chapter 12: nervous tissue Flashcards
Describe the structures of the nervous system
The central nervous system contains the brains and spinal cord
The peripheral nervous system contains: cranial nerves, spinal nerves, enteric plexuses
describe the functions of the nervous system
1.Sensory function. Sensory receptors detect internal stimuli, such as an increase in blood pressure, or external stimuli (for example, a raindrop landing on your arm).
2. Integrative function. The nervous system processes sensory information by analyzing it and making decisions for appropriate responses—an activity known as integration.
3. Motor function. Once sensory information is integrated, the nervous system may elicit an appropriate motor response by activating effectors (muscles and glands) through cranial and spinal nerves.
what us a nerve and what are they made of?
nerves are made of neurons. a nerve is a bundle of hundreds or thousands of axons outside of the brain or spinal cord
are nerves part of the CNS or PNS
PNS
neurons vs neuroglia
neurons transmit signals
Neuroglia support, nourish, and protect neurons, and maintain the interstitial fluid that bathes them
label the neuron
describe the structure of neurons
think about diagram
a fiber is a single axon within the endoneurium. A fascicle is a bundle of fibers within a perineurium. both the endoneurium and the epineurium. a nerve is a bundle of fascicle within an epineurium.
LOTS AND LOTS OF BLOOD VESSELS WITHIN THESE COVERING
endoneurium bs perineurium vs epineurium
endoneurium is the innermost one that covers a single axon (called fiber)
perineurium is the middle layer that covers a bundle of fibers (called a fascicle)
the epineurium is the outermost layer that covers a bundle of fascicles
what is an axon
An axon is a long, thin, cylindrical projection that often joins to the cell body at a cone-shaped elevation called the axon hillock. It propagates nerve impulses toward another neuron, a muscle fiber or a gland cell
describe the sensory division of the PNS
the sensory division of the PNS conveys input to CNS from sensory receptors in the body. provides information about the somatic senses and the special senses.
somatic senses vs special senses
somatic senses: tactile, thermal, pain and proprioceptive sensation (position and movement of our body)
special senses: smell, taste, vision, hearing, equilibrium
CNS vs PNS
Central nervous system: consists of the brain and spinal cord
CNS processes many different incoming sensory info. Is also the source of thoughts, emotions, and memories. Most signals stimulate muscles to contract and glands to secrete originate in the CNS
Peripheral nervous system: consists of all nervous tissue outside the CNS. Consists of nerves and sensory receptors
describe the motor division of the PNS
what 2 systems are they a part of
coveys output from the CNS to effectors (muscles and glands). Division is further subdivided into a somatic nervous system and autonomic nervous system
- Somatic nervous system: conveys output from the CNS to SKELETAL MSCL ONLY because its motor responses can be consciously controlled, the action of this part of the PNS is voluntary
- The autonomic nervous system conveys output from the CNS to smooth muscle, cardiac muscle and glands. Because its motor response not under concious control the action of the ANS is involuntary
parasympathetic vs sympathetic vs enteric plexus
parasympathetic: rest, chill, digest
Sympathetic: fight or flight
Enteric plexus: deals with smooth muscle and wall of GI tract. helps regulate the activity of smooth muscle and glands of the digestive canal.
Can function independently (e plexus), but still communicate with and are regulated by autonomic nervous system
what do neurons do
have electrical excitability and produce action potentials. These action potential enable neurons to rapidly transmit signals from one cell to another
draw out organization of the nervous system
what are the different part of a neuron cell body
only cell body. think head of neuron
- nucleus: surrouned by cytoplasm that contains typical cellular organs
- Nissl bodies: rough ER and free ribosomes are found here for protein sythnthesis. new poteisn used to replace cellular components, as material for growth neurond and to regenerate damaged axons in PNS
- neurofibrils (intermediate filaments) give shape and support; microtubules move material between the cell body and axon
dendrites vs axons
dendrites are the receiving portion of the neurons. they conduct impulses towards the cell body, are highly branched and unmyelinated and have contact with other neurons. (neurofibrils maintain their shape)
axons conduct nerve impulses from the neuron to other cells of the body (neuron, muscles or gland cell)
- conduct impulses away from cell body, end in fine processes called axon terminals; swollen tups called synaptic end bulbs contain vesicles filled with neurotransmitter
what is the different in the structural classifications of neurons? what are the 3 different types and what does it look like
describe multipolar neurons (location)
it has several dendrites and one axon. They make up the majority of the neurons in CNS (interneurons).
Most neurons in the brain and spinal cord are of this type, as well as all motor neurons
describe bipolar neurons
they have one dendrite and on axon. they are found in the retina of your eye, the inner ear and the olfactory area of the brain
explain this photo
- As you touch the pen, a graded potential develops in a sensory receptor in the skin of the fingers.
- The graded potential triggers the axon of the sensory neuron to form a nerve impulse, which travels along the axon into the CNS and ultimately causes the release of neurotransmitter at a synapse with an interneuron.
- The neurotransmitter stimulates the interneuron to form a graded potential in its dendrites and cell body.
- In response to the graded potential, the axon of the interneuron forms a nerve impulse. The nerve impulse travels along the axon, which results in neurotransmitter release at the next synapse with another interneuron.
5.This process of neurotransmitter release at a synapse followed by the formation of a graded potential and then a nerve impulse occurs over and over as interneurons in higher parts of the brain (such as the thalamus and cerebral cortex) are activated. Once interneurons in the cerebral cortex, the outer part of the brain, are activated, perception occurs and you are able to feel the smooth surface of the pen touch your fingers the conscious awareness of a sensation, is primarily a function of the cerebral cortex.
6.A stimulus in the brain causes a graded potential to form in the dendrites and cell body of an upper motor neuron, a type of motor neuron that synapses with a lower motor neuron farther down in the CNS in order to contract a skeletal muscle. The graded potential subsequently causes a nerve impulse to occur in the axon of the upper motor neuron, followed by neurotransmitter release.
7. The neurotransmitter generates a graded potential in a lower motor neuron, a type of motor neuron that directly supplies skeletal muscle fibers. The graded potential triggers the formation of a nerve impulse and then release of the neurotransmitter at neuromuscular junctions formed with skeletal muscle fibers that control movements of the fingers.
8. The neurotransmitter stimulates the muscle fibers that control finger movements to form muscle action potentials. The muscle action potentials cause these muscle fibers to contract, which allows you to write with the pen.
