Respiration and Muscle types Flashcards
Muscle Metabolsim: Direct Phosphorlyation (Creatine Phoshate)
ATP + creatine-Creatine Kinease-> creatine phopshate + ADP
Coupled reaction of creatine phopshate and ADP
Used during first 15 seconds of excerise
1ATP per Creatine phopshate
- When contraction begins, ADP levels rise and the CK catalyses the transfer of the phoshate back to ADP , creates ATP quickly
Anaerobic Pathway (Glycoloysis)
- Glycolysis and latic acid formation
Secondary use of energy after ATP storred as well as direct phosphorlyation is used up.
**Glucose (from glycogen) –> Pyruvic Acid **
C6H1206 –oxidized-> 2C3H6O3 + 2ATP
No oxyegn needed, yields 2ATP per glucose, latic acid
30-40 seconds
Glucose is catabolized to make ATP - Glycolysis breaks down glucose molcules into 2 purivic acid molecules and make 2 ATP
Aerobic Pathway
Requires glucose, pyrivic acid, and yields 32 ATP, CO2,H2O
C3H6O3 –100% oxidation-> co2 + h2o + 36 ATP
There is sufficient oxygen available
- Glucose , pyruvic acid is used for energy
- Aerobic respiration is slower but yields 36 ATP 4 used for the process.
- 2 sources of oxygen: blood and myglobin
How can we recover oxygen?
- Coverts latic acid into glycogen in the liver
- Resynthesis creatine phopshate and ATP in muscle fibers
- Replace oxyge removed from hemoglobin
- Increase heat speeds up reactions
- heart/lung work harder
- Tissue repair increase
Motor Units
Motor Unit: conists of a somatic neuron and the skeletal fiber stimulates.
Each motor neuron contacts avaerage 150 fibers.
When a motor neuron fires all the fibers associated the neuron. Muscles can be fine motor or larger motor.
Twitch Contraction
Twitch Contraction: brief contraction of all the muscles fibers in a unit, response of musle
- Latend Period: muscle action potenitial moves over the sacolemma and Ca+ are released from the SR
- Contraction phase: calcium ions bind to troponin, myosin binding sites are exposed , cross-bridges form and is peak of tension
- Relaxation: calcium is transported back to SR, myosin binding sites covered by tropomyosin. Myosin head detaches.
Refractory Period
A period of lost exictability
- when a muscle fiber recieves enough stimulation to contract it temporaily, but soon loses it and cannot contract. Varies on muscle type ( skeletal fibers can move into a tetanus while the long refractory period in cardiac prevents tetanus
Graded Muscle Contraction ( How do I increase the strength of skeletal muscle contraction)
- The variations needed for the proper control on muscle contractions that very in strength.
- Muscle contractions are graded two ways:
1.** An increase in the frequency of stimulation (causes temporal summation) increase ca deleivery ** - Increase in frequency of stimulation= increase in contraction strength
2. An increase in the strength of the stimulation causes and increase in the number of motor units recruited.
Increase in strength of stimuli** –> more muscle motor units active–> increase contraction strength
**More motor units recruitted = increase in contraction strength **
Fre
4 Frequencies of Stimulation
- A tetanic contraction also called tetanus, is a sustained contraction evoked , when motor nerve that emits high rate of action potentials.
- If second stimulus is recieved before the first can reflex fully, more calcium is released and the contraction increases in magnitiude to maximum contraction.
(Temporal Summation) - If the muscle is stimulated at an increasely fast rate:
1) The relaxation time between stimulus become shorter
2) The Ca concentration in sacroplasam increases
3) The degree of wave summation becomes greater
4) Freq. of stimulation increases , increase in contraction strength
Incomeplete and Complete tetanus
Can be involuntary l
Tetanus can be normal when voluntary ex holding box
Incomplete (unfused): when skeletal muscle is stimiulated at a rate of 20-30 times per second. Causes sustained wave contraction Common in parkisons etc.
Complete (fused) : when muscle is stimulated between 80–100 times per second, muscle does not releax., even higher stimulation freqeuncies.
Higher stimulation frequency causes unfused tetanus.
Wave Summation / Temporal Summation
- When a second stimulus occurs after the refractory period of the first stimulus , but before full relaxation, the second contraction is stronger and the higher the frequnecy the greater contraction.
Motor Unit Summation
As you increase the strength of stimulus you increase the number of motor units recruited
Motor Unit Recruitment
- Process by which the number of active motor units increases
- Allowing for smooth muscle contratcions rather than series of jerking
- Small percise movements–> require small change in tension so only the small muscles are made of smaller motor units
- Larger less percise muscles have larger motor units
- Not all motor units are typically contraction same time, delay muscle faitgue and allow for increased muscle contraction periods
- Small percise motor units are recurited first, and as motor units with larger muscles are recuirted the contraction strength increases.
What is muscle tone
- When at rest, skeletal muscles have some muscle tone due to weak involuntary contractions of its motor units.
- Motor units are active and inactive in alterntaing order to avoid muscle becoming flaccid.
- Maintain the firmness of the muscle but does not produce movement.
Ex ) back and neck
Isotonic Contractions (same tone)
-The tension in the muscle remains very constant while the muscle changes in length. Same tone while length alters. Once able to lift weight needed, muscle shorteens while the tensions remains same.
- Consistent tone or tension in muscle
- Change in length
-** Concentric: **muscle decreases in length ( tension > load) Picking up a book
** Eccentric:** muscle increase in length (tension < load) Lowering the book
Fast Glycolytic Muscle FIbers
- Are the largest in skeletal muscle fiber diameter.
- They have a low capacity for genereating ATP through anaerobic respiration ( no oxyegn) are recruited last
- Fast contraction rate, little resistance to faigue
- Found in higher concentration in the muscles of upper limbs and are responsible for rapid intense movements. , short intense durations.
- Need glycogen
Key differences in Smooth muscle
- Has very small ellipitcaly shaped cells forming continous sheets.
- Does not have an epimysim ( skeletal covering) or perimysium does however contain a endomysium
- Varicosities instead of neuromusclar junctions ( swellings in nerves and will form diffuse junctions spread out on smooth muscles.
- The neurotransmitter will be sprinkeled across the smooth muscle allowing for slow nervous transmission - No T-tubules
- No terminal cisterns
- less eleobroate SR - Caveloae: small pouch like invagainations of plasma membrane that contain extracellular calcium that is used for contraction. This allows cells such as muscle cells to respond to physiological strech and flow. ( Not part of SR) Extracelluar rather than intercell
- Smooth connected by gap junctions: autoryhymicity , myogenic
- Fewer thick elements: 1 thick : thin filaments
- No troponin ( bind to ca and change shape) : still has tropomyosin: Instead, tropomyosin is removed from myosin using calmodulin– couples excititation with contraction
- Smooth Muscle has intermieate filaments instead of z-dics called dense bodies
- Has a decrease in muscle volume not just length: the sacromere is lined with caveoi that are calcium stores, intermiedate filaments indside will connected to dense bodies and reists tension. As contraction occurs, the filaments will pull on the dense bodies and the muscle will shorten
Lacks striations and is smooth
