UNBC Anatomy & Physiology Review of the Nervous System PDF

# Structure and Function of the Neurological System ## Nursing 302 ## Anatomy & Physiology Review ### Central Nervous System (CNS) - Brain - Spinal Cord Which are enclosed in the cranial vault and vertebrae, respectively. ### Peripheral Nervous System (PNS) - Cranial nerves, spinal nerves & t...

# Structure and Function of the Neurological System ## Nursing 302 ## Anatomy & Physiology Review ### Central Nervous System (CNS) - Brain - Spinal Cord Which are enclosed in the cranial vault and vertebrae, respectively. ### Peripheral Nervous System (PNS) - Cranial nerves, spinal nerves & their ganglia - Afferent (ascending) pathways; bring sensory signals towards the CNS. - Efferent (descending) pathways; bring motor signal away from the CNS. Functionally, split into the somatic nervous system (voluntary), and autonomic nervous system (involuntary) - sympathetic & parasympathetic ## The Neuron The primary cell of the nervous system. Detects environmental changes and start body responses to support a steady state. Has 3 parts: - Cell body (soma) - Dendrites (branching fibers of the cell) - Axon - Covered in Myelin (increases the speed of nerve signals) ## Three types of neurons 1. Sensory (afferent, unipolar) - Signal from periphery to the CNS 2. Associational (interneurons, multipolar) - Signals from neuron-to-neuron 3. Motor (efferent, multipolar) - Signal from CNS to periphery ## The Nerve Impulse Neurons produce and conduct electrical and chemical impulses; the spread of these impulses is done by releasing chemicals (neurotransmitters). An unexcited neuron keeps a resting membrane potential, and an action potential is created with an adequately raised membrane potential, then creating a nerve impulse. The stimulus must be strong enough to raise that membrane potential to action potential for it is a all-or-none response. Neurotransmitters travel across the synaptic cleft in order to reach from one synapse to another (one neuron to another). ## The Nerve Impulse & Neurotransmitters Examples of neurotransmitters: - Acetylcholine - Norepinephrine - Serotonin - Dopamine - Histamine ## Anatomy & Physiology Review ### The Brain - Weighs about 3 lbs, receives ~15-25% of the total cardiac output. - Allows a person to reason, function intellectually, expresses personality and mood, and perceive and interact with the environment. - 3 structural divisions: - Forebrain - Midbrain - Hindbrain Together the midbrain, medulla and pons make up the brainstem. ### The Brain 2 cerebral hemispheres; and the surface is divided into lobes. - **Frontal Lobe**: executive functioning, short-term memory, expansion of thought, personality, emotional responses - Broca area (motor speech) - **Parietal Lobe**: somatic sensory input - **Temporal Lobe**: primary auditory cortex - Wernicke area (sensory speech; delivery & understanding) - **Occipital Lobe**: primary visual cortex; receiving input from the retinas ## Anatomy & Physiology Review ### The Spinal Cord - Protected by the vertebral column - Connects the brain and the body - Conducts somatic and autonomic reflexes - Modulates sensory and motor function ## Anatomy & Physiology Review ### Protective Structures of the CNS - **Cranium**: hard outer bone - **Meninges**: 3 protective membranes - Dura mater (tough) - Arachnoid mater (spider) - Pia mater (tender) - **Cerebrospinal Fluid (CSF)**: protects the intracranial and spinal cord structures from jolts and blows - **Vertebral Column**: 33 vertebrae; 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 4 fused coccygeal. Between each vertebrae is an intervertebral disc. ## Anatomy & Physiology Review ### Blood Supply to the Brain - Carotid Arteries - Vertebral Arteries *main two vessels The carotid and vertebral arteries connect to form the **Circle of Willis** ### The Blood Brain Barrier - Reduce harmful substances in the blood from entering the interstitial spaces of the brain or CSF. ## Anatomy & Physiology Review ### Peripheral Nervous System ### Assessment of the PNS - 12 cranial nerves (pg. 321 Table 13.6) - Skin Dermatomes ## Cranial Nerves - **12 PAIRS** - L numbered based on order they arise from nuclei in the brain (except for XI & XII inverted) - I - Olfactory (S) - II - Optic (S) - III - Oculomotor (M) - IV - Trochlear (M) - V - Trigeminal (B) - VI - Abducens (M) - VII - Facial (B) - VIII - Vestibulocochlear (S) - IX - Glossopharyngeal (B) - X - Vagus (B) - XI - Accessory (M) - XII - Hypoglossal (M) - Exit through Foramina - "On Old Olympus' Towering Top, A Finn Van German Viewed A Hop" - "Some Say Marry Money, Buf My Brother Says Big Brains Matter More" ## Background - Area of skin innervated by specific nerve root - ~ 30 total ## Assessment - Neurological Exam - Pinprick Test - Light Touch Test ## Pathologies - **Radiculopathies** - Commonly due to disc herniations from advanced age or trauma. - **Shingles** - Reactivation of Varicella Zoster Virus. ## Aging and the Nervous System ### Structural - Decrease in brain weight and size, markedly frontal regions - Increase in ventricular volume - Fibrosis and thickening of the meninges ### Cellular - Decrease in number of neurons; not always related to changes in mental function - Decrease in myelin - Imbalance in amount and distribution of neurotransmitters - Decrease in glucose metabolism ### Cerebrovascular - Arterial atherosclerosis - Increased permeability of the blood-brain barrier - Decrease in vascular density ### Functional - Decrease in tendon reflexes - Gradual deficit in taste and smell - Decrease in colour vision - Change in gait and posture - Sleep disturbances - Memory impairments - Cognitive changes linked with chronic disease