Download Muscluar System Student

Muscular System
____ Human skeletal
muscles
Unit 3 slide 1
Muscular System
• Helps maintain homeostasis by …
– _______
– __________
– Communication
– Control of body openings and passages
– _____ production
Unit 3 slide 2
Muscle Tissues
• 3 types of muscle tissue
– Skeletal muscle
– _______ muscle
– _____ muscle
• Trivia: about ____% of body mass is
skeletal muscle in someone of
“normal” height and weight
Unit 3 slide 3
Muscles
• A particular muscle, e.g., the biceps
brachii, is an organ composed of
skeletal muscle tissue, connective
tissue, etc.
• “Muscular system” really refers to the
________ muscles
Unit 3 slide 4
Skeletal Muscle
• Connective tissues
– ____mysium, around individual muscle
cells (muscle cells = muscle fibers)
– ____mysium, around fascicles
– ____mysium, around entire muscle, blends
into CT sheets called fascia
Unit 3 slide 5
Unit 3 slide 6
Skeletal Muscle
• Attachment to bone
– ________ attachment – epimysium blends
into periosteum
– __________ attachment – tendon
composed of dense regular CT
– Aponeurosis – broad, flat tendon
connecting muscle to muscle
Unit 3 slide 7
Origin & Insertion
• ______ – the muscle attachment at the
relatively stationary end
• ________ – the muscle attachment at
the more mobile end
• Example, triceps brachii
– O: scapula, proximal humerus
– I: olecranon
Unit 3 slide 8
Unit 3 slide 9
Skeletal Muscle Histology
• “_____” = flesh, so many terms in this
unit have “sarco” in their name
• Sarcoplasm = cytoplasm
• _________ reticulum
= modified endoplasmic reticulum
• ________ = contractile unit
Unit 3 slide 10
Unit 3 slide 11
Sarcomere
• Functional unit of skeletal muscle
• Thick filaments
– ______
• Thin filaments
– _____
– Troponin
– __________
• Transverse tubules (T tubules)
Unit 3 slide 12
Thick and Thin Filaments
• Thick:
– Myosin sort of looks
like a golf ____
• Thin:
– “_____” of g-actin
form a twisted pair of
strands
– Troponin and
tropomyosin
attached
Unit 3 slide 13
Sarcomere
•
•
•
•
A band
I band
H band
Z disc
• Sarcomere = Z disc to Z disc
• Myofibril = many sarcomeres,
end to end
Unit 3 slide 14
Unit 3 slide 15
Contraction
• Occurs when myosin head groups
pull on actin filaments
• Binding site blocked by _______
– Ca+2 ions bind to troponin, troponin
changes shape and pulls tropomyosin
out of the way
– Now myosin can get at the actin
Unit 3 slide 16
Unit 3 slide 17
Excitation-Contraction
Action potential hits T tubules and dives
down into sarcoplasm
1. Voltage-gated Ca+2 channels open in
terminal cisternae of SR, Ca+2 flows
out of the SR and into the sarcoplasm
2. Ca+2 binds to troponin
Troponin pulls tropomyosin away from
myosin binding sites on actin filaments
Unit 3 slide 18
Unit 3 slide 19
Excitation-Contraction
Myosin-ATP complex hydrolyses ATP
to ADP and Pi (activation)
3. Myosin-ADP-Pi complex binds to
actin
4. ADP and Pi float away (power stroke)
5. Myosin releases actin when new
ATP binds to head group
Unit 3 slide 20
Unit 3 slide 21
Excitation-Contraction
Motor neuron stops releasing ACh
Acetylcholinesterase (AChE) clears ACh
from synaptic cleft
Ca+2 pumped back into SR
Tropomyosin moves back to block the
binding sites on the actin filaments
Unit 3 slide 22
Unit 3 slide 23
Muscle Metabolism
• Immediate energy sources
– Use the O2 that’s already there in the muscle
– Use myokinase and creatine kinase to make ATP
• Short-term energy sources
– Emergency use only!
– Anaerobic glycolysis (glycogen, lactic acid)
• Long-term energy sources
– Back to aerobic cellular respiration as the
blood flow to the muscle increases
– A marathon runner tries to go from immediate
energy to long-term energy without short-term
Unit 3 slide 24
Unit 3 slide 25
Unit 3 slide 26
Slow- & Fast-Twitch
• ____-twitch fibers (oxidative)
– Endurance fibers, dark meat
– Lots of myoglobin, mitochondria, capillaries
• ______-twitch fibers (glycolytic)
– Run-away-from-the-tiger fibers, white meat
– Low myoglobin and mitochondria,
not so many capillaries, plenty of glycogen
Unit 3 slide 27
Unit 3 slide 28
Skeletal Muscle Shapes 1
Skeletal Muscle Shapes 2
• ________ muscles
– thick in middle and tapered at ends
– biceps brachii m.
• _________ muscles have parallel fascicles
– rectus abdominis m.
• ___________muscle
– broad at origin and tapering to a narrower insertion
• Pennate muscles
– fascicles insert obliquely on a tendon
– unipennate, bipennate or multipennate
– palmar interosseus, rectus femoris and deltoid
• ________ muscles
– ring around body opening
– orbicularis oculi
Cardiac Muscle
•
•
•
•
Striated like skeletal muscle
Shorter cells, often branched
Only one nucleus per cell
____________ discs between cells
Unit 3 slide 31
Unit 3 slide 32
Smooth Muscle
• One nucleus per cell
• No visible _________
• Contracts in response to changes
in the local environment
– chemical stimuli (hormones, low O2, low pH, etc.)
– stretch (bladder,stomach)
• Or in response to ____________ nerve fibers
Unit 3 slide 33
Unit 3 slide 34
Smooth Muscle
• Still myosin pulling on actin, but not
arranged in ______________
• Actin anchors to plasma membrane,
twisted Nerf football effect
• Calmodulin: Ca+2 binding protein,
sort of equivalent to troponin in
skeletal muscle
Unit 3 slide 35
Unit 3 slide 36