Lab 2: Histology

For the different tissues, write down the different CHARACTERISTICS, LOCATION, AND FUNCTIONS

Cell

• The BASIC UNIT OF LIFE

• Contains ORGANELLES AND CYTOPLASM

Organ

GROUPS OF SIMILAR TISSUES that functions together

Histology

STUDY OF TISSUES

Tissue

GROUP OF SIMILAR CELLS that WORK TOGETHER to CREATE A FUNCTIONAL UNIT

Organ System

GROUP OF ORGANS that work together to create a functional unit (like the integumentary system has many organs that creates that system)

Biopsy

EXAMINE TISSUES by EXTRACTING SOME TISSUE CELLS

Interstitial Fluid

This is a TYPE OF EXTRACELLULAR FLUID that SURROUNDS THE CELLS OF TISSUES

Organism

LIVING THING

Histopathology

This DIAGNOSIS + STUDY OF DISEASE OF TISSUES

Epithelial Tissue

A types of tissue that COVERS BODY SURFACES, LINES CAVITIES AND FORMS GLANDS

• CELLS ARE PACKED TOGETHER

• Function:

  • PROTECTION

  • PREVENT WATER LOSS

  • PREVENT PATHOGEN INVASIONS

Goblet Cell

Type of epithelial tissue that SECRETES MUCUS which are FOUND IN THE DIGESTIVE, RESPIRATORY, URINARY, and REPRODUCTIVE SYSTEM

• Mucus can:

  • Trap pathogens in the respiratory system

  • protect lining of digestive system from acids and abrasions

  • lubricate movement of food

Cilia

These are STRUCTURES that WORK TO MOVE MUCUS (in respiratory system) and MOVE EGGS TOWARDS UTERUS (in the reproductive system)

Squamous, Cuboidal, Columnar Cells

• (1) These are FLATTENED, SCALE-LIKE CELLS in the OUTERMOST LAYER OF THE SKIN where DIFFUSION IS EASY TO DO. The NUCLEI is ALSO FLATTENED

• (2) These are CUBE-LIKE CELLS where the NUCLEI IS LARGER THAN MOST and it’s MORE IN THE CENTER

• (3) These are COLUMN-LIKE CELLS where the NUCLEI IS TOWARDS THE SIDES of the cell

Key tip: LOOK FOR LUMENS BECAUSE EPITHELIAL CELLS SURROUND THEM

Simple VS Stratified Tissues

Simple tissues are SINGLE-LAYERED while stratified tissues HAVE MORE LAYERS

Simple squamous epithelium

• Characteristic: SINGLE LAYER of FLAT, PLATE-LIKE CELLS (looks like fishscales)

• Location: ALVEOLI (AIR SACS) within LUNGS and WALLS OF CAPILLARIES and CAVITIES

• Function: EASY DIFFUSION; EFFICIENT EXCHANGES of materials and waste

Key thing: these (epithelial cells in general) LINE the LUMEN (CAVITIES/SPACES)

Simple cuboidal epithelium

• Characteristic: CUBE-SHAPED CELLS, NUCLEI is in the CENTER, and it’s SINGLE LAYER

• Location: KIDNEYS

• Function: FILTERS BLOOD AND MAKE URINE

Key thing: these (epithelial cells in general) LINE the LUMEN (CAVITIES/SPACES)

simple columnar epithelium

• Characteristic: COLUMN-SHAPED CELLS and the NUCLEI IS ON ONE END OF THE CELL (it’s not in the middle)

• Location: DIGESTIVE TRACT and FALLOPIAN TUBES

• Function:

  • In the digestive tract it, MAKES LUBRICATING MUCUS (via goblet cells) and PROTECTS LINING FROM ACID AND ABRASION

  • In In the respiratory tract, MUCUS TRAPS MICROBES

  • In the fallopian tubes, CILIA MOVES EGGS

Pseudostratified columnar epithelium

• Characteristic:

  • SINGLE LAYER OF COLUMNAR CELLS, but their nuclei appear at different levels

    • MAY CONTAIN SOME CILIA

• Location: TRACHEA

• Function: PROTECTION AND TRANSPORT MICROBES AWAY FROM LOWER RESPIRATORY TRACT

Stratified squamous epithelium

• Characteristic: MULTIPLE LAYERS OF SQUAMOUS CELLS

  • It’s FLAT WITH A LOT OF LAYERS

• Location: EPIDERMIS OF SKIN and LINING OF MOUTH

• Function: PROTECTION

Transitional epithelium

• Characteristic: STRATIFIED TISSUES that LOOK CUBOIDAL (when not stretched) and SQUAMOUS (when stretched)

• Location: URINARY BLADDER

• Function: WITHSTAND STRESS OF BEING STRETCHED as the organ fill up (with pee or some form of liquid)

Key tip: The DEEPEST LAYER (basal layer) looks more CUBOIDAL/COLUMNAR but as it starts reaching towards the surface, the size would vary

Extracellular Matrix

This is the SPACE OUTSIDE ANY CELL/TISSUE which HOLDS TISSUES TOGETHER and HELP CELL COMMUNICATION WITH OTHERS

• Remember, the interstitial fluid is a type of extracellular matrix

• Components are different proteins like collagen, elastin, fibronectin, ETC

Connective Tissue

These are TISSUES that CONNECT, SUPPORT, PROTECT, AND BIND OTHER TISSUES/ORGANS TOGETHER

Fibroblasts

MOST COMMON CELLS in the tissue that MAKE/SECRETE COLLAGEN, ELASTIC, AND RETICULAR

• These are the “FIBER-BUILDERS”

