Human Anatomy Nervous System Quiz

Anatomy & Physiology for the Health Sciences II

• This is a course covering anatomy and physiology for health sciences students.
• The lecture, Overview, Brain & Spinal Cord, introduces the nervous system.

Objectives

• The lecture covers the organization of the nervous system, including the Central Nervous System (CNS) and Peripheral Nervous System (PNS), somatic nervous system, autonomic nervous systems, and the enteric nervous systems.
• It describes the three basic functions of the nervous system (sensory, integrative, and motor), neuron classification, electrical and chemical synapses.
• It describes the four types of neuroglia in the CNS, and the two types in the PNS.
• It covers myelination, multiple sclerosis, and Guillain-Barre syndrome.
• It describes ganglia and nerve tracts.
• It describes the arrangement of gray and white matter in the CNS.
• Identifying major parts of the brain, including the cortex, gyri, fissures, and sulci of the cerebrum, and the lobes of the cerebrum.
• Identifying the functions of the corpus callosum.
• Describing causes and symptoms of epilepsy.
• Describing anatomy and function of sensory, association, and motor areas of the cerebral cortex (including primary somatosensory, visual, auditory, gustatory, and olfactory areas).
• Describing aphasia, fluent and non-fluent.
• Describing the anatomy and functions of the brainstem (Medulla, Pons, and Midbrain).
• Identifying and describing the anatomy and functions of the cerebellum and basal ganglia.
• Describing ataxia.
• Describing the anatomy and functions of the Limbic System, thalamus, hypothalamus, and pineal gland.
• Describing the blood supply to the brain and the protective structures.
• Discussing cerebrovascular accident (CVA) and transient ischemic attack (TIA), blood-brain barrier formation, and circulation of Cerebrospinal Fluid (CSF).
• Describing spinal tap procedures and hydrocephalus.
• Describing the signs, symptoms and causes of Alzheimer's disease.
• Describing the internal and external anatomy of the spinal cord and spinal nerves.
• Describing the organization of gray and white matter in the spinal cord and the location of sensory and motor tracts, cell bodies of sensory, motor and interneurons.

Terminology

• Afferent - Sensory
• Efferent - Motor
• Somatic - Body wall (voluntary)
• Visceral - Organs (involuntary)
• Nuclei - Collection of cell bodies in the CNS
• Ganglia - Collection of cell bodies in the PNS
• Tract - Bundles of axons in the CNS
• Nerve - Bundles of axons in the PNS
• Presynaptic neuron - Transmits signals toward a synapse
• Postsynaptic neuron - Transmits signals away from a synapse.

The Nervous System

• An intricate network of neurons and neuroglia.
• One of the smallest but most complex body systems in human beings.
• Protected by bony structures such as the skull and vertebral column.
• Components include the brain, spinal cord, nerves, enteric plexuses, and sensory receptors.

Organization of the Nervous System - Anatomical organization

• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Cranial nerves, spinal nerves, ganglia, enteric plexuses, and sensory receptors.

Organization of the Nervous System - Functional organization

• Somatic Nervous System (SNS): Voluntary, including somatic afferent (touch, pain, pressure), and efferent neurons (skeletal muscle contractions).
• Autonomic Nervous System (ANS): Involuntary; visceral afferent (pain, stretch), and efferent neurons (smooth and cardiac muscle, glandular secretions), including sympathetic (fight, flight, fright), and parasympathetic (rest and digest) divisions.
• Enteric Nervous System (ENS): Involuntary; located in the gastrointestinal tract and controls numerous functions of the GI tract.

Functions of the Nervous System

• Sensory: Detects internal and external stimuli using sensory receptors. This input is relayed to the CNS.
• Integrative: Processes and determines appropriate responses to sensory input. This involves relaying information within the brain and spinal cord via interneurons.
• Motor: Motor responses are elicited, and motor output is relayed to effectors (muscles and glands) via efferent neurons

Neurons

• Cell body - contains the nucleus and organelles of the nerve cell, including Nissl bodies (prominent clusters of rough endoplasmic reticulum).
• Dendrites - Branching processes that extend away from the cell body, receiving input from other neurons or receptors.
• Axon - Elongated projection that transmits signals away from the cell body to other cells or effectors.
• Axon terminals - Branching tips of the axon at the ending point that release neurotransmitters initiating signals to the postsynaptic cells or effectors.

