Nervous System (Nurs 215) PDF Notes

Parts of Chapters 4, 11, 12 in Textbook  Nervous system subdivisions: 1. Central nervous system (CNS) ▪ Brain ▪ Spinal cord 2. Peripheral nervous system (PNS) ▪ Cranial nerves ▪ Spinal nerves ▪ Ganglia  The CNS and PNS general...

Parts of Chapters 4, 11, 12 in Textbook  Nervous system subdivisions: 1. Central nervous system (CNS) ▪ Brain ▪ Spinal cord 2. Peripheral nervous system (PNS) ▪ Cranial nerves ▪ Spinal nerves ▪ Ganglia  The CNS and PNS general functions: 1. Collecting information ▪ Receptors ▪ Detect changes (internal/external) ▪ Pass information to CNS 2. Processing and evaluating information ▪ CNS determines response 3. Responding to information ▪ CNS initiates nerve impulses to effectors  Two types of cells: Nervous tissue  Neurons (nerve cells) ▪ Electrically excitable ▪ Transmit and receive impulses  Glial cells ▪ Support/protect  Basic structural unit of the nervous system  Conduct nerve impulses  Special characteristics:  High metabolic rate  Extreme longevity  Mostly non-mitotic  All have cell body and one or more processes  Cell body: biosynthetic center  Dendrites: short processes branch from cell body  Receive nerve impulses  Axons transmit nerve impulses to other cells  Axon hillock: axon connects to the cell body  AKA neuroglia  In CNS and PNS  Vs. neurons = smaller + mitosis + more of them  Protect and nourish neurons  Brain tumors  Likely glial cells  PNS: Satellite cells Schwann cells  Four types of glial cells in CNS: 1. Astrocytes-bind blood vessels to neurons, form blood brain barrier, provide support/ nutrients to neurons 2. Ependymal cells-lines various regions, produces cerebrospinal fluid (more later) 3. Microglial cells-immune response for CNS 4. Oligodendrocytes- generate myelin (insultation for CNS axons)  Satellite cells:  Surround neuron cell bodies in PNS (similar to astrocytes of CNS)  Schwann cells:  Form myelin sheaths around nerve fibers of PNS (insulation)  Also helps regenerate fibers  Cable-like bundle of axons  Connective tissue:  Endoneurium: Around each axon  Perineurium: Around individual fascicles  Epineurium: Around the entire nerve  What is the difference between the CNS and PNS?  What are the 2 different parts of neurons and their functions?  Which type of neuroglia cell is responsible for helping form the blood brain barrier?  Four major regions: 1. Cerebrum 2. Diencephalon 3. Brainstem 4. Cerebellum *We will have a brief overview of their features  Gray matter:  Cell bodies, dendrites, unmyelinated axons  Forms the cortex ▪ Brain surface  Forms clusters (deep) ▪ Nuclei  White matter:  Myelinated axons  Deep to cortex  Brain is protected by many structures – Bony cranium – Protective connective tissue (meninges) – Cerebrospinal fluid – Blood-brain barrier  Cerebrospinal fluid (CSF):  Buoyancy  Protection  Transports nutrients and wastes  4 ventricles contain CSF:  Two lateral ventricles  Third ventricle (diencephalon)  Fourth ventricle (between pons and cerebellum)  3 layers:  Pia mater  Arachnoid mater  Dura mater  Functions:  Separate brain and bones  Protects blood vessels  Contains CSF  Cerebrum is the location of conscious thought processes and origin of intellectual functions Surface is marked by sulci, gyri, and deep grooves called fissures  Left and right cerebral hemispheres  Longitudinal fissure  Corpus callosum: connects the two hemispheres  Cortex of cerebrum divided into lobes  Contains conscious mind, interprets sensations (consciously), controls voluntary movements  Frontal lobe  Voluntary motor function, concentration, verbal communication, decision making, planning, and personality  Parietal lobe  Touch sensation and spatial positioning interpretation  Occipital Lobe  Visual interpretation  Insula (deep to temporal)  Taste interpretation, visceral (organ) sensations  Temporal lobe  Hearing and smell interpretation  *These are summaries of the main functions, there are some others, and some functions overlap  What are some of the ways in which the brain is protected?  Which cerebral lobe is responsible for hearing interpretation? What about higher thought processes such as decision making?  Final relay point for sensory information that will be processed  Diencephalon includes:  Thalamus  Paired oval masses  Relay point for processing of sensory info ▪ Receives info, sends info to cerebral cortex (or other) regions for processing  Epithalamus:  Pineal gland: Secretes melatonin (circadian rhythm)  Habenular nuclei: multiple roles including stress response, pain processing, and others  Functions: Master control of many autonomic nervous system (subconscious) functions + endocrine system (hormones) Regulates temperature Regulars sleep/ wake cycle Control of some emotional behavior Control of food and H2O intake Infundibulum attaches to pituitary gland  Regions: 1. Midbrain 2. Pons 3. Medulla oblongata  Functions:  Passageway ▪ Cerebrum to spinal cord  Autonomic centers ▪ Regulation of many physiological processes/ reflexes  Midbrain:  Cerebral aqueduct-connects ventricles  Auditory reflex (startle)  Produces dopamine  Pons:  Helps regulate breathing (along with medulla)  Passageway of many fibers  Contains many autonomic nuclei:  Cardiac center ▪ Heart rate, contraction strength  Vasomotor center ▪ Regulates vasoconstriction/vasodilation (blood pressure)  Medullary respiratory center ▪ Respiratory rate  Other nuclei involved in coughing, sneezing, salivation, swallowing, and vomiting  Coordinates and fine-tunes skeletal muscle (along with cerebral cortex)  Receives proprioceptive (sensory) information from joints  Monitors the position of each body joint and its muscle tone  Stores movement patterns  Aids in equilibrium and posture  12 pairs of nerves originating directly in the brain innervate parts of the head region  Some also innervate other organs  *Don’t need to memorize them  Spinal cord: Signals travel to and from brain to rest of body Some reflexes process in spinal cord also Spinal nerves (PNS): Connected to spinal cord, pathway for sensory and motor impulses  Shorter than the vertebral canal Inside vertebral foramen Tapered end = conus medullaris This is the official “end” of the spinal cord Group of axons (inferiorly) = cauda equina Filum terminale (pia mater anchor to coccyx)  Continuous with cranial meninges  Dura mater:  Fuses with connective tissue of spinal nerves  Arachnoid mater  Subarachnoid space = CSF  Pia mater  Delicate, elastic/collagen fibers  Epidural space: Dura mater and periosteum Connective tissue, blood vessels, fat Subdural space   Gray matter in spinal cord (horns): Dendrites, cell bodies, unmyelinated axons, interneurons and glial cells White matter (columns): Myelinated axons  Posterior (dorsal) horns: Sensory nuclei, receive sensory input from the body Anterior (ventral) horns: Somatic motor nuclei, send signals to skeletal muscles (conscious) Lateral horns: Autonomic motor nuclei, sends signals to organs and glands (unconscious)  Anterior (ventral) root + posterior (dorsal) root = spinal nerve  Travel within intervertebral foramen ▪ Both motor and sensory axons  31 pairs:  8 cervical nerves  12 thoracic nerves  5 lumbar nerves  5 sacral nerves  1 coccygeal nerve  What are the 3 parts of the brain stem? Please provide one function for each  What is the cauda equina?  What is the difference in the anterior (ventral) and posterior (dorsal) horns of the spinal cord?