UNIT ONE: LECTURE CONTENT

https://docs.google.com/document/d/1i-2oD81JIvwhEIJHd__qsMt0rb-edy1OCy4SKP-ylUI/edit?tab=t.0

-ABOVE IS THE GOOGLE DOC WITH SCANNED IMAGES OF MY NOTES

-(More in depth lecture notes, also includes skeletal and muscle tissue.)

Summary of the characteristics and functions of the four human tissue classes:

-All epithelial tissue is tightly packed with cells with little extracellular matrix. This forms continuous sheets to cover body surfaces as well as line body cavities.

-Epithelial Tissue functions for protection(acts as a barrier against injury and illness), secretion (produces various substances such as mucus), absorption (facilitates the uptake of substances), and excretion(elimination of waste products from the body).

-Connective tissue, inversely has less of an abundance of cells and more extracellular matrix compared to epithelial tissues.

-Connective tissue functions for support (provides a structural framework for organs and tissues), storage of nutrients (bone, blood, fat), storage of body fluid (plasma, bone [cement], cartilage [rubber]), movement (bones, ligaments, tendons), defense from infection, and physical protection.

-Muscle tissue is composed of long cells that can contract to produce movement. They are excitable which means the cells respond to a stimulus and the response is usually contraction.

Skeletal Muscle: Striated (protein fibers involved w/ contraction), generate mostly voluntary contractions for movement, helps with heat regulation (shivering)

Smooth Muscle: Not striated, small uninucleate cells, generate involuntary contractions to propel substances along internal passageways.

Cardiac Muscle: Short, branched cells that form connections called intercalated discs (help heart contract in unison); autorythmic (beat on their own). Propel blood by way of the cardiovascular system w/ involuntary contractions.

-Nervous Tissue features neurons which are exciteable, and send an electrical impulse as well as neuroglial cells which support the neurons.

-Nervous Tissue functions for communication between our outside environment and our body. When our sensory receptors receive information our central nervous system processes it to make decisions and then sends that decision to an effector via electrical impulses.

Where each kind of epithelial tissue can be found in the body:

-Simple squamous epithelium: lines alveloi in the lungs

-Stratified squamous epithelium: the skin (epidermis)

-Simple cuboidal epithelium: lines the kidney tubules

-Stratified cuboidal epithelium: salivary glands

-Simple columnar epithelium: lines the stomach

-Pseudostratfied columnar epithelium: nasal passageway

-Transitional epithelium: the bladder

Hierarchical classification of subtypes of connective tissues:

1.) Loose connective tissue:

-Areolar tissue

-Adipose tissue

-Reticular tissue

1a.)Dense connective tissue:

-Dense regular connective tissue

-Dense irregular connective tissue

-Elastic connective tissue

2.) Specialized connective tissue:

2a.) Cartilage

-Hyaline cartilage

-Elastic cartilage

-Fibrocartilage

2b.) Bone

-Spongy bone

-Compact bone

2c.) Blood

-Plasma

-Formed elements

Name and explain the meaning of at least five (5) characteristics shared by all epithelial tissues. Why is each characteristic important in epithelial tissues?

-ALL epithelial tissues have/are:

Cellularity: Epithelial tissue is very densely packed with cells. This is important because it allows for effective barriers against our bodies outside environment. Like seperating our internal organs from external surroundings. The brick like wall that ET puts up is also crucial for defending us against sickness and injury. The tight junctions between cells help keep fluids inside, and it also helps to maintain selective permeability (not just letting everything in).

Innervated: Epithelial tissues are innervated but avascular (no blood vessels). Hence when you get a papercut you do not bleed. The avascularity helps contribute to a protective barrier. If epithelia was super vascular there would be too much blood loss. Since it is intervated epithelia has nerve endings. The nerve endings help convey sensation. They are also avascular because if an invader gains access to the blood supply they gain access to the entire body.

High rate of Regeneration: Epithelial tissue has a high rate of regeneration due to the rapid cell division rates. This is important because epithelia is prone to a lot of wear and tear. Without high rates of regeneration damaged cells would not be able to be quickly replaced, and it would lead to a damage in barrier efficiency and overall health.

Attachment to Basement Membrane: Epithelia is found bound to connective tissue. Areolar connective tissue is used as the glue that binds the CT to the epithelium. The basement membrane provides structural support and helps in the exchange of nutrients and waste products between ET and CT.

Polarity: This means that the top (apical) and the bottom (basal) are different. The apical surface is exposed to the outside environment and the basal surface on internal organs is attached to the underlying connective tissue. The apical surface faces the inside of hollow organ and often has extensions like cillia or microvilli to help with absorption or movement of substances. The nuclei are closer to the bottom and this serves as a protective mechanism. It helps certain epithelial tissues perform certain functions.

Compare and contrast the categories of loose versus dense CT proper. Support your comparison using an example of a specific type in each category (one loose and one dense), including a function (FX) and location (LOC) for each instance.

Loose connective tissue:

Cells of connective tissues:

White blood cells

Mast cells

Stem cells for creating fibroblasts

Fibroblasts:produce fibers and ground substance

Fibrocytes: cell that is no longer producing but maintaining

Matrix:

Collagen fibers: strength

Elastic fibers: Elastic

Reticular fibers: mesh forming

-Loose CT has fewer protein fibers and much more space in the tissue this allows for more room to support other roles for the tissue

-TYPES OF LOOSE CT PROPER:

Areolar: all cells, mostly fibroblasts

Fluid sticky hair gel matrix

THIS HELPS EPITHELIAL STICK TO BASEMENT MEMBRANE

-Areolar is also the main tissue for immune battles

-It also has room for plumbing (routing blood vessels and nerves) 

Reticular: all cells, mainly fibroblasts

Ground substance is BLOOD

All fibers present most common is reticular fibers

Found in all soft organs (thymus, spleen, etc.)

Forms mesh like framework of many organs

Adipose: all cells are present

Stores lipids, helps w/ long term energy storage

Watery matrix

Found in subcutaneous part of skin, heart, liver, mesenteries

Dense regular CT: 

Cells are all present, but its mostly protein fibers-mostly collagen few elastic

Little ground substance

Conveys strength in the way collagen fibers are pulling, but little strength in any other direction can be….

FOUND IN TENDONS!! (MUSCLE TO BONE), LIGAMENTS (BONE TO BONE)

 Dense IRREGULAR CT:

Same cells/ground substance as Dense regular CT except it conveys strength in all directions, bind tissues together, protect, wraps many organs on the outside

Can be found in dermis of skin, submucosa lining

Elastic Ct:

All cells-mainly fibroblasts

All fibers-mostly elastic

Serves as suspension and shock absorbers

Can be found in arteries