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For more information, please see full course syllabus of Anatomy & Physiology
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Lecture Comments (22)

1 answer

Last reply by: Bryan Cardella
Wed Nov 26, 2014 9:48 AM

Post by Anmol Chowdhary on November 25, 2014

Hi, where can I find more about muscular tissues and nervous tissues?

1 answer

Last reply by: Bryan Cardella
Wed Oct 15, 2014 12:42 AM

Post by David Gonzalez on October 14, 2014

This might be a silly question, but who knows, it might be plausible: you mentioned that the sebaceous glands release "whole" cells- does this mean that hairs contain nutritional value? Even in very small trace amounts? I'd love to hear your input! Thank you!  

3 answers

Last reply by: David Gonzalez
Sun Oct 12, 2014 8:20 PM

Post by David Gonzalez on October 11, 2014

Does the extracellular matrix exist only in connective tissue? Thanks!

1 answer

Last reply by: Bryan Cardella
Mon Feb 24, 2014 6:50 PM

Post by Jessica Ferriday on February 23, 2014

This is great, Bryan, thanks! I've done anat before and I am currently having to restudy it and this is just what I need!

1 answer

Last reply by: Bryan Cardella
Thu Jan 2, 2014 11:52 AM

Post by Gyung Ae Jang on January 1, 2014

Could you explain the process of how CO2 is carried out through the capillary and alveolar cells please?

0 answers

Post by aljona brahaj on December 16, 2013

I liked very nice thanks

1 answer

Last reply by: Bryan Cardella
Wed Dec 11, 2013 12:18 PM

Post by Susan Paterson on December 10, 2013

For me personally, I don't know about others... maybe I'm just a slow learner, but, it would be more helpful if you actually wrote out the definition of each word that you're explaining so I can reference it as you explain the word for easy note taking.  It also helps with the amount of times I have to watch a section of the video, which feels like a huge time sucker...  Note that I suggest "writing it out as you explain the term" instead of having it pre-typed because it helps to slow down your explanation for a better connection.  I also suggest writing a bit larger, your penmanship is somewhat hard to read...    

6 answers

Last reply by: ido montia
Sat Feb 15, 2014 9:11 AM

Post by Nathan Dodd on November 18, 2013

This lecture keeps crapping out at around the 21:00 mark

Related Articles:


  • Tissues are groups of cells that have a collective purpose or set of functions together
  • Histology is the study of tissues
  • Epithelial tissues lines the outer and inner surfaces of body organs
  • The types of epithelial tissues are named after how many layers of cells they have and the shape of the cells
  • Types of epithelial tissues include: simple squamous, stratified squamous, simple columnar, stratified columnar, pseudostratified columnar, simple cuboidal, stratified cuboidal, transitional, and glandular
  • Glandular epithelial includes merocrine, apocrine, and holocrine glands
  • Connective tissue, the most abundant tissue in the body, helps connect the organ systems to each other to make the body a cooperative, cohesive unit of trillions of cells
  • Connective tissue contains fibers such as collagen, elastin, and reticular fibers
  • Connective tissue cells include fibroblasts, macrophages, mast cells, lymphocytes, adipocytes, and melanocytes
  • Connective tissue examples (combinations of fibers and cells) include muscle tissue, tendons/ligaments, blood, cartilage, bone and muscle
  • Did you know…
    • Q: If holocrine glands are releasing whole cells into the gland, is there a chance that the gland would run out of cells faster than a merocrine gland?
    • A: No, they wouldn’t since the rate of mitosis would be different. Holocrine glands would require a faster rate of mitosis to replace the cells that have been sloughed off (released), while merocrine glands would be replacing cells less often because they are only letting go of the products within tiny secretory vesicles from the glandular cells.


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.

