Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
43 Cards in this Set
- Front
- Back
|
Nervous system separated into two divisions |
Central nervous system CNS Peripheral nervous system PNS - these nerves are communication lines that link all parts of the body to the CNS |
|
|
CNS |
brain and the spinal cord (dorsal body cavity) - the command center - interprets sensory input and dictates motor output
|
|
|
PNS |
nerves and nerve endings |
|
|
function of the nervous system |
master controlling and communicating system of the body. - every thought, action, and emotion reflects the activity of the nervous system
FUNCTION: to control and regulate (like our government) |
|
|
There are 3 overlapping functions of the nervous system |
Sensory input, integration, motor output |
|
|
Sensory input |
there are millions of sensory receptors to monitor whats going on inside and outside the body - the gathered information is called sensory input - ie: you see a glass a water |
|
|
Integration |
the process of the nervous system processing and interpreting sensory input, and then making a decision of what to do - ie: I'm thirsty, so do I drink the water or not? |
|
|
Motor output |
the response - occurs by activating muscles (and glands) - ie: drinking the water |
|
|
receptors |
receive stimuli or sensations form the body |
|
|
somatic receptors |
receptors in the ns in the skin muscle and joints, muscle/joints respond to excessive stretch and postition |
|
|
cutanteous sennsation |
somatic receptors in the skin |
|
|
visceral receptor |
present in the viscera organs hungry stomach pain, \also detect other stimuli such as temp, pressure, and ph |
|
|
Receptors can also be classified by location:] |
- inside body - outside body - within the musculoskeletal system
|
|
|
So how does a receptor send a message to the control center? |
- receptors are the endings of nerves …… but not the axon terminals we talked about in the last section - remember, axon terminals stimulated muscle contraction directly. they didn't detect stimuli and send messages TO the brain --> they transmitted a signal AWAY from the brain to the muscle |
|
|
So how can a signal be sent to the brain? |
- When a stimulus is received, it is sent to the control center via a dendritic extension - dendritic endings are specially modified Na+ gates open in the dendritic endings --> action potential is generated (if threshold is reached) --> action potential travels along the dendrite up to the control center |
|
|
dendrites |
specialized neurons receive stimuli on these extensions |
|
|
The two extensions on every neuron are |
dendrites and axons |
|
|
Afferent Pathway |
Sensory Pathway - somatic and visceral receptors are called somatic and visceral afferents, bc they are part of this pathway - sensory = carries action potentials created by sensations such as pain, temperature, stretch, etc… - part of the PNS (peripheral nervous system) = nerves and nerve endings |
|
|
Where do you think these specialized dendritic endings/sensory recptors are located? |
-> eye, ear, taste buds, and nose |
|
|
CONTROL CENTER |
brain and the spinal cord = CNS (central nervous system) - these 2 organs receive all the input along the afferent pathways, and analyze it against a set point - is it too hot? cold? too much pressure? |
|
|
once the brain receives the input and analyzes it --> sends the info along the |
Efferent Pathway (Motor pathway |
|
|
the info travels FROM control center TO effector via |
AXONS part of the PNS (nerve and nerve ending |
|
|
voluntary response vs involuntary response |
Voluntary: the brain tells the body what to do and it does it: skeletal muscle picking up a glass of water involuntary: Movement without control system telling it: intestine moving the food along or heart beats |
|
|
Two types of efferent pathways |
Autonomic nervous system: carries involuntary responses Somatic nervous system: carries voluntary repsonses |
|
|
autonomic nervous system ANS |
used in the response of fight or flight, see cop car from red light ran then the action potential goes to the brain, carried to the heart lungs, pupils telling all the organs there is danger |
|
|
ANS is responsible for |
digestive, resting state after you eat a full meal ass well |
|
|
ANS division |
parasympathetic and sympathetic these 2 work in opposition to each other--what one stimulated the other inhibits |
|
|
sympatheitc |
flight or flight responses not just danger, responses when you exercise, so your heart rate and breathing provides adequate blood and oxygen activity |
|
|
parasympathetic |
digestive, resting state, rest |
|
|
So what are the EFFECTORS in all these motor pathways? |
- the effector = endpoint - somatic (voluntary) nervous system -> skeletal muscles - autonomic (involuntary) nervous system -> cardiac and smooth muscles - can also be glands (think salivary glands, you dry up when nervous) |
|
|
Glial Cells |
- smaller cells that surround and wrap delicate neurons - also called neuroglia - there are 6 major types -> 4 in the CNS; 2 in the PNS
Glial cells in the CNS:
- like neurons, these have long octopus legs and a central body - but they are much smaller than neurons - there are tons more glial cells than neurons (10:1) -> make up about half of the mass of the brain |
|
|
Astrocytes (glial cells in CNS) |
- "star cells" - the most abundant, and most versatile - connected by gap junctions - cling to neurons and capillaries - Fxn: - aide in exchange of nutrients from blood capillaries to neurons * control the permeability of capillaries that feed the brain. only certain substances are allowed in --> blood brain barrier
- guide migrating neurons - can also respond to nerve impulses and neurotransmitters - since they are connected by gap junctions, they can signal to each other and release extracellular chemical messengers |
|
|
Microglia (glial cells in CNS) |
- "thorny" processes - their processes touch nearby neurons, and when they sense danger (injury) microglia migrate to the neurons - Fxn: defense -> they transform into a macrophage type cell that can phagocytize either microorganisms or dead neurons
Why is this important? Immune system does NOT have access to the nervous system. -->blood brain barrier
|
|
|
Ependymal cells (glial cells in CNS) |
- "wrapping garment" - can be squamous or columnar, and may be ciliated - they line the cavities of the brain and the spinal cord - Fxn: produce cerebrospinal fluid (CSF, that cushions the brain and spinal cord) and protects it from injury - beating cilia helps to circulate the fluid |
|
|
Oligodendrocytes (glial cells in CNS) |
- these have fewer processes/extensions - Fxn: wrap around axons of neurons in the CNS and form myelin sheaths -> insulators |
|
|
Satellite cells (glial cells in the PNS) |
surround neuron cell bodies that are in the PNS - have most of the same functions as astrocytes, but in the PNS - remember, the PNS doesn't have a blood brain barrier - satellite cells regulate the cellular fluid around neurons -> control the chemical environment around a neuron |
|
|
Schwann cells (Glial cells in the PNS) |
form myelin sheaths around axons in the PNS = insulation around the axons in the PNS - critical for regeneration of damaged peripheral nerve fibers - increases the speed of nerve impulse transmission |
|
|
Neurons |
there are billions of neurons (nerve cells) in the nervous system - structural units of the nervous system - large cells, compared to others we've discussed (cell body 5-140mm) - all have a cell body and one or more octopus legs (processes) - major function: to conduct nerve impulses (send messages) - the plasma membrane is the site of electrical signaling |
|
|
Special Characteristics of Neurons |
longevity: live and function 100 yr amitotic: cant be replaced don't undergo cel div high Metabolic rate: cont o2 and glucose, live few sec if no o2
|
|
|
neuron cell body |
Soma, contains nucleus, cell center--> contains all the usual organelles |
|
|
Processes of neuron |
octopus legs, 2 types dendrites and axons |
|
|
Dendrites |
short, branching extensions - motor neurons have 100's of these clustering close to the cell body - Fxn: - transmit impulses TOWARD the cell body - increase surface area for receiving signals |
|
|
axons |
- each neuron has a single axon - efferent pathway
- Fxn: processes that carry impulses AWAY from the nerve cell body |
