Chapter 3: Histology: The Study of Tissues

What is histology?

the study of tissues

What are tissues?

groups of cells located in a distinct region of the body that work together to carry out a specific function

What are the types of tissues in the human body?

epithelial tissue

connective tissue

muscle tissue

nerve tissue

What is epithelial tissue?

a tissue that typically occurs as a sheet of cells that covers or lines surfaces and cavities in the body

What are the 3 different arrangement of cells in epithelial tissues?

simple epithelium

stratified epithelium

pseudostratified epithelium

Simple epithelium:

one cell layer thick; found where substances are absorbed, filtered, or passed through like the lungs, kidneys, or intestines.

Stratified epithelium:

made of two or more layers of cells; found in areas that need protection, like the skin, mouth, and esophagus.

Pseudostratified epithelium:

looks like it has multiple layers but is actually one layer of cells; found in areas like the respiratory tract, where it helps move mucus.

What are the 4 shapes of cells that can be found in epithelial tissue?

squamous cells

cuboidal cells

columnar cells

transitional cells

What are squamous cells like?

these cells are flat/scale like and allow diffusion

What are cuboidal cells like?

these cells are are cube-shaped and help with secretion and absorption

What are columnar cells like?

these cells are tall and aid absorption and secretion (found in stomach and intestines)

What are transitional cells like?

these cells can change shape to allow stretching (found in bladder and ureters).

What are features of the epithelial tissue?

the cells are arranged in sheets and packed closely together

the tissue is avascular

the tissue has a nerve supply

the tissue has a high regeneration reate

What are the functions of the epithelial tissue?

protection, absorption, filtration, excretion, secrtetion, and sensory reception

What is the apical surface of the epithelial tissue?

the upper layer of tissue that is exposed to the exterior or the body cavity

it may contain micorvilli or cilia

What is the basement membranes function?

it holds the epithelial tissue in place and regulates movement of materials between the epithelium and connective tissue

What is the basal lamina?

the top layer of the basement membrane that is secreted by the cells of the epithelial

What is the function of the basal lamina?

it acts as a filter that determines which molecules will diffuse from the connective tissue

What is the reticular lamina?

the bottom layer of the basement membrane that is secreted by cells of the connective tissue

What is the function of the reticular lamina?

to provide support for the epithelial tissue above it

Simple sqamous epithelium structure, function, and location:

made of a single layer of flat, thin cells. Its function is to allow easy diffusion, filtration, and osmosis. It is found in areas where these processes are important, such as the blood vessels (endothelium).

simple cuboidal epithelium structure, function, location:

one cube-shaped layer of cells; functions in secretion and absorption; found in kidneys, glands, and ducts.

simple columnar epithelium structure, function, location, features:

one tall, rectangular layer of cells that functions in absorption and secretion;

can be ciliated (moves substances) or non-ciliated;

often contains goblet cells that secrete mucus;

found in stomach, intestines, and respiratory tract.

stratified squamous epithelium structure, function, location:

multiple layers of flat cells

functions in protection against abrasion and pathogen invasion

can be keratinized (tough, in skin) or non-keratinized (moist, in mouth)

stratified cuboidal epithelium structure, function, location:

two or more layers of cube-shaped cells; functions in protection and secretion of numerous hormones; found in sweat glands, salivary glands, and mammary gland

urothelium structure, function, location:

multiple layers of cells that change shape; functions to allow stretching and protect underlying tissues; found in the urinary bladder, ureters, and part of the urethra.

Psuedostratified epithelium structure, function, location:

one layer of cells that looks like multiple layers; functions in secretion and movement of mucus; often ciliated and contains goblet cells; found in the respiratory tract.

What is the most abundant tissue in the body?

Connective tissue

Features of Connective tissue:

extensive nerve supply

most types are highly vascular (have a rich blood supply)

What are the functions of connective tissue?

binds structures together

provides support, movement

protects, provides immunity

insulates,pads

thansports materials throughout the body

storage

heat production

What are the 3 basic elements connective tissue is composed of?

Cells

Fibers

Ground Substance (matrix + fibers)

Cells of connective tissue:

make up the bulk of the tissue

What are fibers general purpose in connective tissue?

to provide support and strength to the tissue

What are the 3 types of fibers that can be found in connective tissue?

collagen fibers

reticular fibers

elastic fibers

Collagen fibers:

strong but not strechy

abundant in the skin, bones, and cartilage R

Reticular fibers:

form an internal framework for organs

(supportive network inside orangs that gives them shape while also letting cells, blood, and fluid move through them)

Elastic fibers:

composed of a protein called elastin that allows for them to be very stretchy

abundant in tissues associated with lungs and arteries

The ground substance:

the material that surround connective tissue cells that is made up of the matrix and fibers combined

it gives connective tissue its consistency (fluid, gelatinous, solid)

What is mesenchyme?

embryonic connective tissue that develops early and then specializes into different connective tissues that make up the body

What are the types of connective tissue?

