Intro to Histology: The Four Tissue Types. 2022

Studying anatomy at the whole body level is straightforward enough but it gets harder

at the microscopic level.

This jumble of cells looks just like this jumble of cells even though they’re totally

different organs.

This study falls within the field of histology, anatomy at the microscopic level.

While it seems intimidating now, if you pursue this field, you’ll find a beautiful, colorfully

stained perspective of human anatomy that looks nothing like the macroscopic version.

You can also gain clinical insight into pathologies and disease that you can more accurately understand

through a microscope.

But before we can appreciate the more ornate histology, we have to get down some basics,

specifically, four types of tissue that make up every organ in our bodies.

IF you’re new here, welcome, my name is Patrick and right off the bat, I want to tell

you, the goal of this video is to give you somewhere to start.

I’ll have follow up videos so you can get more in depth with the physiology of each

tissue type, but the goal of this video is to get you on your feet and unconfuse those

of you who are feeling lost right now.

Okay, so at the big picture level, the body has all these organs that do different jobs,

and each of your organs has different types of specialized tissue that do jobs within

them.

Each of these tissues are made of specialized cells which work together to get their collective

jobs done.

The four types are:

Muscle tissue in your skeletal muscles, heart, and around blood vessels, nervous tissue in

your brain, spinal cord, and nerves, epithelial tissue in your skin and organs, and connective

tissue pretty much everywhere else which includes stuff like cartilage and tendons but also

your bones and fat cells.

We’ll start with muscle since we only have three types: skeletal, cardiac, and smooth.

All of which have different needs, so they’ll all look and function differently.

Skeletal muscle is the long, spindly stuff that you picture when you hear muscle.

You can usually tell skeletal muscle from its stripey, parallel fibers, or striations,

just like when you’re looking at a piece of steak or chicken breast — that's skeletal

muscle.

It also has multiple nuclei per muscle fiber, these dark dots, which makes it easy to find.

If we took a cross section of it, we’d see distinct bundles of muscle fibers.

Skeletal muscle has quite a bit of variation from sample to sample since muscles have different

shapes and arrangements, but there’s only one of the next muscle.

Cardiac muscle is the other type of striated muscle but is found exclusively in the heart.

This muscle type is built to contract and send signals super quickly, so their structure

reflects that.

Cardiac muscle is more rectangular shaped and has a single nucleus, but it’s dead

giveaway are these things, the intercalated discs.

They’re little passages that open between cardiac cells and let messages pass super

quickly from cell to cell.

The final muscle type is smooth muscle, a muscle type that surrounds organs that need

to expand and constrict like blood vessels, the uterus, and bladder.

They’re the smallest type of muscle and organized into jumbled up sheets, which lets

them contract simultaneously.

That makes them great squeezers, but they’d be terrible biceps.

So when you’re trying to figure out the difference between skeletal, cardiac, and

smooth muscle, look at the shape and layout first.

With a little bit of flashcard time, the patterns become imprinted pretty easily since there’s