Anatomy: What Is It And Why Is It Important?

The humerus is classified as a long bone because it is longer than it is wide. Long bones, such as the humerus, are characterized by having a shaft (diaphysis) and two expanded ends (epiphyses). They provide support, mobility, and protection to the body and are found in the limbs.

A head on a bone refers to a rounded projection that is typically found on the end of a bone, particularly where it articulates with another bone. This projection allows for movement and provides a point of attachment for muscles and ligaments. The neck refers to the narrower portion of the bone that connects the head to the rest of the bone. Therefore, a rounded projection on a neck accurately describes the structure and function of a head on a bone.

Bone is not responsible for storing ATP (adenosine triphosphate). ATP is the primary source of energy for cellular processes and is typically stored in the mitochondria of cells. While bone does play a role in movement, storage of energy (in the form of minerals like calcium and phosphorus), and blood cell production, it does not store ATP.

The bony orbits that house your eyes are formed of both facial and cranial bones. This means that the orbits are not made entirely of cartilage or contain only cranial or facial bones. The facial bones involved in forming the orbits include the maxilla, zygomatic, lacrimal, ethmoid, and palatine bones, while the cranial bones include the frontal, sphenoid, and ethmoid bones. These bones together create a protective structure that surrounds and supports the eyes.

A suture is an immovable joint found only between skull bones. It is formed by fibrous connective tissue that holds the skull bones together. Sutures are important for maintaining the shape and stability of the skull, as well as protecting the brain. They allow for some growth and flexibility in the skull during infancy and childhood, but become more rigid and fused as a person matures. Sutures are different from other types of joints, such as synovial joints, which allow for movement.

Muscle is derived from the mesoderm. The mesoderm is one of the three primary germ layers in the early embryo, responsible for giving rise to various tissues and organs in the body. It specifically gives rise to the mesenchyme, which is a type of embryonic connective tissue that eventually differentiates into muscle cells. Therefore, muscle tissue originates from the mesoderm layer during embryonic development.

The rhythmic movements of breathing refer to the expansion and contraction of the thorax, which is the chest cavity. As we inhale, the muscles involved in breathing contract, causing the thorax to expand and lift. This allows the lungs to expand and fill with air. On the other hand, as we exhale, the muscles relax, causing the thorax to depress and return to its original position. This movement of lifting and depressing the thorax is essential for the process of breathing and the exchange of oxygen and carbon dioxide in the lungs.

The structural unit of compact bone is the osteon. An osteon, also known as a Haversian system, is a cylindrical structure that is composed of concentric layers of bone tissue called lamellae. Each osteon contains a central canal, which houses blood vessels and nerves, as well as osteocytes, which are mature bone cells. The osteon provides strength and support to compact bone, allowing it to resist bending and breaking.

Cardiac muscle is autorhythmic because it has the ability to generate its own electrical impulses without any external stimulation. These electrical impulses are responsible for initiating and coordinating the contraction of the cardiac muscle, allowing the heart to beat in a coordinated and rhythmic manner. Unlike skeletal and smooth muscles, which require external stimulation from nerves to contract, cardiac muscle cells are interconnected through specialized gap junctions, allowing the electrical impulses to spread rapidly throughout the heart and ensure its regular and synchronized contractions.

The alternative name for myofiber is "muscle cell" because myofiber refers to a single muscle cell. A muscle cell, or myofiber, is a specialized cell that is responsible for generating force and movement in the body. It contains myofilaments, which are protein structures that contract and relax to produce muscle contractions. Therefore, muscle cell is the correct alternative name for myofiber.

When Socbob's arm was in a cast for 6 weeks, the muscles in his right forearm were immobilized and not being used. This lack of use caused muscle atrophy, where the muscles became smaller and weaker. As a result, when the cast was removed, his right forearm appeared thinner compared to his left forearm. The muscles in his right forearm lost muscle tone and became smaller and weaker due to the immobilization caused by the cast.

Osteoclasts are the cells responsible for the process of bone resorption. They break down and remove old or damaged bone tissue, allowing for new bone formation. This process is essential for maintaining bone health and remodeling. Osteocytes are mature bone cells that are involved in maintaining bone structure and regulating mineral metabolism. Stem cells have the potential to differentiate into various cell types, including osteoblasts, which are responsible for bone formation. Chondrocytes are cells found in cartilage, not bone.

Muscle tone refers to the number of muscle fibers that are in a contracted state even when the muscle is otherwise relaxed. It is the continuous and partial contraction of muscles that helps maintain posture and stability. This muscle tone is regulated by the central nervous system and is important for maintaining muscle strength and readiness for movement.

The cervical curvature refers to the natural curve in the neck region of the spine. It is concave posteriorly, which means that it curves inward towards the back of the body. This curvature helps to maintain balance and support the weight of the head.