• Looks CIRCULARISH under the microscope

Elastic Fibers

These are STRETCHY FIBERS made of protein elastin which ALLOWS STRETCH AND RECOIL (like a rubber band)

• THIN, DARK LINES in the microscope

• Kinda looks like stretch marks under the microscope

• Made from elastin (a type of fiber)

Collagen Fibers

These are FIBERS that RESIST STRETCH and MAKES THE SKIN MORE TIGHT

• PREVENTS SAGGING AND WRINKLES

  • Losing collagen → more wrinkles around the face and body

• These look THICK

Areolar Connective Tissue

• Characteristics:

  • LOOSE CONNECTIVE TISSUE

  • CONTAINS FIBROBLASTS

    • PRODUCE ELASTIC AND COLLAGEN FIBERS

      • Arranged in a MESSY, IRREGULAR PATTERN

• Location: DERMAL LAYER of the SKIN

• Function: CUSHIONING, HYDRATION, ELASTICITY, STRENGTH

  • Think CHES

Adipose connective tissue

• Characteristics: LOOSE CONNECTIVE TISSUE with cells called adipocytes (these LOOK LIKE EMPTY SACS)

  • Contains MOSTLY of EXTRACELLULAR MATRIX

• Location: HYPODERMAL LAYER OF SKIN

• Function: INSULATION, ENERGY STORAGE

Tip: these LOOK SKINNYYYYYYY with a lot of empty space (adipocytes) in the middle

Adipocytes

These APPEAR LIKE EMPTY SACS, but it’s ACTUALLY COLORLESS LIPIDS with things that are stored inside

Dense regular connective tissue

• Characteristic: Has TIGHTLY PACKED COLLAGEN FIBERS that MAKE A WAVE-LIKE PATTERN

• Location: TENDONS/LIGAMENTS

• Function: STRENGTH

Cartilage connective tissue

These are AVASCULAR CONNECTIVE TISSUES with DENSE MATRIX

• These are tissues that DON’T HAVE BLOOD CELLS

Tip: ANYTHING WITH __________ CONNECTIVE TISSUES ARE AVASCULAR

Chondrocytes

These are CARTILAGE CELLS that MAINTAIN AND FORM CARTILAGE MATRIX

Lacunae (s. lacuna)

These are EMPTY, SMALL SPACES IN THE CARTILAGE AND BONE where the chondrocytes would live in

• THINK OF A UNFINISHED, NEW YORK APARTMENT (these are typically SMALL)

Hyaline cartilage connective tissue

• Characteristic: These are AVASCULAR TISSUES that have A LOT OF COLLAGEN FIBERS

• Location: ENDS OF LONG BONES

• Function: REDUCE FRICTION BETWEEN MOVING BONES

The difference between the hyaline and the elastic cartilage connective tissue is that the _____ IS MORE PINK TONED, while the ELASTIC IS MORE PURPLE TONES

• Both have lacunae and chondrocytes though

Elastic cartilage connective tissue

• Characteristic:

  • DARK-STAINED ELASTIC FIBERS

  • LOOKS LIKE EYEBALLS

• Location: EXTERNAL EAR STRUCTURE; EPIGLOTTIS

• Function: GIVE MORE FLEXIBILITY

Fibrocartilage connective tissue

• Characteristic: SLIGHTLY LESS FIRM MATRIX which means we could SEE THE COLLAGEN FIBERS; still has the chondrocytes and lacunae

• Location: VERTEBRAL DISKS

• Function: GIVE MORE SUPPORT AND PADDING

Bone connective tissue

• Characteristic: HAS OSTEOCYTES that LIVE IN LACUNAE; The FUNCTIONAL UNIT of a bone is the OSTEON which HAS THE LAMELLAE and CANALICULI (little canals) that connect osteocytes

• Location: ALL BONES OF SKELETON

• Function: GIVE STRUCTURAL FRAMEWORK, PROTECT UNDERLYING TISSUES, STORE IMPORTANT NUTRIENTS

Blood connective tissue

• Characteristic: HAS PLASMA and THREE CELL TYPES (erythrocytes, leukocytes, thrombocytes).

• Location: WITHIN CIRCULATORY SYSTEM

• Function: Erythrocytes carry gases; leukocytes function within the immune system; thrombocytes play a role in blood clotting

Erythrocytes

These are RED BLOOD CELLS that CARRY OXYGEN

Leukocytes

WHITE BLOOD CELLS that FIGHT INFECTIONS/DISEASES

Thrombocytes

PLATELETS which HELPS IN BLOOD CLOTTING

Skeletal muscle tissue

• Characteristic:

  • VOLUNTARY

  • MULTINUCLEATE

  • STRIATIONS

• Location: Attaches to bones to move the body

• Function: Contract to produce body movements

Looks more CLEAN and NOT BRANCHY LOOKING

Cardiac muscle tissue

• Characteristic:

  • INTERCALATED DISCS

  • THIN STRIATION

  • BRANCHY

  • UNINUCLEATE

• Location: HEART

• Function: Allows the heart to pump blood throughout the body

This looks VERY BRANCHY

Smooth muscle tissue

• Characteristic:

  • INVOLUNTARY

  • NO STRIATION

  • SMOOTH

• Location: INTERNAL ORGANS (IRIS in the eye OR DIGESTIVE TRACT)

• Function: CONSTRICT BLOOD VESSELS/CONTRACT MUSCLES

Nervous tissue

• Characteristic: Made of NEURONS and NEUROGLIAL CELLS. There’s a CELL BODY, DENDRITE, and AXON.

• Location: BRAIN AND SPINAL CORD

• Function: TRANSMIT ELECTRICAL SIGNALS for the brain and body to process certain things