Cells and Tissue lecture presentation

Introduction and Tissues

Human Anatomy

 BIOL 1010
 Liston Campus     
                                                                        

What is Anatomy?

• Anatomy (= morphology): study of body’s structure
• Physiology: study of body’s function
• Structure reflects Function!!!
• Branches of Anatomy
• Gross: Large structures
• Surface: Landmarks
• Histology: Cells and Tissues
• Developmental: Structures change through life
• Embryology: Structures form and develop before birth

Hierarchy of Structural Organization
Each of these build upon one another to make up the next level:

• Chemical level
• Cellular
• Tissue
• Organ
• Organ system
• Organism

Hierarchy of Structural Organization

• Chemical level
• Atoms combine to make molecules
• 4 macromolecules in the body
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

Hierarchy of Structural Organization

• Cellular
• Made up of cells and cellular organelles (molecules)
• Cells can be eukaryotic or prokaryotic
• Organelles are structures within cells that perform dedicated functions (“small organs”)

Hierarchy of Structural Organization

• Tissue
• Collection of cells that work together to perform a specialized function
• 4 basic types of tissue in the human body:
• Epithelium
• Connective tissue
• Muscle tissue
• Nervous tissue

Hierarchy of Structural Organization

• Organ
• Made up of tissue
• Heart
• Brain
• Liver
• Pancreas, etc……

Hierarchy of Structural Organization

• Organ system (11)
• Made up of a group of related organs that work together
• Integumentary
• Skeletal
• Muscular
• Nervous
• Endocrine
• Cardiovascular
• Lymphatic
• Respiratory
• Digestive
• Urinary
• Reproductive

Hierarchy of Structural Organization

• Organism
• An individual human, animal, plant, etc……
• Made up all of the organ systems
• Work together to sustain life

 













Anatomical Directions

• Anatomical position
• Regions
• Axial vs. Appendicular
• Anatomical Directions-It’s all Relative!
• Anterior (ventral) vs. Posterior (dorsal)
• Medial vs. Lateral
• Superior (cranial) vs. Inferior (caudal)
• Superficial vs. Deep
• Proximal vs. Distal
• Anatomical Planes
• Frontal = Coronal
• Transverse = Horizontal = Cross Section
• Sagittal

Anterior – (ventral) Closer to the front surface of the body	Posterior – (dorsal) Closer to the rear surface of the body	Frontal Plane
Medial – Lying closer to the midline	Lateral – Lying further away from the midline	Sagittal Plane
Superior – (cranial) Closer to the head in relation to the entire body (More General)	Inferior – (caudal) Away from the head or towards the lower part of the body	Horizontal Plane
Superficial – Towards the surface	Deep – Away from the surface	Surface of body or organ
Proximal – Closer to the origin of a body part (More Specific)

Tissues: groups of cells closely associated that have a similar structure and perform a related function

• Four types of tissue
• Epithelial = covering/lining
• Connective = support
• Muscle = movement
• Nervous = control
• Most organs contain all 4 types
• Tissue has non-living extracellular material between its cells

EPITHELIAL TISSUE: sheets of cells cover a surface or line a cavity

• Functions
• Protection
• Secretion
• Absorption
• Ion Transport

Characteristics of Epithelium

• Cellularity
• Composed of cells
• Specialized contacts
• Joined by cell junctions
• Polarity
• Apical vs. Basal surfaces differ
• Supported by connective tissue
• Avascular
• Innervated
• Highly regenerative

Classification of Epithelium-based on number of layers and cell shape

• Layers
• Simple
• Stratified
• Stratified layers characterized by shape of apical layer
• Psuedostratified
• Shapes
• Squamous
• Cuboidal
• Columnar
• Transitional

 

 Types of Epithelium

• Simple squamous (1 layer)
• Lungs, blood vessels, ventral body cavity
• Simple cuboidal
• Kidney tubules, glands
• Simple columnar
• Stomach, intestines
• Pseudostratified columnar
• Respiratory passages (ciliated version)
• Stratified squamous (>1 layer)
• Epidermis, mouth, esophagus, vagina
• Named so according to apical cell shape
• Regenerate from below
• Deep layers cuboidal and columnar
• Transitional (not shown)
• Thins when stretches
• Hollow urinary organs

Special Epithelium

• Endothelium
• Simple squamous epithelium that lines vessels
• e.g. lymphatic & blood vessel
• Mesothelium
• Simple squamous epithelium that forms the lining of body cavities
• e.g. pleura, pericardium, peritoneum

