2 regulatory systems
Nervous and endocrine system
he nervous system constantly monitors the body’s X and its X
internal environment (e.g., blood chemistry, muscle tension, temperature, etc.), external environment (outside temperature, light, etc.)
central nervous system (CNS) is the body’s main X center and includes the X
integration brain and spinal cord,
The sensory (afferent) division detects stimuli in the PNS and sends afferent information from its receptors to neurons in the CNS. The sensory division includes two subdivisions: the somatic and visceral divisions:
Somatic sensory division: Conducts im- pulses from receptors in the skin, skeletal muscles, and joints to the CNS
Visceral sensory division: Conducts im- pulses from smooth muscle and cardiac muscle to the CNS.
The motor (efferent) division conducts im- pulses from the CNS to effectors (muscles and glands) in the PNS. Like the sensory division, the motor division includes two divisions: the somatic and autonomic nervous systems:
Somatic nervous system: Includes somatic motor neurons that conduct impulses from the CNS to skeletal muscles. Since you can consciously control skeletal muscles, this division is also called the voluntary motor division.
Autonomic nervous system (aw-toe-NOM-ik): Includes visceral motor neurons that conduct impulses from the CNS to smooth muscle, cardiac muscle, and glands. Since you have no voluntary control over these effectors, this division is sometimes called the involuntary nervous system. Furthermore, this system includes two subdivisions: the sympathetic and parasympathetic divisions. When the sympathetic division is more active, the parasympathetic division is less active, and when the sympathetic division is less active, the parasympathetic division is more active.
Glial cells (GLEE-ul; glue) are part of the nervous system, but unlike neurons, cannot conduct impulses. Instead, they support and protect neurons. Many brain tumors are gliomas (glee-OH-muz), consisting of glial cells dividing uncontrollably. Glial cells in the CNS include astrocytes, ependymal cells, microglia, and oligodendrocytes, and glial cells in the PNS include Schwann cells and satellite cells (Figure 10-1).
Astrocytes (AS-tro-sites; astro, star) are the most abundant type of glial cell and help maintain homeostasis in the ECF around neurons. They have many branches and resemble a star. They surround capillaries and regulate the movement of materials between the blood and neurons. Astrocytes are found only in the CNS.
Ependymal cells (ee-PEN-duh-mul; “upper garment”) contain cilia and exist within cavities of the brain and spinal cord (i.e., they are found only in the CNS). They secrete and circulate a clear cerebrospinal fluid that circulates through the central nervous system.
Microglia (my-cro-GLEE-uh) display many pseudopodia (extensions of the plasma membrane) that engulf foreign particles; thus, microglia are phagocytic and clean the ECF around neurons. Microglia are the least abundant glial cells, existing only in the CNS.
Oligodendrocytes (ol-ih-go-DEN-dro-sites; oligo, few; dendro, tree-like) are octopus-shaped cells that form protective wrappings called myelin sheaths (MY-uh-lin) around axons in the CNS. Myelin is a lipoprotein material that insulates the axon and increases the rate at which it conducts impulses.
Schwann cells form myelin sheaths around axons in the PNS. Schwann cells are also called neurolemmocytes (newer-oh-LEM-oh-sites; lemma, husk).
Satellite cells form protective coverings around neuron cell bodies in the PNS. Their function in the PNS is similar to that of astrocytes in the CNS.
A neuron’s cell body (also called the soma, “body”) contains the nucleus and most of the cell’s organelles. The cytoplasm that surrounds the nucleus is called the perikaryon (per-i-KAIR-ē-on; peri, around; karyon, nucleus). Like other cells, RNA synthesis (transcription) occurs in the nucleus and protein synthesis (translation) occurs in the cytosol at ribosomes. Protein synthesis maintains the neuron’s supply of enzymes and the proteins that function as channels and pumps in the cell membrane or become part of other intracellular structures.
The neuron’s nucleus is diploid (2n), with 46 chromosomes (23 maternal and 23 paternal), but mitosis does not usually occur after embryonic development. Consequently, neurons in adults do not usually divide. However, in a few locations, special cells develop into neurons to replace those that are damaged or worn out. For example, these cells periodically replace olfactory neurons that function in smelling.
