Exam 3 Flashcards
Nervous System and Muscular System
4 parts of the nervous system
Central Nervous System, Peripheral Nervous System, Autonomic nervous system, and enteric nervous system
CNS
Brain & Spinal Cord
PNS
Sensory/ Motor nerves, cranial nerves, spinal nerves,
Autonomic nervous system
portion of the nervous system that regulates the activity of cardiac muscle, smooth muscle, and the glands
Enteric
has input from CNS, also autonomous
Meninges
layers of non-nervous tissue that surround / protect brain & spinal cord
Dura mater
membrane that encloses brain & spinal cord
Arachnoid
cushions, helps with blood brain barrier
pia mater
covers brain, encases blood vessels that supply the brain
cerebrospinal fluid
lies in space between arachnoid & pia mater. cushions to help diminish transmission of shocking forces
cerebrum
largest part of the brain; controls memory, conscious thought, speech, motor and sensory functions
Cerebellum
controls automatic regulation of movement, balance, posture, skilled movements
medulla oblongata
brain stem; controls heart rate, respiration and temperature
spinal cord
continuation of brain, provides pathways between brain & body
Efferent nerves
motor nerves; innervate muscles and glands, send impulses from CNS to muscles and glands
Afferent nerves
sensory nerves; send sensory information and nerve impulses from receptors to brain
cranial nerves
12 pairs (24 nerves) either sensory or motor; 10 originate in brain stem
Cranial nerve 1
smell
cranial nerve 2
vision
cranial nerves 3, 4, 6
motor nerves, control eyes
cranial nerve 5
sensation of head face, movements of jaw
cranial nerve 7
facial; taste, movement of face, secretions of tears and saliva
cranial nerve 8
acoustic
cranial nerve 9
taste, secretion of saliva, movement of pharynx
cranial nerve 10
vagus: taste, primes digestive system for incoming food
cranial nerve 11
spinal accessory: movements of pharynx, larynx and head/shoulders
cranial nerve 12
movement of tongue
different types of spinal nerves
cervical, thoracic, lumbar, sacral, coccygeal
2 parts of the ANS
sympathetic and parasympathetic
sympathetic nervous system
stimulates; preps body for emergency; shifts energy and blood toward skeletal muscles
parasympathetic nervous system
inhibits / slows; energy conservation, restores energy; digestion responses, eliminates waste, decreases heart rate
reflexes
fixed patterns of responses similar for any given stimulus
stretch reflex
results in contraction of a muscle when it is stretched suddenly
withdrawal reflex
sudden contraction and removal of a body segment due to painful stimulus
synapes
where neurons communicate, at the end of a neuron
slow axonal transport
moves material by axoplasmic flow at .2-2.5 mm/day
fast axonal transport
moves organelles at rates of up to 400 mm/day
anterograde transport
forward; from cell body to axon terminal;
retrograde transport
backward; axon terminal to cell body
Steps of fast axonal transport
- peptides are synthesized on rough ER and packaged by Golgi apparatus
- fast axonal transport walks vesicles and mitochondria along microtubule network
- vesicle contents are released by exocytosis
- synaptic vesicle recycling
- retrograde fast axonal transport
- old membrane components digested in lysosomes
how are neurons classified
shape/structure
divergence
one cell influences multiple cells
convergence
multiple cells influence one cell
serial processing
one cell to the next and so on; a straight line
parallel processing
one cell to multiple cells that each go to a new cell and so on
reverberation
a feedback loop of cells
what prevents backflow of an action potential
closure of Na+ channels during the refractory period
what type of axons conduct signals the fastest?
myelinated axons
when does repolarization occur in an axon
when potassium leaves
why do myelinated axons send signals faster
the signal can “jump” the insulated pieces to each node of ranvier
What creates the myelin sheaths in the PNS
Schwann cells
what do satellite cells do in the PNS
support cell bodies
what other function do Schwann cells have?