Classification of Neurons

• Multipolar
• Bipolar
• Unipolar

Neuronal Synapses

• Electrical synapses - Action potentials conduct directly between adjacent cells through gap junctions allowing for rapid communication, coordinating impulses between pre and post synaptic neurons/cells.
• Chemical synapses - Action potentials conduct indirectly across the synaptic cleft via the release of neurotransmitters, converting electrical signals into chemical signals at the presynaptic neuron and postsynaptic neuron converting chemical signals into electrical signals.

Neuroglia

• Neuroglia are support cells of the nervous system with diverse functions Characteristics: Small, numerous, non-conducting, regenerative
• CNS neuroglia: Astrocytes, oligodendrocytes, ependymal cells, microglia
• PNS neuroglia: Satellite cells and Schwann cells

Meninges

• Protective coverings of the central nervous system (CNS) continuous with spinal meninges.
• Layers include Dura mater, Arachnoid mater and Pia mater.

Blood Supply

• The brain is primarily supplied with blood by internal carotid arteries and vertebral arteries
• The circle of Willis is the major arterial structure that distributes blood throughout the brain. Blood vessel structures also return blood from the brain back to the heart via the internal jugular veins.

Cranial Nerves

• Different cranial nerves such as CN III (Oculomotor), CN IV (Trochlear), CN V (Trigeminal), CN VI (Abducens), CN VII (Facial), and CN VIII (Vestibulocochlear) have differing functions and have nuclei in the brain.

Clinical Correlates

• Multiple Sclerosis
• Guillain-Barre syndrome
• Aphasia
• Epilepsy
• Ataxia
• Hydrocephalus
• Cerebrovascular Accident (CVA) or stroke
• Transient Ischemic Attack (TIA)
• Various other conditions

Major Parts of the Brain

• Cerebrum
• Diencephalon
• Cerebellum
• Brainstem (Midbrain, Pons and Medulla oblongata)

Cerebrum

• The outer region of gray matter (the cerebral cortex) is involved in executive functioning.
• Folds called gyri, separated by fissures and sulci, organize the cortex.
• The cortex is divided into lobes (frontal, parietal, temporal, occipital, and insula).
• Specific areas within the cortex are associated with sensory and motor functions.
• Deep cerebral gray matter nuclei are found within structures of the white matter.

Cerebellar Lobes

• Vermis - divides the cerebellum into hemispheres.
• Anterior lobe - governs subconscious movements.
• Posterior lobe- governs subconscious movements.
• Flocculonodular lobe - contributes to equilibrium and balance

Cerebellar Functions

• Evaluating motor output.
• Coordinating complex contractions of skeletal muscles.
• Regulating posture and balance.
• Involved in cognition and speech.

Basal Ganglia

• Located deep within the cerebral hemispheres (major parts include caudate nuclei, lentiform nuclei, putamen, globus pallidus)
• Involved in motor function, initiation and termination of movement, suppressing unwanted movement, regulation of muscle tone and cortical function

Limbic System

• The "emotional brain" with structures along the inner border of the cerebrum and the floor of the diencephalon.
• Parts include limbic lobe, dentate gyrus, amygdala, mammillary bodies, thalamic nuclei and olfactory bulbs.
• Functions include emotions (e.g., pleasure, pain, affection, fear, anger), olfaction, and memory.

Spinal Cord

• Located within the vertebral canal, extending from the foramen magnum to the 1st or 2nd lumbar vertebrae.
• It exhibits cervical and lumbar enlargements
• Tapered termination - Conus medullaris.
• The continuation of the spinal cord below the conus medullaris is the cauda equina
• Anchored to the coccyx by the filum terminale .