Answer :
Rotation in development: Rotation is critical in human development, particularly during the embryonic stage, as it helps position the organs correctly. For example, stomach rotation is essential for proper alignment in the body cavity. If this doesn't occur properly, it can lead to anatomical abnormalities leading to health issues.
Neural crest cell: Neural crest cells migrate throughout the embryo and are crucial in developing various structures, including parts of the nervous system. Improper migration can lead to conditions like congenital megacolon (Hirschsprung's disease), where the absence of nerve cells in a portion of the intestine causes severe bowel function issues.
Organizer - Notochord: The notochord functions as a secondary organizer by providing signals that guide the differentiation and patterning of the surrounding tissues, crucial for proper vertebral column formation.
Organizer - Primitive streak: The primitive streak is a primary organizer and serves as the initial site of gastrulation. It is key in defining the body's axes and forming three primary germ layers (ectoderm, mesoderm, endoderm).
Sex differentiation: While physical and hormonal changes occur during puberty, sex determination happens at fertilization, where either an X or Y chromosome from the sperm decides the genetic sex of the individual.
Epithelial-mesenchymal interactions: These interactions are pivotal in organogenesis. For example, teeth formation (tooth bud development) and kidney development (nephron formation) are both results of epithelial-mesenchymal crosstalk.
Teratology: The susceptibility to teratogens (agents causing malformation) is highly dependent on the developmental stage; for instance, exposure during the first trimester when organs are forming is more critical than later development stages.
Skeletal muscle: Antagonist muscles are important as they ensure balance and coordination during movements, ensuring smoother and more controlled actions.
Muscle contraction - Concentric: Concentric contractions occur when a muscle shortens under tension, essential for producing movement, such as lifting an object.
Muscle contraction - Eccentric: Eccentric contractions help control and decelerate movement like descending stairs, preventing injury by absorbing shock and providing stability.
Prime mover - Iliopsoas: The iliopsoas is a primary flexor of the thigh, crucial for activities like walking and maintaining posture compared to other thigh flexors.
Muscle: A muscle crossing multiple joints will affect all because it creates movement wherever it has attachments, such as the sartorius, which acts on both the hip and knee.
Muscle - Functional importance of length & number of fibers: Longer muscle fibers increase range of motion (e.g., sartorius), while more fibers increase force (e.g., quadriceps).
Muscle nomenclature: Muscle names often provide insight into their action, location, and structure, aiding in understanding their functions, such as the "biceps" indicating two heads.
Synergist muscle: A synergist aids a prime mover by adding extra force (e.g., brachialis assisting biceps in elbow flexion) or by reducing unnecessary movements (e.g., the rotator cuff stabilizing the shoulder).
Skeletal muscle: Fiber direction influences the type of movement; for example, oblique muscles allow twisting motions.
Muscle - Functional importance of length & number of fibers: Same as item 13.
Muscle - Red vs. White: Red muscles are more suited for posture maintenance due to their endurance and resistance to fatigue, while white muscles are better for short bursts of power.
Fixator muscles: These muscles stabilize one part of the body while another completes a movement, such as shoulder stabilizers during arm movements, or the abdominal muscles during a squat.
Synovial joint: The shoulder has a greater range of motion compared to the hip but also less stability due to its shallow socket.
Antagonist muscle: These muscles prevent overstretching of the agonist for balanced movement and joint stability.
Cardiac muscle: Cardiac muscle cells work as a syncytium meaning they are electrically connected, allowing coordinating contractions across the heart.
Muscle: Knowing two aspects (origin and insertion) of a muscle helps deduce its action. For example, a muscle connecting shoulder to the forearm likely flexes the forearm.
Muscle contraction: Both actin and myosin are necessary for effective contraction because interactions between these proteins allow muscle fibers to contract.
Sesamoid bones: These bones develop within tendons, such as the patella in the knee, to increase leverage and reduce tendon wear, enhancing joint function and durability.
