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Lecture Comments (2)

1 answer

Last reply by: Bryan Cardella
Sat Sep 20, 2014 1:20 PM

Post by IBRAHIM FORNA on September 19, 2014

which is volkmann's canals

Skeletal System

  • The functions of bones include support, storage, production of blood, protection, and leverage
  • Bone anatomy includes terms such as: compact bone, spongy bone, epiphysis/diaphysis, periosteum, articular cartilage, lacunae, canaliculi, matrx, osteons, central canal, and medullary cavity
  • Bone cell types include osteocytes, osteoblasts, and osteoclasts
  • Bone movements can be related to a lever with the terms fulcrum, resistance, and force
  • Nutrition, hormones, and exercise can affect bone growth and development (ossification)
  • Bone marrow is red or yellow and contained within bone for blood cell production and fat storage
  • Bone conditions/disorders include fractures, osteopenia, osteoporosis, osteochondrodysplasia, and rickets
  • Did you know…
    • Q: Is it possible to have overactive osteoblasts?
    • A: Yes, if osteoblast activity were too high then a person would be making too much bone tissue (when it’s not necessary). One example is fibrodysplasia ossificans progressiva, which is mentioned later on in the muscular system lesson (it’s a disorder that turns damaged muscle tissue and other tissues into bone when healing!)

Skeletal System

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Functions of Bones 0:04
    • Support
    • Storage
    • Production of Blood
    • Protection
    • Leverage
  • Bone Anatomy 1:43
    • Spongy Bone
    • Compact Bone
    • Epiphysis / Diaphysis
    • Periosteum
    • Articular Cartilage
    • Lacunae
    • Canaliculi
    • Matrix
    • Osteons
    • Central Canal
    • Medullary Cavity
  • Bone Cell Types 7:39
    • Osteocytes
    • Osteoblasts
    • Osteoclasts
  • Bone Movement in Relation to Levers 10:11
    • Fulcrum
    • Resistance
    • Force
  • Factors Affecting Bone Growth 11:24
    • Nutrition
    • Hormones
    • Exercise
  • Bone Marrow 13:58
    • Red Marrow
    • Yellow Marrow
  • Bone Conditions / Disorders 15:06
    • Fractures
    • Osteopenia
    • Osteoporosis
    • Osteochondrodysplasia
    • Rickets

Transcription: Skeletal System

Hi and welcome back to

This is the skeletal system.0002

There are many functions of bones in your skeleton in general.0004

First one is support.0009

Without bones you will be a blob, you do not have any posture, you will not be able to move.0010

Your body will not be your body if you do not have bones.0018

When it comes to storing stuff, the bones have a lot in their plate.0024

Lipids there are a lot of fat contain in the bones for storage purposes.0029

You also have your blood making ability within the bones.0036

Most of the weight in the bones is a lot of calcified compounds that you can release when you are running low on those things.0040

If you are not getting much in your diet your bones can let go some of that to help other organs.0048

The downside is if you continue to not enough from your diet your bones are going to lose density and mass.0054

As I mentioned a second ago, production of blood not just red blood cells but all of your blood cells are produced in the marrow within your bones.0061

Protection, your skull, rib cage, pelvic bones, there is a lot of protection going on.0071

Think about the times you fall on your head, if it was not for your skull you might get brain damage.0081

Leverage, in other words movement.0086

It is the ability to push the door open, turn the knob.0090

You have muscles pulling on bones in different ways to allow you manipulate the environment to help whatever you got to get done.0094

When you look at a typical bone, there are lots of things you need to know to understand how a bone is working. 0103

Compact bone versus spongy bone.0111

If we look at this cross section here you can see that there is this term cancelous bone that is another term for spongy bone.0113

You can see when you look at here there are lots of little wholes and spaces and it looks spongy.0122

These little areas of bones that are not the spaces are called trabeculae.0128

They are like criss crossing little units of bone tissue and it helps reinforce them.0133

It is like engineering when you look at how people are making buildings and they will criss cross beams to help with the weight distribution and to help to keep that stable. 0141

It is very similar more at the ends of your bones.0155

Here is the end of a bone, if we look at the other end right here you will see a high concentration of that spongy bone.0158

The compact bone tends to be more on the outer rim.0165

You can see that it is just pure white here that is compact bone.0170

It is much more densely compacted bone tissue.0174

You are going to have that on the outsides.0178

The epiphysis versus diaphysis.0180

Let us continue this bone drawing a little further.0183

Let us pretend that is the other end.0187

The epiphysis would be here and here.0189

The diaphysis is the middle portion.0197

This term applies mainly to the long bones when we look at the humerus, femur, or thigh bones.0202

The diaphysis would be the middle straight region and the two ends are the epiphysis.0210

The periosteum is a term for the outer layer of bone.0216

It is going to be most obvious in the section of the diaphysis.0222

The outer layer that you will have ligaments attached to, 0226

the part that you will be holding if you have your hands around your diaphysis you are touching the periosteum.0231

The articular cartilage is articular because it is when your bones articulate in respect to one other.0238

