Skeletal Joints and Human Circulatory System Functions

Skeletal Joints: Structure and Classification

Joints: These structures, also known as articulations or knuckles, consist of tissues that unite different parts of the skeleton. More technically, a joint is defined as the set of hard and soft parts that constitute the union of two or more contiguous bones.

Joints can be classified into two large categories based on:

• Structure (morphology).
• Function (physiology).

Morphological Joint Types

Morphologically, different types of joints are classified according to the connecting tissue into several categories:

• Fibrous joints
• Cartilaginous joints
• Synovial joints (Diarthroses)

Physiological Joint Types

Physiologically, the human body features several joint types:

• Synarthrosis: Immobile joints.
• Symphysis: Joints allowing single-axis motion (often grouped under limited movement).
• Amphiarthrosis: Joints with very limited movement.
• Synovial Joints (Diarthrosis): Joints allowing a greater breadth and complexity of movement.

Movement Division (Bichat's Classification)

Based on the type and degree of motion present, joints are termed:

• Synarthrosis: No movement.
• Amphiarthrosis: Little movement.
• Diarthrosis: Extensive movement.

These correspond to the structural classifications:

• Fibrous joints (equivalent to synarthrosis).
• Cartilaginous joints (equivalent to amphiarthrosis).
• Synovial joints (equivalent to diarthrosis).

Human Circulatory System Mechanics

Systemic Circulation (General Circulation)

This tour begins with oxygenated blood leaving the left ventricle of the heart. It extends along the aorta and its arterial branches to the capillary system, where oxygen is exchanged, forming veins that carry oxygen-poor blood. This blood flows into one of the two venae cavae (superior or inferior), which drain into the right atrium.

Pulmonary Circulation (Lesser Circulation)

Oxygen-poor blood starts from the right ventricle and travels through the pulmonary artery, dividing into both lungs. In the pulmonary alveolar capillaries, the blood is oxygenated. It then returns via the four pulmonary veins, which drain oxygen-rich blood into the left atrium of the heart.

The Heart Organ

The Heart is the main organ of the circulatory system. It is a muscular organ located in the conical chest cavity. It functions as a pump, propelling blood throughout the body. It is divided into four chambers:

• Two upper chambers: the right atrium and the left atrium.
• Two lower chambers: the right ventricle and the left ventricle.

Cardiac Phases

The contraction of the heart (either an atrium or a ventricle) to eject blood into the tissues is called systole.

The relaxation of the heart to receive blood from the tissues is called diastole.