Features of Apical Surface of Epithelium

• Microvilli: (ex) in small intestine
• Finger-like extensions of the plasma membrane of apical epithelial cell
• Increase surface area for absorption
• Cilia: (ex) respiratory tubes
• Whip-like, motile extension of plasma membrane
• Moves mucus, etc. over epithelial surface 1-way

Features of Lateral Surface of Epithelium

• Cells are connected to neighboring cells via:
• Contour of cells-wavy contour fits together
• Cell Junctions (3 common)
• Desmosomes
• Proteins hold cells together to maintain integrity of tissue
• Tight Junctions
• Plasma membrane of adjacent cells fuse, nothing passes
• Gap junction
• Proteins allow small molecules to pass through

Features of the Basal Surface of Epithelium

• Basement membrane
• Sheet between the epithelial and connective tissue layers
• Attaches epithelium to connective tissue below
• Made up of:
• Basal lamina: thin, non-cellular, supportive sheet made of proteins
• Superficial layer
• Acts as a selective filter
• Assists epithelial cell regeneration by moving new cells
• Reticular fiber layer
• Deeper layer
• Support

Glands

• Epithelial cells that make and secrete a product
• Products are water-based and usually contain proteins
• Classified as:
• Unicellular vs. multicellular
• Exocrine vs. Endocrine

Glands: epithelial cells that make and secrete a water-based substance w/proteins

• Exocrine Glands
• Secrete substance onto body surface or into body cavity
• Activity is local
• Have ducts
• Unicellular or Multicellular
• (ex) goblet cells, salivary, mammary, pancreas, liver

Glands: epithelial cells that make and secrete a water-based substance w/proteins

• Endocrine Glands
• Secrete product into blood stream
• Either stored in secretory cells or in follicle surrounded by secretory cells
• Hormones travel to target organ to increase response (excitatory)
• No ducts
• (ex) pancreas, adrenal, pituitary, thyroid

  

  Connective Tissue (CT):
most abundant and diverse tissue

• Four Classes
• Functions include connecting, storing & carrying nutrients, protection, fight infection
• CT contains large amounts of non-living extracellular matrix
• Contains a variety of cells and fibers
• Some types vascularized
• All CT originates from mesenchyme
• Embryonic connective tissue

Fibers in Connective Tissue

• Fibers For Support
• Reticular:
• form networks for structure & support
• (ex) cover capillaries
• Collagen:
• strongest, most numerous, provide tensile strength
• (ex) dominant fiber in ligaments
• Elastic:
• long + thin, stretch and retain shape
• (ex) dominant fiber in elastic cartilage

Components of Connective Tissue

• Fibroblasts:
• cells that produce all fibers in CT
• produce + secrete protein subunits to make them
• produce ground matrix
• Interstitial (Tissue) Fluid
• derived from blood in CT proper
• medium for nutrients, waste + oxygen to travel to cells
• found in ground matrix
• Ground Matrix (substance): 

• part of extra-cellular material that holds and absorbs interstitial fluid
• Made and secreted by fibroblasts
• jelly-like with sugar & protein molecules
• Connective Tissue Proper

 

Two kinds: Loose CT & Dense CT

• Functions
• Support and bind to other tissue
• Hold body fluids
• Defends against infection
• Stores nutrients as fat
• Each function performed by different kind of fibers and cells in specific tissue

 












 Defense from Infection

• Areolar tissue below epithelium is body’s first defense
• Cells travel to CT in blood
• Macrophages-eat foreign particles
• Plasma cells-secrete antibodies, mark molecules for destruction
• Mast cells-contain chemical mediators for inflammation response
• White Blood Cells = neutrophils, lymphocytes, eosinophils-fight infection
• Ground substance + cell fibers-slow invading microorganisms

Loose CT Proper

• Areolar CT
• All types of fibers present
• All typical cell types present
• Surrounds blood vessels and nerves

Specialized Loose CT Proper

• Adipose tissue
• Loaded with adipocytes, highly vascularized, high metabolic activity
• Insulates, produces energy, supports
• Found in hypodermis under skin
• Reticular CT
• Contains only reticular fibers
• Forms caverns to hold free cells, forms internal “skeleton” of some organs
• Found in bone marrow, holds blood cells, lymph nodes, spleen

