TISSUES

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Cells Tissues Organs Organ systems Organism

Cells are not found by themselves; they’re with others. These are called tissues.

TISSUE: A group of cells, usually similar, which share a particular function.

ORGAN A group of tissues which share a particular function.

ORGAN SYSTEM: A group of organs which share a particular function (digestive system, nervous system).

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Cell Differentiation

Through the process of cell differentiation (growing up and maturing, becoming a specialist), each cell develops a characteristic set of structural features.

Each cell has to contribute one piece toward the overall function of the organism, so that all the vital functions can be covered.

During differentiation, cells in nearby locations become able to work together.

After differentiation, cells do not change their function throughout their life cycle

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TYPES OF TISSUES WE’LL DISCUSS: EPITHELIUM: a sheet of cells that makes up the

surface of the skin and also lines tubes in the body.

CONNECTIVE TISSUE: deep to the epithelium; supplies oxygen and nutrients to epithelium.

Fibrous (Proper) Connective Tissue Special Connective Tissue (cartilage, bone, blood,

muscles, nerves) MUSCLE TISSUE: makes up muscles, and these cells

are able to contract, unlike fibrous connective tissue. It is bound together by areolar connective tissue. (discussed in later lectures)

NERVOUS TISSUE: makes up brain and nerves (discussed in later lectures)

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EPITHELIA: (plural form of epithelium): sheets of cells that makes up the surface of the skin and also lines tubes in the body.

Function of epithelia:

The epithelial cells are the type of tissue that protects the underlying structures

What is the difference between epithelium and epidermis?

Epidermis is the outermost layer of skin. It consists of epithelial cells, but epithelium is also found in areas lining the tubes of the body (digestive, respiratory, urinary systems, etc)

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Epithelium

Epithelium is the tissue that covers the outside of the body (the top layer of the skin), and it also lines the tubes within the body.Digestive tractRespiratory tractCardiovascular systemUrinary tractReproductive tractSweat glands and other exocrine glands

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The hollow space within each of these tubes is called a lumen.

The lumens are always lined by epithelial cells.

Kidney

Sweat glands

Trachea

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Basement Membrane

All epithelia sit on top of connective tissue, and is connected to it by a BASEMENT MEMBRANE (which is not a cell membrane), made of protein fibers that connect to epithelium.

The only function of the basement membrane is to attach the epithelium to the connective tissue beneath it.

Epithelia get oxygen and nutrients from the blood vessels in the connective tissue beneath the basement membrane.

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Microvilli

Villus = finger-like projection. The presence of large numbers of microvilli on the exposed surfaces of epithelial cells indicates that this is the area where absorption and secretion take place.

These cells are transportation specialists.

They are probably located along portions of the digestive and urinary tracts

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Special Characteristics of Epithelia

Figure 4.1

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Epithelium

Epithelium is always BIPOLAR:

APICAL SIDE: touches the lumen (inside heart, stomach, etc).

BASAL SIDE: touches the basement membrane

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Classifications of Epithelia

Figure 4.2

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SIMPLE EPITHELIUM

SIMPLE EPITHELIUM has only one cell layer.

SIMPLE SQUAMOUS EPITHELIUM:

SIMPLE CUBOIDAL EPITHELIUM

SIMPLE COLUMNAR EPITHELIUM

PSEUDOSTRATIFIED EPITHELIUM

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SIMPLE SQUAMOUS (thin) EPITHELIUM

SIMPLE SQUAMOUS (thin) EPITHELIUM are flat cells that allow diffusion of materials between the cells.

This type of epithelium is in regions where a lot of diffusion is needed from one compartment to another, such as the lungs and a region in the kidney called the glomerulus.

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Simple Squamous Epithelium

Figure 4.3a

Found in the lungs

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Simple Squamous EpitheliumFound in the lungs Found in the kidneys

(glomerulus)

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SIMPLE CUBOIDAL EPITHELIUM

SIMPLE CUBOIDAL EPITHELIUM is cube shaped and is also found in areas where there is a lot of material going across from one compartment to another.

This cell type has plenty of room for organelles.

This epithelium is found in the intestines, and a region of the KIDNEY called the convoluted tubules, and places that need diffusion as well as room for cell organelles.

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Simple Cuboidal Epithelium

Figure 4.3b

Found in the kidneys (convoluted tubules)

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Glomerulus

Tubule

KIDNEYTubules are simple cuboidal

Glomerulus is simple squamous

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SIMPLE COLUMNAR EPITHELIUM

SIMPLE COLUMNAR EPITHELIUM is shaped like a column and are found in areas where the cells are needed for secretion and absorption (intestines).

When they are differentiated into GOBLET CELLS, they produce mucus.

