an ascending and descending nerve tract?
Sensory info from the periphery is transmitted via action potentials along sensory pathways or TRACTS, to the brain.
Ascending nerve tracts transmit conscious and unconscious sensory inputs. Names indicate their origin/termination. First half of name indicates origin while second half indicates its termination. Usually begin with “spino” because they originate in the spinal cord. Excellent chart pg. 476 and 477.
Descending pathways “descend” from brain to spinal cord. Through these routes, cerebral cortex may reduce the conscious perception of sensations such as pain.
Name the 5 cranial nerves associated with the medulla oblongata.
cranial nerves VIII (vestibulocochlear - it is ONE HALF OF THIS CRANIAL NERVE, either the vestibulo part or the cochlear part), IX (glossopharyngeal), X (vagus), XI ( accessory), and XII (hypoglossal)
What is the importance of the gyri on the surface of the cerebrum?
Gyri greatly increase the surface area of the cortex of the cerebrum.
Name the major nuclei found in the medulla oblongata and describe their function?
The gracile nuclei (is one of the dorsal column nuclei that participate in the sensation of fine touch and proprioception) of the lower body and legs and cuneate nuclei (cuneate nucleus receives somatosensory information from the upper half of the body and arms) are located in the posterior aspect of the medulla; The nuclei of cranial nerves XII, X, IX, and part of VIII are located in the medulla
Describe the characteristics of the blood brain barrier and the blood cerebral spinal fluid barrier.
What are arachnoid villi and arachnoid granulations. What are their functions
Arachnoid granulations (or arachnoid villi) are small protrusions of the arachnoid (the thin second layer covering the brain) through the dura (the thick outer layer). They protrude into the venous sinuses of the brain, and allow cerebrospinal fluid (CSF) to exit the brain, and enter the blood stream.
What is the purpose of the ventricles within the brain?
The ventricles within the brain are an interconnected series of cavities that bathe the brain with CSF. CSF fills all the open spaces of the CNS, including the ventricles, the subarachnoid space of the brain and spinal cord, and the central canal of the spinal cord. Not only does CSF bathe the brain and spinal cord, it provides a protective cushion around the CNS, allows the brain to float within the cranial cavity, and protects the brain against the shock of rapid head movements. Also provides some nutrients to CNS tissues.
What is found filling the subarachnoid space?
Between the arachnoid mater and the Pia mater is the SUBARACHNOID space, which contains strands of arachnoid mater and the blood vessels supplying the brain. This space is also filled with CSF.
What is the choroid plexus? Where is it found? What is its function?
A choroid plexus is a structure made from specialized ependymal cells and blood vessels. These structures are located within certain regions of the ventricles. They secrete CSF, which flows through the ventricles of the brain. A choroid plexus is found in each ventricle of the brain.
What are the names of the dural folds? Where are they located? What is their function?
Dural folds are tough CT partitions that extend INTO the major brain fissures. They help hold the brain in place within the skull and keep it from moving around too freely. Largest of the dural folds is the FALX CEREBRI which is located in the longitudinal fissure that separates the L and R hemispheres. Two other important dural folds are the TENTORIUM CEREBELLI which lies between the cerebrum and the cerebellum. Last, the FALX CEREBELLI, which lies between the two cerebellar hemispheres.
“The Dural folds like to hold” - help hold brain in place
How big is the human brain?
The human brain is roughly the size of two clenched fists and weighs about 3 pounds, 2% of body mass.
Describe how the PNS and CNS work together in obtaining, processing and acting on a stimulus.
Your peripheral nervous system is the network of nerves that transmit (carry) signals from all over your body to your spinal cord, which is part of your central nervous system.
Your central nervous system is your brain and spinal cord. It receives and interprets nerve signals from your peripheral nervous system. Your brain integrates these messages (inputs) to inform everything you do, including how you move, feel, behave and think. Some reactions are reflexive, happening below the level of consciousness, like moving your hand away from a hot stove.
When a nerve sends an electrical impulse:
The signal travels down the axon, the “wiring” connection of the nerve.
The message converts to a chemical signal at the end of the nerve called the axon hillock.
