Exam 3 Flashcards
What are the three types of muscle?
Skeletal
Cardiac
Smooth
What are the special characteristics of muscle tissue?
Excitability - Can receive and respond to stimuli
Contractability - Ability to shorten
Extensibility - Ability to be stretched
Elasticity - Ability to recoil to resting length
What are the main functions of muscle?
Movement of bones or fluids
Maintain posture and body position
Stabilizing joints
Heat generation
What are additional functions of muscle?
Protects organs
Forms valves
Controls pupil size
Causes goosebumps
What is the epimysium?
Covers entire muscle
What is the membrane called that covers the entire membrane?
Epimysium
What is the perimysium?
Covers a fascicle
What is the membrane called that covers a fascicle?
Perimysium
What is the endomysium?
Covers the muscle fibers
What is the membrane called that covers a muscle fiber?
Endomysium
What is the sarcolemma?
Plasma membrane of muscle cells
What is the plasma membrane of muscle cells called?
Sarcolemma
What is a myofibril?
Complex organelle composed of bundles of myofilaments
What are the two types of myofilaments?
Actin - Thin myofilaments
Myosin - Thick myofilaments
What is a sacromere?
A contractile unit in a myofibril
What is the sarcoplasm?
Cytoplasm of a muscle cell
What is the H zone?
Area of myofibril where actin and myosin are not overlapping
What is titin?
Elastic filament that helps connect myosin to z-discs
Allows recoil after contraction
What are the functions of myosin heads?
Binding sites for actin
Binding sites for ATP
ATPase enzymes
What is F actin?
Structural protein
Has sites for G actin
Found in Actin
What is G actin?
Serves as a binding site for myosin heads
Found in actin
What is tropomyosin?
Regulatory protein that covers g actin binding site in resting state
Found in actin
What is troponin?
Protein that holds tropomyosin in position during rest
Calcium binds to troponin to move tropomyosin during contraction
Found in actin
What is the sarcoplasmic reticulum?
Network of smooth endoplasmic reticulum
Stores and releases calcium ions
What is a T tubule?
An extension of the plasma membrane
Transmits messages to muscles
Penetrates cell’s interior at A-band - I-band junction
Conduct electrical impulses deep into the muscle cell
What is a terminal cistern?
Thick parts of sarcoplasmic reticulum
Involved in calcium storage
What is a triad?
Two terminal cisterns and a t tubule
What happens after a nerve sense travels through the sarcolemma?
Goes to t-tubule
Gets spread across sarcoplasmic reticulum by t-tubule
Muscle contraction
What is the sliding filament model of contraction?
Generates force but doesn’t always shorten fibers
Actin slides past myosin during contraction
Occurs when cross bridges are made
What happens when cross bridges are made?
Myosin heads bind to actin and move actin
I bands shorten
H bands disappear
Where is an action potential generated?
In sacrolemma
Generated by nervous system
What must happen for skeletal muscle contraction to occur?
Activation
Excitation
What are the parts of a neuron cell?
Dendrites
Soma
Axon
What are the three steps through which action potential occurs?
End Plate Potential
Depolarization
Repolarization
What happens in End Plate Potential?
Acetylcholine opens ligand gated ion channels
Sodium rushes in and potassium comes out
Threshold occurs
What does it mean for a cell to reach threshold?
Change in resting membrane potential by + 15-20 mv
What is the typical muscle resting membrane potential?
-90 - 95 mv
What occurs in depolarization?
Generation and propagation of an action potential
What occurs during re-polarization?
Restores electrical conditions of resting membrane potential
Sodium channels close and voltage gated potassium channels open
Refractory period
What is a refractory period?
Period where muscle cannot be stimulated until repolarization is complete
What is rigor mortis?
Dying cells take in calcium and cause muscle stiffness
Cross bridge detachment requires ATP which isn’t present after death
What is the force of contraction dependent on?
The number of cross bridges made?
What is the number of cross bridges made dependent on?
Number of muscle fibers stimulated (recruitment)
Relative size of fibers
Frequency of stimulation
Degree of muscle stretch
What is a motor unit?
One motor nerve and all the muscle fibers that it stimulates
What happens in a muscle twitch?
There is a delay (latent period) between neuron and muscle contraction
Contraction of muscle
Relaxation
What is wave or temporal summation?
Each stimuli builds off last, contracts a little more each time
What is complete tetanus?
Stimulus comes all at once causing complete and maximal contraction
Adrenaline situations
What is the velocity and duration of muscle contraction influenced by?