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Simple Columnar Epithelium

Figure 4.3c

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PSEUDO-STRATIFIED COLUMNAR EPITHELIUM

PSEUDO-STRATIFIED COLUMNAR EPITHELIUM is a single layer of cells that appears to be more than one layer thick, but it is not. The nucleus on one cell is at the top, and the nucleus of the next cell is at the bottom.

Pseudostratified epithelium always has cilia on its apical surface. Each cilium is a hair-like structure that moves back and forth to move material in a certain direction.

This type of epithelium needs goblet cells nearby to produce the mucus that contains the material to be swept. These cells will be found in the respiratory tract (the trachea), where the mucous catches the debris you inhale and the cilia sweeps the material up to your throat where you cough and swallow it.

Its only functions are protection and mucous production.

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Pseudostratified Columnar Epithelium

Figure 4.3d

Found in the trachea

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A Cilium

Figure 4.8

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STRATIFIED EPITHELIUMSTRATIFIED EPITHELIUM has more than one cell layer. The

type of epithelium is named by the APICAL layer.

STRATIFIED SQUAMOUS EPITHELIUM:

1) Keratinized stratified squamous epithelium

2) Non-keratinized stratified squamous epithelium  

STRATIFIED CUBOIDAL EPITHELIUM

STRATIFIED COLUMNAR EPITHELIUM

TRANSITIONAL EPITHELIUM

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STRATIFIED SQUAMOUS EPITHELIUM

STRATIFIED SQUAMOUS EPITHELIUM: the type is named by the apical cells. Stratified squamous epithelium is found in regions of the body where there is a lot of abrasions or wear-and tear, and it is the most protective (it is the thickest).

1) KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM has apical cells that contain a protein called keratin, which is waterproof. All of our dry skin is this type, and it is especially thick in the palms and soles. It is very good at resisting abrasions.

2) NON-KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM does not have the keratin, so it will be moist skin, like what is found lining the mouth and esophagus.

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Stratified Squamous Epithelium (keratinized)

Found in dry skin

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Stratified Squamous Epithelium (non-keratinized)

Figure 4.3e

Found in moist skin (mouth and esophagus)

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STRATIFIED CUBOIDAL EPITHELIUM

STRATIFIED CUBOIDAL EPITHELIUM usually consists of only two layers, and there is almost no diffusion between them.

It is found in sweat glands.

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Stratified Cuboidal Epithelium

Figure 4.3f

Found in sweat glands

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Stratified Cuboidal Epithelium

Found in Sweat Glands

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STRATIFIED COLUMNAR EPITHELIUM

STRATIFIED COLUMNAR EPITHELIUM usually has just a few layers and this type of epithelium inhibits diffusion of materials.

It is relatively rare, providing protection along portions of the pharynx, urethra, and anus.

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Stratified Columnar Epithelium

Figure 4.3g

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TRANSITIONAL EPITHELIUM

TRANSITIONAL EPITHELIUM can stretch and change shape.

This type is what lines the urinary bladder and it looks like this as it goes from empty to full.

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Transitional Epithelium

Figure 4.3h

Found in the urinary bladder

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Connective Tissues

Types of Connective Tissues

FIBROUS (PROPER) Connective tissues

SPECIAL CONNECTIVE TISSUE

Functions of Connective Tissues

Defend the body from invasion by microorganisms

Provide protection for delicate organs

Establish a structural framework for the body

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FIBROUS (PROPER) Connective tissues

FIBROUS (PROPER) Connective tissuesADIPOSE (fat)RETICULAR (lymph nodes)LOOSE (aka AREOLAR; upper dermis)DENSE

REGULAR (tendons and ligaments) IRREGULAR (lower dermis and joint capsules)

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Adipose

ADIPOSE

Main cell type is an adipocyte (stores fat)

Functions: Cushions organs Food Storage Insulation

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Adipose Tissue

Figure 4.12c

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Lipoma

These are benign fat nodules in the hypodermis, usually associated with high cholesterol levels. They are easily surgically excised (removed)

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LiposarcomaPatients usually note a deep

seated mass in their soft tissue. Only when the tumor is very large do symptoms of pain or functional disturbances occur.

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Most frequent in middle-aged and older adults (age 40 and above), liposarcomas are the second most common of all soft-tissue sarcomas . Annually 2.5 cases occur per million population.The prognosis varies depending on the site of origin, the type of cancer cell, the tumor size, the depth, and proximity to lymph nodes. Well-differentiated liposarcomas treated with surgery and radiation have a low recurrence rate (about 10%) and rarely metastasize.

Why you got fathttp://www.youtube.com/watch?v=mNYlIcXynwE

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Are you more drunk than you think?, http://fxn.ws/TqUdz9

Women have a higher fat-to-water ratio than men do.

