MUSCULAR SYSTEM Notes
Types of Muscle Tissue:
Skeletal
| Smooth
| Cardiac
Muscle and Muscle Fiber Structure:
A muscle is composed of many muscle fibers arranged in bundles called __________________________
Individual muscles are separated by fascia, which also forms _______________________________
What is plantar fasciitis?
A muscle also contains 3 different layers of connective tissue:
__________________________ - outermost layer, surrounds entire
muscle
__________________________ - separated and surrounds the
FASCICLES (bundles)
__________________________ - surrounds each individual muscle fiber
Muscle Cells
The muscle fiber membrane is called the ___________________________________
The cytoplasm is called _______________________________________
Within the sarcoplasm are many parallel fibers known as ___________________________________
Each myofibril is made of many MYOFILAMENTS. There are two types:
MYOSIN - thick filaments
ACTIN - thin filaments
Structure of a SARCOMERE (functional unit of a muscle)
A Bands = dArk = thick = MYOSIN
I Bands = lIght = thin = ACTIN
Sarcomere = the area between two Z-lines
Hierarchy: Muscles → Fascicles (bundles) → Myofibrils → Myofilaments (actin & myosin)
II. How Muscles Work with the Nervous System
NEUROMUSCULAR JUNCTION (also called the motor unit) - where a ____________________and muscle
fiber come together.
MOTOR END PLATE - specialized part of the sarcolemma located at the neuromuscular junction, has
many folds
SYNAPTIC CLEFT - An actual "gap” which exists between the motor neuron endings and the motor end
plate.
SYNAPTIC VESICLES - where _________________________ are stored before being released into the
synaptic cleft.
The neurotransmitter that crosses the gap is __________________________________. This brings
about muscle contractions.
CHOLINESTERASE is an enzyme that breaks down acetylcholine
III. The Sliding Filament Theory
The theory of how muscle contracts is the sliding filament theory. The contraction of a muscle occurs as
the thin filament slide past the thick filaments. The sliding filament theory involves five different
molecules and calcium ions.
*Handout on the Sliding Filament Model
IV. ENERGY SOURCE:
Provided by ATP from cellular respiration which occurs in the___________________________
* Creatine Phosphate provides energy for the regeneration of ATP
* Only 25% of energy produced during cellular respiration is used in metabolic processes - the rest is in
the form of HEAT - maintains body temperature
ATP = adenosine triphosphate | ADP = adenosine diphosphate
V: Other Terms (define)
1. Threshold Stimulus
2. All-or-None Response
3. Motor Unit
4. Recruitment
5. Muscle Tone
6. Muscular Hypertrophy
7. Muscular Atrophy
8. Muscle Fatigue
9. Muscle Cramp
10. Oxygen Debt / Lactic Acid
11. Origin / Insertion