Histology- Study of Histology- Study of TissuesTissues

Physiological Physiological systemssystems are made up of are made up of organsorgans that serve specific functions. that serve specific functions.

Organs are made up of Organs are made up of tissuestissues, which , which are then made up of cells.are then made up of cells.

Four types of tissue:Four types of tissue:►EpithelialEpithelial►ConnectiveConnective►MuscleMuscle►NervousNervous

Epithelial tissuesEpithelial tissues are sheets of tightly are sheets of tightly connected connected epithelial cells.epithelial cells.

The tissuesThe tissues form skin and line hollow form skin and line hollow organs.organs.

Some epithelial cells can:Some epithelial cells can:►Secrete substances, like hormonesSecrete substances, like hormones►Move substances with ciliaMove substances with cilia►Act as chemical receptorsAct as chemical receptors►Create boundariesCreate boundaries►Control filtration and transportControl filtration and transport

Function of Epithelial cellsFunction of Epithelial cells

Cells in Epithelial TissueCells in Epithelial Tissue

► Squamous Cells- Simple /StratifiedSquamous Cells- Simple /Stratified► Columnar Cells- Simple/pseudostratifiedColumnar Cells- Simple/pseudostratified► Cuboidal Cells- Simple/stratifiedCuboidal Cells- Simple/stratified► Transitional CellsTransitional Cells

Epithelial Tissue (A)

Stratified squamous epithelium, nonkeratinized, Stratified squamous epithelium, nonkeratinized, from human mouth. LM, H&E stain.from human mouth. LM, H&E stain.

Simple columnar epithelium from human Simple columnar epithelium from human intrahepatic bile duct. LM, trichrome stain.intrahepatic bile duct. LM, trichrome stain.

Simple cuboidal epithelium lining follicles of Simple cuboidal epithelium lining follicles of human thyroid gland. LM, H&E stain.human thyroid gland. LM, H&E stain.

Pseudostratified columnar epithelium lining a Pseudostratified columnar epithelium lining a human bronchus; cilia on many cells. LM.human bronchus; cilia on many cells. LM.

Transitional epithelium line the urethra of a male Transitional epithelium line the urethra of a male infant. LM, H&E stain.infant. LM, H&E stain.

Pigmented epithelium from a person of African Pigmented epithelium from a person of African descent. LM, H&E stain.descent. LM, H&E stain.

Skin from human foot; note thick keratin layer. Skin from human foot; note thick keratin layer. LM, H&E stain.LM, H&E stain.

Cross section of human hair follicle. LM, H&E Cross section of human hair follicle. LM, H&E stain.stain.

Sweat glands in human skin. LM, H&E stain.Sweat glands in human skin. LM, H&E stain.

Common wart on human skin, caused by human Common wart on human skin, caused by human

papillomavirus (HPV). LM, H&E stainpapillomavirus (HPV). LM, H&E stain..

Epithelial Tissue (B)

► Simple cuboidal epithelium is found Simple cuboidal epithelium is found in glandular tissue and in the kidney in glandular tissue and in the kidney tubules. tubules.

Muscle tissuesMuscle tissues consist of elongated consist of elongated cells that generate force and cause cells that generate force and cause movement. movement.

Three types of muscle tissues: Three types of muscle tissues: ►SkeletalSkeletal►CardiacCardiac►SmoothSmooth

►SkeletalSkeletal: responsible for locomotion and : responsible for locomotion and other body movements (e.g., breathing, other body movements (e.g., breathing, shivering).shivering).

►CardiacCardiac: makes up the heart and is : makes up the heart and is responsible for the heartbeat and blood responsible for the heartbeat and blood flow.flow.

►SmoothSmooth: involved in movement and : involved in movement and generation of forces in internal organs generation of forces in internal organs (e.g., gut, blood vessels).(e.g., gut, blood vessels).