A 150-pound man holds more water than a 150-pound woman; after one drink, the woman will have a higher concentration of booze in her blood. That leads to greater intoxication. And her liver has to work harder to metabolize that alcohol, prolonging her buzz. 

For every drink a woman has, it’s the equivalent of a drink and a half for a same-sized man.

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Reticular Connective Tissue

Figure 4.12d

Found in lymph node

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Reticular Connective Tissue45

Loose Connective Tissue

LOOSE (AREOLAR) connective tissue

This is the least specialized connective tissue.

The main cell type in loose and dense connective tissue is a FIBROBLAST (a type of cell, not just a part of a cell). Fibroblasts are what make collagen and elastic fibers, and they also and repair wounds.

Areolar is common in areas just deep to epidermis (upper dermis).

It does NOT have much collagen as dense because it does not have many fibroblasts.

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Areolar Connective Tissue

Figure 4.12b

Found in dermis

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Dense Regular Connective TissueDENSE REGULAR connective tissue

Dense regular and irregular connective tissue has lots of COLLAGEN FIBERS

Dense regular has more collagen than irregular.

Dense regular fibers have a pattern, and run in same direction

Even more strong than irregular, but only in one direction

Ligaments and tendons are dense regular CT. Note: tendons are not muscle tissue; they are

dense regular connective tissue.

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Dense Regular Connective Tissue

Figure 4.12f

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NOTE: If you get injured, you’d rather break a bone than tear a ligament, why?

The number of fibroblasts is the same, but the ligament has a lot more collagen to be made by each fibroblast.

And the blood supply to bone is much better than a ligament.

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Dense Irregular

DENSE IRREGULAR connective tissue Has lots of COLLAGEN FIBERS Fibers have irregular position; no pattern Extremely strong in all directions Found in areas of body where strength is needed

(joint capsules and deeper layer of the dermis).

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Dense Irregular Connective Tissue

Figure 4.12e

Found in joint capsules and dermis

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Scleroderma Scleroderma is a chronic systemic autoimmune disease (primarily of the

skin) characterized by fibrosis (or hardening), vascular alterations, and autoantibodies. There are two major forms:

Limited systemic sclerosis/scleroderma involves cutaneous manifestations that mainly affect the hands, arms, and face. It was previously called CREST syndrome in reference to the following complications: Calcinosis, Raynaud's phenomenon, Esophageal dysfunction, Sclerodactyly, and Telangiectasias. Additionally, pulmonary arterial hypertension may occur in up to one-third of patients and is the most serious complication for this form of scleroderma.

Diffuse systemic sclerosis/scleroderma is rapidly progressing and affects a large area of the skin and one or more internal organs, frequently the kidneys, esophagus, heart, and lungs. This form of scleroderma can be quite disabling. There are no treatments for scleroderma itself, but individual organ system complications are treated.

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Scleroderma

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GranulomaA granuloma is an inflammation found in many

diseases. It is a collection of immune cells known as macrophages.

Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate.

Such substances include infectious organisms such as bacteria and fungi as well as other materials such as keratin and suture fragments.

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Lightning Strike

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Special Connective TissueSpecial Connective Tissue

Cartilages Hyaline cartilage (most joints) Elastic cartilage (ear) Fibrocartilage (intervertebral discs)

Bone tissues Compact bone (shaft of long bones) Spongy bone (ends of long bones)

BloodMuscles (discussed more in later lectures)Nerves (discussed more in later lectures)

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CartilageCartilages

Main cell type is CHONDROCYTEExtracellular matrix is dense collagen; almost

solid, very rigidAvascular (no blood vessels. Torn cartilage

won’t heal).There are three types of cartilage:

HYALINE CARTILAGE ELASTIC CARTILAGE FIBROCARTILAGE

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Hyaline Cartilage

Figure 4.12g

Found in most joints

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Hyaline Cartilage

Hyaline Cartilage

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Hyaline Cartilage

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Elastic Cartilage (elastin fibers)

Figure 4.12h

Found in the ear

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Elastic Cartilage

Found in the outer ear

LacunaeElastic fibersChondrocytes

Elastic cartilage

Chondrocytes

Lacunae

Elastic fibers

Outer Ear

Fibrocartilage Found in intervertebral discs; resists compression

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Fibrocartilage

Chondrocytes

Lacunae

Collagen fibers

Vertebral discs

Fibrocartilage

Chondrocytes

Lacunae

Collagen fibers

Vertebral discs

Bone

Bone tissues Main cell type is OSTEOCYTE = “bone cell”Extracellular matrix is solid, full of minerals

(instead of fluid)Minerals are: Calcium carbonate and

Calcium phosphate (same as limestone)

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Bone Tissue: Compact Bone

Figure 4.12j

Found in shaft of long bones

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Spongy Bone

Found in ends of

long bones

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Blood

Blood tissueMain cell type is ERYTHROCYTEExtracellular matrix is PLASMA (no elastin

or collagen because it would form clots)

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Blood Tissue

Figure 4.12k

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Types of Membranes

Synovial

Mucous

Serous

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Synovial MembranesThis membrane lines the inside of fluid-filled

joints.

