Physiology Exam Review #1 Flashcards
Explain Negative Feedback Loops
Receptors detect change in the body and send the information to the Integrating center which will assess change around a set point and send instructions to the Effector (muscle or glands) which makes the appropriate adjustments to counter the change from the set-point
Moves in the opposite direction from the change
Makes the change from the set-point smaller
Reverses the change in the set-point
A continuous process, always making fine adjustments
Explain Positive Feedback Loop
The end product in a process stimulates the process
The action amplifies the changes that stimulated the effectors
Positive feedback could not work alone, but does contribute to many negative feedback loops
Forming a blood clot is a process of positive feedback loop
Strength of uterine contractions is regulated by positive feedback loop
- For this to occur, the membrane must be selectively permeable
- There must be a difference in the concentration of a solute on the two sides of the membrane
- Water moves from higher concentration to lower concentration
- Diffusion of solvent instead of solute
Osmosis
- Found in the kidneys, eyes, lungs, salivary glands, and the brain
- Specific proteins present in the plasma membrane that serve as water channels and permit osmosis
Aquaporins
permit the passage of ions
ion channels
Ions that are osmotically active
polar molecules
glucose
ions
does not require energy and moves from higher to lower concentration
passive transport
requires the expenditure of energy and sometimes cells need to move molecules against their concentration gradient (lower to higher concentration)
active transport
- Attached to bones
- Makes up 40% of body weight
- Responsible for locomotion, facial expressions, posture, respiratory movements
- voluntary
- striated
skeletal muscle
- in the walls of hollow organs, blood vessels, eye, glands, uterus, and skin
- propel urine, mix food in digestive tract, dilating/constricting pupils
- regulating blood flow
- no sarcomeres (non-striated)
Smooth muscle
- striated
- myosin and actin filaments form sarcomeres
- fibers are short, branched, and connected via gap junctions
Cardiac muscle
plasma membrane of skeletal muscles
sarcolemma
Light bands are also known as
I bands
Dark bands are also known as
A bands
dark lines in the middle of the I bands
Z disks
site where a motor neuron connects to a muscle fiber
neuromuscular junction
postsynaptic membrane of the muscle fiber
motor end plate
contains only thin filaments, primarily of the protein actin
I bands
contains all of the thick filament with some thin filament overlap; thick filament is the protein myosin
A bands
center of the A band with no thin filament overlap
H band (H zone)
lines found in the center of each I band
Z discs
basic subunit of striated muscle contraction that runs from Z disc to Z disc
sarcomere
anchor which Actin is attached at
the Z discs
found in the center of the A band; helps hold myosin
M line
a protein that runs from the Z disc to the M line through center of myosin. Stabilizes it, prevents overstretch, and creates elasticity
titin
each somatic motor neuron, together with all of the muscle fibers that it innervates is known as a
motor unit
which motor units are used the most often
the smaller motor units
when contractions of greater strength are required, larger and larger motor units are activated in a process known as
recruitment of motor units
Describe steps of Na+/K+ pump
- found in all body cells and half of daily calories are utilized
- 3 Na+ out of the cell and 2 K+ into the cell
- 3 Na+ from the cytoplasm move into the pump and bind
- ATPase activated to hydrolyze ATP to ADP and P which blocks both openings
- ADP released causing a shape change that allows 3 Na+ to exit pump to outside of cell
- 1 K+ enter carrier from the outside, releasing P
- Pumps returns to original shape and release 2 K+ to the inside
Characteristics of resting membrane potential
- resting potential of -70mV
- established by large negative molecules inside the cell
- sodium potassium pumps
- limited permeability of the membrane to positively charged inorganic ions
- at rest, high concentration of potassium inside the cell and sodium outside of the cell
emergency situations; “fight or flight”
sympathetic nervous system
normal functions; “rest and digest”
parasympathetic nervous system
wraps of this cell make up the myelin sheath in the PNS
Schwann cells
the myelin sheath is produced by these cells in the CNS
oligodendrocytes
produces the myelin sheath but not a neurilemma ( no cytoplasm or organelles)
myelin sheath in CNS
when the membrane potential inside the cell increases (becomes more positive). Positive ions enter the cell
depolarization
a return to resting potential is called
repolarization
when the membrane potential inside the cell decreases (becomes more negative). When positive K+ leave the cell or negative Cl- ions enter the cell.
hyperpolarization
depolarization of the cell is called
excitatory
hyperpolarization is called
inhibitory
ICF
intracellular fluid
ECF
extracellular fluid
the process of cellular respiration that takes place in the presence of oxygen gas to produce energy from food
aerobic respiration
the type of respiration through which cells can break down sugars to generate energy in the absence of oxygen
anaerobic respiration
Also called slow oxidative; slower contraction speed; sustain contraction for long periods without fatigue; rich capillary supply; more mitochondria; more myoglobin
slow twitch
faster contraction speed; fatigue fast; thick and fewer capillaries; fewer mitochondria and less myoglobin. Can metabolize anaerobically and found in stronger muscles
fast twitch
a protein found in striated muscles and supplies oxygen to the cells
myoglobin
ADP is combined with P from this using this
Phosphocreatine
- modified endoplasmic reticulum that stores calcium when muscle is at rest
- when a muscle fiber is stimulated, calcium diffuses out of the calcium release channels
- at the end of a contraction, calcium is actively pumped back in this
sarcoplasmic reticulum
Explain sliding filament theory
- produced by several cross bridges that form between myosin and actin
- myosin head serves as myosin ATPase enzyme, splitting ATP into ADP+P. Allows the head to bind to actin when the muscle is stimulated.
- release of P cocks the myosin head, producing a power stroke that pulls the thin filament toward the center
- After power stroke, ADP is released and a new ATP binds
- myosin head straightens out and rebinds
- 2 ATP are needed for each stroke
general structure of neurons include:
a cell body, dendrite, and an axon
contains the nucleus, Nissl bodies, and other organelles; cluster in groups called nuclei in the CNS and ganglia in the PNS
cell body
receive impulses and conducts a graded impulse toward the cell body
dendrites
conducts action potentials away from the cell body
axon
the functional connection between a neuron and the cell it is signaling
synapses
if one neuron is signaling another neuron, the first is called the
presynaptic neuron
supportive cell that forms the myelin sheath around peripheral axons in the PNS
Schwann cells
support cell bodies within the ganglia of the PNS
satellite cells
form myelin sheath around the axons of CNS neurons
oligodendrocytes
migrate around CNS tissue and phagocytize foreign and degenerated material
microglia
most abundant glial cell. Have extensions (perivascular feet) that contact blood capillaries and stimulate them to form a seal called the blood-brain barrier
astrocytes
line the ventricles central canal of the spinal cord and secrete cerebrospinal fluid in the CNS
ependymal cells
positively charged ion
cation
negatively charged ion
anion
period after an action potential when the neuron cannot become excited again
refractory period
occurs during the action potential. Na+ channels are inactive
absolute refractory period
when K+ channels are still open. Only a very strong stimulus can overcome this.
relative refractory period
Process of saltatory conduction
- myelin provides insulation, improving the speed of cable properties
- Nodes of Ranvier allow Na+ and K+ to cross the membrane every 1 to 2 mm
- Na+ ion channels are concentrated at the nodes
- action potentials leap from node to node
