Chapter 4 - 2Chapter 4 - 2

HistologyHistologyTissues and MembranesTissues and Membranes

Adipose Connective TissueAdipose Connective Tissue Mature cells are specialized for storage of Mature cells are specialized for storage of

triglycerides and largest cells in body.triglycerides and largest cells in body. Adipocytes are derived from fibroblast cells.Adipocytes are derived from fibroblast cells. Cells fill up with triglycerides which push cell Cells fill up with triglycerides which push cell

nuclei to the periphery of the cell.nuclei to the periphery of the cell. Most adipose in adults is white adipose Most adipose in adults is white adipose

tissue.tissue. Brown adipose tissue gets its coloration from Brown adipose tissue gets its coloration from

rich vascular supply and is less common.rich vascular supply and is less common. Functions as insulation, energy storage, Functions as insulation, energy storage,

protects and supports organs.protects and supports organs. Usually found with or close to areolar tissue.Usually found with or close to areolar tissue.

Adipose Connective TissueAdipose Connective Tissue

Reticular Connective TissueReticular Connective Tissue

Composed of interlacing reticular fibers Composed of interlacing reticular fibers with various types of cells interspersed with various types of cells interspersed among the fibers.among the fibers.

Forms the stroma of the liver, spleen and Forms the stroma of the liver, spleen and lymph nodes and helps to bind smooth lymph nodes and helps to bind smooth muscle cells.muscle cells.

Reticular Connective TissueReticular Connective Tissue

Dense Regular Connective Dense Regular Connective TissueTissue

Composed of bundles of collagen fibers Composed of bundles of collagen fibers regularly arranged in parallel patterns.regularly arranged in parallel patterns.

Fibroblasts are interspersed between the Fibroblasts are interspersed between the collagen fibers.collagen fibers.

Main component in ligaments, tendons, Main component in ligaments, tendons, aponeuroses and fascia.aponeuroses and fascia.

Has a wavy appearance on slides.Has a wavy appearance on slides. Forms tendons to attach muscles to bone Forms tendons to attach muscles to bone

and ligaments to attach bones to bones.and ligaments to attach bones to bones.

Dense Regular Connective Dense Regular Connective TissueTissue

Dense Irregular Connective Dense Irregular Connective TissueTissue

Similar to areolar connective tissue but Similar to areolar connective tissue but collagen fibers are much thicker.collagen fibers are much thicker.

Fibers run in different planes making this Fibers run in different planes making this a very strong tissue and resistant to a very strong tissue and resistant to strong tensions from all directions.strong tensions from all directions.

Found in dermis; fibrous capsules Found in dermis; fibrous capsules surrounding kidneys, bones and lymph surrounding kidneys, bones and lymph nodes; and in the submucosa of the GI nodes; and in the submucosa of the GI tract.tract.

Dense Irregular Connective Dense Irregular Connective TissueTissue

Dense Irregular Connective Dense Irregular Connective TissueTissue

Elastic Connective TissueElastic Connective Tissue

High content of branching elastic fibers.High content of branching elastic fibers.

Very distensible, allows for stretching and Very distensible, allows for stretching and returning to original shapes.returning to original shapes.

Found in lung tissue, large elastic Found in lung tissue, large elastic arteries, and suspensory ligaments .arteries, and suspensory ligaments .

Elastic Connective TissueElastic Connective Tissue

CartilageCartilage

Three types:Three types:

1.1. Hyaline cartilageHyaline cartilage

2.2. Fibrocartilage Fibrocartilage

3.3. Elastic cartilageElastic cartilage

Hyaline CartilageHyaline Cartilage

Consists of a dense network of collagen Consists of a dense network of collagen fibers embedded in a gel-like ground fibers embedded in a gel-like ground substance containing chondroitin sulfate substance containing chondroitin sulfate with chondrocytes situated in lacunae.with chondrocytes situated in lacunae.

Matrix appears homogeneous and clear Matrix appears homogeneous and clear of fibers.of fibers.

The predominant cartilage found in the The predominant cartilage found in the trachea, bronchi, articular cartilages, trachea, bronchi, articular cartilages, nose and ribs.nose and ribs.

Hyaline CartilageHyaline Cartilage

Elastic CartilageElastic Cartilage

Consists of chondrocytes located in Consists of chondrocytes located in lacunae surrounded by a network of lacunae surrounded by a network of elastic fibers.elastic fibers.

