The Nervous System Flashcards
Function of the Central Nervous System
A rapid communication system which acts as the main coordinator of body functions.
- Regulates the internal environment
- Regulates and coordinates all other body systems (including higher functions ie. thinking, reasoning, emotions)
How does the nervous system communicate?
Through the use of electrical and chemical signals carried out by neurons.
Basic structures of the Neuron
- Dendrites
- Cell body
- Axon
- Axon terminals
How is information sent through the Nervous System?
- Information comes in through the sensory receptors (eys, skin, fingers, etc).
- It is transmitted as sensory input to the CNS (brain and spina cord).
- The CNS integrates this information.
- The CNS sends motor output out to the body.
- This output triggers the effector, causing muscles to move according to the signal sent.
Parts of the Central Nervous System
(CNS)
The CNS is made up of the brain and the spinal cord.
Thes organs contain neural tissue, blood vessels and connective tissues.
Parts of the Peripheral Nervous System
PNS is comprised of the cranial and spinal nerves and all nerves outside the CNS.
Function of the CNS
Integrates, processes and coordinates sensory data and motor commands.
Function of the PNS
Sends sensory data from the sense organs to the CNS and motor commands from the CNS to the peripheral tissues and organs.
Two Divisions of the Peripheral Nervous System
- Afferent Division - sensorty data from the sense organz to the CNS
- Efferent Division - Motor commands from the CNS to the effector organs
Two Parts that Make up the Efferent Division of the PNS
- Somatic Nervous System - controls muscle contractions
- Autonomic Nervous System - Controls reflexes, organs and tissues not under voluntary control.
What is the Efferent Division of the Nervous System?
Part of the Peripheral Nervous Sytem.
Controls motor commands from the CNS to the effector organs.
What is the Afferent Division?
Part of the PNS.
Nerves pass sensory information from the sense organs to the CNS.
Somatic Nervous System
Controls skeletal muscle contractions. Conscious ability to move your muscles.
Autonomic Nervous System
Controlled at subconscious level.
This includes reflex actions, all organs and tissues not under voluntary control (including smooth muscle of the walls of airways and blood vessels).
Separated into two systems:
- Sympathetic
- Parasympathetic
Two Parts of the Autonomic Nervous system
- Sympathetic - mobilizes the body during stressful situations (flight or flight)
- Parasympatheic - responsible for aquisition and storage of resources, predominates when the body is at rest.
Sympathetic Autonomic Nervous System
Responsible for mobilizing the body to deal with stressful situations (fight or flight) and predominates during times of stress.
Parasympathetic Autonomic Nervous System
Responsible for the acquisition and storage of resources and predominates when the body is at rest.
Four Parts of the Brain
- Cerebrum
- Diencephalon
- Brain Stem
- Cerebellum
Cerebrum
Divided into two cerebral hemispheres.
Each hemisphere controls the contralateral side of the body.
What is the Diencephalon composed of?
- Thalamus
- Hypothalamus
Function of the Thalamus
Comprised of several clusters of neurons.
Is the main relay center for sensory information arriving in the brain.
Screens out unimportant information beforing routing the signals to the appropriate area of the cerebral cortex.
Plays an important role in controling voluntary movement.
Function of the Hypothalamus
Lies beneath the thalamus.
Is connected to the pituitary gland.
Controls the release of hormones from this gland.
Made up of a large number of (neuron) nuclei.
Repsonsible for regulating sleep and wake cycles, apetite, thirst, water balance, sexual behavior, and body temperature.
Overall control of the Autonomic Nervous System.
Three Structures of the Brain Stem
- Medulla Oblongata
- Pons
- Midbrain
What type of tissue is found in the brain stem?
The tissue in the brain stem is different than that of the rest of the nervous system.
It is composed mainly of white matter with small clusters (nuclei) of gray matter scattered throughout.
Reticular formation
Nuclei of gray matter scattered throughout the brain stem.
Function of the Brain Stem
A two way conduction system.
Sensorty pathways conduct signals up from the spinal cord to the rest of the brain, and motor pathways conduct signas down from the brain to the spinal cord.
Some nerve fibers pass through, but most synapse in the brain stem.
Reticular Activating System
(RAS)
Neurons of the reticular formation (gray matter nuclei scattered throughout the brain stem) receive sensory imput and communicate nervous energy to the cerebral cortex, cardiovascular and respiratory systems.
Stimulation of RAS Nerves…
Arouses and maintains consciousness, maintains alertness and attention,
Lack of Stimulation of RAS nerves….
(ie darkness or a quiet room)
Induces drowsiness.
How to general anesthetics function?
Supress the RAS nerves.
How is clinical manifestation of brain death determined?
Lack of electrical activity in the brain stem.
Vital Centers associated with Autonomic Reflexes found in the medulla include:
- The Cardiovascular Center - Controls the rate and force of contraction of the heart.
- The Respiratory Center - controls the rate and depth of breathing
- The Reflex Centers - irriation of airways or stomach activate the reflex centers in the medulla to induce coughing, sneezing or vomitting ot remove the irritant. Swallowing and blinking reflexes are also associated with the medulla.
Cardiovascular Center
Found within the medulla.
Controls the rate and force of the contraction of the heart.
Also contains the vasomotor center which controls the diamater of blood vessels (especially arterioles and arteries).
Vasomotor Center
Located within the Cardiovascular center of the medulla (in the brain stem).
Controls the diamter of blood vessels (especially arterioles and arteries).
Respiratory Center
Located in the medulla within the brain stem.
Controls the rate and depth of breathing.
Functions in close association with similar nuclei in the pons.
Reflex Centers
Located in the medulla of the brain stem.
Irritation in the airways or stomach activate this reflex center which induces coughing, sneezing or vomiting to remove the irritant.
Swallowing and blinking reflexes are also associated with the medulla.
