Lab Exam 1 Flashcards
Homeostasis
the dynamic constancy of the internal physiological environment while buffering the challenged of the external environment
What is the importance of homeostasis?
For the health of an organism, homeostasis must be maintained. Failure to regulate will cause conditions to deteriorate and it may be fatal
How is homeostasis maintained?
feedback control mechanisms
Feedback Control Mechanisms: 1. Stimulus
produces change in variable
Feedback Control Mechanisms: 2. Receptor (sensor)
change detected
Feedback Control Mechanisms: 3. Control center – Input:
information sent along afferent pathway
Feedback Control Mechanisms: 4. Effector - Output:
information sent along efferent pathway
Feedback Control Mechanisms: 5. Response
feeds back to influence magnitude of stimulus and returns variable to homeostasis
Negative Feedback System
the response of the control system is negative or opposing to the stimulus.
Positive Feedback System
the response of the control system is positive or promoting the stimulus; act to amplify the initial response to the stimulus. How to stop a positive feedback system? – Remove the initial stimulus.
Plasma membrane
external cell barrier, selectively permeable, amphipathic – hydrophilic (phosphate heads) and hydrophobic region (fatty acid tails).
Passive transport
No use of cellular energy. Simple diffusion, Facilitated diffusion
Simple Diffusion
substance move from an area of high concentration to an area of low concentration (equilibrium). Unassisted transport (not use integral protein).
Facilitated diffusion
help of a protein molecule
Facilitated diffusion (channel mediated)
protein molecule forms a channel or a little tunnel that goes through the plasma membrane so molecules can just pass through; help move small polar molecules and ions. Is faster.
Facilitated diffusion (carrier mediated)
protein molecule is going to carry the substance across; reserved for large polar molecules.
Active Transport
energy is going to be used somewhere; move a substance against its concentration gradient. Low concentration to high concentration. Primary active and secondary active.
Primary active
has a direct use of cellular energy; “pump”.
Secondary active
downhill movement of one molecule drives the uphill movement of another molecule. Indirect use of ATP.
Vesicular transport
bulk transport of substances into or out of the cell. Endocytosis and exocytosis
Endocytosis
substances are taken into the cell; Phagocytosis – “cell eating”; Pinocytosis – “cell drinking”.
Exocytosis
substances that are released from the cell; accounts for most secretion processes.
Osmosis
the passive diffusion of water against a concentration gradient across a semi-permeable membrane. Water is moving along its own concentration gradient but at the same time it is moving against the concentration gradient of our solutes. Water will move to the area where the concentration of solute is high in efforts to dilute it some.
Degrees of tonicity
a comparative term. Hypertonic, hypotonic, isotonic
Hypertonic
the concentration of solutes is higher than what you are comparing it to.
Hypotonic
the concentration of solutes is lower than in the solution you are comparing it to.
Isotonic
same concentration of solutes on either side of the membrane.
Osmotic pressure
influenced by the non-penetrating solutes so the ones that cannot cross the membrane, the ones that cannot penetrate.
Shrivel up
crenate or undergo crenation
Explode
lyse or undergo lysis
Skeletal muscles
the muscles that attach to bones to allow the movement of the skeleton.
Skeletal muscle nucleus
Skeletal muscles are multi-nucleated which means it has multiple nuclei per cell. Nuclei are peripherally located meaning that you’ll see them located around the edges of the muscle fiber or muscle cell.
Skeletal muscle voluntary or involuntary?
Skeletal muscle can be both voluntary and involuntary so some muscles do have an involuntary component but they are typically voluntary
Involuntary meaning
Involuntary meaning that contractions are controlled by the autonomic nervous system which happens automatically or independent of voluntary nerve activity,
Organization of skeletal muscle: Epimysium
surrounds muscle group
Organization of skeletal muscle: Perimysium
Surrounds fascicle
Organization of skeletal muscle: Endomysium
Surrounds muscle fiber/cell.
Within each muscle fiber there are
myofibrils, within each myofibril we have our myofilaments which are contractile proteins like actin and myosin.