Muscle fiber type
Load
Recruitment
What are the three muscle fiber types?
Type I - slow oxidative fibers
Type II a - Fast oxidative fibers
Type II b - Fast glycolytic fibers
What is EPOC?
Excessive Post-Exercise Oxygen Consumption
The body is making up for the oxygen debt that it went into to
What are the aerobic adaptations to exercise?
Increased capillaries
Increased number of mitochondria
may convert fast glycolytic fibers to slow twitch
What are the resistance training adaptations to exercise?
Muscle hypertrophy (muscles get bigger)
Increased mitochondria, myofilaments, connective tissue and glycogen stores
Increased muscle strength and size
What kind of tissue replaces lost muscle tissue?
Fibrous connective tissue
What percentage of body mass does skeletal muscle make up?
Male - 42%
Female - 36%
What are the functions of the nervous system?
Sensory input - Info about internal and external changes
Integration - Processing and interpretation of sensory input
Motor unit - Activation of effector organs to cause a response
What are the two divisions of the nervous system?
Central nervous system
Peripheral nervous system
What is the central nervous system?
Consists of brain and spinal cord
Integrating and control center of nervous system
Interprets sensory input and dictates motor output
What is the peripheral nervous system?
Consists of nerves that extend from brain and spine
Spinal and cranial nerves
What are spinal nerves and what are cranial nerves?
Spinal nerves carry impulses to and from spine
Cranial nerves carry impulses to and from brain
What is the PNS divided into?
Sensory (afferent) division - from organs to CNS
Motor (efferent) division - from CNS to organs
What are the two fiber types in the afferent division?
Somatic sensory fibers
Visceral sensory fibers
What is the function of somatic sensory fibers?
Convey impulses from skin, skeletal muscle and joints to central nervous system
What is the function of visceral sensory fibers?
Convey impulses from internal organs to central nervous system
What is the function of the motor (efferent) division?
Transmits impulses from CNS to effector organs
Divided into the somatic and autonomic subdivions
What is the somatic nervous system?
Composed of somatic motor nerve fibers that conduct impulses from the CNS to skeletal muscle
Voluntary nervous system
What is the autonomic nervous system?
Composed of visceral motor nerve fibers
Controls smooth muscles, cardiac muscles and glands
Involuntary nervous system
What is the autonomic nervous system divided into?
Sympathetic and parasympathetic
What does the sympathetic nervous system do?
Increases heart rate and blood flow to muscles
Fight or flight
What does the parasympathetic nervous system do?
Slows down heart rate, breathing rate
Increases blood flow to abdominal organs
Rest and digest
What are the two types of cells that make up nervous tissue?
Neuroglia
Neurons
What are neuroglia?
Small cells that surround and wrap delicate neurons
What are neurons?
Nerve cells that are excitable and transmit electrical signals
Structural units of nervous system
What are the types of CNS neuroglial cells?
Astrocytes
Microglial cells
Ependymal cell
Oligodendrocytes
What are astrocytes?
CNS neroglial cells
Connect neurons to capillaries
Allow exchange of nutrients between neurons and capillaries
What are microglial cells?
CNS neuroglial cells
Defense cells
Help expel waste
What are ependymal cells?
CNS neuroglial cells
Line the central cavities of brain and spinal cord
Form permeable barrier between cerebrospinal fluid and tissue fluid
Create cerebrospinal fluid circulation
What are oligodendrocytes?
CNS neuroglial cells
Help insulate neuron
Form myelin sheaths
What are the types of PNS neuroglial cells?
Satellite cells
Schwann cells
What are satellite cells?
PNS neuroglial cells
Surround neuron cell bodies
Similar functions as astrocytes
What are schwann cells?
PNS neuroglial cells
Form myelin sheaths
Allows regeneration of damaged PNS fibers
What is a soma?
Cell body of a neuron
Has a well developed rough ER
Synthesizes proteins, membranes and other chemicals
What is a nuclei?
Cluster of neuron cell bodies in the CNS
What is a ganglia?
Cluster of neuron cell bodies in the PNS
What are neuron processes?
Extensions from the cell body
Dendrites and axons
What do dendrites do?
Produce graded potentials
The receptive region on neurons
What do axons do?
Conduct and generate nerve impulses
What are the areas of the axon/
Axon hillock - area where axon meets soma
Axon collaterals - branching of axon
Axon terminal - end of axon
What are the two terms that describe movement in the axon?
Anterograde - away from soma, uses kinesins
Retrograde - toward soma, uses dyneins
What is the myelin sheath?