When you look at how a bone connects to other bone the joint, the articular cartilage is going to be 0246

a nice cushion that is going to be at the ends touching the other bones.0254

Lacunae if we zoom in really close to what is going on here, a lacuna is going to be a home for bone cell also called an osteocyte.0260

Here is an osteocyte with its nucleus.0276

The red is that chamber deep within the matrix of the bone or the hard parts of the bones where you are going to have bone cells.0281

There are cells in every bone of the body.0289

They make up a very small portion of the mass of the bones because most of the bone is all that hard stuffs, 0292

all that calcified components that your cells help produce and keep there.0299

Canaliculi if we look at this lacuna and lacunae will be plural you have passageways that extend from this chamber.0306

These two little passageways are like canals that help get nutrients to the cells of the bones, help get waste out, helps gases get in and out.0320

It is like this crazy canal system and you can see in this particular cross section all of these little canals.0334

These are just major ones, there are still smaller canals connecting all these like freeways compared to surface streets.0342

The bone matrix is that all hard bone stuff.0352

All of these here are bone matrix.0359

It is mostly salts that will be full of calcium so it is calcium carbonated is a major one.0363

A lot of secretion from your osteocytes to talk more about in a second that give your bones that hardness.0372

Osteons are like these circular units.0380

Here and here you can see there are these circular regions that have tinier concentric circles within them those are the osteons.0387

That is how you have a lot of orientation within bone.0398

You can see that we are in compact bone here and when we go more towards the inner part here you are going to have more of these spongy bones.0402

Osteons are very common units within the structure of compact bone.0412

Central canal you are going to see here and here.0419

Within each osteon there is a major fair of blood flow to those sections.0428

Finally, the medullary cavity.0438

The word medulla means inner.0442

Medullary cavity this region within the middle here that is hollow is the medullary cavity.0446

There you are going to have a lot of bone marrow.0454

There are 3 major types of bone cell types.0457

Osteocytes one of them is pictured below are mature bone cells.0464

As an adult your osteocytes helps maintain your bone density, keep the bone what it is.0470

If it was not for osteocytes your bones will degrade.0478

Keeping up that bone density without osteocytes it will not happen.0481

Osteoblasts and osteoclasts are exact opposites.0487

Osteoblasts help make bone and osteoclasts get rid of bone.0491

Osteoblasts are most active when your bones are growing from being an embryo to being a baby to being an adolescent and so on.0501

Osteoblasts can be very active.0510

They are actively secreting bone matrix tissue and their development and helping your bones grow.0511

It is going to start out as a cartilage when you are a baby but as time goes one that bones mature and gets harder as it grows.0521

If you have a fracture, for instance I broke my collar bone, when I broke my collar bone the osteoblasts will went into an overdrive.0529

They help secrete more of that bone matrix tissue that helps connect those two separated parts and grew around.0538

My collar bone is thicker now than it was before I broke my collar bone.0545

Thanks to osteoblasts they help bring it back together as a full pledged connected bone and reinforced it in the process.0551

Osteoclasts secrete chemicals usually acids that helps get rid off bone.0559

You might wonder why do we need that?0565

One example is if you remember on the previous slide with the medullary cavity you got a section in the middle that is completely hollow.0567

How did it get that way?0579

It is because of the osteoclasts.0581

Also spongy bone, how do spongy bones get those little holes in it?0582

It is because of osteoclasts.0586

Also when it comes to my collar bone since I broke it about 15 years ago, it is not quite as bumpy as it used to be.0587

It has smoothened out a little bit and that is thanks to osteoclasts.0599

They wear away bone that you do not need.0601

If there is more than you need in the area you will have osteoclasts wearing it away.0605

Let us look at bone movement in terms of you moving a body part and you can relate it to physics.0610

There is fulcrum, resistance, and there is force that you are applying. 0620

The fulcrum is that point with which this lever is working that is your joints.0626

Let us take your humerus and ulna radius, these are the 2 forearm bones.0633

If I want to lift something let us say I am doing bicep curls, my fulcrum will be at my joint.0639

Resistance is if I am just lifting that arm there is not very much resistance but let us say there is a heavy weight in my hand that is the resistance.0649

That is the load that we are trying to move up.0656

The force comes from the muscles.0660

When I have my bicep pulling on these bones here I am exceeding the load here in bringing it up.0663

Whatever move that you are making with bones you can relate it with muscles on how the lever works.0671

Factors affecting bone growth.0684

There are 3 major ones, nutrition comes in play.0687

The amount of calcium you take in and the amount of vitamin D in your diet.0690

Also vitamin D you can make some of that in your skin from the UV radiation that is why they say get some sunlight or drink some vitamin D.0696

If you are wondering how does vitamin D relate to it? 0704

You can drink and consume all the calcium that your heart desires but if you do not have sufficient vitamin D 0707

you are not going to absorb that calcium into your body as it goes to your digestive tract.0715

Nutrition is very important in maintaining your bones and affecting how your bones grow.0725