  1. Intro
    • Tissue Overview
    • Epithelial Tissue
    • Types of Epithelium
    • Simple Squamous Epithelium
    • Stratified Squamous Epithelium
    • Histological Slide of Esophagus / Stomach Connection
      • Simple Columnar Epithelium
      • Stratified Columnar Epithelium
      • Pseudostratified Columnar Epithelium
      • Simple Cuboidal Epithelium
      • Stratified Cubodial Epithelium
      • Transitional Epithelium
      • Glandular Epithelium
      • Connective Tissues
      • Connective Tissue Fibers
      • Connective Tissue Cells
      • Connective Tissue Examples
      • Intro 0:00
      • Tissue Overview 0:05
        • Epithelial Tissue
        • Connective Tissue
        • Muscle Tissue
        • Neural Tissue
        • Histology
      • Epithelial Tissue 2:25
        • Attached to a 'Basal Lamina'
        • Avascular
        • Consistently Damaged by Environmental Factors
      • Types of Epithelium 5:35
        • Cell Structure / Shape
        • Layers
        • Example
      • Simple Squamous Epithelium 6:39
        • Meant for Areas That Need a High Rate of Diffusion / Osmosis
        • Locations: Alveolar Walls, Capillary Walls
      • Stratified Squamous Epithelium 9:10
        • Meant for Areas That Deal with a Lot of Friction
        • Locations: Epidermis of Skin, Esophagus, Vagina
      • Histological Slide of Esophagus / Stomach Connection 10:46
      • Simple Columnar Epithelium 12:02
        • Meant for Absorption / Secretion Typically
        • Locations: Lining of the Stomach, Intestines
      • Stratified Columnar Epithelium 13:29
        • Meant for Protection
        • Locations: Epiglottis, Anus, Urethra
      • Pseudostratified Columnar Epithelium 14:46
        • Meant for Protection / Secretion
        • Locations: Lining of the Trachea / Bronchi
      • Simple Cuboidal Epithelium 16:51
        • Meant for Mainly Secretion / Absorption
        • Locations: Kidney Tubules, Thyroid Gland
      • Stratified Cubodial Epithelium 18:18
        • Meant for Protection, Secretion, Absorption
        • Locations: Lining of Sweat Glands
      • Transitional Epithelium 19:15
        • Meant for Stretching and Recoil
        • Locations: Urinary Bladder, Uterus
      • Glandular Epithelium 20:43
        • Merocrine
        • Apocrine
        • Holocrine
      • Connective Tissues 25:06
        • Most Abundant Tissue
        • Connect and Bind Together All the Organs
      • Connective Tissue Fibers 26:13
        • Collagen Fibers
        • Elastic Fibers
        • Reticular Fibers
      • Connective Tissue Cells 30:52
        • Fibroblasts
        • Macrophages
        • Mast Cells
        • Lymphocytes
        • Adipocytes
        • Melanocytes
      • Connective Tissue Examples 36:39
        • Adipose Tissue
        • Tendons and Ligaments
        • Blood
        • Cartilage
        • Bone
        • Muscle

      Transcription: Tissues

      Hi and welcome back to

      This is the lesson on tissues.0002

      When we say tissues we are not talking about blowing your nose kind of tissues.0004

      We are talking about a bunch of cells together with some common purpose or functional goal in terms of what they are doing for your body.0010

      These cells organized into group for a specific set of functions or purposes.0018

      Sometimes for just one purpose but a lot of times it is many.0023

      Epithelial tissues are the first we are going to talk about.0027

      An epithelium is always cells that are on the outermost, the most superficial layer of an organ or the innermost part or deepest part of an organ.0029

      If they are on the innermost parts that organs has some kind of passageway or hallow area called the lumen.0042

      The cells on the innermost part or those epithelial cells are helping to move something through, 0049

      absorbing and secreting chemicals, it could be variety of things.0055

      An epithelium is very important to our body.0060

      Connective tissues are the most abundant tissue in your body.0063

      Connective tissue is a lot of different kind of cells functioning together.0068

      It does connect your body parts to each other and help bind organs to neighboring tissues.0072

      Muscle tissue and neural tissue are technically a type of connective tissue but are major tissues in the body.0079

      You are going to find muscle tissue all through out the body even in the parts where you do not realize it is there 0086

      because some of the muscles are doing involuntary actions that you do not directly control consciously.0091

      The muscles are in your dermis, in your skin, that you do not consciously move but they do contract and relax.0097

      Neural tissues are also all through out the body.0107

      It is not just the brain, not just the spinal cord, we are talking about every single nerve, all the neurons, billions of cells.0111

