Getting On Our Nerves
What are the (3) main functions of the Nervous System?
1. Detect changes and feel sensations.
2. Initiate responses to changes.
3. Organize and store information.
Name the 3 types of Neurons (nerve fibers) and a brief description of each.
1. Sensory- carry impulses from receptors to CNS. Somatic or visceral.
2. Motor- carry impulses from CNS to effectors. (these neurons make up the autonomic nervous system)
3. Interneurons- entirely within the CNS.
Functions of the Spinal Cord?
Location of Spinal Cord?
A cross section of the cord (fig 8-3) shows the gray matter in the center in the shape of an H or butterfly and the outer layer is called White matter. What is each type of matter made of?
transmits impulses and integrates spinal cord reflexes.
Within vertebral canal- extends from foramen magnum to the disc between the 1st and 2nd lumbar vertebrae.
Gray Matter- cell bodies
White Matter- Myelinated axons and dendrites arranged in nerve tracts.
The Brain has many parts that function as a whole.
Start on page 178- Name the main parts and give a very brief description.
(The Response section will contain brief summaries of definition and function.)
Ventricles- 4 cavities- 2 lateral and 3rd and 4th ventricles. contains the choroid plexus- a network of capillaries that make CSF.
Medulla- posterior to the Pons. has centers that regulate vital functions (HR, RR, BP) and centers for reflexes (cough, sneeze, swallow, vomit)
Pons-works with the medulla: regulates respiratory patter.
Midbrain- extends to the Pons to the hypothalamus. Contains reflex centers: visual, auditory, righting
Cerebellum- Posterior to the Pons and Medulla; two hemispheres and is concerned with voluntary movement, regulation of muscle tone, regulation of equilibrium, stopping movements appropriately, and contributing to sensations of weight and texture.
Hypothalamus- Above pituitary gland, below thalamus. Produces antidiuretic hormone, oxytocin, releasing hormones (like GHRH), regulates body temp, food intake, autonomic nervous system and visceral responses, and body rhythms.
Thalamus- Below the cerebrum and above the hypothalamus.- groups sensory impulses, suppresses unimportant sensations, contributes to alertness and memory.
Cerebrum- two hemispheres with many parts- (This part gets its own question)
Name and Describe the 2 divisions of the Nervous System.
1. Central Nervous System (CNS)- consists of brain and spinal cord.
2. Peripheral Nervous System (PNS)- cranial nerves and spinal nerves, includes nerves to and from skin and skeletal muscles, and the autonomic nervous system.
A nerve is a group of axons and/or dendrites of many neurons, with blood vessels and connective tissue. Name the 3 types of nerves.
This term- __?__ -refers to a group of neurons within the CNS. All the neurons within this- are sometimes referred to as white matter because the myelin sheaths of the neurons give them a white color.
Sensory Nerve- made of sensory neurons
Motor Nerve- made of motor neurons
Mixed Nerve- made of both sensory and motor.
Nerve tract-group of neurons
Ascending tracts- carry sensory impulses ___ the brain.
Descending tracts- carry motor impulses ___ the brain.
The ______ contains cerebrospinal fluid and is continuous (through the spinal cord) with cavities in the brain called ventricles.
Name the membrane that covers the spinal cord and brain.
to the brain.
Away from the brain.
Central Canal
Meninges (cover the spinal cord and brain) Another way to describe that, would be to say the meninges line the vertebral canal and cranial cavity.
Name the 3 Meningeal layers.
CSF is the tissue fluid of the CNS. It is produced where in the brain? What are the functions of CSF?
Dura Mater (outer), Arachnoid Membrane(middle), Pia Mater(inner)
Produced in the ventricles. Its functions are to provide nutrients, remove waste, and act as a cushion.
Neuron Cell Body- what do they contain and where in the body are they located?
What part of the neuron carries electrical impulses away from the cell? Which part carries impulses toward the cell body?
Cell body contains the nucleus. They are in the CNS or in the trunk and are protected by bone.
Away from cell- Axon
Toward the cell-Dendrites
Define Saltatory conduction.
Impulse transmission is very rapid. The presence of a ____ ____ increase velocity of impulses by making the neuron "shorter" since only to Nodes of Ranvier depolarize.
The rapid transmission of a nerve impulse from one node of Ranvier to the next; characteristic of myelinated neurons.
Myelin Sheath
There are 31 pairs of spinal nerves- Each Spinal Nerve has two roots. The Dorsal Root (which also has the dorsal root ganglion) and the Ventral Root.
