#2 Tissues, Part1

The thing about amoebas is that they do everything in the same place.

They take in and digest their food, and regect their waste, and get through everything else they need to do, all within a single cell.

 

Every cell in your body has its own specific job description related to maintaining your homeostasis, that balance of materials and energy that keeps you alive.

Groups of similar cells come together to perform a common function.

 

Tissues are like the fabric of your body. In fact, the term literally means "woven."

And when two or more tissues combine, they form our organs.

The type of tissue difines its funtion.

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<Nervous, Muscle, Epithelial & Connective Tissues>

• Nervous tissue provides us with control and communication
• Muscle tissues give us movement
• Epithelial tissues line our body cavities and organs, and essentially cover and protect the body
• Connective tissues provide support

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<History of Histology>

HISTOLOGY
The study of our tissues 

To actually see a specimen under a microscope, you have to first preserve, or fix it, then slice it into super-thin, and then stain that material to enhance its contrasts.

Because different stains latch on to different cellular structures, this process lets us see what's going on in any given tissue sample, down to the specific parts of each individual cell.

Some stains let us clearly see cell's nuclei and as you learn to identify different tissues, the location, shape, size, or even absence of nuclei will be very important.

CARMINE
A red dye derived from the scales of a crushed-up cochineal insects.

The combination of the right microscope and the right stain could open up our understanding of all of our body's tissues and how they make life possible.

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<Nervous Tissue Forms the Nervous System>

The nervous system - that is, the brain and spinal cord of the central nervous system, and the network of nerves in your peripheral nervous system. Combined, they regulate and control all of your body's functions.

 

That basic nervous tissue has two big functions - sensing stimuli and sending electrical impulses throughout the body, often in response to those stimuli.

And this tissue also is made up of two different cell types - neurons and glial cells.

Neuronas are the specialized building blocks of the nervous system.

The cell body, or soma, is the neuron's life support. It's got all the necessary goods like a nucleus, mitochondria, and DNA.

The bushy dendrites look like the trees that they're named after, and collect signals from other cells to send back to the soma. They are the listening end.

The long, rope-like axon is the transmission cable - it carries messages to other neurons, and muscles, and glands.

The glial cells are like the neuron's pit crew, providing support, insulation, and protection, and tethering them to blood vessels.

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<Muscle Tissue Facilitates All Your Movements>

Muscle tissue is well-vascularized, meaning it's got a lot of blood coming and going, and it comes in three flavors: skeletal, cardiac, and smooth.

Your skeletal muscle tissue is what attaches to all the bones in your skeleton, supporting you and keeping your posture in line.

Skeletal muscle tissues pull on bones or skin as they contract to make your body move.

Cardiac muscle tissue works involuntarily.

This tissue is only found in your heart, and its regular contractions are what propel blood through your circulatory system.

Cardiac muscle tissue is also striped, or striated, but unlike skeletal muscle tissue, their cells are generally uninucleate, meaning that they have just one nucleus.

Smooth muscle tissues are sort of short and tapered at the ens, and are arranged to form tight-knit sheets.

This tissue is also involuntary, because like the heart, these organs squeeze substances through by alternately contracting and relaxing, without you having to think about it.