The chemical releases molecules called neurotransmitters, into a space that bridges the space between one neuron to another. These bridges are called synapses.
The neurotransmitter binds to a receptor on the muscle or connecting neuron and converts to another electrical signal.
Electrical signals travel up the length of that next neuron.
The process repeats until the message reaches its target.
How are the brain and the endocrine similar?
Both are regulatory systems. The brain uses electrical signals while the endocrine system uses chemical signals.
What could lesions in the limbic system cause?
many individual components comprise the limbic system, all of which play specific roles in the greater whole of the functionality of the limbic system. Emotion, memory, and social processing are essential functions when considering the whole of human health. Generally, clinical disorders involving bilateral lesions of individual parts of the limbic system are rare. However, in much more prevalent disorders, such as schizophrenia, asymmetry and cortical volume loss of limbic system components is common. Possible causes: schizophrenia, memory loss, dementia, epilepsy.
What are the generalized functions of the cranial nerves?
Transmit and really information to and from the brain, much like spinal nerves do, but they skip that step altogether and relay info DIRECTLY to the brain. May have more than one function depending on nerve (sensory, somatic, and/or parasympathetic).
Which part of the nervous system gets the body ready for rest?
Parasympathetic division of the autonomic nervous system of the PNS.
Which part of the nervous system gets the body ready for activity (fight or f light)?
Sympathetic division of the autonomic nervous system of the PNS.
What are the two divisions of the autonomic nervous system?
2 divisions of the autonomic nervous system are the sympathetic division (fight or flight) and the parasympathetic division (rest and digest).
What is the function of the midbrain?
Midbrain serves important functions in motor movement, particularly movements of the eye, and in auditory and visual processing. Contains the tectum (corpora quadrigemina - superior and inferior colliculi), tegmentum (red nuclei, cerebral peduncles, substantia nigra). pg 443-444
Where does alcohol affect the brain?
Alcohol affects the brain at the Blood-Brain-Barrier. Ethanol travels to the brain within the arteries that lie between the skull and the brain itself. These arteries branch out into capillaries, which dive deep into the brain tissue. Ethanol must pass through these capillaries to reach all cells (e.g., neurons) in the brain. For most molecules, it’s not so easy to get into the brain. There is a barrier called the blood-brain-barrier that protects the brain from foreign substances that could potentially harm this highly specialized organ. Unfortunately for the brain, there is no barrier for ethanol. Ethanol crosses the blood-brain-barrier very easily (Diffusion, type of diffusion is filtration). This is due to its chemical characteristics—although it is somewhat polar, it is also lipophilic, and so it mixes easily with the fat in the membrane.
What is the function of the cerebellum?
Cerebellum or “little brain” - function involves controlling posture, locomotion, and fine motor coordination, thereby producing smooth, flowing movements. If you are planning, practicing, or learning complex movements, you can be sure your cerebellum is responsible. Cerebellar cortex has more neurons than entire cerebral cortex. Contains Purkinje cells (largest cells in CNS, receiving about 200,000 synapses from passing fibers - they are inhibitory neurons). Pg. 444
What is the difference between somatic and autonomic nervous systems?
Somatic nervous system is the VOLUNTARY division of the MOTOR division (conscious control of moving your skeleton). The autonomic nervous system is the INVOLUNTARY division of the MOTOR division. Regulates activities without our conscious control such as contractions of smooth muscle, cardiac muscle, and secretions of certain glands. Ex: HR increases when hear a loud, unexpected sound. ANS has two sets of neurons. Pg 372 in textbook.
What is a mixed nerve?
Mixed nerves contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions. Example: spinal nerves and some cranial nerves are mixed nerves.
What are the types of nerve fibers found in the PNS?
Three nerve fiber types: type A, type B, and type C.
PNS nerve fibers are mostly going to be type A, which are large diameter, myelinated axons that induct action potentials quickly. Motor neurons supplying skeletal muscles and most sensory neurons have type A fibers. Pg 391 textbook
Where is the reticular formation and what is its function?
