Skeletal System: Lessons 1 and 2 Practice Flashcards

Flashcards covering the functions, types, anatomy, and cellular composition of the human skeletal system based on Chapter 4, Lessons 1 and 2.

What components make up the human skeletal system?

The human skeletal system consists of all of the bones, cartilage, tendons, and ligaments in the body.

Approximately what percentage of a person’s body weight is made up by the skeleton?

The skeleton makes up about 20 percent of a person’s body weight.

In an adult, how many bones are found in the human endoskeleton?

There are 206 bones in the adult human skeleton.

How does an endoskeleton differ from an exoskeleton?

An endoskeleton is a living structure capable of growth, adaptation, and repair located within soft tissues, while an exoskeleton is a non-living structure located on the outside of the body (e.g., in crabs).

What is the function of cartilage in the skeletal system?

Cartilage is a semi-rigid form of connective tissue that provides flexibility and smooth surfaces for movement in areas where bones move.

What is the primary role of ligaments?

Ligaments are bands of dense and fibrous connective tissue that are key to the function of joints.

Which specific structure in the skeletal system protects the brain?

The Skull protects the brain.

What are the five general functions of the skeletal system?

The five functions are Support, Protection, Assistance in Movement, Mineral Homeostasis (Storage and Release), Blood Cell Production (Hemopoiesis), and Triglyceride Storage.

What specific minerals are primarily stored in bone and used for muscle contraction and nerve activity?

Calcium ($Ca$) and Phosphorus ($P$).

Where is 99% of the body's total Calcium ($Ca$) found?

99% of total Calcium is found in the bones.

What is hemopoiesis and where does it occur?

Hemopoiesis is the process of making red blood cells, white blood cells, and platelets, which occurs in the red bone marrow.

In adolescence, where is red bone marrow ($RBM$) specifically found?

It is found in the epiphyses of long bones, vertebrae, ribs, and cranium.

What is the function of yellow bone marrow?

Yellow bone marrow consists of adipose cells that store triglycerides, serving as a potential chemical energy reserve.

What is the chemical composition of a fully developed bone?

Fully developed bone is composed of 20% water, 30 to 40% organic protein material, and 40 to 50% inorganic material (Calcium salts).

What is the primary ingredient for proper bone density?

Calcium phosphate ($CaPO_4$).

What is calcification?

Calcification is the process initiated by osteoblasts where mineral salts crystallize in the microscopic spaces between collagen fibers, causing the tissue to harden.

Compare the distribution of compact bone and spongy bone in the human skeleton.

Compact bone makes up 80% of the skeleton, while cancellous or spongy bone makes up 20%.

What is the basic functional unit of compact bone?

The Osteon or Haversian system.

What are the irregular lattice-work plates of bone found in spongy bone called?

Trabeculae.

How are long bones defined and what is an example?

Long bones have a length greater than their width and act as levers; examples include the femur, humerus, and radius.

What are sesamoid bones and what is their function?

Sesamoid bones are small, round bones resembling sesame seeds (e.g., the patella) that eliminate friction and provide support.

Describe the diaphysis of a long bone.

The diaphysis is the shaft or long main portion of the bone, a hollow cylinder containing yellow bone marrow.

What is the epiphyseal plate?

The epiphyseal plate, or growth plate, is a layer of hyaline cartilage in the metaphysis that allows the diaphysis to grow in length.

Define the periosteum and its two layers.

The periosteum is a fibrous membrane covering the diaphysis with an outer fibrous layer (dense irregular connective tissue) and an inner osteogenic layer (containing bone cells).

What are the five types of bone cells?

The five types are Osteogenic/Osteoprogenitor cells, Osteoblasts, Osteocytes, Osteoclasts, and Bone Lining cells.

Which bone cells are responsible for bone destruction and resorption?

Osteoclasts, which are huge phagocytic cells derived from the fusion of up to 50 monocytes.

What is the difference between lacunae and canaliculi?

Lacunae are "little lakes" or tiny cavities where osteocytes are found, while canaliculi are tiny canals radiating from lacunae that provide routes for nutrients and oxygen.

What are Volkmann's canals?

Also known as perforating canals, they serve as communication pathways for vessels and nerves from the periosteum to penetrate the compact bone.

Define a foramen in bone markings.

A foramen is an opening through which blood vessels, nerves, or ligaments pass (e.g., Foramen Magnum).

What is a trochanter and where is it found?

A trochanter is a large, blunt projection found only on the femur.