areolar connective tissue

adipose tissue

reticular tissue

Dense regular connective tissue

dense irregular connective tissue

cartilage

bone tissue

blood

What is the function/purpose of areolar connective tissue?

to provide strength, support, elasticity to the body structures

What are other functions/features of areolar connective tissue?

anchors epithelium in place (its below it)

serves as a packaging tissue when body is inflamed, it soaks up excess fluid

it is a very strong tissue

Is areolar connective tissue classified as a loose connective tissue or dense connective tissue?

classified as a loose connective tissue because all 3 types of fibers are loosley arranged

What is the function/purpose of adipose tissue?

fat tissue is an insulator, source of stored energy, and padding

Is adipose tissue classified as a loose connective tissue or dense connective tissue?

loose connective tissue

What are adipocytes?

mature cells in adipose tissue specialized for fat storage

What is the subcutaneous layer composed of?

areolar tissue and adipose tissue

What is the function of the subcutaneous layer of fat?

it attaches the skin to tissues and muscles

What is white fat?

typical fat in adults

What is brown fat?

fat in developing fetus/infants.

it generates heat for the baby and it gets its brown color from the blood vessels in the tissue

What is the function/purpose of reticular tissue?

it holds structures together and can form a framework for blood cells to attach to

it is very abundant in lymphatic structures

What type of fibers is reticular tissue made of?

Reticular fibers only

Is reticular tissue classified as a loose connective tissue or dense connective tissue?

loose connective tissue.

What is the function/purpose of dense regular connective tissue?

it provides strength and support to body structures because of the collagen fibers it contains

Is dense regular connective tissue classified as a loose connective tissue or dense connective tissue?

it is classified as a dense connective tissue

What are both tendons and ligaments composed of?

Dense regular connective tissue

What is the function/purpose of a tendon?

to attach muscle to bone

What is the function/purpose of a ligament?

to attach bone to bone

What is the function/purpose of dense irregular connective tissue?

to form sheets of tissue over organs and structures to protect them

Is dense irregular connective tissue classified as a loose connective tissue or dense connective tissue?

it is classifeid as a dense connective tissue.

Why is it called dense IRREGULAR connective tissue?

because the fibers in the tissue are irregularly arranged

Where can dense irregular tissue be found?

in heart valves and periosteum

What is the general function/purpose of cartilage?

to provide support and cushioning

Describe the fibers in cartilage:

the fibers are packed tightly together

What are chondroblasts?

immature chondrocytes that secrete new cartilage matrix

What is an important feature of cartilage?

it has a greatly reduced blood and nerve supply, that makes it slow growing and slow to heal

What is the function/purpose of hyaline caritlage?

to reduce friction and absorb shock at the ends of bones

What type of cartilage forms the growth plates and embryonic skeleteon?

hyaline cartilage

Where is hyaline cartliage located?

at the end of long bones

What type of cartliage forms the ears, nose, glottis, and epiglottis?

elastic cartliage

What is the function/purpose of fibrocartilage?

to form pads in teh body that can withstand extreme pressure

What is an example of fibrocartilage in the body?

intevertebral discs between the vertebrate bones in the spinal cord

What is the function/purpose of bone tissue?

to support and protect body structures

What type of connective tissue is extremly hard and stores calcium and phosphorus for the body?

bone tissue

What makes up the skeleton of the body?

bone and cartilage

What type of bone forms the external covering over all human bones?

Compact bone

What type of bone is composed of thin plates called traberculaes?

spongey bone

Is compact bone or spongy bone composed of Haversian Systems?

Compact bone is

What 4 components make up a Haversian System?

osteocytes

lamella

canaliculi

Haversian canals

What are trabeculae that make up spongy bone composed of?

osteocytes and lamellae

What is an osteocyte?

a mature bone cell located in lacunae

What is lamellae?

rings of matrix

What are canaliculi?

small canals that extend from lacunae that pass nutrients and waste

What are haversian canals?

holes that contain blood vessels and nerves

What kind of matrix does blood have?

a liquid matrix

What is the liquid matrix of blood called?

plasma

what are the components of blood?

plasma and formed elements

What are the formed elements made up of in blood?

cells and cell fragments

What cells are found in blood?

erythrocytes

leukocytes

thrombocytes

What do erythrocytes do?

they carry oxygen to body cells and carbon dioxide to the lungs

What do leukocytes do?

they fight infection

What do thrombocytes do?

blood clottingt

What is the function/purpose of muscle tissues?

move bones, provide the body with support protection, and heat prouction

How are muscle tissues able to generate force for muscle contractions?

because of the special cells called muscle fibers

What are the types of muscle tissue in body?

skeletal muscle tissue

cariac muscle tissue

smooth muscle tissue

What is the function of skeletal muscle tissue?

to attach to and move bones

Is skeletal muscle tissue striatated/non striated and voluntary/involuntary?

it is striated and voluntary (we decide if we want to move or not)

What is the function of cardiac muscle tissue?

this tissue is responsible for pumping blood throughout the body

Is cardiac muscle tissue striated/non striated and voluntary/involuntary?

it is striated and involuntary (our brain pumps our heart for us)