The cytoskeleton of a neuron is similar to that of other cells, but the names of the components are specific for neurons. For example, the neuron’s microfilaments are neurofilaments and the microtubules are called neurotubules. The cell body is supported by bundles of microfilaments and microtubules called neurofibrils, which appear visible under the light microscope. A neuron’s rough endoplasmic reticulum stains readily in histological preparations and appears as dark regions called Nissl bodies (NIS-sul). These bodies are responsible for the “gray” The cytoskeleton of a neuron is similar to that of other cells, but the names of the components are specific for neurons. For example, the neuron’s microfilaments are neurofilaments and the microtubules are called neurotubules. The cell body is supported by bundles of microfilaments and microtubules called neurofibrils, which appear visible under the light microscope. A neuron’s rough endoplasmic reticulum stains readily in histological preparations and appears as dark regions called Nissl bodies (NIS-sul). These bodies are responsible for the “gray” appearance of gray matter.
The dendrites (DEN-drytz; dendr, tree) of a neuron are short branches that conduct graded potentials directly to either the cell body or an axon. Since dendrites lack voltage-gated channels, they cannot conduct impulses. In sensory neurons, dendrites display specialized structures called sensory receptors that respond to various stimuli. For example, you have sensory receptors in your skin that respond to touch. Upon stimulation, these receptors transmit graded potentials to the axon, which in turn, transmits an impulse to the CNS for interpretation. In some neurons, a dendrite may have multiple branches at its distal ends (end farthest away from the cell body).
A neuron’s cell body (also called the soma, “body”) contains the nucleus and most of the cell’s organelles. The cytoplasm that surrounds the nucleus is called the perikaryon (per-i-KAIR-ē-on; peri, around; karyon, nucleus). Like other cells, RNA synthesis (transcription) occurs in the nucleus and protein synthesis (translation) occurs in the cytosol at ribosomes. Protein synthesis maintains the neuron’s supply of enzymes and the proteins that function as channels and pumps in the cell membrane or become part of other intracellular structure
For example, the neuron’s microfilaments are neurofilaments and the microtubules are called neurotubules. The cell body is supported by bundles of microfilaments and microtubules called neurofibrils, which appear visible under the light microscope. A neuron’s rough endoplasmic reticulum stains readily in histological preparations and appears as dark regions called Nissl bodies (NIS-sul)
The dendrites (DEN-drytz; dendr, tree) of a neuron are short branches that conduct graded potentials directly to either the cell body or an axon. Since dendrites lack voltage-gated channels, they cannot conduct impulses. In sensory neurons, dendrites display specialized structures called sensory receptors that respond to various stimuli.
Which brainch of the nervous system has sensory/motor?
CNS
Is sensory afferent or efferent?
Afferent
Is motor afferent or efferent
efferent
Does sensory CNS have autonomic signals?
No, just out from brain and spinal cord
pns controls
motor and glands
Somatic PNS controls
skeletal muscles
What stage are neurons in? Can they divide?
No
Branches of neurons are called
DendritesS
Synapse
Connection between 2 cells
Synaptic cleft
Gap between 2 cells with interstitual fluid
Excitatory DEpolarizes
Inhibitory HYperpolarizes
Stimulation can be either
excitatory or inhibitory
Nerves
Bundles of axons (tracts that carry info to and from the brain)
Axon
Nerve diber
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8/26- Intro to H Phys36
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Week of 8/26 Vocab1
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CWP chapter 127
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Chapter 5 CWP76
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Chapter 5 EOC and study statements24
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Chapter 5 study statements8
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Other chapter 5 study statements4
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Chapter 7 CWP56
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Ch 7 study statements7
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Chapter 7 based on crossword puzzles69
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Chapter 7- Study statements6
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Chapter 7 notes56
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More chapter 7 study statemtnts25
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Chapter 8 stuff47
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Chapter 9 stuff71
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Chapter 10 notes49
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End of chapter 921
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Chapter 1529
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Chapter 15 cwp37
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Ch 15 eoc22
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Ch 132
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Ch 13 quiz50
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13 EOC41
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13 CWP32
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Ch 11 EOC41
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Ch 11 CWP44
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Ch 16 notes114
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Ch 16 ppt58
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Ch 17 study statements and notes43
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Topics to review40
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Topics to review part 218
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Topics to review part 3156
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Part 41
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Practice exam50
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10/30 pre32
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Ch 18 Statements29
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Ch 19 notes47
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ECG worksheet60
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ECG part 228
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CHapter 1971
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Chapter 205
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Chapter 1446
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14 contd80