The primary reason more bone is resorbed than deposited is to increase blood calcium levels. Resorption is the process of breaking down bone tissue and releasing calcium into the bloodstream. This occurs when the body needs to maintain a balance of calcium in the blood for various physiological functions, such as muscle contraction, nerve signaling, and maintaining healthy bones. When blood calcium levels are low, the body resorbs bone to release calcium into the bloodstream, ensuring that there is enough calcium available for these essential functions.

Motor units consist of a motor neuron and the muscle fibers it innervates. The motor neuron sends signals to the muscle fibers, causing them to contract. This coordinated contraction allows for smooth and efficient movement. The associated Schwann cells are not directly involved in the contraction of muscle cells. The postsynaptic motor neurons and presynaptic neurotransmitter vesicles are also not directly related to the muscle fibers themselves.

The temporal bones have a pair in the cranium. The cranium is the part of the skull that encloses and protects the brain. It is made up of several bones, including the frontal, sphenoid, ethmoid, occipital, and temporal bones. The temporal bones are located on the sides and base of the skull, and they house important structures such as the middle and inner ear, as well as the temporomandibular joint. Having a pair of temporal bones ensures symmetry and stability in the cranium.

Cardiac muscle tissue is characterized by being involuntary, branched, striated, and uninucleate. However, it is not characterized by having spindle-shaped cells.

A hinge joint allows for movement in only one plane, similar to the movement of a door hinge. In this case, the joint involves a cylinder in a trough, suggesting a cylindrical bone fitting into a concave surface. This type of joint allows for extension and flexion in a single plane, making it the most suitable explanation for the given scenario.

A meatus is a canal-like passage. It refers to a narrow opening or passageway in the body, such as the auditory meatus in the ear or the urethral meatus in the urinary system. These passages allow for the passage of fluids, air, or other substances.

Muscles are not responsible for the production of blood cells. Blood cell production occurs in the bone marrow, specifically in the spongy bone tissue. Muscles have various functions, including thermogenesis (generating heat), regulation of volumes (such as controlling blood flow and pressure), and movement of bones (by contracting and relaxing). However, they do not play a direct role in the production of blood cells.

The clavicle is not a bone of the axial skeleton. The axial skeleton consists of the skull, vertebral column, and ribcage, which are all involved in protecting and supporting the central axis of the body. The clavicle, also known as the collarbone, is part of the appendicular skeleton, which includes the bones of the limbs and their attachments to the axial skeleton. It plays a role in connecting the upper limb to the trunk.

Ossification and growth at the epiphyses of long bones is accomplished by secondary ossification. Secondary ossification refers to the process where ossification occurs in the epiphyseal plates, which are cartilaginous areas at the ends of long bones. This process allows for the growth of long bones by adding new bone tissue to the epiphyses. It is different from primary ossification, which occurs in the diaphysis or shaft of the long bone. Secondary ossification is essential for the proper development and growth of long bones during childhood and adolescence.

Prudent exercise does not cause the development of joint problems as we age. In fact, regular exercise is beneficial for joint health as it helps to maintain strength, flexibility, and mobility. Exercise can also help to reduce the risk of developing conditions such as osteoarthritis. Therefore, the statement that prudent exercise causes development of joint problems is not true.

A synergist muscle is a muscle that assists the prime mover muscle in producing a desired effect. It helps to stabilize the joint and provide additional support to the prime mover muscle, allowing it to work more efficiently. The synergist muscle does not necessarily produce the same movement or have the same function as the prime mover, but it works in coordination with it to achieve the desired action.

The vertebral foramina of the vertebrae contain the spinal cord and protect it. This is because the vertebral foramina are the openings in the vertebrae through which the spinal cord passes. The spinal cord is a vital part of the central nervous system and is responsible for transmitting signals between the brain and the rest of the body. The vertebral foramina act as a protective barrier, surrounding and shielding the delicate spinal cord from potential damage or injury.

Rotation refers to the movement of a joint around its long axis. This movement allows the joint to twist or turn in a circular motion. In the context of the given question, turning a joint of its long axis is specifically referring to rotation. This means that the joint is being rotated or twisted around its central axis, rather than being flexed, extended, or moved in any other direction.

When cardiac muscle cells die, the result is fibrosis. Fibrosis refers to the formation of excess fibrous connective tissue in the heart, which replaces the dead muscle cells. This can lead to the stiffening and scarring of the heart tissue, impairing its ability to contract effectively and compromising its overall function.

Synarthrotic joints are a type of joint that allows very little or no movement. These joints are highly stable and provide strong connections between bones. They are found in areas where stability and support are crucial, such as the skull or pelvis. Unlike other types of joints, synarthrotic joints do not have a large joint cavity and are not cartilaginous. Instead, they are held together by dense connective tissue or fibrous ligaments, which restrict movement and promote stability.