Found in epiglottis, pinna of the ear and Found in epiglottis, pinna of the ear and the internal auditory canal (Eustachian the internal auditory canal (Eustachian tube)tube)

Elastic CartilageElastic Cartilage

FibrocartilageFibrocartilage

Consists of chondrocytes in lacunae Consists of chondrocytes in lacunae scattered among bundles of collagen scattered among bundles of collagen fibers.fibers.

Most predominant in intervertebral discs, Most predominant in intervertebral discs, pubic symphysis, and menisci of knee pubic symphysis, and menisci of knee joints.joints.

Fibro cartilageFibro cartilage

BoneBone

Two types: Compact and SpongyTwo types: Compact and Spongy

CompactCompact bonebone consists of osteons consists of osteons (Haversian systems) osteocytes in lacunae (Haversian systems) osteocytes in lacunae and lamellae.and lamellae.

Spongy boneSpongy bone is characterized by is characterized by trabeculae surrounded by spaces filled with trabeculae surrounded by spaces filled with red bone marrowred bone marrow

BoneBone Two types: a) Compact b) SpongyTwo types: a) Compact b) Spongy

Compact BoneCompact Bone

BloodBlood

Consists of liquid portion (plasma)Consists of liquid portion (plasma) Erythrocytes (RBC)Erythrocytes (RBC) Leukocytes (WBC’s = 5 types)Leukocytes (WBC’s = 5 types) Platelets (Thrombocytes)Platelets (Thrombocytes)

Functions to carry nutrients and waste Functions to carry nutrients and waste products to and from tissues as well as products to and from tissues as well as protect body against foreign invaders and protect body against foreign invaders and infection. Also active against bleeding infection. Also active against bleeding maladies and hemorrhage.maladies and hemorrhage.

BloodBlood

ErythrocytesErythrocytes Small anucleated cells in bloodSmall anucleated cells in blood Donut shapedDonut shaped Most numerous cells in a blood smearMost numerous cells in a blood smear

LeukocytesLeukocytes

Includes Agranulocytes and Includes Agranulocytes and Granulocytes.Granulocytes.

AgranulocytesAgranulocytes: lymphocytes and : lymphocytes and monocytesmonocytes

GranulocytesGranulocytes: neutrophils, eosinophils : neutrophils, eosinophils and basophilsand basophils

Never Let Monkeys Eat Bananas (Most Never Let Monkeys Eat Bananas (Most abundant to least abundant)abundant to least abundant)

neutrophils>lymphocytes>monocytes>neutrophils>lymphocytes>monocytes>eosin-ophils>basophils eosin-ophils>basophils

LeukocytesLeukocytes

NeutrophilsNeutrophils Medium-sized leukocytes (10-12 um)Medium-sized leukocytes (10-12 um) Most numerous white blood cells (60-70%) Most numerous white blood cells (60-70%) Granular cytoplasm but granules not easily Granular cytoplasm but granules not easily

discernable discernable Nucleus is multi-lobed and variable shapedNucleus is multi-lobed and variable shaped

LymphocytesNucleus is spherical and dark purple inside pale blue cytoplasm (5-17 um)Second most prominent wbc (20-25%)

MonocytesMonocytes Largest of the wbc’s (14-24 um)Largest of the wbc’s (14-24 um) Third most abundant wbc’s (3-8%)Third most abundant wbc’s (3-8%) Nucleus is “U” or kidney shapedNucleus is “U” or kidney shaped Cytoplasm is bluish in colorCytoplasm is bluish in color

Eosinophils•Nucleus is bi-lobed

•Reddish cytoplasmic granules•Similar size to neutrophils (10-14 um)•Fourth most abundant wbc’s (2-4%)

BasophilsBasophils

Nucleus is bilobed; (8-10 um)Nucleus is bilobed; (8-10 um) Large blue-purple cytoplasmic granulesLarge blue-purple cytoplasmic granules Least common wbc (0.5-1%)Least common wbc (0.5-1%)

Leukocytes summaryLeukocytes summary

Body membranesBody membranes

Cutaneous membranes Cutaneous membranes = skin (more = skin (more later)later)

Mucous membranesMucous membranes = line body cavities = line body cavities that that open directly to the exterioropen directly to the exterior (digestive, respiratory, reproductive and (digestive, respiratory, reproductive and urinary tracts). urinary tracts).

Serous membranesSerous membranes = line body cavities = line body cavities not directly open to exteriornot directly open to exterior

Synovial membranesSynovial membranes = line joint = line joint cavitiescavities

Mucous membranesMucous membranes Vary considerably throughout the body where Vary considerably throughout the body where

they exist.they exist.

