Muscle contraction involves activation of tension-generating sites within cells. Muscle tension can occur without length change, like holding heavy objects. Contraction requires interaction between thin actin and thick myosin filaments
Mesothelium is a simple squamous epithelial cell layer derived from embryonic mesoderm. Forms lining of pleura, peritoneum, and pericardium. Covers internal organs as visceral mesothelium and surrounding body walls as parietal mesothelium. Surrounds male testis as tunica vaginalis
Head and face includes eyes, ears, nose, mouth, and facial features. Upper body consists of shoulders, arms, chest, back, and limbs. Lower body features hips, legs, knees, feet, and supporting structures
Five muscles surround the abdomen, forming a flexible but firm wall. Core muscles support trunk movement and maintain body stability. Abdominal muscles help with breathing, vomiting, and childbirth. They maintain uniform pressure to protect abdominal organs
Solar plexus is located at T12/L2 level in upper abdomen. Connects gut and brain through autonomic nervous system. Controls peristalsis and digestive processes. Regulates blood pressure and breathing
Rectus abdominis is a vertical muscle forming the 'six pack' in low-fat individuals. Extends from rib cage to pubic bone, forming a horizontal 'grid iron' shape. Divided by linea alba and contains three tendinous intersections. Located within rectus sheath formed by merging of other abdominal muscles