The reticular formation is scattered throughout the brainstem. It controls many brainstem activities, including motor control (posture), pain perception, rhythmic contractions (swallowing, breathing, HR), and the sleep-wake cycle. This system is an interconnected system of loosely packed nuclei scattered through brainstem. Play roles in arousal and awareness (consciousness). Contains the RAS - reticular activating system which is what your anesthesiologist gets paid to mess with)
Is the brain stem involved in higher thought processes?
No, the brain stem involves essential functions/reflexes concerned with keeping the body alive. Functions of the medulla, pons, midbrain, and reticular formation. Location of cranial nerve nuclei.
What is the function of the medulla oblongata?
AKA the “medulla,” most inferior part of brainstem. Contain nuclei for vital reflexes: regulating HR, blood vessel diameter, respiration, swallowing, vomiting, hiccuping, coughing, sneezing. Contains the olives (balance, coordination, sound modulation) and the pyramids (conscious control of skeletal muscles).
What is the function of the pons?
Pontine nuclei, located within the pons, relay info from the cerebrum to the cerebellum. Pons also contains the pontine sleep center (initiates REM sleep), and the pontine respiratory center, which works with respiratory centers in the medulla oblongata to help control respiratory movements.
Name the primary functions of the hypothalamus.
So many functions!! Pg 447 chart in textbook.
Autonomic - HR, urine release, GI tract (digestion), blood vessel diameter
Endocrine - secretions from pituitary gland, metabolism, ion %, sexual functions, ADH hormone and oxytocin production
Muscle control - swallowing muscles, shivering
Body temp. regulation - Increases sweat when temp increases (promotes heat loss) and stimulates shivering (promotes heat production)
Food/water intake regulation - satiety center and thirst center
Emotions - fear, rage, emotional influences over body productions, stress-related illness
Sleep-wake cycle - coordinates with other brain areas (ex. reticular activating system), suprachiasmic nucleus receives direct input from eyes from light/dark cycles
Sexual development/behavior - development, arousal, prep-tic area larger in males
What are the three parts of the brain stem?
- Medulla oblongata
- Pons
- Midbrain
**reticular formation is a functional unit that spans all three divisions.
What are the basal ganglia and what is their function?
Basal ganglia or basal nuclei are located beneath the cortex (subcortical). Largest nuclei in brain. Help control motor functions.
What are the components of the limbic system and what is the limbic system’s function.
Limbic system includes parts of cerebrum and diencephalon grouped together. Limbic meaning “border,” it refers to the ring around the cerebral cortex and structures beneath. Major role in motivation, emotion, learning, and memory. Influences endocrine/autonomic nervous systems. “Emotion center” of brain. 6 areas (pg 450 in text) in which 2 include the hippocampus and the hypothalamus.
What is the function of the thalamus, hypothalamus and the epithalamus?
Thalamus: major sensory relay center - ALL SENSORY info (except olfactory); influences mood and movement.
Hypothalamus: Major control center for maintaining homeostasis and resulting endocrine function. The hypothalamic nuclei are important to functions related to mood, motivation, and emotion. This is one reason that strong emotional experiences may affect person’s desire/ability to eat, drink, have sex etc.
Epithalamus: Contains nuclei involved in MOTIVATION and reward behavior, and contains pineal gland which controls the sleep-wake cycle.
Pg 440 in text (chart)
What are the parts of the diencephalon?
Parts of the diencephalon include the thalamus and the hypothalamus. (thalamus, sub thalamus, epithalamus which contains pineal gland, and hypothalamus). Area of the third ventricle.
pg 440 in text for illustration and text
What is the cerebral cortex?
The gray matter on the outer surface of the cerebrum is the cerebral cortex. Thickness of the cortex ranges, from 2-3 layers in primitive areas of brain to 6 layers in more advanced areas.
What are gyri…sulci?
They are folds on the surface of the brain.
Gyri (increase surface area of cortex) and sulci (divide hemispheres into lobes). Sulci are the grooves between the gyri.
Describe the structure of the cerebrum
Largest portion of total brain weight. Larger body = larger brain (not higher intelligence). Divided into left/right hemispheres. Has gyri (increase surface area of cortex) and sulci (divide hemispheres into lobes). Contains basal nuclei and the limbic system.
Pg 449 textbook.
What are the major divisions of the brain?
