8. Nervous System
Define and describe the parts of the general sensory systems within the sensory nervous system
- A complex system of nerve cells that responds to changes to the surface or internal state of the body. Made up of: a. Somatic sensory systems - Cutaneous (Exteroceptive) - Musculoskeletal (Proprioceptive) b. Visceral (Interoceptive) sensory systems
Define Associate Neurons
- A nerve cell that is within the central nervous system and that links sensory and motor neurons
Define Microglial cells
- A type of glial cell in the central nervous system - As the resident macrophage cells, they act as the first and main form of active immune defense in the central nervous system - Microglia are key cells in overall brain maintenance — they are constantly scavenging the CNS for plaques, damaged or unnecessary neurons and synapses, and infectious agents
Define Ependymal cells
- A type of glial cell in the central nervous system - Ependyma is the thin epithelial lining of the ventricular system of the brain and the central canal of the spinal cord, made up of ependymal cells - Ependyma is one of the four types of neuroglia in the central nervous system (CNS) - It is involved in the production of cerebrospinal fluid (CSF), and is shown to serve as a reservoir for neuroregeneration
Define Astrocytes
- A type of glial cell in the central nervous system - Perform many functions, including biochemical support of endothelial cells that form the blood-brain barrier, provision of nutrients to the nervous tissue, maintenance of extracellular ion balance, and a role in the repair and scarring process of the brain and spinal cord following traumatic injuries
Define Oligodendrocytes
- A type of glial cell in the central nervous system - Their main functions are to provide support and insulation to axons in the central nervous system, equivalent to the function performed by Schwann cells in the peripheral nervous system.
Define Satellite Cells
- A type of glial cell in the peripheral nervous system - Cover the surface of nerve cell bodies in sensory, sympathetic and parasympathetic ganglia - Derived from the neural crest of the embryo during development - Play a variety of roles, including control over the microenvironment of sympathetic ganglia. - They supply nutrients to the surrounding neurons and also have some structural function. Also act as protective, cushioning cells.
Define Schwann Cells
- A type of glial cells in the peripheral nervous system - Two types: myelinating and nonmyelinating. Myelinating Schwann cells wrap around axons of motor and sensory neurons to form the myelin sheath.
Define Interneurons
- A type of neuron - Create neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS).
Define Motor Neurons
- A type of neuron - Nerve cell (neuron) whose cell body is located in the spinal cord and whose fiber (axon) projects outside the spinal cord to directly or indirectly control effector organs, mainly muscles and glands - Motor neurons' axons are efferent nerve fibers that carry signals from the spinal cord to the effectors to produce effects
Autonomic Nervous System
- Division of the peripheral nervous system that influences the function of internal organs - The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal - The autonomic nervous system has two branches: the sympathetic nervous system and the parasympathetic nervous system
Describe the visceral (autonomic) motor system
- Division of the peripheral nervous system that influences the function of internal organs - The autonomic nervous system is a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal - The autonomic nervous system has two branches: the sympathetic nervous system and the parasympathetic nervous system
Define Glial Cells
- Non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems.
Parasympathetic Nervous System
- One of the two divisions of the autonomic nervous system, the other being the sympathetic nervous system - Responsible for stimulation of "rest-and-digest" or "feed and breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion and defecation
Sympathetic Nervous System
- One of the two main divisions of the autonomic nervous system, the other being the parasympathetic nervous system - Its primary process is to stimulate the body's fight-or-flight response - It is, however, constantly active at a basic level to maintain homeostasis
Somatic Nervous System
- Part of the peripheral nervous system - Associated with skeletal muscle voluntary control of body movement - Consists of afferent nerves and efferent nerves
Afferent Nerves
- Responsible for relaying sensation from the body to the central nervous system (CNS) - They include all the non-sensory neurons connected with skeletal muscles and skin. - The a- of afferent and the e- of efferent correspond to the prefixes ad- (to, toward) and ex- (out of).