Wraps and coats axon
What are the functions of the myelin sheath?
Protects and electrically insulates axon
Increases speed of nerve impulse transmission
What is the node of ranvier?
Gaps that are not myelinated on axons
Speeds up action potential/electrical conduction
What is white matter?
Regions of the brain and spinal cord with dense collections of myelinated fibers
What is gray matter?
Area without myelination
What are multipolar neurons?
Neurons with three or more processes
Most common type of neuron
What are bipolar neurons?
Neurons with two processes
One is a dendrite, other is an axon
Found in retina
What are unipolar neurons?
Neuron with only on process
One side is receptive and other is secretory
What are the three functional classifications of neurons?
Sensory
Motor
Interneurons
What are sensory neurons?
Neurons that transmit impulses to the brain
Almost all unipolar
What are motor neurons?
Carry impulses from CNS to effectors
What are interneurons?
Connect sensory and motor neurons
99% of body’s neurons
What is voltage?
Measure of potential energy generated by seperated charge
What is current?
Flow of electrical charge between two points
What is resistance?
Hindrance to chrage flow
What are the two types of resistance?
Insulator - high electrical resistance (myelin)
Conductor - low electrical resistance
What is Ohm’s law?
Current (I) = Voltage (V) / Resistance (R)
What are the two main types of ion channels?
Leakage and gated
What are leakage ion channels?
Always open
Allow things to travel down concentration gradient
What are the three types of gated ion channels?
Chemical (ligand)
Voltage
Mechanically
What are chemical gated ion channels?
Ion channels that open with the binding of a specific neurotransmitter
What are voltage gated ion channels?
Ion channels that open and close in response to changes in membrane potential
What are mechanically gated ion channels?
Ion channels that open and close in response to physical deformation of redceptors
What is the resting membrane potential?
Electrical difference across the membrane of a resting cell
What are the two types of signals that a change in membrane potential will produce?
Graded potential
Action potential
What is graded potential?
Incoming signals operating over short distances
Found in dendrites
What are action potentials?
Long distance signals of axons
What is depolarization?
Membrane potential decreases
Inside of membrane becomes less negative
What is hyperpolarization?
Membrane potential increases
Potassium plays the major role
What is summation and where does it occur?
Summation is the adding of graded potentials to form an action potential
Occurs in the axon hillock
What does it mean for graded potentials to be decremental?
The strength of the signal decays with distance
What are the two types of voltage gated ion channels?
Activation gates
Inactivation gates
What are activation gates?
Closed at resting state
Open with depolarization
What are inactivation gates?
Open at rest
Block channel when closed to prevent more ions from entering the cell
What gates are open during depolarization?
Sodium voltage gated channels are open
What gates are open during repolarization?
Sodium inactivation gates close
Potassium channels open up
What is the absolute refractory period?
Voltage gated channels open
But neurons are unable to respond to stimulus
What is the relative refractory period?
After absolute refractory period
Requires an exceptionally strong stimulus
What does the rate of action potential propagation depend on?
Axon diameter
Degree of myelination
What is multiple sclerosis?
Autoimmune disease that destroys CNS myelin sheaths
What are the four classifications of nerve fibers?
Group A
Group B
Group C
What are group A nerve fibers?
Large diameter
Myelinated somatic sensory
Transmit at 150 m/s
What are group B nerve fibers?
Intermediate diameter
Transmit at 15 m/s
What are group C nerve fibers?
Smallest diameter
Unmyelinated
Transmit at 1 m/s
What are synapses?
Junctions that allow neurons to transfer info
What are the classifications of synapses?
Axeodendritic
Axosomatic
What are axeodendritic synapses?
Between axon terminals and dendrites of another cell
What are axosomatic synapses?
Between axon terminals and soma of another cell
What is a presynaptic neuron?
Neuron that sends info toward synapses
Sensory neuron
What is a postsynaptic neuron?
Neuron receiving info from synapses
Neuron, muscle cell or gland cell
What is the deep fascia?
Binds muscles to other muscles
What is the H band?
Area in the center of the A band containing only thick filaments
What is the I band?
Area of the sarcomere containing only thin filaments
What is concentric contraction?
Contraction of the muscle in which the muscle shortens and does work
What is isometric contraction?
Contraction of muscle during which the tension continues to increase but the muscle neither shortens nor lengthens
What is isotonic contraction?
Contraction of muscle during which the tension continues to increase but the muscle neither shortens nor lengthens
What binds calcium ions in a smooth muscle, causing contraction?
Calmodulin