they secrete neurotrophic factors
what creates the myelin sheaths in the CNS
oligodndrocytes
what do ependymal cells do in the CNS
create barriers between compartments; also a source of neural stem cells
what do astrocytes do in the CNS
take up potassium, water, neurotransmitters; help form and maintain BBB
what do microglia do in the CNS
act as scavengers that secrete neurotrophic factors, help form the blood brain barrier and provides substrates for ATP production
what does the blood brain barrier do
separates circulating blood from the brain’s extracellular fluid
Glial Cells
provide support and protection to neurons
how does myelin formation occur in the PNS
Schwann cells rap themselves around the axon, then push the nucleus to the outside of the sheath
Node of Ranvier
section of unmyelinated axon membrane between 2 Schwann cells
Peripheral Neuron Injury
when an axon is cut, the part toward the cell body continues to live; the section towards the axon disintegrates. in some cases, Schwann cells are capable of reforming a synapse with the proper target
What are the basic characteristics of muscle tissues
- excitability
- contractility
- elasticity
- extensibility
what are the 3 types of muscle tissues
- skeletal (voluntary control)
- cardiac (involuntary control)
- smooth (involuntary control)
General functions of voluntary muscle
- movement - they can only contract in one direction, multiple muscles are involved in this
- stabilize movements and joints
- protection of underlying structures (stronger muscle = more protection)
General Functions of involuntary muscle
- shivering
- maintenance of posture
shivering thermogenesis
initiated by hypothalamic nuclei in the primary motor center. inhibited when body temperature is back to normal
static reflexes
long term contractile events
phasic reflexess
dynamic and short term corrective responses
stretch reflexes that are involved in maintaining posture are regulated by…
gamma neurons; these adjust tension in the muscle spindles
skeletal muscle is composed of
connective tissue, muscle fascicle (which have muscle fibers) blood vessels and nerves
what is in muscle fibers (cells)
sarcolemma, T-tubules, sarcoplasm, multiple nuclei
what are myofibrils composed of
troponin, actin, tropomyosin, myosin, titin, nebulin
thin filament are made of
troponin, g-actin molecules (in a helical arrangement), tropomyosin, nebulin
thick filaments are made of
myosin
the smallest functional unit of skeletal muscle
sarcomere
sarcomeres are composed of various microfilaments and supporting structures such as
titin, Z disk, M line, Myosin crossbridges, Z disk
Titin
largest elastomeric protein; connects myosin to z disk; crucial in sarcomere development
Myosin molecules have a tail, hinge and heads that contain
active sits for actin and ATP
M-line consists of
myomesin and skelemin proteins
what doe the M line do
stabilizes myosin filaments; aid in transmission of force from sarcomere to cytoskeletl intermediate filaments
what does the Z disk do
anchors filaments; interacts with cytoskeletal framework
why are thin filaments anchored
so that the muscle can contract / shorten by the filaments going past each other
what are the three broad steps of muscle contraction
- synaptic transmission at the neuromuscular junction
- excitation - contraction coupling
- contraction - relaxation cycle
what are myofibrils
structures in muscle fibers that enable them to contract due to their contractile proteins
ATP use is required for
maintenance of resting membrane potential, exocytosis of Ach, moving myosin heads back to energized state, return of Ca2+ into sarcoplasmic reticulum
sources of ATP for muscle action
free ATP, phosphagen system, glycolysis, aerobic respiration
3 sources of ATP for aerobic muscle
carbohydrates, fats, amino acids / proteins
what causes muscles to fatigue?
decrease in neurotransmitter release, receptor activation, Ca2+ release, depletion theories, etc.
oxidative muscle
uses aerobic processes, long term
glycolytic muscle
fast contraction action, anaerobic, not long term
slow twitch oxidative muscle fibers
small diameter, dark due to myoglobin; fatigue resistant
fast twitch glycolytic muscle fibers
large diameter, pale, fatigues easily
Muscle twitch
response of skeletal muscle to an action potential
isomeric contraction
resistance is greater than force of contraction
4 types of muscle fiber
Type I (slow oxidative), Type II a (fast oxidative), Type II x & b (fast glycolytic)
ways to increase contraction
increase frequency of action potentials, alter length of muscle prior to contraction, increase number of functional motor units, muscle hypertrophy, muscle hyperplasia
muscle hypertrophy
increase in size of muscle cells
muscle hyperplasia
formation of new muscle cells
similarities between cardiac and skeletal muscle
striated, sarcomere structured
differences between cardiac and skeletal muscle
shorter fibers, can be branched, single nucleus, larger t-tubules & they are over the z disks
similarities between cardiac and smooth muscle
electrically linked - can have pacemaker potentials, under sympathetic and parasympathetic control as well as hormone control
adaptations for increased contractions
increase in vascularity, mitochondria, levels of myoglobin and adaptations in order to prevent summation
