Chapter Four - The Nervous System Flashcards
What are the 2 Main Divisions of the NS?
- CNS: Brain, & Spinal Cord.
- PNS: Outside the skull, most nerves project from spinal cord except the 12 pairs of nerves called cranial nerves which project from the brain.
Nerve vs. Tract?
- Nerve: collection of axons outside the CNS.
- Tract: collection of axons inside the CNS.
Afferent vs. Efferent?
- Afferent = towards area of interest.
- Efferent = away from area of interest.
What neurons are often found in a cluster?
- Ganglion = a cluster or neuron cell bodies outside the CNS.
- Nucleus = a cluster of neuron cell bodies insdie the CNS.
What are the two subdivisions of the PNS?
- Somatic NS.
- Autonomic NS.
Somatic Nervous System?
- Interacts with the body’s external environment [body surface and muscles].
ANS?
- Interacts with the body’s internal environment [internal organs].
- Efferent nerves are divided into two systmes based on where their cell bodies are located within the spinal cord.
ANS 2 Subdivisons?
- Sympathetic.
- Parasympathetic.
Sympathetic NS?
- motor nerves project from neurons in the lumbar and thoracic spine regions.
- controls involuntary movement of various internal organs.
- prepares body for fight or flight.
- arousal.
- increases heart rate, facilitates breathing, dilates pupil, inhibits digestion.
Parasympathetic NS?
- motor nerves project from neurons in thebranial and sacral regions.
- decreases breathing, heart rate, and constricts pupil, and stimulates digestion.
Spine & Vertebrate Sections?
33 vertebrates.
- Cervical spine = 7 in the neck.
- Thoracic spine = 12 in the upper back.
- Lumbar spine = 5 in lower back.
- Sacrum spine = 5 fused vertebrates.
- Coccyx spine = 4 fused vertebrates.
What structures protect the CNS?
- Physical protection = bones, membranes, and CSF.
- Chemical protection = BBB.
What are the 3 Meninges?
- Dura Mater = closest to skull.
- Arachnoid Membrane = arachnoid.
- Pia Mater = closest.
How many cranial nerves project from the brain?
- 12 nerves.
Ventricular System:
- 4 ventricles in the brain: 2 lateral, one third, and one foruth ventricle.
Two main functions of CSF?
- Acts as a shock absorber.
- Provides an exchange medium between blood and brain.
- CSF is produced by a network of capillaries of blood vessels, called chorid plexus, an organ protruding into the ventricles.
Blood Brain Barrier:
- Tightly packed cells of blood vessel walls prevent the entry of many molecules.
- Functions: protects brain from foreign substances, hormones, transmitters, and maintains a constant environment for the brain.
What are the two types of cells in the NS?
- Neurons.
- Glia.
Glia to neuron ratio?
- Outnumber neurons 10:1.
Four main classes of Glial cells?
- Oligodendocrytes.
- Schwann Cells.
- Astrocytes.
- Microglia.
Forebrain?
[ what are the long terms]
- Telencephalon.
- Diencephalon.
Midbrain?
[ long name]
Mesencephalon.
Hindbrain?
[long names]
- Metencephalon.
- Myelencephalon.
How many pairs of spinal nerves are there?
- 31 pairs of spinal nerves.
Gray vs. White Matter?
- Gray: inner component, primarily cell bodies.
- White: outer area, mainly myelinated axons.
Hindbrain Structures?
- Medulla.
- Pons.
- Cerebellum.
- Reticular Formation.
Medulla?
- Composed largely of axon tracts.
Pons?
- Some nuclei involved in sleep and arousal, others invovles in movement and muscle tone.
Cerebellum?
- Consists of cerebellar cortex and subcortical cerebellar nuclei.
- Involves in motor control.
Midbrain Structures?
- Tectum.
- Tegmentum.
Tectum?
- Doral part.
- consists of 2 pairs of bumps, (1) superior colliculis, which recieves visual info, and (2) inferior colliculus, which recieves auditory info.
Tegmentum?
- Ventral part.
- consists of reticular formation, periaqueductal gray, substantia nigra, and the red nucleus.
- periaqueductal gray = gray matter around the acquduct, mediating pain sensation.
- substantia nigra and red nucleus = involved in motor function.
Forebrain Structures?
- Thalamus.
- Hypothalamus.
- Basal ganglia.
- Limbic system.
- Cerebral cortex.
Thalamus?
- 2 lobed structure sitting on top of the brainstem.
- The main relay station of the brain.
- Made up of many nuclei, each of which recieves different sensory info.
- Laterl geniculate nuclei = visual.
- Medial ^ = auditory.
- Ventral posterior nuclei = somatosensory.
Hypothalamus?
- Locaed ventral of the thalamus.
Basal Ganglia?
- consits of amygdala, striatum, & globus pallidus.
- necessary for sensory-driven and goal directed voluntary movement.
Limbic System?
- A group of structures surrounding the thalamus like a ring shape.
- Hippocampus, amygdala, fornix, cingulate cortex, septum, and mammillary bodies.
- Involved in the four Fs: fighting, feeding, fleeing , sexual behaviours.
Cerebral Cortex?
- Right and left hemispheres.
- Hemispheres conncected by corpus callosum.
- Four lobes: parietal, frontal, occipital, and temporal.
4 Lobes Responsibilities?
- Frontal = higher cognition, motor function.
- Parietal = somatosensation.
- Occipital = visual perception.
- Temporal = hearing, language, & memory.