      Histology is a very important kind of branch or study related to anatomy and physiology, that is the study of tissues.0120

      We know that it is looking up close at a tissue to see what the cells look like and how they are oriented related to each other.0129

      That is why it is typically with the microscope that you are going to be looking at histological picture.0135

      Later on in this lesson we will show you a histology slide.0140

      The first kind of tissue that we are going to be talking about is epithelial tissue or also called epithelium.0144

      The purpose of the epithelium is to cover every external and internal surface of the body.0152

      Not just on the outside but internal organs as well.0157

      These epithelial tissues are always attached to a basal lamina also known as basement membrane.0160

      That is the synonym for this term.0170

      Here is what we mean by that.0174

      You are going to see pictures that we draw for you or have displayed on slide later on in this lesson.0180

      It is always cells bound to look like just a line.0184

      It looks like a cement line that the cells are attached to or anchored to.0189

      That basement membrane or basal lamina is made of cells.0195

      Think of it like organic protein glue that is anchoring all of those cells to those surface.0200

      That basal membrane is connected to what tissue immediately below or deep to it.0208

      You are going to find basal membrane associated with epithelium.0214

      Also epithelium is a vascular.0217

      It gets nutrients and gas from diffusion and osmosis.0220

      What is a vascular means specifically?0223

      Let us take the cardiovascular system.0226

      It always has to do with transporting fluids.0231

      First is a vascular plant like a tree, it is called that because the tree is able to suck water up and get it up through osmosis to the top of its leaves.0234

      We are vascular because we are able to move fluids against gravity all through out our0244

      body but the specific tissue is a vascular because when you look at blood vessels and the transport of fluid related to this, the blood vessels do not go right up into it.0250

      You are not seeing capillaries, those tiny bundles of super bodies feeding this directly with oxygen nutrients.0262

      The oxygen in nutrients, that gases that are going to be given to these tissues get there from whatever tissue right next to it.0268

      It is diffusion and osmosis that is getting the nutrients and gases to the epithelial tissues.0276

      Because we are talking about the parts that are on the very outside of your body, the passageways that you are swallowing stuff into or inhaling air into,0282

      they are consistently damaged by a wide variety of environmental factors regenerating with stem cells.0293

      You are getting pretty much regeneration of these epithelial tissues depending on where they are in the body.0300

      Let us take the epithelium in the surface of the tongue.0306

      It needs to be regenerated a lot because every time that tongue cells get rubbed against by something you are chewing or eating, you need to replace those.0309

      It is same with the epidermis or the outer parts of your skin.0320

      You need to regenerate them as it gets damaged.0324

      Those are the characteristic of epithelial tissues in general.0330

      They are named based on cell structure and shape and is it one layer, two layers, or many layers?0333

      Let us look at some examples.0349

      A simple squamous epithelium, why is it simple and why is it squamous?0351

      Simple has to do with how many layers.0355

      This means one layer.0359

      That is how simple as it gets.0361

      Later on you are going to see a stratified, it is the opposite of one layer.0363

      We are talking about many layers on top of another.0370

      Squamous means round or disk like.0374

      They look like that.0383

      That is a squamous cell.0389

      One layer of round or disk like cells.0390

      That is what simple squamous epithelial is.0393

      You are going to see more detail about that later on in this lesson.0395

      Here it is simple squamous epithelium.0400

      One layer of point shaped cells that look like this.0402

      It is mean for areas that need a high rate of diffusion and osmosis through the cells.0408

      Think about inhaling air or transporting nutrients to blood vessels, you want to get the oxygen to your cells as quickly as possible.0414

      You want to get nutrients like sugar, proteins, and fats as quickly as possible.0422

      You do not want to have them drift through layers of cells it would take longer and harder to get that stuff around the body.0428

      Two examples are the alveolar walls and capillary walls.0434

      Let us see.0438

      Here is a good picture of how they look.0439

      Let us say we were to take a capillary which is the tiniest blood vessel type in the human body.0442

      If you were to cut that capillary down the middle and we can look down it with a microscope, the cells would be one cell thick 0448

      simple and squamous because if look from the outside of it you see all these disk like cells that make up these.0460

