Anatomy and Physiology Lecture Exam 3
What are the two main divisions of the nervous system & the organs that make them up
central nervous system and peripheral nervous system. CNS is the brain and spinal cord. PNS is the dorsal body cavity
What are the 4 main characteristics of muscle tissue
excitability, contractility, extensibility, elasticity
How does skeletal muscle attach to bone?
By insertion and origin
How does the CNS determine if a stimulus is weak or strong?
By the frequency of impulses
How are muscle responses graded?
1. Changing the frequency of stimulation 2. Changing the strength of the stimulus
What is the function of a chemically gated ion channel?
Changing membrane potentials; opened by chemical messengers such as neurotransmitters
What are concentric contractions? What are eccentric contractions?
Concentric - muscle shortens and does work. Eccentric- muscle lengthens and generates force
What is the functional role of a dendrite
Convey incoming messages toward cell body as graded potential
What is the resting membrane potential?
Difference in electrical charge across the membrane at rest; -70mV
Describe the sliding model during contraction
During contraction, thin filaments slide past thick filaments causing actin and myosin to overlap
What is excitation-contraction coupling? how does it take place in the muscle cell?
Events that transmit AP along Sarcolemma side of Myofliaments
What are the five general characteristics of a neuron
Extreme longevity, amiotic, high metabolic rate,
What are caveolae?
Folds on the surface of smooth muscle cells that correspond to T tubules in skeletal muscle cells that contain numbers Ca2 channels that allow rapid influx of extra cellular Ca2
What are the regions of the Sarcomere?
I Band, H Zone, A band, M Line, Z Disc
Why does rigor mortis occur after death?
Intracellular calcium levels increase because ATP is no longer synthesized
What is an isometric contraction? What is a isotonic contraction?
Isometric Contraction- no shortening, tension increases but does not exceed Isotonic- muscle shortens because tension exceeds
What are the functions of the ependymal cell?
Line central cavities of the brain and spinal cord and form barrier between cerebral spinal fluid
What are the functions of the micro glial cells?
Migrate to injured neurons, transform to phagocytize microorganisms
What are the three processes a cell can use to generate ATP needed for contraction
Move and detach cross bridge, pump calcium back into Sarcoplasmic Reticulum, and pump Sodium out of the cell and potassium into the cell
What are the four main FUNCTIONS of muscle tissue
Movement, posture, stability, heat
Where are you most likely to find multipolar neurons? Uni? Bi?
Multipolar are mostly found in the CNS. Unipolar are found in the PNS and Bipolar are mainly found in the retina and olfactory regions of the body
What is the refractory period?
Muscle fibers cannot be stimulated for a time until repolarization
What nervous factors regulate smooth muscle contraction?
Nerves, hormones, local chemical changes
What cells are considered supportive
Neuralgia/ Glial cells
What cells are excitable and transmit electrical signals?
Neurons/ nerve cells
What factors affect the force of muscle contractions
Number of muscle fibers stimulated, relative size of fibers, frequency of stimulation, degree of muscle strength
What is the function of voltage gated ion channels?
Open or close in response to voltage channels in membrane
How does myelination differ between the PNS and the CNS
PNS: formed by Schwann cells, no channels or carriers. Myelin gaps present CNS: formed by oligodendrocytes, present myelin gap, white and grey matter
Which type of ion channel is always open?
Passive (leakage)
What is the stress relaxation response of smooth muscle
Responds to stretch briefly and adapts, Ability to contract on demand
What are Myofibril Striations and how are they formed?
Striped formed by repeating series of dark and light bands along each myofibril
What are the functions of an Astrocyte
Supports and brace neurons, exchange capillaries, control chemical environment around neurons, respond to nerve impulse
What is the function of Schwann Cells
Surround PNS and form the myelin sheath. They are vital to regeneration of damages peripheral nerve fibers
What is the sarcolemma? Sarcoplasm? Sacroplasmic Reticulum? Myofibrils?
The Sarcolemma is fiber in the plasma membrane. The Sarcoplasm is fiber in the cytoplasm. The Sarcoplasmic Reticulum is a modified organelle and Myofibrils are densely packed elements
What is the endomysium and what is it made of?
The endomysium is FINE AREOLAR TISSUE surrounding each fiber
What is the epimysium and what is it made of?
The epimysium is a layer of DENSE IRREGULAR connective tissue that surrounds the entire muscle
What is muscle fatigue
The loss of force or power output in response to voluntary effort leading to reduced performance.
What is the perimysium and what is it made of?
The perimysium is a layer of FIBROUS CONNECTIVE TISSUE that surrounds fascicles
How are smooth muscle sheets arranged in hollow organs?
They are tightly packed in a longitudinal or circular layer
What is a motor unit?
A motor neuron and all of the muscle fibers it innervates
What is the composition of thin filaments and thick filaments?
Thin Filaments are composed of Actin that extends across the IBand and Thick Filaments are composed of Myosin which extends across the A Band and connected to the MLine
What are T-tubules?
Tube formed by protrusion of sarcolemma deep into cell interior
How does repolarization occur?
When NA+ channels are inactivating and K+ channels open
Why does repolarization occur?
When some K+ channels remain open and NA+ channels reset
What's re the functions of oligodendrocytes
Wrap CNS fibers & they are found forming the myelin sheath in think fibers
What happens to the regions of the sarcomere as a muscle contracts
Z disc pulled toward M Line and come closer, I band shorten, A band moves closer to another and H zone disappears
What is a triad?
area formed from terminal cistern of one sarcolemma
Describe the events of end plate potential
ACh is released from motor neuron and binds to ACH receptors on Sarcolemma
What is the neurotransmitter involved in skeletal muscle contraction ?
Acetylcholine
What does insertion mean? Origin?
Attachment to moveable bone; attachment to immobile bone
What's the the two cells involved in a synapse.
Axodendritic & Axosomatic
Why do males tend to have more muscle mass than females?
having a greater ability to enlarge muscle fibers and testosterone
What are the three phases of a muscle twitch
latent period, period of contraction, period of relaxation
What are two main types of ion channels
leakage channels and gated channels
What are dense bodies
located on sarcolemma of smooth muscle cells that attach actin filaments so contraction causes a corkscrew twisting that shortens the cell
What are the three structural classes of a neuron
multipolar, bipolar, unipolar
What is the sarcoplasmic reticulum?
network of smooth endoplasmic reticulum tubules surrounding each myofibril
What are varicosities?
numerous swellings located at intervals along the axons of postganglionic neurons
What is saltatory conduction?
saltatory conduction is the "jumping" of an action potential between the unmyelinated nodes of ranvier
What are the three main functions of the nervous system?
sensory input, integration, motor output
What are the three types of muscle tissue
skeletal, smooth, cardiac
What is a sacromere?
smallest contractile unit of a muscle fiber
What is a graded potential?
temporary, localized change in resting potential caused by stimulus
What is action potential?
the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.
What is meant by threshold
the minimum voltage needed in order to activate muscle contraction
What is the function of the myelin sheath
to protect the neuron, provide insulation, and increase the speed of impulse transmission
What protein does calcium bind to?
troponin; it changes the shape and moves tropomyosin