Briefly explain the pathway of impulses on each root and Define Dorsal Root Ganglion.
As the 2 roots merge just before exiting the backbone, the nerve formed is a ____ nerve.
Dorsal- Carries impulses to spinal cord
Ventral- carries motor impulses from spinal cord
Dorsal Root Ganglion- enlarged part of dorsal root that contains the cell bodies of the sensory neurons.
Mixed.
CSF is made continuously in the ventricles of the brain by choroid plexus, from blood plasma. It circulates from the ventricles to the ____ ____ of the spinal cord and to the cranial and spinal _________ spaces.
It is reabsorbed from the cranial subarachnoid space, through the _____ ___, into the blood in the cranial venous sinuses.
central canal, subarachnoid
Arachnoid villi
The membranes of these cells form the myelin sheath of peripheral neurons and their nuclei and cytoplasm form the neurolemma.
What is the neurolemma essential for?
Schwann Cells
Neurolemma is Essential for the regeneration of damaged axons or dendrites.
The small gap or space between an axon of one neuron and the dendrites or cell body of the next neuron is called the ____. This gap ensures ___-___ transmission of impulses because the impulses cannot go backward across them.
These gaps- can be termed excitatory- they transmit the impulse to another neuron, muscle cell, or gland. Others are termed inhibitory- causing _________- meaning the membrane becomes even more + outside, and no impulse is transmitted.
Synapse, one-way
Hyperpolarization: (Inhibitory synapses are important- examples are slowing heart rate, prohibiting excessive muscle contraction, etc.)
Define a stretch reflex and its purpose.
This reflex causes withdrawl with painful stimulus and its purpose is protection.
-A stretch reflex causes a muscle that is stretched to contract and its purpose is to keep the body upright.
-Flexor reflex
Let's talk Cerebrum. The ___ ____ connects and permits communication between the two hemispheres.
The ___ ___ is the surface gray matter- consists of cell bodies of neurons and is folded extensively into convolutions.
___ ___ consists of nerve tracts that connect the lobes of the cerebrum to one another and other parts of the brain.
___ ___'s have 3 main areas. Premotor area- regulates sequence of movements. Prefrontal area for aspects of social behavior. ____'s Motor speech area regulates the movements involved in speech.
___ ____ are small masses of gray matter within the cerebral hemispheres that regulate accessory movements like gestures, facial expression, and muscle tone.
1. Corpus Callosum. 2. Cerebral Cortex 3. White matter. 4. Broca's 5. Basal ganglia
Neuroglia-glial cells- specialized cells found only in the brain and spinal cord.
Name the 3 neuroglia and their specific functions.
Oligodendrocytes- Forms the myelin sheath in the central nervous system (CNS)
Microglia- phagocytes that are constantly moving-clean up cellular debris, damaged cells, and phagocytize pathogens.
Astrocyte-Regulate blood flow within the brain and contribute to the Blood-Brain Barrier.
A neuron not carrying an impulse is in a state of _?__, membrane as a + charge outside and a - charge inside.
Depolarization is the entry of _?_+ ions and reversal of charges on either side of the membrane.
What happens during repolarization, and what is the term for an impulse, that is, depolarization followed by repolarization?
Polarization
Na+
During Repolarization, K+ ions leave the cell and restore charges on the membrane to + outside and - inside.
Action Potential-The term for an impulse- for depolarization followed by repolarization.
A ______ is an involuntary response to stimulus- an automatic action stimulated by a specific change.
Spinal cord reflexes are those that do not depend directly on the ____.
A reflex arc is a pathway that nerve impulses travel when a reflex is elicited. Name the 5 essential parts of this arc and brief statement about what they do.
Reflex.
Brain.
1.Receptors- detect stimulus; generate impulse. 2. Sensory Neurons-transport impulse to CNS. 3. CNS- contains synapses. 4. Motor Neurons-transmit impulses from CNS to effector. 5. Effector- performs action.
1. Which lobes (Temporal, Parietal, Occipital) contain each set of areas?
A. Visual areas for vision and interpretation areas for spatial relationships.
B. General sensory area, speech areas, part of taste areas.
C. Auditory, olfactory, and speech areas.
2. These areas are found in all lobes, for abstract thinking, reasoning, learning, memory, and personality. What are they called?
3. ___ ____ is the ability of the brain to adapt to changing needs.
1. A. Occipital Lobes B. Parietal Lobes C. Temporal Lobes 2. Association Areas 3. Neural plasticity