Doing endurance exercise typically leads to an increase in resistance to fatigue, not a decrease. This is because endurance exercise improves cardiovascular fitness, increases muscle strength and stamina, and enhances the efficiency of oxygen utilization by the muscles. These adaptations result in the ability to sustain physical activity for longer periods without experiencing excessive fatigue. Therefore, a lower resistance to fatigue would be an unexpected result of doing endurance exercise.

The correct answer is osteoblasts and osteoclasts. The periosteum is a protective tissue that covers bones, and its inner layer, known as the osteogenic layer, is primarily composed of osteoblasts and osteoclasts. Osteoblasts are responsible for bone formation, while osteoclasts are involved in bone resorption. These two cell types work together to maintain the balance of bone growth and remodeling in the body.

Trabeculae are the thin, bony strands that make up spongy bone. They are responsible for providing strength and support to the bone. When trabeculae align along the lines of stress, they are positioned in a way that can withstand and distribute forces that act on the bone. This alignment helps to make the spongy bone stronger and more resistant to fractures or damage.

At birth, the spinal curvatures that are present are the thoracic and sacral curvatures. The thoracic curvature is located in the upper back region and the sacral curvature is located in the lower back region. These curvatures develop during fetal development and help to provide stability and support to the spine as the baby grows and begins to sit and stand. The lumbar and cervical curvatures develop later as the baby starts to lift its head and eventually walk.

The correct answer is annulus fibrosis, nucleus pulposis. The annulus fibrosis is the outer ring of fibrocartilage that surrounds the intervertebral disc, providing support and stability. The nucleus pulposis is the inner gel-like substance within the disc, which acts as a shock absorber and helps distribute pressure evenly throughout the disc.

When a lever operates at a mechanical disadvantage, it means that the load is far from the fulcrum and the effort is applied near the fulcrum. This means that a smaller amount of effort is required to move a larger load, but the load will move a shorter distance than the effort. This results in a mechanical disadvantage because the effort exerted is greater than the force exerted by the load.

The tibia is in contact with the talus. The talus is a bone in the foot that sits between the tibia and the calcaneus (heel bone). It forms the ankle joint with the tibia and fibula, allowing for movement and stability in the foot and ankle.

Menisci are cartilage pads that subdivide synovial cavities. These pads are found in certain joints, such as the knee joint, and help to distribute the forces placed on the joint during movement. They also provide cushioning and stability to the joint, reducing the risk of injury. Menisci are made of fibrocartilage, which is a tough and flexible type of cartilage.

The correct answer is "rare because of the strong ligament reinforcement." The hip joint is supported by strong ligaments that help stabilize it and prevent excessive displacement. In contrast, the shoulder joint is more prone to displacements due to its greater range of motion and less ligamentous support.

The H zone consists of only thick filaments in a sarcomere. This region appears lighter because it lacks thin filaments. The thick filaments in the H zone are composed of myosin protein and are responsible for muscle contraction.

The epimysium wraps an entire cell. It is the outermost layer of connective tissue that surrounds a muscle and separates it from surrounding tissues and organs. It provides support and protection to the muscle fibers within and helps to maintain the shape and integrity of the muscle.

The sarcolemma is the correct answer because it is the part of the muscle cell that receives the acetylcholine neurotransmitter signal. The sarcolemma is the cell membrane of the muscle fiber, and it contains receptors for acetylcholine. When acetylcholine binds to these receptors, it triggers a series of events that lead to muscle contraction.

A myofibril with much myoglobin, many mitochondria, a slow contraction velocity, and a high resistance to fatigue indicates that it is an intermediate red (oxidative) type. This type of myofibril has a high capacity for aerobic metabolism due to the presence of myoglobin and mitochondria, allowing it to generate energy efficiently through oxidative phosphorylation. The slow contraction velocity suggests a slower twitch speed, and the high resistance to fatigue indicates that it can sustain contractions for longer periods without tiring easily.

Smooth muscle is noted for having diffuse junctions for autonomic nervous system fibers to apply the stimulus to the muscle to contract. Unlike skeletal and cardiac muscles, which have specific neuromuscular junctions, smooth muscles have diffuse junctions where the autonomic nervous system fibers release neurotransmitters over a wider area. This allows for coordinated contractions of smooth muscles in various organs, such as the digestive system and blood vessels.

Multiunit smooth muscle is the correct answer because it is characterized by having only one nucleus, no sarcomeres, and only a few gap junctions between cells. Unlike other muscle types, such as skeletal muscle which has multiple nuclei and sarcomeres, multiunit smooth muscle consists of individual muscle fibers that contract independently. This type of muscle is typically found in structures like the iris of the eye and the walls of blood vessels, where precise control of muscle contraction is required.

Each myofiber in skeletal muscle is surrounded by a capillary bed. This capillary bed is responsible for delivering oxygen and nutrients to the myofiber and removing waste products such as carbon dioxide. The close proximity of the capillary bed to the myofiber ensures efficient exchange of these substances, allowing for optimal muscle function during physical activity.