      I am also going to draw a little nucleus.0468

      Since it is a one cell thick, what a capillary does is it gets oxygen to the tissues around it so you get a very quick diffusion 0474

      which is a passive natural movement of gases and nutrients out of the capillary into the tissue and vice versa with CO2 and waste and it will take it back to the lungs.0483

      Having one cell thick is great for quick diffusion and osmosis.0497

      In alveolar walls, if you look at the capillaries in the lungs you want to get CO2 out of the capillaries and into the passageways of your lungs and vive versa with oxygen.0500

      The microscopic bubbles that make up the alveoli of your lungs, you have hundreds of thousands of these sacs.0513

      They are also one cell thick.0521

      Here is an alveolar bundle if you take a cross section through the alveolar bundle it is also one cell thick.0525

      It is brilliant in terms of getting oxygen that you inhale to your lungs into the capillaries quickly and efficiently.0536

      That is ideal for diffusion and osmosis.0544

      Stratified squamous epithelium we still have those round, plate looking cells, but a stack of them, many layers of it.0550

      It is meant for areas that have to deal with a lot for friction and rubbing like the epidermis of the skin 0560

      it is being touched and you need to regenerate those cells because you are going to lose them.0569

      The esophagus is the tube that takes food from your throat area down to your stomach every time you swallow a chunk of food.0575

      It is rubbing against the inner part of that esophagus and it is called the mucosa.0585

      You are losing those cells and you need to be able to regenerate that epithelial tissue.0590

      The vagina or anus you have friction to those areas depending on what activity you are engaged in.0594

      You got to be able to regenerate these epithelial tissues because of those environmental sources of friction.0601

      Here is a little image of what they look like.0609

      You could see that they are still roundish and as you get towards the surface, the superficial part of it, this could be the epidermis of the skin.0611

      It makes sense that these flatten cells here were worn away from the top and down here, the cell division of these 0620

      in the sense of stem cells are going to be providing the new cells that gradually move away from the blood supply down here.0625

      This black line down here this is the basal lamina or basement membrane.0632

      This is stratified squamous epithelium ideal for friction or protection.0639

      Here is the histological slide of part of the esophagus and stomach connection.0645

      These are some actual micrographs which mean photographs taken with a microscope.0651

      This is something close.0657

      This passageway is the lumen of the lower part of the esophagus or the most inferior part of the esophagus.0659

      Here is the beginning of the stomach and here is the lumen of the stomach.0666

      You are going to have mucosa lining that inner part of that stomach.0671

      You are going to have some mucous glands that are going to be on the esophagus but 0675

      we also need to have stat on the inner most part of the esophagus is lot these stratified squamous epithelium.0681

      You could that there are stacks and stacks of those round cells because every time food is rubbed against it, it is going to damage parts of it.0692

      The mitosis down here is bringing up new epithelium here.0699

      You are going to see all kinds of epithelial tissues in the stomach.0704

      For instance, right here you got some glandular epithelium.0707

      You are going to here about that later.0711

      These are secreting gastric juice and all those little chemicals and molecules inside the stomach to help with the digestion process.0712

      Another kind of epithelium is simple columnar.0720

      This is one layer because it is simple and column shaped cells like its name says.0725

      It is meant for absorption and secretion typically.0729

      It depends on what specific organ it is in.0732

      Sometimes they are absorbing something or they are taking something in from the passageway or they are secreting something in to that passageway or lumen.0734

      Sometimes they have what is called microvilli and I will draw some microvilli for you here.0743

      They look like little hairs on the surface.0749

      Epithelial cells are known as cells with polarity meaning that one end of the cell usually 0755

      functions a little bit differently than the other end in terms of the look in the structure.0762

      You could see with the simple columnar down here this is the anchored part of the cell that is going to be adjacent to the base membrane.0767

      Up at this end if we are talking about space or lumen, this is the end that actually doing the absorbing or secreting.0775

      These little microvilli are going to be looking like this.0783

      For instance, in the lining of the stomach and intestines you have to be absorbing and secreting stuff.0786

      If we take the small intestine, you have the ability to further the process of digestion.0794

      The small intestine is a very long tube in the body that is doing absorption.0801