Efferent Nerves
- Responsible for sending out commands from the CNS to the body, stimulating muscle contraction - They include all the non-sensory neurons connected with skeletal muscles and skin - The a- of afferent and the e- of efferent correspond to the prefixes ad- (to, toward) and ex- (out of)
Describe the motor system
- The motor system is the part of the central nervous system that is involved with movement - It consists of the pyramidal and extrapyramidal system (which contains basal ganglia and cerebellar systems)
Define the peripheral nervous system
- The part of the nervous system that consists of the nerves and ganglia on the outside of the brain and spinal cord - The main function of the PNS is to connect the central nervous system (CNS) to the limbs and organs, essentially serving as a communication relay going back and forth between the brain and spinal cord with the rest of the body - It is divided into the somatic nervous system and the autonomic nervous system
Describe the sensory nervous system
- The sensory nervous system is a part of the nervous system responsible for processing sensory information. - It consists of the general sensory systems and the special sensory systems
Describe the branches of spinal nerves
1. Anterior rami: The anterior ramus (ventral ramus) is the anterior division of a spinal nerve. The anterior rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the posterior rami. 2. Posterior rami: The posterior rams (dorsal rams) of spinal nerve refers to the posterior division of a spinal nerve. The posterior ramus is one of two major branches of a spinal nerve that emerge after the nerve emerges from the intervertebral foramen. The posterior ramus carries information that supplies muscles and sensation to the human back.
Describe the structural components of central nervous system
1. Brain: The brain and spinal cord contain two main types of tissue: grey matter, which originates and processes nerve impulses; and white matter, which transmits them. 2. Spinal Cord: The spinal nerves (shown here from the front) carry sensory nerve impulses towards the spinal cord and brain. They also carry motor nerve impulses from the brain to the rest of the body. Each spinal nerve has motor and sensory nerve roots. The sensory nerve roots enter the back of the spinal cord to join fibres that lead to the brain. Nerve fibres carrying signals from the brain join motor nerve roots leaving the front of the cord.
Describe the roots of spinal nerves
1. Dorsal (Posterior) roots 2. Ventral (Anterior) roots
What are the functional systems of the nervous system?
1. Motor 2. Sensory 3. Associative
Describe the somatic components of spinal nerves
1. Motor: Somatic efferent -- to voluntary (skeletal) muscles 2. Sensory: Somatic afferent -- from cutaneous and musculoskeletal receptors
Describe the visceral components of spinal nerves
1. Motor: Visceral efferent -- to autonomic ganglia; to involuntary (smooth and cardiac) muscle and glands 2. Sensory: Visceral afferent -- from visceral and vascular receptors
What are the two major types of cells in the nervous system?
1. Neurons 2. Glial cells
What types of cells make up the central nervous system?
1. Neurons a. Motor b. Interneurons 2. Glial a. Astrocytes b. Oligodendrocytes c. Microglial cells d. Ependymal cells
What types of cell make up the peripheral nervous system?
1. Neurons a. Motor b. Sensory 2. Glial a. Schwann cells b. Satellite cells
What parts make up the general form of spinal nerves?
1. Roots 2. Trunk 3. Branch
Describe the structural components of the peripheral nervous system
1. Sensory receptors: Pick up stimuli from inside or outside the body 2. Motor endings: Axon terminals of motor neurons and they innervate effectors (muscles are effectors) 3. Nerves: Bundles of peripheral axons 4. Ganglia: Clusters of peripheral neuronal cell bodies
What are the functional components of spinal nerves?
1. Somatic and visceral (autonomic) 2. Sensory and motor
Define and describe the parts of the associative part of the nervous system
??? 1. Neuromodulatory systems- Sleep and arousal 2. Regulatory systems- Homeostasis 3. Limbic system- Emotion, motivation and memory 4. Cognitive systems- Perception, thought, planning
Define and describe the parts of the special sensory systems within the sensory nervous system
Special senses are the senses that have specialized organs devoted to them: - vision (the eye) - hearing and balance (the ear, which includes the auditory system and vestibular system) - smell (the nose) - taste (the tongue) Made up of: a. Chemical sensory systems (taste and smell) b. Visual system c. Auditory system d. Vestibular system
Describe the trunk of spinal nerves
The ventral (anterior) and dorsal (posterior) nerve roots join to form a single nerve trunk and then split into anterior and posterior rami.
Describe the Hypothalamic neurosecretory system within the motor system
Visceral motor systems (autonomic nervous system)