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Anatomy Midterm #2

Terms in this set (27)

4 functions of the muscle tissue
1. produce movement
2. open and close body passageways (sphincters function as valves; open to allow passage and contract to close passageway)
3. maintain posture and stabilize joints (enable the body to remain sitting or standing; muscle tone helps stabilize synovial joints)
4. generate heat (muscle contractions produce heat)
skeletal muscle tissue
-attached to skeleton and moves body by moving the bones
-makes of 40% of body weight
-cells are striated
-skeletal muscle is innervated by voluntary division of the nervous system
smooth muscle tissue
-squeezes fluids and other substances through hollow organs
-occupies the walls of hollow organs
-cells lack striation
-innervated by involuntary division of the nervous system
types of muscle tissues
skeletal, cardiac, and smooth
cardiac muscle tissue
-occurs only in the walls of the heart
-cells are striated
-contraction is involuntary
deep muscles of the thorax (provide movement for breathing)
1. external intercostal muscles
2. internal intercostal muscle
3. diaphragm
external intercostal muscles
lifts the rib cage
internal intercostal muscles
aid expiration during heavy breathing
diaphragm
most important, flattens as it contracts to increase the volume of the thoracic cavity; separates thoracic cavity from abdominal cavity
dendrites (4)
-Extensively branching from the cell body
-Transmit electrical signals toward the cell body
-Chromatophilic bodies—extend only into the basal part of dendrites and to the base of the axon hillock
-Function as receptive sites for receiving signals from other neurons
axons (5)
-Neuron has only one
-Impulse generator and conductor
-Transmits impulses away from the cell body (toward axon terminals)
-Chromatophilic bodies are absent
-No protein synthesis in axon
axons continued
-Neurofilaments, actin microfilaments, and microtubules: provide strength along length of axon and aid in transport of substances to and from the cell body (axonal transport)
-Branches along length are infrequent (axon collaterals)
-Multiple branches at end of axon (Terminal arboration) (telodendria): End in knobs called terminal boutons (axon terminals)
nerve impulse
-Generated at the initial segment of the axon body
-Conducted along the axon to the terminal boutons: neurotransmitters are released from vesicles at the terminal boutons
neuroglia cells in the CNS
-have branching processes and a central cell body
-outnumber neurons 10-1
-make up half the mass of the brain
-can divide throughout life
astrocytes
-most abundant of glial cells
-sense when neurons release glutamate
-extract blood sugar from capillaries for energy
-take up and release ions to control environment around neurons
-Involved in synapse formation in developing neural tissue
-Produce molecules necessary for neuronal growth (BDTF)
-Propagate calcium signals involved with memory
microglia
-smallest and least abundant glial cell
-Phagocytes—the macrophages of the CNS
-Engulf invading microorganisms and dead neurons
-Derive from blood cells called monocytes
-Migrate to CNS during embryonic and fetal periods
ependymal cells
-line the central cavity of the spinal cord and brain
-bear cilia-help circulate the cerebrospinal fluid
oligodendrocytes
-have few branches
-wrap their cell processes around axons in CNS
-produce myelin sheaths in the CNS
division of the autonomic nervous system
1. sympathetic
2. parasympathetic
3.ganglionic- presynaptic and postsynaptic
Sympathetic
-mobilizes body during extreme situations
-Flight or fight
-Activated in extreme situations i.e. exercise, excitement, emergencies
Parasympathetic
-controls routine maintenance functions
-calming
Sympathetic responses
-Increase heart rate and breathing rate
-Increase blood and oxygen to skeletal muscles
-Dilate pupils and bronchioles
-Inhibit mobility of digestive tract and urinary tracts
Parasympathetic responses
-Active when body is at rest
-Conserve energy
-Direct digestion, elimination of feces and urine
-Heart rate, blood pressure, respiration at low-normal levels
-REST AND DIGEST
Issues from dif. Regions of CNS
-Sympathetic - thoracolumbar division
-Parasympathetic - craniosacral division
Length of postganglionic fibers
-Sympathetic - long
-Parasympathetic - short
branching fibers
-Sympathetic - highly branched, influence multiple organs at a time (long fibers)
-Parasympathetic - few branches, localized effect (short fibers)
Neurotransmitter released by postganglionic axons
-Sympathetic - release norepinephrine (adrenergic)
-Parasympathetic - release acetylcholine (cholinergic)
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