      These cells are perfect for that.0805

      Stratified columnar is very similar to the previous picture but you are going to see stacks of these cells.0808

      These also have cell on the top but not necessarily.0832

      Stratified columnar epithelium is many layers foam shaped cells and meant for protection.0841

      Similar function to that stratified squamous epithelium but the cells are shaped differently.0848

      The location is the epiglottis.0853

      The epiglottis is a flap that comes down on the entrance to the airway to your trachea every time you swallow.0855

      Often times, when human being is swallowing they are getting food or liquid down into the digestive track.0864

      You do not want it going down into the lungs.0869

      The epiglottis is a nice flap that protects us from aspirating on something other that air.0872

      The anus and urethra also need protection based on what is going through those areas.0878

      Pseudostratified columnar epithelium, pseudo meaning fake or false, stratified meaning many layers and columnar shaped.0886

      It is a false stratification because it appears to be layered but it is one layer of palm shaped cells.0896

      The reason why it appears to be layered is that varying heights of the nuclei giving the illusion of being many layers.0903

      Let me draw you a picture.0911

      Sometimes you will get one of them being smashed in like that.0916

      I will do another one that is smashed in.0923

      You can see that this is one layer of epithelium of column shaped cells but you will see this.0931

      Because you have varying heights of nuclei at first glance you might think that is 2 layers but it is not.0940

      It just appears that way and sometimes this have cilia.0952

      I have mentioned cilia on the other side but let me explain more here.0956

      Similar to microvilli the difference is that cilia are helping dress something along rather than absorbing or secreting.0965

      Think about the lining of the trachea and bronchi, these are tubes associated with breathing in air and exhaling.0977

      You generate mucous in your lungs and if it was not for the sweeping up or brushing up of mucous you can drown in your own fluid especially when you are sick.0983

      The brushing up of that mucous that is generated on the passageway of your lungs is very important.0997

      In the trachea and bronchi you are going to see lots of cilia brushing up mucous.1003

      Simple cuboidal epithelium is one layer of cube shaped cells meant mainly for secretion and absorption.1008

      Secretion, absorption, or protection or SAP that is the way I remember it.1017

      Those are the three major functions of epithelium.1023

      Those are the big three you are going to see a lot.1027

      Secretion, absorption, protection, one or the other or some combination of the three.1028

      When you look at the kidney tubules, the little tubes that help make you urine you are going to see this.1033

      The thyroid gland which has a lot to do with regulating your metabolic rate these secrete hormones into your blood stream.1041

      These two definitely have simple cuboidal.1048

      If you look at one of the passageways to which urine or thyroid glands secretion are found, you are going to see cube shapes.1051

      They are not quite round and squared off edges and here is the nuclei. 1064

      This is your average looking kidney tubule epithelium. 1071

      You could see that it is good for secreting and absorbing stuff easily makes thing go in and out.1076

      It is same as simple squamous epithelium except for the cell structure.1082

      It make sense that you can easily have secretions going in and absorbing through this as well.1088

      Stratified cuboidal is similar to just what I drew except that they are just one layer you are going to see additional layers of these cube shaped cells.1097

      I am not going to draw all of them.1110

      You are going to have stacks of them.1112

      It seems stacks next to tubular structure or luminous, this is called stratified cuboidal.1116

      It is meant for secretion, protection, and absorption like I have said earlier.1131

      The lining of sweat glands like in the dermis of your skin often times if you cut through it 1141

      and you look at it under a microscope that histological view is going to show you stacks of cube shaped cells.1148

      Transitional epithelium is meant for stretching and recoil.1155

      You have certain structures in the human body, certain organs where you need to expand and then go back whatever what is inside that is left.1160

      When relaxed, it looks a lot like columnar.1167

      Here is your relaxed transitional epithelium like the lining of the urinary bladder or uterus.1171

      When relaxed they look like that then when it is stretched let us say the urinary bladder has closed to urinating that means that person need to urinate.1187

      It is stretched quite significantly.1202

      When you stretched out those cubed shaped cells they do not look cubed, the column shaped cells they do not look columnar anymore because they are stretched.1204