The cellular layers are incomplete, with gaps between adjacent cells to allow the fluid to escape into the joint to serve as a cushion.

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Mucous Membranes

Mucous membranes are covered in epithelium, which are involved in absorption and secretion.

They line cavities that are exposed to the external environment and internal organs.

They are located at the nostrils, the mouth, the lips, the eyelids, the ears, the genital area, and the anus.

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Serous MembranesSerous membranes secrete a watery fluid.

The fluid reduces friction from muscles or organs rubbing against each other. Its major function is to produce tiny amounts of watery liquid on their opposing surfaces to reduce friction.

The serous membrane covering the heart is the pericardium. Inflammation here is called pericarditis.

The serous membrane surrounding the lungs is the pleura. Inflammation here is called pleuritis.

The serous membrane lining the abdominal cavity is the peritoneum. Inflammation here is called peritonitis.

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Another way to classify epithelium

1. MOIST EPITHELIUM: there are two types:

a. MUCOSA is the cell type that produces mucous. Therefore, pseudo-stratified columnar epithelium is a mucous epithelium, or a mucosa.

b. SEROSA is an epithelium that has watery secretions on the surface. This is found in sweat glands.

2.DRY EPITHELIUM is keratinized stratified squamous epithelium.

How would non-keratinized stratified squamous epithelium be classified?

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Collagen

COLLAGEN

This is a type of fiber that is found in all connective tissues (other than blood).

It gives connective tissues an elastic consistency.

It has very little blood supply, so it does not regenerate well.

It does not interfere with diffusion of materials from one area to another; it just provides support for connective tissues.

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Collagen fibers79

Types of Glands

Exocrine GlandSecretes substances into a duct (a tunnel) and then

excretes it into the lumen or onto the skin (e.g. sweat, oil)

Endocrine GlandSecretes substances into the blood to be transported

to another part of the body, where it is used (e.g. hormones). Endocrine glands are ductless. We will discuss endocrine glands in a separate lecture.

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Exocrine Glands

Classification of Exocrine GlandsType of secretionMethod of secretionStructure

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Exocrine Glands

EXOCRINE GLANDS

1. Classified based on the type of secretion

a. SEROUS GLANDS secrete water, as found in sweat glands.

b. MUCOUS GLANDS secrete mucous, as found in goblet cells

c. MIXED GLANDS secrete mucous and water as found in salivary glands.

d. OIL GLANDS secrete waxy and oily substances, as found in sebaceous glands and ear wax.

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Glands

2. Classified by the method of secretion

Merocrine (Eccrine) glands

Apocrine glands

Holocrine glands

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Merocrine Gland Exocytosis

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2. Classified by the method of secretiona. MEROCRINE (Eccrine) GLANDS produce a secretion by a process called EXOCYTOSIS. Example is sweat gland

Cell of merocrine gland

Vesicle with secretion inside

The vesicle moves to and binds with the cell membrane, pops open and releases the secretion

Merocrine Gland Functions

Thermoregulation

Inhibiting the growth of bacteria on the skin

Excretion of water, electrolytes, and some drugs

They do not function as a lubricant for the skin.

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Apocrine Glandsb. APOCRINE GLANDS accumulate material in the apical section, the top of the cell breaks off, and the material is released. The cells that broke down will grow again. Examples are the mammary glands and oil glands associated with pubic hairs.

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Holocrine Glands

c. HOLOCRINE GLANDS are those where the entire cell breaks off with all the contents inside, such as sebaceous (oil) glands. After the cell breaks off, the other cells move in quickly and close up the gap.

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Exocrine Glands

3. Classified by their structure (what they look like)

a. UNICELLULAR GLANDS, for example a GOBLET CELL.

Goblet cells are found in the trachea and secrete mucous to trap debris; then you cough it up.

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GOBLET CELL89

Glandsb. MULTICELLULAR GLANDS

Alveolar

Simple alveolar

Compound alveolar (mammary glands)

Tubular

Simple tubular (sweat glands)

Compound tubular

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Multicellular Glands

Alveolar Tubular

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Types of Multicellular Exocrine Glands

Figure 4.6

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Brown Recluse Spider

They like dark spaces & woodpiles. Also cool areas in the attic

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Day 3

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Day 5

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Day 6

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Day 9

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Day 10

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Brown Recluse Spider

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Get a Venom Extractor Kit

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Get a Venom Extractor Kit

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