Figure 40.4 Filaments in Skeletal Muscle Cells

Connective tissuesConnective tissues are dispersed cells in an are dispersed cells in an extracellular matrix extracellular matrix that they secrete.that they secrete.

The matrix contains protein fibers: The matrix contains protein fibers: ► CollagenCollagen: strong and resistant to stretch, : strong and resistant to stretch,

supports skin and connections between supports skin and connections between muscles and bonesmuscles and bones

► ElastinElastin: can be stretched and then recoils; : can be stretched and then recoils; found in tissues that stretch (e.g., lungs, found in tissues that stretch (e.g., lungs, arteries)arteries)

Areolar connective tissue; elastic and collagenic Areolar connective tissue; elastic and collagenic fibers in a rat. LM, silver stain.fibers in a rat. LM, silver stain.

Elastic connective tissue in dog aorta; fenestrated Elastic connective tissue in dog aorta; fenestrated membranes. LM, resorein blue.membranes. LM, resorein blue.

Connective tissues:Connective tissues: ►CartilageCartilage provides structural support provides structural support

and is flexible: has and is flexible: has chondrocyteschondrocytes; cells ; cells that secrete the extracellular matrix.that secrete the extracellular matrix.

►BoneBone: provides support and is : provides support and is hardened by calcium phosphate hardened by calcium phosphate deposition in the matrix. Bone cells are deposition in the matrix. Bone cells are osteocytes.osteocytes.

Hyaline cartilage in cat larynx. LM, H&E stain.Hyaline cartilage in cat larynx. LM, H&E stain.

Cartilage

Fibrocartilage in a mammalian intervertebral disc. Fibrocartilage in a mammalian intervertebral disc. LM, H&E stain.LM, H&E stain.

Elastic cartilage from a pig's earElastic cartilage from a pig's ear..

Human compact bone, transverse section. LM, Human compact bone, transverse section. LM, Schmorl's stain.Schmorl's stain.

More connective tissues:More connective tissues:►Adipose tissueAdipose tissue: includes adipose cells : includes adipose cells

that form and store lipids. Cells are that form and store lipids. Cells are adipocytes.adipocytes.

►BloodBlood: consists of cells in a very liquid : consists of cells in a very liquid extracellular matrix, the blood extracellular matrix, the blood plasmaplasma. . There are red blood cells (erythrocytes), There are red blood cells (erythrocytes), white blood cells (leukocytes), and white blood cells (leukocytes), and platelets (thrombocytes).platelets (thrombocytes).

Blood cells from domestic chicken (Blood cells from domestic chicken (Gallus gallusGallus gallus). ).

LM, Giemsa stainLM, Giemsa stain..

Normal human adipose cells. LM, H&E stain.Normal human adipose cells. LM, H&E stain.

Nervous tissuesNervous tissues contain two contain two basic cell types: basic cell types: neuronsneurons and and gliaglia..

Neurons encode information as Neurons encode information as electrical impulses that travel electrical impulses that travel over over axonsaxons to their targets. to their targets.

Chemical signals from the neuron Chemical signals from the neuron stimulate a response in the stimulate a response in the target cell, via receptors.target cell, via receptors.

Glia provide support for neurons.Glia provide support for neurons.

Nervous Tissue Includes Neurons and Glia (A)

Nervous Tissue Includes Neurons and Glia (B)

OrgansOrgans consist of multiple consist of multiple tissues. tissues.

An An organ systemorgan system is a group of is a group of organs that function together.organs that function together.

Different Tissues make up an Different Tissues make up an organorgan

Example: The stomach wall is Example: The stomach wall is arranged in layers:arranged in layers:

►Epithelial cellsEpithelial cells►Connective tissueConnective tissue►Smooth muscle Smooth muscle ►Neurons Neurons ►Connective tissueConnective tissue

Figure 40.7 Tissues Form Organs

Fig 40.7 whole figure except stomach

Figure 40.17 Brown Fat