bones bones and more bones that's exactly what we're going to be talking about today in our ait's version 7 more specifically human anatomy and physiology where we're going to be discussing the skeletal system let's get started the skeletal system performs a crucial role of supporting the body and protecting our internal organs Beyond these functions it serves as a reservoir for essential minerals facilitates the production of red and white blood cells and enables movement in coordination with muscles it's important to remember that body systems do not operate independently many textbooks refer to muscular skeletal system emphasizing the interdependence between our skeletal and muscular systems an adult typically has 26 bones what's interesting is that babies are born with slightly more bones which often fuse together as they grow up into adulthood the human skeletal system is categorized into two main parts we have the axial SK SK and the appendicular skeletal starting with our axial skeletal which forms the central axis of our body comprises of our skull bones the oses within our ears the hode bone found in our throat the vertebral column as well as our rib cage this structure not only supports our head and our neck movements but it helps facilitate breathing and it's also providing a foundational base when it comes to our appendicular skeleton the appendicular skeleton in includes all the bones of our arms and the shoulder girdle which comprises of our collar bones and our shoulder blades this is crucial when it comes to the function of our arms as well as our hands additionally encompasses the bones of our legs and our pelvic girdle which is vital for enabling movement next up we're going to dive into bone shapes and how we classify them starting with our long bones this term doesn't necessarily refer to their length in the most literal sense instead it's more related to that cylindrical shapee and the fact that they are longer than they are wide these bones are typically involved in movement facilitated by muscle contractions examples of long bone can be our femur which is the prominent long bone found in our leg as well as our tibia and our fibula in our arms we have the humoris the Anna and our radius and then lastly within our hands and our feet we have the fanges the metacarpal found in our hand and the metatarsals found in our feet unlike long bone short bones resemble cubes where their length and their width are going to be roughly equivalent these bones are mobilized through muscle contraction and provide significant stability examples can include the carpal that we find in our wrists and the tarsel that are found in our ankles next up we have sesamoid bones and these are small round bones that often resemble something like a sesame seed these types of Bones excel in handling pressure and are typically found embedded with within tendons or muscles a well-known example of a sesamoid bone is our patella that's found in our knee flat bones despite their name are not actually flat they're often curved and thin these bones include the cranial bones that are found in our skull and our scapula or our shoulder blades which play a crucial role when it comes to body structure as well as protection and then lastly we have irregular bones and these kind of bones defy regular shape classifications you're going to see much more complex shapes that don't fit standard descriptions irregular bones like the vertebrae are adapted to protect against a variety of forces and support bodily movements in multiple directions let's dive into the internal structures of Bones which consists of two primary bone tissues compact bone tissue forms the outer layer of our bones providing a hard durable surface for protection beneath our compact bone we have spongy bone tissue which which comprises of our bone marrow and a network of porous honeycomb like structures on the atits you're going to hear words like cancellus or tricular bone which is just another way of referring to this spongy bone material you'll also find two types of bone marrow within our spongy bone we have red bone marrow and yellow bone marrow yellow bone marrow is rich in fat and serves as a reservoir for long-term energy storage red bone marrow is vital when it comes to hematopoesis which is the production of blood cells it can generate red blood cells which are crucial for transporting gases like oxygen and carbon dioxide white blood cells which play a key role when it comes to our immune defense and platelets which is not actually a true cell but a cellular fragment which is essential for blood clotting this complexity shows why bones are considered vascular because they possess a rich blood supply fractures that result from intense trauma such as long bones we see in our femur can not only lead to substantial internal bleeding but can also possess additional risks as we discussed since bones contain yellow marrow that stores fat severe fractures might release fat into our bloodstream while the body can generally manage a small amount of fat release a severe case might lead to a very rare but potentially serious condition known as a fat embolism syndrome another interesting side note is that in emergency situations when we're unable to get intravenous access in the arm or anywhere throughout the body Medical Treatments like fluid and medication administration can be administered directly into our bone marrow this route of administration is called intra OAS meaning within the bone there are cells that play crucial roles in bone and carage formation and maintenance starting with osteoblast these cells are bone Builders they are responsible for creating new bone and as they mature they differentiate into osteocytes osteocytes are the primary cells in the bone tissue and are essential for maintaining our bone structure and