Dense/Fibrous Connective Tissue

• Contains more collagen
• Can resist extremely strong pulling forces
• Regular vs. Irregular
• Regular-fibers run same direction, parallel to pull
• (eg) fascia, tendons, ligaments
• Irregular-fibers thicker, run in different directions
• (eg) dermis, fibrous capsules at ends of bones

Components of CT Proper Summarized

• Chondroblasts produce cartilage 
• Cartilage
• Chondrocytes mature cartilage cells
• Reside in lacunae
• More abundant in embryo than adult
• Firm, Flexible
• Resists compression
• (eg) trachea, meniscus
• Avascular (chondrocytes can function w/ low oxygen)
• NOT Innervated
• Perichondrium
• dense, irregular connective tissue around cartilage
• growth/repair of cartilage
• resists expansion during compression of cartilage

Cartilage in the Body

• Three types:
• Hyaline
• most abundant
• fibers in matrix
• support via flexibility/resilience
• (eg) at limb joints, ribs, nose
• Elastic
• many elastic fibers in matrix too
• great flexibility
• (eg) external ear, epiglottis
• Fibrocartilage
• resists both compression and tension
• (eg) meniscus, annulus fibrosus

Components of Cartilage Summarized

• Well-vascularized
• Function:
• support (eg) pelvic bowl, legs
• protect (eg) skull, vertebrae
• mineral storage (eg) calcium, phosphate (inorganic component)
• movement (eg) walk, grasp objects
• blood-cell formation (eg) red bone marrow

Bone Tissue

• Osteoblasts
• Secrete organic part of bone matrix
• Osteocytes
• Mature bone cells
• Sit in lacunae
• Maintain bone matrix
• Osteoclasts
• Degrade and reabsorb bone
• Periosteum

Image

• Bone Tissue: (a bone is an organ)

• External layer of CT that surrounds bone
• Outer: Dense irregular CT
• Inner: Osteoblasts, osteoclasts
• Endosteum
• Internal layer of CT that lines cavities and covers trabeculae
• Contains osteoblasts and osteoclasts

Compact Bone

• External layer
• Osteon (Haversian system)
• Parallel to the long axis of the bone
• Groups of concentric tubules (lamella)
• Lamella = layer of bone matrix where all fibers run in the same direction
• Adjacent lamella fibers run in opposite directions
• Haversian Canal runs through center of osteon
• Contains blood vessels and nerves
• Connected to each other by perforating (Volkman) canals
• Interstitial lamellae fills spaces and forms periphery

Bone Anatomy: Spongy bone

• Spongy bone (cancellous bone): internal layer
• Trabeculae: small, needle-like pieces of bone form honeycomb
• each made of several layers of lamellae + osteocytes
• no canal for vessels
• space filled with bone marrow
• not as dense, no direct stress at bone’s center

Shapes of Bones
Image
Anatomy of a Long Bone

• Diaphysis
• Medullary Cavity
• Nutrient Artery & Vein
• 2 Epiphyses
• Epiphyseal Plates
• Epiphyseal Artery & Vein
• Periosteum
• Does not cover epiphyses
• Endosteum
• Covers trabeculae of spongy bone
• Lines medullary cavity of long bones

2 Types of Bone Formation

• Intramembranous Ossification
• Membrane bones: most skull bones and clavicle
• Osteoblasts in membrane secrete osteoid that mineralizes
• Endochondral Ossification: All other bones
• Begins with a cartilaginous model
• Cartilage calcifies
• Medullary cavity is formed by action of osteoclasts
• Epiphyses grow and eventually calcify
• Epiphyseal plates remain cartilage for up to 20 years

Bone Growth & Remodeling

• Appositional Growth = widening of bone
• Bone tissue added on surface by osteoblasts of periosteum
• Medullary cavity maintained by osteoclasts
• Lengthening of Bone
• Epiphyseal plates enlarge by chondroblasts
• Matrix calcifies (chondrocytes die and disintegrate)
• Bone tissue replaces cartilage on diaphysis side
• REMODELING
• Due to mechanical stresses on bones, their tissue needs to be replaced
• Osteoclasts-take up bone ( = breakdown) release Ca 2++ , PO 4 to body fluids from bone
• Osteoblasts-form new bone by secreting osteoid
• Ideally osteoclasts & osteoblasts work at the sam
• GROWTH
• e rate!
• Components of Bone Tissue Summarized

 













 

• Blood: Atypical Connective Tissue
• Function:
• Transports waste, gases, nutrients, hormones through cardiovascular system
• Helps regulate body temperature
• Protects body by fighting infection
• Derived from mesenchyme
• Hematopoiesis: production of blood cells
• Occurs in red bone marrow
• In adults, axial skeleton, girdles, proximal epiphyses of humerus and femur