Cerebrum, brainstem, cerebellum
What is the epidural space?
Space between the dura and vertebral bones within the vertebral canal.
What is the function of cerebrospinal fluid?
It bathes the brain and the spinal cord and provides a protective cushion around the CNS. Allows brain to float within cranial cavity so it doesn’t rest directly on skull or dura mater. Protects against shock of rapid movements. Provides some nutrients to CNS tissues.
It’s a clear fluid similar to blood serum but w/out most of proteins.
Pg 454 textbook
Where is cerebrospinal fluid found in the meninges?
SUBARACHNOID SPACE
Explain convergent and divergent neuron pathways.
In reference to neuronal pathways and circuits, a convergent pathway is when multiple neurons converge upon and synapse with a smaller number of neurons. Example: muscle contraction, through summation, activated by converging neurons stimulating the production of more EPSPs than IPSPs. Muscle contraction would be inhibited if the converging neurons stimulated the production of more IPSPs than EPSPs.
In a divergent neuronal pathway a smaller number of presynaptic neurons synapse with a larger number of postsynaptic neuron to allow info transmitted in one neuronal pathway to diverge into two or more pathways. These pathways allow one part of the nervous system to affect more than one other part of the nervous system. Example: sensory input to the CNS can go to both the spinal cord and the brain.
pg 402 textbook
Explain the blood brain barrier and how the capillary structure strengthens this barrier.
BBB is a highly selective permeability barrier of the capillaries of arteries in brain tissue. Regulates the movement of materials from the blood into the brain. It’s formed by tight junctions between the capillary endothelial cells. Astrocytes promote the formation of these tight junctions between the endothelial cells. Materials that would enter many tissues by passing between the endothelial cells of capillaries cannot pass through the BBB because of the tight junctions. Most materials that enter the brain pass through the endothelial cells. O2, nicotine, ethanol can freely diffuse through the plasma membranes of the endothelial cells and enter the brain. Pg 456 textbook.
How does summation help a local potential reach threshold?
Many presynaptic action potentials cause many graded potentials in the postsynaptic neuron. Graded potentials combine in summation at the trigger zone for the postsynaptic neuron, either exceeding threshold at the trigger zone or not. If threshold is passed, an action potential is produced. Textbook page 401: spatial and temporal summation. Wikipedia: multiple simultaneous inputs (spatial summation) vs. repeated inputs (temporal summation)
What is the primary function of the corpus callosum?
Function: ensures both sides of the brain can communicate and send signals to each other. Corpus callous is the largest bundle of commissural fibers. Commissural fibers connect one cerebral hemisphere to the other hemisphere.
Name the major skull bones that protect the cerebrum
There are eight bones that surround your brain: one frontal bone; two parietal bones, two temporal bones, one occipital bone, one sphenoid bone and one ethmoid bone. These eight bones make up the cranium.
What structure in the ventricles produces the cerebral spinal fluid?
Ventrical image in textbook, pg 453.
Answer: choroid plexus. There is a choroid plexus in each ventricle of the brain, but most CSF is formed by the choroid plexus in the the lateral ventricles of the brain (about 80% - 90%).
What is the function of the arachnoid granulations?
Arachnoid granulations are small protrusions of the arachnoid mater (the thin second layer covering the brain) into the outer membrane of the dura mater (the thick outer layer). They protrude into the dural venous sinuses of the brain, and allow cerebrospinal fluid (CSF) to exit the subarachnoid space and enter the blood stream. Function: Diffusion across the arachnoid granulations into the superior sagittal sinus returns CSF to the venous circulation, or to simply put, drainage of CSF.
What is found in the subarachnoid space?
The subarachnoid space (between the arachnoid mater and Pia mater) contains strands of arachnoid mater and blood vessels which supply the brain. You can also find CSF here.
Where would a subdural hematoma occur?
The dura mater lines the skull and surrounds the brain. In a subdural hematoma, the blood seeps between the dura mater and the arachnoid mater layers, called the subdural space. Blood collects inside the brain’s tough outer lining. This bleeding often comes from a blood vessel that breaks within the space around the brain.
Describe the three layers of the meninges and their functions.