      That is a big difference between this and this.1223

      Think about any organ that is meant to expand.1231

      The urinary bladder has urine in it.1234

      You got to stretch the uterus when you have a baby.1239

      I will tell you about glandular epithelium.1242

      It is meant for producing and releasing secretion.1245

      Anytime that you have a gland whether it is releasing a secretion outside of the body into a body cavity 1248

      it is made of glandular epithelium in terms of the production that is being secreted and the act of secreting it.1255

      The three main types of glandular epithelium are merocrine, apocrine, and holocrine.1261

      I remember this mnemonic device MAH and the reason for that is because the order will help you remember what this one.1267

      You will see why.1277

      The merocrine type an example is salivary glands.1279

      Here we have the different types of salivary glands that is three pairs total of 6 salivary glands in humans.1282

      You got the peroded, sublingual, submandibular, and all of these have the glandular epithelium that is the merocrine type.1290

      Merocrine secretes just a little bit of substances from the cells.1299

      The cells in the epithelium are not leaving just bits of the substance.1304

      For example, let us say this is the gland and here is the opening in which the secretion actually comes into your mouth.1308

      Along the edge of it, you have cells that are responsible for producing saliva and secreting it into the cavity or the lumen.1317

      Secretion into here or exits in the opening of the mouth to help you dissolve things you are eating.1328

      They are little sacs or vesicles and inside you have water and enzymes.1342

      These little sacs will fuse with the edge of the cell and you will end up getting water and this enzyme package exiting.1353

      That is saliva.1368

      If you remember that merocrine is the smallest bit of secretion.1370

      You will see that with apocrine it is a little bit more.1375

      When we look at apocrine glandular epithelium an example is mammary glands.1378

      The glands that release milk.1382

      When we look at a mammary gland you will see it is a little bit different.1385

      Here the cells that are lining that actual lumen or opening.1390

      Instead of being little pockets that are released, they are actually parts of cell but not the whole cell.1397

      Here is what it look like.1404

      You would have this organelles and parts getting rid of the section of the cell and all this little cell parts together make up the milk.1406

      All those carbohydrates, proteins, lipids, hormones, etc, they are in breast milk.1428

      Apocrine is a little bit more is released, not just little pockets but parts of cell.1434

      Then we will look at holocrine, sebaceous glands we will look at hairs there are glands adjacent to the base of the hair shaft near the follicle.1440

      They release an oily substance to help coat and protect your hairs.1458

      Holocrine helps in secretion in terms of the amount that is released.1464

      Hol means whole, like a whole cell.1471

      The MAH that I have mentioned before, the merocrine releases little bits, apocrine releases parts of cells, holocrine releases whole cells.1479

      This is the lining of the gland here, the sebaceous gland.1489

      You will see the whole cell being released as a part of that oily glandular secretion.1495

      Those are the three different name types of glandular epithelium.1502

      The connective tissues this is an important tissue in the body.1505

      It is the most abundant tissue.1511

      It is all over the place.1513

      It is connecting the body parts to each other, stabilizing the body, giving it structure and stability.1514

      It is meant to connect and bind together all the organs and organ systems to form a cohesive and cooperative body as a whole.1520

      Any of the different skeleton here and here, on the far right, we got a gorilla, chimpanzee, gibbon, orangutan.1527

      Whether you are looking at a monkey or ape, or human, the skeleton is made up of connective tissue.1537

      When we look at connective tissue, anything that is found through out the body helping to 1550

      bind organs to each other, helping the body to communicate with itself, it is a connective tissue.1555

      When you think about bones, it connects the body parts to each other.1562

      If it was not for your bones, you will not be alive.1566

      Connective tissue is made up of fibers and cells.1571

      First we will talk about the fibers.1577

      The fibers are made up of protein.1579

      Protein is the most abundant substance, you are going to move all the water from the body, protein is the next most abundant substance.1580

      Collagen fibers are the most abundant protein in the body.1589

      It is a bundle of protein humans that are slightly flexible.1594

      They are typically strong and arranged in one direction.1598

      A good example of that would be tendons.1602

      Tendons help connect muscle to bone.1605

      Ligaments help connect bone to bone.1609

      A tendon like the calceneal tendon or the Achilles tendon if you think about how it connects your calf muscle to your heel, that Achilles tendon is a bundle in one direction.1611