Blood Cells

• Erythrocytes: (RBC) small, oxygen-transporting
• most abundant in blood
• no organelles, filled w/hemoglobin
• pick up O 2 at lungs, transport to rest of body
• Leukocytes: (WBC) complete cells , 5 types
• fight against infectious microorganisms
• stored in bone marrow for emergencies
• *Platelets = Thrombocytes:
• fragments of cytoplasm
• plug small tears in vessel walls, initiates clotting
• Components of Blood Summarized

 
 
 















Muscle Tissue

• Muscle cells/fibers
• Elongated
• Contain many myofilaments: Actin & Myosin

• FUNCTION
• Movement
• Maintenance of posture
• Joint Stabilization
• Heat Generation
• Three types: Skeletal, Cardiac, Smooth

Skeletal Muscle Tissue
(each skeletal muscle is an organ)

• Cells
• Long and cylindrical, in bundles
• Multinucleate
• Obvious Striations
• Skeletal Muscles-Voluntary
• Connective Tissue Components:
• Endomysium-surrounds fibers
• Perimysium-surrounds bundles
• Epimysium-surrounds the muscle
• Attached to bones, fascia, skin
• Origin & Insertion

Cardiac Muscle

• Cells
• Branching, chains of cells
• Single or Binucleated
• Striations
• Connected by Intercalated discs
• Cardiac Muscle-Involuntary
• Myocardium-heart muscle
• Pumps blood through vessels
• Connective Tissue Component
• Endomysium: surrounding cells

Smooth Muscle Tissue

• Cells
• Single cells, uninucleate
• No striations
• Smooth Muscle-Involuntary
• 2 layers-opposite orientation (peristalsis)
• Found in hollow organs, blood vessels
• Connective Tissue Component
• Endomysium: surrounds cells

 

Nervous Tissue

• Neurons: specialized nerve cells conduct impulses
• Cell body, dendrite, axon
• Characterized by:
• No mitosis (cell replication)
• Longevity
• High metabolic rate

Nervous Tissue: control

• Support cells (= Neuroglial): nourishment, insulation, protection
• Satellite cells-surround cell bodies within ganglia
• Schwann cells-surround axons (PNS)
• Microglia-phagocytes
• Oligodendrocytes-produce myelin sheaths around axons
• Ependymal cells-line brain/spinal cord, ciliated, help circulate CSF
• Brain, spinal cord, nerves

Integumentary System

• Functions
• Protection
• Mechanical, thermal, chemical, UV
• Cushions & insulates deeper organs
• Prevention of water loss
• Thermoregulation
• Excretion
• Salts, urea, wa
• Sensory reception

Microanatomy - Layers of the Skin

• Epidermis
• Epithelium
• Dermis
• Connective tissue
• Hypodermis / subcutis
• Loose connective tissue
• Anchors skin to bone or muscle
• Skin Appendages = outgrowths of epidermis
• Hair follicles
• Sweat and Sebaceous glands
• Nails

Cell Layers of the Epidermis

• Stratum corneum
• Dead keratinocytes
• Stratum lucidum
• Only in “thick” skin
• Dead keratinocytes
• Stratum granulosum
• Water proofing
• Stratum spinosum
• Resists tears and tension
• Stratum basale
• Sensory receptors
• Melanocytes
• Keratinocytes (in all layers)

Layers of the Dermis

• Highly innervated
• Highly vascularized
• Collagen & Elastic fibers

• 2 layers:
• Papillary layer (20%)
• Areolar CT
• Collagen & Elastic fibers
• Innervation
• Hair follicles
• Reticular layer (80%)
• Dense irregular CT
• Glands
• sebum
• 2.5 million sweat glands!!
• Smooth muscle fibers
• Innervation

Hypodermis

• Also called superficial fascia
• Areolar & Adipose Connective Tissue
• Functions
• Store fat
• Anchor skin to muscle, etc.
• Insulation

Structure of Tubular Organs

LUMEN

• Serosa – suspends organ in the peritoneal
• Tunica Mucosa
• Lamina epithelialis
• Lamina propria
• Lamina muscularis mucosa
• Tunica Submucosa
• Tunica Muscularis
• Inner circular
• Outer longitudinal
• Tunica Adventitia / Serosa
• Adventitia – covers organ
• cavity