Muscle Contraction, Joint Anatomy, and Skeletal Movement
Muscle Contraction and Anatomy Fundamentals
Steps in Skeletal Muscle Contraction
- Calcium ions are released from the sarcoplasmic reticulum.
- Calcium ions bind to troponin.
- Myosin cross-bridges bind to the actin filament.
- The myosin head pivots toward the center of the sarcomere (Power Stroke).
- The myosin head binds an ATP molecule and detaches from actin.
- The free myosin head splits ATP, resetting the head position.
Key Muscle Fiber Structures and Definitions
- Triad (E): Terminal cisternae abutting a T-tubule.
Understanding Muscle and Bone Structure for Movement
The Musculoskeletal System
Muscles are composed of elongated cells called muscle fibers. These organs have the ability to contract and relax. There are several types of muscles:
Smooth Muscle
Characterized by slow, involuntary contractions. Smooth muscle fibers form the walls of various internal organs.
Heart Muscle
This involuntary muscle contracts rapidly. Its fibers are found in the heart (myocardium).
Skeletal Muscle
These muscles enable fast, voluntary movements and are attached to the skeleton. Each
Read MoreSpinal and Thoracic Joint Anatomy: Ligaments & Movement
Spinal Column Joints and Ligaments
The vertebrae are linked together through their vertebral bodies by interposing between them a fibrocartilage disc (fibrous synchondrosis). This synchondrosis occurs in the center, a gelatinous core known as the nucleus pulposus. Around the nucleus pulposus, which is a remnant of the embryonic notochord, is the cartilaginous ring (annulus fibrosus). The fibers of the annulus fibrosus are oriented in layers, similar to an onion, with their direction changing: vertically
Read MoreHuman Spine Anatomy: Vertebrae, Joints, and Curvatures
Spine Anatomy Fundamentals
The spine supports the head and provides mobility to the vertebral column. It combines flexibility (vertebrae) and firmness (intervertebral discs). The vertebrae are larger towards the base of the spine, narrowing superiorly.
Physiological Curvatures of the Spine
The adult spine exhibits four physiological lateral curvatures:
- Cervical Lordosis: An anterior convexity in the neck region.
- Thoracic Kyphosis: An anterior concavity in the upper back.
- Lumbar Lordosis: An anterior convexity
Essential Concepts in Chemistry and Biology
Thermodynamics Fundamentals
The first law of thermodynamics establishes the notion of internal energy for a thermodynamic system. All energy transfers must be accounted for to ensure strict conservation of the total energy of a thermodynamic system and its surroundings. This law states that energy can be neither created nor destroyed; however, energy can change forms and flow from one place to another. The total energy of an isolated system remains constant.
The second law of thermodynamics states
Read MoreAnatomy of Pelvis, Lower Limb Bones, and Muscles
Pelvic Girdle Anatomy
Bones of the Pelvic Girdle
The pelvic girdle bones are the innominate (or iliac) bones, the sacrum, and the coccyx.
Pelvic Girdle Joints
The joint connecting the two pelvic bones is called the symphysis pubis.
Features of the Ilium
The iliac or innominate bone is formed from the fusion of three bones: the ilium, pubis, and ischium.
Iliac Crest Function
The iliac crest serves as an insertion point for the abdominal muscles.
Lower Limb Bone Anatomy
The Femur
Femur Articulations
The femoral
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