Divisions of the Nervous System Flashcards
What is the central nervous system (CNS)?
The CNS is a primary division of the nervous system, consisting of:
Brain and spinal cord.
It is housed within the cranium (brain) and spinal column (spinal cord).
The CNS is responsible for processing and integrating information to coordinate bodily functions.
What are the key functions of the brain and spinal cord in the CNS?
Brain:
Processes sensory stimuli from the body.
Controls voluntary and involuntary responses.
Responsible for psychological processes and consciousness.
Spinal Cord:
Carries sensory information (e.g., touch, temperature, pain) to the brain.
Sends motor signals from the brain to muscles, organs, and glands.
Produces reflexive behaviors with minimal brain involvement.
How is the central nervous system (CNS) protected?
Meninges: Three protective layers surround the brain and spinal cord:
Dura mater
Arachnoid mater
Pia mater
Cerebrospinal fluid (CSF): Fills the space between the meninges (subarachnoid space) and acts as a shock absorber.
Blood-brain barrier: Tightly packed blood vessel cells prevent toxins from entering the brain and spinal cord from the bloodstream.
What is the peripheral nervous system (PNS) and how does it relate to the CNS?
PNS: A network of nerves outside the brain and spinal cord, extending throughout the body.
Vulnerability: PNS cells are more exposed and vulnerable to trauma and toxins than CNS cells.
Connection to CNS: The CNS and PNS are connected, as motor neurons that control muscles and organs have their cell bodies within the spinal cord (CNS) but extend through the PNS.
What are the differences between nerves and tracts in the nervous system?
Nerve: A bundle of axons in the PNS (e.g., optic nerve).
Tract: A bundle of axons in the CNS.
Commonalities: Nerves and tracts consist of neurons that share common connections, follow the same path, and serve a common function.
Example: The optic nerve transmits visual information from the eye (PNS) to the brain (CNS).
What are nuclei and ganglia in the nervous system?
Nucleus (pl. nuclei): A group of neuronal cell bodies in the CNS.
Ganglion (pl. ganglia): A group of neuronal cell bodies in the PNS.
Both nuclei and ganglia contain cell bodies with similar anatomical connections and functions.
What is the somatic nervous system (SNS) responsible for?
The SNS is part of the PNS and is involved in:
Voluntary control of movement.
Detecting sensory stimuli (e.g., touch, temperature) and relaying it to the CNS.
It uses cranial nerves to control muscles and receive sensory input from the head and neck.
Spinal nerves handle sensory input and motor control from the neck down.
What is the role of the autonomic nervous system (ANS)?
The ANS controls involuntary functions, regulating:
Internal organs (e.g., heart, intestines).
Smooth muscles (e.g., blood vessels).
Hormone glands.
Maintains homeostasis by adjusting cardiovascular, respiratory, digestive, hormonal, and thermal functions.
Functions autonomously, without conscious control. (slide 46)
How do autonomic nerves function in the autonomic nervous system (ANS)?
Distinct from SNS Nerves: Autonomic nerves differ from spinal and cranial nerves of the somatic nervous system (SNS) that control voluntary movement.
Motor Functions: Primarily motor nerves that regulate bodily functions (e.g., increasing heart rate).
Sensory Functions: Include sensory nerves that provide feedback about the body’s internal state, helping the ANS maintain regulation.
How do the somatic and autonomic nerves differ in organization?
Somatic Nervous System (SNS):
Direct Connection: Motor neurons exit the CNS (e.g., spinal cord) and connect directly to target muscles (e.g., bicep).
Autonomic Nervous System (ANS):
Indirect Connection: Autonomic neurons make multiple connections before reaching their target (e.g., the heart).
What is the structure and function of autonomic nerves in the autonomic nervous system (ANS)?
The autonomic nerve pathway consists of:
Preganglionic Neurone: Originates in the spinal cord and connects to the postganglionic neurone.
Postganglionic Neurone: Innervates target organs (e.g., the heart).
The ANS is divided into sympathetic (fight or flight) and parasympathetic (rest and digest) systems.
What is the structure and function of sympathetic neurones in the autonomic nervous system?
Sympathetic preganglionic neurones originate from the lumbar and thoracic segments of the spinal cord and connect to the sympathetic chain (ganglia) alongside the spinal cord. These ganglia contain cell bodies of postganglionic neurones, which innervate various organs and glands. Most neurones in the chain are interconnected, allowing them to respond in unison and function symbiotically.
What is the structure and function of sympathetic neurones in the autonomic nervous system?
Sympathetic preganglionic neurones originate from the lumbar and thoracic segments of the spinal cord and connect to the sympathetic chain (ganglia) alongside the spinal cord. These ganglia contain cell bodies of postganglionic neurones, which innervate various organs and glands. Most neurones in the chain are interconnected, allowing them to respond in unison and function symbiotically.
How do the neurotransmitters of the parasympathetic and sympathetic neurones affect organ function?
Sympathetic Neurones:
Preganglionic neurones release acetylcholine.
Postganglionic neurones release noradrenaline (norepinephrine), except in sweat glands, which release acetylcholine.
Parasympathetic Neurones:
Both preganglionic and postganglionic neurones release acetylcholine.
This difference in neurotransmitters allows each system to have distinct effects on organs.
What is Fight and Flight?
Are the effects of sympathetic activity during stressful situations.The sympathetic nervous system activates “fight or flight” responses by:
Increasing blood flow to muscles.
Stimulating adrenaline release to raise heart rate.
Constricting blood vessels in the skin to direct blood to muscles.
Increasing sweating to cool the body.
Dilating pupils for enhanced vision.
Producing piloerection (goosebumps in humans) in furry animals.
This prepares the body for action.
What are the effects of the parasympathetic system on the body?
The parasympathetic system relaxes the body and aids recuperation by:
Reducing heart rate.
Increasing salivation.
Enhancing gastric and intestinal motility (bowel movements).
Inducing secretion of digestive juices.
Increasing blood flow to the gastrointestinal system.
This process aims to restore and increase the body’s supply of stored energy.
How do the sympathetic and parasympathetic systems interact in autonomic control?
Most organs are innervated by both systems, which are active simultaneously and have antagonistic effects. The body’s overall activity reflects the balance between sympathetic and parasympathetic stimulation, determining whether an organ’s activity increases or decreases based on which system is more active.