A myofibril is composed of
repeating segments called sarcomeres
Sarcomere
is the functional unit of a muscle which means that it’s the most basic unit of muscle contraction. Extends from z-line to z-line so that defines the boundaries of one sarcomere
M-line
is the region with a protein myomesin structure
I-Band
is the region composed of actin only.
A-band
is going to span the length of the myosin filament so its composed of myosin and then whatever overlapping actin we have there
H-band (h-zone)
is composed of myosin only
Excitation-Contraction Coupling Step 1
Ach is released at the NMJ and binds to receptor site on the sarcolemma
Excitation-Contraction Coupling Step 2
Action potential in muscle membrane
Excitation-Contraction Coupling Step 3
Depolarization of T tubules causes Ca2+ channels to open
Excitation-Contraction Coupling Step 4
Intracellular concentration of Ca2+ increases
Excitation-Contraction Coupling Step 5
Ca2+ binds to troponin on the thin filaments
Excitation-Contraction Coupling Step 6
Tropomyosin moves to allow the interaction of actin and myosin
Excitation-Contraction Coupling Step 7
Cross-bridge cycling begins and force is generated
Excitation-Contraction Coupling Step 8
Ca2+ reaccumulated by the SR and the muscle relaxes
Sliding filament theory (released) 1
ATP binds to myosin causing the dissociation of the actin-myosin complex
Sliding filament theory (cocked) 2
ATP is hydrolyzed, causing myosin heads to return to their resting conformation
Sliding filament theory (cross bridge) 3
Myosin head binds to actin monomer forming cross bridge
Sliding filament theory (power stroke) 4
P is released. Myosin heads change conformation; the filaments slide past each other
Sliding filament theory (attached) 5
ADP is released. Starts over
Motor unit
Motor unit consists on one motor neuron so one nerve and then all the muscle fibers that it innervates. Called motor unit because when that single motor neuron fires all the associated muscle fibers that it innervates will contract as a unit
Motor unit size
Size of motor units is important because it tells us the kinds of movements that we are able to perform
Small motor units are involved with
fine (precise) motor activities
Large motor units are involved with
gross (large movement) motor activities
Isometric
stays the same length: force generated does not overcome load
Isotonic
the same tension but able to change the length of muscle fiber because you are able to overcome the load.
Concentric
muscle shortens
Eccentric
muscle lengthens
Agonist
primary mover
Synergistic
muscles that assists the agonist group
Antagonistic
muscle that oppose the agonist
Type I muscle fiber
slow twitch, myoglobin rich, contains large number os oxidative enzymes, high mitochondrial volume, surrounded by more dense capillary networks, fatigue resistant, slower maximal shortening velocity, highly efficient
Type IIX muscle fiber
fast twitch, small number of mitochondria, less resistant to fatigue, rich in glycolytic enzymes, generate the highest power output
Type IIA muscle fiber
fast twitch, intermediate fibers, mixture of type I and type IIX
Hypertrophy
An increase in muscle fiber diameter due to an increase in myofibril size
Muscle soreness
Result from microscopic injury to the muscle fibers.
Delayed Onset Muscle Soreness (DOMS) appears 24-48 hours post microscopic injury.
NOT a result of lactic acid accumulation
Sex differences
When absolute strength (the total amount of force applied) is compared in untrained men and women, men are typically stronger.
Rigor Mortis
Postmortem muscle stiffness resulting from rigor crossbridges in the absence of adenosine triphosphate. Peaks after 12 hours after death
Sarcopenia (aging)
is the age-related decline is muscle mass that occurs naturally throughout our lifetime and there are two distinct phases, a slow phase beginning at age 25 to 50 losing 10%. Rapid phase loses 40% of muscle as you approach last quarter of your life (50-80). Loss of fast twitch, increase of slow twitch
Muscular dystrophy
a group of hereditary muscle diseases that results in the weakening of skeletal muscles. More than 100 different types
Most common muscular dystrophy
Most common is Duchene muscular dystrophy caused by a defective gene for the protein dystrophin which helps us maintain the structural integrity of the sarcolemma
Without dystrophin
we lose muscle very easily and we lose that regenerative capacity so the damaged cells will undergo apoptosis or programmed cell death. Most common in men because it is an x-linked recessive gene. No cure, live short lifespan. Diaphragm weakens and respiratory failure.