      It is very tough and strong and slightly flexible because anytime that you contract that muscle you are going to be pulling up on your heel.1630

      When you relax it, the opposite is going to happen.1643

      All of those are aligned in one direction help keep it stable, connect that muscle effectively to that bone.1645

      It is very strong and anyone who has snapped that tendon knows it is very painful and they will realize how important that tendon is.1651

      Typically when it snaps away from the bones surgery is required to reconnect it.1661

      Collagen fibers are not just tendons and ligaments, it is found all through out of your skin.1665

      It is in your bones.1671

      It is very important.1672

      Elastic fiber is another example that connects the tissue fiber.1674

      This is not quite as strong but a lot more flexible.1677

      A bundle of protein units that are very flexible and elastic.1682

      It is strong but not quite as strong as collagen.1686

      An example is intra vertebral disk.1691

      Intra vertebral disk if you look at the vertebrae, this side is the anterior side towards the front of your spine bones and this is the posterior or dorsal side.1694

      This will be that little bony extension that makes up those bumps you see in someone’s back when they bend over.1715

      This is a little process that connects to the ribs and also muscles can connect there.1723

      This bone on the top and bottom of it you are going to see a disk.1730

      That is why it is called inter vertebral disk because they are in between the vertebrae.1738

      It has to be flexible.1743

      They have to have some give in elasticity because think about when someone jumps off of 1745

      the ledge the force of the bones coming together when you hit the ground, you will have that cushioning.1750

      You do have slight elasticity there.1760

      As time goes on, the integrity of these and thickness can drop a bit and that is why some older people get a little bit shorter.1763

      My grandmother is used to be being close to 5 ft now she is more like 4’10.1776

      We can blame some of those intra vertebral disks for that little drop in height.1781

      They are made up of these elastic fibers and a good example of elastic fiber is the name elastin.1786

      You are going to find that in those inter vertebral disks.1794

      Reticular fibers same sub units is collagen but not in one direction not like in tendons we have 1797

      the collagen lined up in one direction because that is how the muscle contracts.1804

      It contracts along one point back and forth.1809

      With reticular fibers, reticular means net and if you took biology you will remember that 1812

      the endoplastic reticulum that organelle in the cell looks like little net next to the nucleus.1818

      Reticular fibers they are net like.1825

      A good example is inside the liver.1828

      These net like fibers are found through out the liver to help keep it together and keep it stable.1830

      You would not want collagen fibers to just line up along one direction of the liver but you want them spread out all through out the tissue to help give it stability.1836

      Those are connective tissue fibers.1849

      Connective tissue cells are another important part of connective tissue.1851

      When you get a cut in your skin, fibroblasts are helping heal back the cut and remake those proteins to help bind it together.1856

      If it is not a thick cut you would not need stitches.1871

      If it s a thin cut your body takes care of it and often times it would not scar.1878

      You can think fibroblasts for secreting this connective tissue with fibers to help rebind those parts of the skin that has been separated.1883

      Macrophages that mean big eater and these are giant cells that look like pacman.1892

      They will engulf foreign bodies.1902

      Let us say you got a bacterial cell that is potential harmful to your body.1905

      Here is a nucleus inside of your macrophage and all these little lysosomes or little organelles 1913

      that have enzymes that are meant for breaking down foreign bodies.1923

      Once the macrophage swallows up, that foreign body, those enzymes inside these lysosomes will fuse with the pocket that is now engulf this bacterial cell.1929

      Those enzyme will break it down and get rid of it.1938

      Macrophages some of them are fixed, they are like permanent resident of organs or tissues in the body.1944

      Others are free, they migrate in and out.1950

      The amazing thing is that these macrophages can flatten themselves and squeeze it in between the cells or tissues.1953

      The ones that are free migraters are amazing how they will go in target of foreign bodies and get that immune response going.1960

      Mast cells secrete a couple of different things, they secrete histamine and heparine.1968

      Histamine is one of the main things they secrete and if you have ever taken anti histamine you are familiar with the opposite of what this does.1976