Brain meninges (3)
- Dura mater: thickest, most superficial. Dense irregular CT. Tightly adheres to cranial bones, creates potential space aka epidural space.
- Arachnoid mater: very thin, wispy membrane just below dura mater. Very small space between arachnoid and dura mater is a space containing very small amount of serous fluid called the subdural space.
- Pia mater: bound very tightly to brain’s surface! Subarachnoid space between Pia mater and arachnoid mater, contains blood vessels supplying brain. Filled with CSF.
What is white matter…. gray matter?
Gray matter: groups of neuron cell bodies, their dendrites, unmyelinated. In CNS, gray matter located on surface of brain (cortex) and deep within brain in clusters called “nuclei.” In PNS, gray matter is clustered neuron cell bodies, or “ganglia.”
White matter: myelinated, propagate action potentials. In CNS, white matter forms nerve tracts from one area in CNS to another. In PNS, make up what we call “nerves” which are bundles of axons and their connective tissue sheaths.
What is an axoaxonic regulation?
First, have to know what an AXOAXONIC SYNAPSE is. Pg 400 in text. That’s when the axon of one neuron synapses with the presynaptic terminal (axon) of another. The neuron that synapses on the axon of presynaptic neuron can influence/modulate/regulate the release of presynaptic neuron’s neurotransmitter, either inhibiting the amount (presynaptic inhibition) or increasing the amount (presynaptic facilitation). And this, I assume would be called AXOAXONIC REGULATION. Textbook doesn’t explicitly mention this.
What is the anaxonic neuron?
No axons. Only dendrites. Engage in graded potentials only. No action potentials. Found in brain and retina.
Where are unipolar neurons located?
Located in both the PNS and CNS. They have one branch called the peripheral process which extends to periphery and has dendrites… and another called the central process which extends to CNS.
Great resource for simplified info:
https://www.khanacademy.org/science/biology/human-biology/neuron-nervous-system/a/overview-of-neuron-structure-and-function
What is the primary function of a bipolar neuron?
Bipolar neurons often have specialized dendrites to receive the stimulus, and the axon conducts the action potentials to the CNS. Special sensory organs have bipolar neurons such as the retina of the eye and the nasal cavity.
Describe the four different STRUCTURE classes of neurons?
Multipolar neurons - many dendrites, one axon. Example: CNS neurons and motor neurons of PNS.
Bipolar neurons - one dendrite and one axon. Example: some sensory organs.
Pseudo-unipolar neurons (aka unipolar) - Have single process extending from cell body which splits into two branches, one to the periphery and the other to the CNS. Example: most sensory neurons are this one.
Anaxonic neurons - no axons, only dendrites projecting from cell body (only use graded potentials aka electrical synapses, NO ACTION POTENTIALS WITH THIS ONE). Example: Found within brain and retina.
What is axoplasm?
Axoplasm is another name for the cytoplasm of an axon. Pg 374 in textbook. Know other terms such as axon hillock, trigger zone, axolemma, presynaptic terminal, synaptic vesicles, neurotransmitters.
What comprises the CNS and the PNS?
CNS comprised of BRAIN and SPINAL CORD
PNS comprised of RECEPTORS, NERVES, GANGLIA, and PLEXUSES (any nervous tissue outside the CNS).
What is a plexus?
A plexus (in any context) essentially means “network.” In this instance, we’re talking about a network, or plexus of nerves. Different nerves can join to form a plexus.
Which type of neuroglial cells are found in the PNS.
Schwann cells
Satellite cells
Which types of neuroglial cells are found in the CNS?
Astrocytes
Ependymal cells
Microglia
Oligodendrocytes
Name the different types of neuroglial cells and their functions?
Neuroglial cells are glial cells. All glial cells support/aid neurons of CNS and PNS.
CNS: Astroctyes, Ependymal Cells, Microglia, Oligodendrocytes
PNS: Schwann cells and Satellite cells
Click audio for their functions.
What are an ascending and a descending pathway?
Ascending pathway carry conscious/unconscious sensation. Essentially it’s an action potential carrying sensory info from the periphery of body to the brain via tracts (pathways).
Descending pathway reduce conscious perception of sensation. “Descend” from brain to spinal cord.