Are an important barrier to foreign microbes Are an important barrier to foreign microbes and agents that could invade the body.and agents that could invade the body.

Composed of epithelial tissues with underlying Composed of epithelial tissues with underlying connective tissue support.connective tissue support.

Contain numerous mucus and goblet cells that Contain numerous mucus and goblet cells that keep the membranes moist.keep the membranes moist.

Serous Membranes (SM)Serous Membranes (SM) Composed of areolar (loose) connective Composed of areolar (loose) connective

tissue and covered by simple squamous tissue and covered by simple squamous epitheliumepithelium

Serous membranes line body cavities that are Serous membranes line body cavities that are not exposed to the outside and also cover the not exposed to the outside and also cover the organs within the cavities. There are 2 layers organs within the cavities. There are 2 layers with a space between them.with a space between them.

Parietal layerParietal layer = attached to body wall = attached to body wall Visceral layerVisceral layer = covers and attaches to = covers and attaches to

organsorgans Serous fluidSerous fluid = clear fluid between two layers = clear fluid between two layers

Specialized Serous Specialized Serous MembranesMembranes

PericardiumPericardium = = serous membrane serous membrane surrounding the surrounding the heart as a sac and heart as a sac and covering the covering the heart. heart.

PleuraPleura = serous = serous membranes lining membranes lining the thoracic cavity the thoracic cavity and covering the and covering the lungs.lungs.

Specialized Serous Specialized Serous MembranesMembranes

PeritoneumPeritoneum = = serous membrane serous membrane lining the lining the abdominal cavity abdominal cavity and covering most and covering most abdominal organs, abdominal organs, except the except the kidneys, kidneys, duodenum, and duodenum, and parts of the colon.parts of the colon.

Synovial membranesSynovial membranes Line joint cavitiesLine joint cavities Consist of fibrous Consist of fibrous

connective tissue and connective tissue and enclose the joint enclose the joint cavities.cavities.

This will be covered This will be covered in greater detail in in greater detail in the next unit when the next unit when we talked about joints we talked about joints and articulations.and articulations.

MuscleMuscle

Three typesThree types1.1. Skeletal muscleSkeletal muscle

2.2. Smooth muscleSmooth muscle

3.3. Cardiac muscleCardiac muscle

Skeletal MuscleSkeletal Muscle Most prominent characteristic is parallel Most prominent characteristic is parallel

large cylindrical cells with multiple nuclei.large cylindrical cells with multiple nuclei.

Cross-striations are present.Cross-striations are present.

Voluntary muscle; under willful control.Voluntary muscle; under willful control.

Attached to bones and tendons and skin.Attached to bones and tendons and skin.

Skeletal MuscleSkeletal Muscle

Cardiac muscleCardiac muscle

Branching cells that interdigitate as a Branching cells that interdigitate as a syncytium.syncytium.

Intercalated discs present at cell junctions.Intercalated discs present at cell junctions. Generally uni-nucleateGenerally uni-nucleate Found in walls of heart only (myocardium)Found in walls of heart only (myocardium) Characterized by auto-rhythmicityCharacterized by auto-rhythmicity Involuntary muscleInvoluntary muscle Cross striations are present.Cross striations are present.

Cardiac muscleCardiac muscle

Smooth MuscleSmooth Muscle

Cells are spindle shapedCells are spindle shaped Single nucleusSingle nucleus DOES NOT HAVE cross striationsDOES NOT HAVE cross striations Involuntary muscleInvoluntary muscle

Found in walls of most hollow organs Found in walls of most hollow organs (vessel walls, intestinal tract walls, (vessel walls, intestinal tract walls, reproductive tract, urinary tract, reproductive tract, urinary tract, respiratory tract, etc.).respiratory tract, etc.).

Smooth MuscleSmooth Muscle

Nervous tissueNervous tissue

Two cell type: Neurons and neuroglial cellsTwo cell type: Neurons and neuroglial cells

NeuronsNeurons are branching elongated cells, are branching elongated cells, highly specialized for generating nerve highly specialized for generating nerve impulses.impulses.

NeuroglialNeuroglial cells are of multiple shapes and cells are of multiple shapes and functions and are considered as supporting functions and are considered as supporting cells.cells.

Nervous tissueNervous tissue Neurons and neuroglial cellsNeurons and neuroglial cells