Not enough vitamin D can lead to something like rickets.0731

Rickets is where your bones do not grow properly.0736

Your joints get messed up and often times you will find people being bow legged because they did not get that nutrient when they are developing.0739

Hormones, bone growth is going to be related to hormones.0746

Growth hormones from your pituitary gland is going to be ones that is going to affect that.0752

I have this picture here because this gentleman is Robert Wadlow he is the world record for being the tallest man in recorded history.0758

He is almost 9ft tall.0766

He had a tumor in his pituitary gland that is causing to be overactive.0768

He is releasing way too much growth hormone from a very small baby all the way up to his early 20’s when he passed away.0773

He never stops growing and that is abnormal. 0783

Your pituitary gland regulates how much growth hormone is going out of it.0786

When you are at my age, you do not need much of that because you are full grown.0792

Exercise, if you do not have enough exercise you are not going to have your bone grow its full potential.0798

If your mom tells you to go outside and run a bit, take her advice.0805

Studies shows that as muscles move and as they pull on bone that can stimulate some mitosis 0810

within those growing parts of the bone near the epiphysial plate if you look in an x ray.0818

If you want to reach your full height, eat well and exercise a lot and you will get to the height that your body is meant to get to.0824

When we look deep inside the bones you have bone marrow and there are 2 main kinds.0835

The bone marrow looks red and you can see that from this picture, that is where you are going to have production of blood cells.0844

Your red blood cells are being made every second of your life in your red marrow.0852

It is tend to be more concentrated in the spongy bone and you can see that in this drawing here.0856

The little redness in the spaces of the spongy bone and you will also see it down here.0862

You can have some overlap, you can have some of it in the medullary cavity.0866

The reason why I am showing you this picture because this is the head of the femur, the head of your thigh bone looking down, 0871

they actually removed a part of the periosteum and they are looking in there to show you a little spot of yellow.0878

You can see that the yellow marrow tends to be more concentrated in this region, in the medullary cavity and it is yellow because of lipids. 0884

You have a lot fat storage in the medullary cavity of your bones especially a large bone like the femur and humerus.0895

For some bones conditions and disorders, the big one is fractures.0906

It is the same thing as bone break.0911

There are a lot of different kinds of fractures and here is one in this particular image.0913

This is the tibia, the main sheen bone and this is the fibula off to the lateral end.0919

This is the medial part.0928

You could see down here there is a little fracture that happened.0930

This can be called a spiral fracture meaning that it broke and it did a slight twist.0934

Depending on how bad it is, you maybe going to a surgeon and put it in a metal rod into the medullary cavity to help stabilize it 0942

and encourage the correct formation in terms of ostification which is the process of making bone tissue.0955

There are a lot of other kinds of fractures.0963

A hair line fracture it could be like this.0964

It looks like a crack where the bone has not moved at all.0968

It is the easiest one to repair.0972

A green stick fracture will look like a little crack in it those typically heal much more easily than spiral fracture.0975

Another one is called the common nuded fracture that is if the bone look shattered in terms of being a lot of different pieces 0986

and that is a more significant kind of fracture especially in a major bone like this.0998

Depending on how severe the fracture is you might be wearing a cast for a lot longer depending on what bone is it in1002

that is going to affect your prognosis in terms of how long it is going to take to develop. 1006

Like I have mentioned earlier with making bone like with my particular left collar bone, this clavicle still has a slight bump 1014

so you are going to have making of bone tissue wrapping around this.1025

Osteopenia is a reduced amount of bone hardness.1030

It is much more common in middle aged women but it also can happen to men.1038

Osteopenia is a sign that maybe eventually moving on to osteoporosis.1043

If you were to take a test to measure your bone density in terms of how much hardness your bone have.1048

If it is lower than it should be they diagnose you with this and they will encourage you to take in your diet to get1058

a lot of calcium and remain active to encourage your bones to get more hard.1062

If osteopenia is not dealt with, eventually it will be osteoporosis and it is much harder to get back that bone density.1070

It means your bones are way too porous and it is much more likely that you will get fracture and bone breaks when you fall and you have osteoporosis.1079

A lot of middle aged women or younger senior citizens are encouraged to take calcium supplements 1089

and get calcium in their diet naturally to avoid having either of these.1096

This long word here osteochondrodysplasia is an umbrella term for different types of bone 1102

and cartilage developmental disorders in terms of how it forms in the body.1111

A lot of different forms of these in terms of inadequate cartilage production, inadequate bone development.1116

Speaking of inadequate bone development, rickets is a very strange disorder that can happen 1123

if a younger person or a child is not getting enough calcium absorb in to their body.1129

Lack of vitamin D could affect the ability to get calcium absorbed in to the blood stream then into the bones.1135

Rickets, if you have this severely one of the signs of it is the bones in your legs will be curvy and the person will look bow legged.1142

When they stand up straight their legs are not straight, they look like this.1152

An x ray will reveal that odd bone development and that is due to lack of calcium absorption early on to the development of the skeletal system.1157

Thanks for watching