      An anti histamine is going to get rid of the swelling especially your nasal cavity.1992

      If you have a stuffy nose it is very uncomfortable and that is your body’s natural response to getting some kinds of infection or irritation on your upper respiratory tract.1997

      You will get inflammation in that area to get more blood flow and try to get rid off that foreign invader that is causing the problem.2007

      It is very uncomfortable so you will take an anti histamine to reduce the swelling.2013

      That tells you that histamine is the cause of inflammation.2020

      This is released to make blood vessels get dilated and that results in swelling.2024

      Heparine is an anti coagulant.2030

      That means that this will prevent or get rid off blood clots.2037

      Sometimes blood clots are good thing.2042

      A clot prevents more blood from exiting out of a wound but once the healing has happened 2044

      and you prepare the wall of the blood vessel you want to get rid off that clot.2053

      You do not want it to stay there.2058

      If it gets dislodged that clamp of a clot and that will cause a problem.2059

      Heparine will actually thin the blood and get rid of those clots.2067

      Lymphocytes are important cell of the lymphatic system and lymphatic tissue is all through out the body that is connecting body parts to each other.2071

      Lymphocytes are responsible for making anti bodies and this gives rise to plasmacytes. 2080

      Plasmacytes helps get anti bodies to areas where you have foreign invader and anti bodies are part of that immune response.2090

      Adipocytes look like giant yellowish cells and in the corner it is shed over to the side you will see a nucleus.2103

      Some people say that a cross section of adipocytes looks like a pus ring because the pus membrane 2114

      can look a little different and yellow but inside you are going to see lots of yellow.2123

      The point is that it looks like a pus ring because you have that edge and then this little nucleus 2129

      to the side becomes squeezed to one corner and that looks like the jewel of the pus ring.2136

      I have drawn this in yellow because lipids or fats in the body are stored in adipocytes.2140

      This means cells that contains fat.2149

      We have all these fat gem packed inside of the plasma ring in the cytoplasm of this cell and the nucleus is squeezed over to the side because of that fat.2152

      That is the typical look for an adipocyte.2164

      Melanocytes they make melanin.2167

      Melanin is that pigment that gives your skin hair and iris within the eye’s color.2176

      These cells are found all through out your skin.2186

      They are stimulated to make melanin and our genetic factors associated with that and environmental factors like UV radiation.2189

      Connective tissue example when you get combinations of those fibers that I have told you about in cells that make different kinds of connective tissues.2198

      Adipose tissue like I have mentioned before you are going to have adipocytes storing that fat in the body.2208

      The most abundant site for adipose tissue is going to be the deepest parts of your integumentary system.2215

      The lowest parts or deepest part of your skin called the epidermis is a site where you have lots of adipocytes.2223

      The amount of that stored varies for most person and in different parts of the body.2230

      Your buttocks area typically has a lot more adipose storage than in your hands.2236

      Tendons and ligaments are made up of a lot of connective tissue fibers but you also have cells in 2242

      the neighborhood like fibroblasts that can reinforce or make little repairs.2250

      If you tear your ACL you will need surgery to get a strong ligament in there.2255

      If you have microscopic tears that causes a little bit of pain after you got that injury happen, you have cells that reinforce and remake parts of those fibers.2266

      Sometimes people do not need surgery with those tiny little tears.2279

      Your body can compensate for that.2283

      Blood is definitely a connective tissue.2285

      There are lots of blood proteins associated with this particular tissue and there all kinds of blood cells.2290

      Marcophages is just a typical in terms of cells that are assisting in terms of blood flow around your body.2299

      Cartilage are soft bone.2309

      Cartilage found in every movable joint in your body found in the nose, ears, etc. are very important.2312

      You not only have a lot of fibers associated with cartilage but cells that can produce those fibers and release them to make that cartilage.2320

      Bone is a lot harder than cartilage.2330

      Collagen fibers are very abundant in bone.2334

      Without cells in the bone you are not going to be able to produce that collagen and maintain the integrity of your bones.2339

      Muscles are made up of muscle fibers and those fibers in your muscle cells are jam packed with proteins.2349

      These are just several examples of connective tissue types in human body.2359

      Thank you for watching 2363