lastly we have OC class which are bone resorbing cells what's fascinating about Osteo class is their method for breaking down bone they contain numerous lomes which are organel filled with enzymes these enzymes along with acids produced by the osteoclast effectively dissolve bone tissue this process is vital when it comes to bone remodeling and calcium homeostasis in the body you might ask yourself why does the body intentionally break down Bones the reason is that the body continuously adapts to various stresses they do this through a process known as bone remodeling where old bone is systematically removed and new bone is formed in its place this continuous cycle involves several distinct phases the resting resorption reversal formation mineralization and then back to our resting state during our initial resting state the bone surface and bone cells are osteocytes osteoblast and osteoclast are all inactive as we move into the resorption stage you're going to find that osteoclasts are going to attach to the Bone surface and create an acidic environment that's going to help dissolve that mineral component of the bone matrix it's also going to degrade that organic Matrix resulting in the formation of a resorption pit this phase is crucial for removing that old damaged and unnecessary bone tissue forming new bone and helping regulate our calcium levels after absorption we have a brief period of reversal where we're going to see mononuclear cells appear on the bone surface these cells are going to Signal the end of that resorption phase and the start of the formation phase phase in that formation phase you're going to find that osteoblasts are going to begin to lay down new osteoid at the resorption site osteoids are just unmineralized bone matrix osteoblasts are going to replenish the bone that was lost during the resorption phase maintaining that skeletal strength and integrity in mineralization the newly formed osteoid begins to mineralize calcium and phosphate from the body fluids crystallize onto the collagen f of the osteoid it's going to harden that new bone to restore the Bone's mechanical strength and its ability to support and protect the body Additionally the process of bone breakdown serves an important physiological Purpose By releasing minerals that the body needs a key mineral that is stored in bones is calcium specific hormones from the endocrine system regulate the release of calcium from the bones and its disposition back into them calcium plays crucial roles for various bodily functions for instance as we demonstrated in the video on the muscular system calcium is essential for the activation of muscle contraction bone cells collaborate closely with other cell types such as condr blasts condr blasts are responsible for producing the connective tissue known as cartilage as they mature condr blasts become condr sites which are essential for maintaining the structure of the cartilage cartilage plays a critical role in supporting bone structure particularly in joints for bones meet it also acts as a template for bone development during fetal development cartilage formed by those condra blasts initially serve as the framework for future bone growth over time most of the cartilage Matrix is replaced by bone though not entirely lastly we're going to discuss what happens when a bone fractures initially a fractured hematoma is going to form at the side of the break this hematoma is a collection of blood resulting in that high vascularity from the bones the accumulation of blood can block the supply of nearby bone cells typically causing them to die fortunately condr sites and osteoblasts quickly spring into action to stabilize the fracture they do this by forming a callus which is a thicken part of the soft tissue similar to what you would see if we had that thickening of our skin from lifting weights with our hands the internal callus is primarily made up of cartilage and the external callus is going to be a mix of both cartilage as well as bone these calluses function together to secure and stabilize that fracture site during the healing process osteoblast plays a crucial role in removing the damaged portions of the bone clearing way for its repair subsequently osteoblasts begin their remodeling phase creating new bone to replace what was lost there are five different kinds of fractures that you're going to need to be familiar with a Clos fracture also known as a simple fracture is a fra Ure that does not penetrate the skin the broken bone is contained within the body minimizing the risk of infection as well as external bleeding open fractures however also known as compound fractures occur when the bone breaks through our skin this type exposes that bone as well as deep tissues to the external environment greatly increasing our risk of infection communed fractures are fractures where the bone shatters into three or more pieces this type of fracture is particularly severe and often occurs due to high impact trauma impacted fractures also known as buckle fractures often occur when the ends of the bones are driven into each other typically seen in arm fractures among children and then lastly we have green stick fractures which again are common among children because their bones tend to be softer and more flexible when we're taking a closer look at a green stick fracture this occurs when the bone kind of bends or it cracks but it does not break all the way through I hope that this video is helpful in understanding everything you're going to need to know when it comes to the skeletal system if you have any additional questions make sure that you leave them down below I love answering your questions head over to nurse Chun store.com there's a ton of additional resources in order to help you Ace those atits exams and as always I'm going to catch you in the next video bye