IA Study Session 4

What you need to know:
- Joint Capsule : SURROUNDS the Joint Cavity and RETAINS the Synovial Fluid.
- Fibrous Capsule : The OUTER/EXTERNAL component.
- Synovial Membrane : the INNER/INTERNAL component
- Synovial Fluid : The fluid that acts as a LUBRICANT; Offers NUTRIENTS to articular cartilage ; Remove the WASTE



- Joint Cavity : Narrow SPACE
- Articular Cartilage : Covers the FACING SURFACES of bones
- Reduces BONE on BONE grinding
- Hyaline Cartilage

-Articular Disc: Cushion PAD across ENTIRE joint cavity.
- Fibrocartilage

- Menisci : Articular Discs that do NOT cross ENTIRELY across.
- Fibrocartilage

​

General Anatomy of Synovial Joints

What you need to know:

- Tendons : Attaches a MUSCLE to BONE.
- Ligaments : Attaches BONE to BONE.
- Bursae : Sac filled with SYNOVIAL fluid; Helps tendons SLIDE more EASILY over JOINTS.

​

Accessory Structures

What you need to know:
- Name
- Joint Motion

​- Know these examples

​What you need to know:
1) NAME/ID the joint
2) CLASSIFY the joint
3) ID the joint component
4) Name the MAJOR/BROAD classification
- Not very common but still seen.

• Most of these terms are in skeletal muscle cells.

What you need to know: Largest to Smallest
- Muscle : Composed of fascicles
- Fascicle : Bundle of myofibers;
- Enclosed in fibrous perimysium
- Myofiber : A single muscle cell; densely packed bundle of myofibrils.
- Myofibril : Bundle of proteins.
- Fill MOST of the sarcoplasm.
-Sarcomere : a SEGMENT of myofibril; Functional contractile subunit.
- Z disc to Z disc
- Myofilaments will SLIDE over each other.

​

Structural Hierarchy

What you need to know:
- Sarcolemma : the plasma membrane
- T-Tubules : Carries electrical signals from cell surface to SR.
- Sarcoplasmic Reticulum: the endoplasmic reticulum.
- Stores calcium; released upon electrical signal.
- Sarcoplasm : the cytoplasm
- the space that holds organelles.
- Myofibrils : the contractile units within the cell.
- calcium attach; stimulates sarcomeres.

​

Ultrastructures of Muscle Fibers

What you need to know:
- Axon Terminal : Nerve ending swelling
- Synaptic Vesicle - Filled with acetylcholine
- Acetylcholine : chemical neurotransmitter
- Synaptic Cleft : Narrow space between nerve and muscle.
- Post Synaptic Membrane folds - Increase surface area.
- Acetylcholinesterase - Enzyme that breaks DOWN acetylcholine.

Neuromuscular Junction

What you need to know:
- Sarcomere : Segment of Myofibril; Functional contractile subunit.
- Myofilament
- Thick Myofilament : is MYOSIN; Contractile proteins.
- Thin Myofilament : is ACTIN; Contractile proteins.
- Tropomyosin: WRAPS around the ACTIN; Myosin CANT access when RELAXED.
- Regulatory protein
- Troponin; NEEDS to be UNLOCKED by CALCIUM; "Unlocks"/reveals actin by REMOVING tropomyosin
- Regulatory proteins.

​

​

What you need to know: Identify
- A band : Length of a thick myofilament.
- H zone : Central region of A band; lack of thin myofilament.
- M line : Midline of A band; Anchors thick myofilament.

- I band : Stripe of thin myofilament only.
- Z disc : Midline of I band; Defines the boundary of sarcomere.
​- Elastic filament (Titin) : Anchors thick filament; Z disc to M line)