Cells & Tissues

Anatomy & PhysiologyChapter

Cellular Membrane & Transport

Introduction:A. The human body consists of 75 trillion cells that vary considerably in shape and size yet have much in common.B. Differences in cell shape make different functions possible.

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Cell Structure: A cell consists of three main parts---

the nucleus, the cytoplasm, and the cell membrane.

Within the cytoplasm are specialized organelles that perform specific functions for the cell.

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Inside the cell: Cytoplasm The cytoplasm consists of a clear liquid

(cytosol), a supportive cytoskeleton, and networks of membranesand organelles

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Inside the cell: Cell Nucleus: large organelle bounded by a double-layered

nuclear membrane—also selectively permeable The site of cellular control Holds genetic information—DNA & RNA Contains the nucleolus

composed of RNA and protein and is the site of ribosome production

Contains chromatin loosely coiled fibers of protein and DNA

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Cell Nucleus

Inside the cell: Ribosomes Found attached to rough ER or scattered

throughout the cytoplasm Composed of protein and RNA Functions in protein synthesis

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Inside the cell: Endoplasmic Reticulum (ER) made up of membranes, flattened sacs, & vesicles provides a tubular transport system inside

the cell Rough ER: ER + ribosomes functions in

protein synthesis Smooth ER: ER without ribosomes functions

in lipid synthesis

Rough ER & Smooth ER

Inside the cell: Golgi Apparatus (GA)

composed of flattened sacs, and refines, packages, modifies, & delivers proteins

vesicles formed on ER travel to the GA GA modifies vesicles contents chemically-

prepares them for transport out of cell Vesicles form a “delivery service”, carrying chemicals

throughout the cell (vesicle trafficking).

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Protein Synthesis and Transport

Inside the cell: Mitochondria the “powerhouses” of the cell contain enzymes needed for aerobic respiration the inner membrane of the mitochondrion is

folded into cristae which hold the enzymes needed in

energy transformations to make ATP (energy used by body)

Very active cells contain thousands of mitochondria

example: skeletal muscle

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Mitochondria

Inside the cell: Lysosomes & Peroxisomes

Lysosomes are the "garbage disposals" of the cell & contain digestive enzymes to break up old cell components and bacteria

Peroxisomes contain enzymes that function in the synthesis of bile acids, breakdown of lipids, degradation of rare biochemicals, and detoxification of alcohol

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Cell Extensions Cilia and flagella are motile extensions from the

cell shorter cilia are abundant on the free surfaces of

certain epithelial cells (example: respiratory linings) a lengthy flagellum can be found on sperm cells

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Cilia Flagellum

Cellular Membrane

Separates cell contents from the surrounding environment

Very DYNAMIC in many cellular activities

What is meant by the term dynamic?

Active, participates in cellular functions

Plasma Membrane Structure

Bimolecular lipid layer contains:1. Proteins2. Glycoproteins3. Cholesterol

Plasma Membrane Structure: Proteins

Functions: Act as receptors (binding sites) for

hormones (chemical messengers) Aid in transport of materials through

membrane Pores for transport of water or water-

soluble substances Act as carriers by binding to

substances and carrying them through lipid bilayer

Plasma Membrane Structure: Glycoproteins

Sugar clusters attached to proteins Function:

Determines blood types Receptors for bacteria, viruses or

toxins

Plasma Membrane Structure: Cholesterol

Stabilizes membrane and keeps it fluid

Cell Physiology

Cells perform METABOLISM What is metabolism?

      the use of nutrients to build new materials       the break down of substances       make ATP       digest foods       dispose of waste       reproduce       grow, move & respond to stimuli

Membrane Transport Definitions

Solution: a homogenous mixture of 2+ components Ex: air (mixture of gases), seawater

(salt, water and gases) Solvent: the substance presenting

the largest amount within the solution Ex: water = bodies major solvent

Membrane Transport Definitions

Solutes: substance present in smaller amounts within a solution Ex: oxygen in the atmosphere

Intracellular Fluid: a solution within cells; containing small amounts of gases, nutrients and salts—all dissolved in water

Membrane Transport Definitions

Interstitial or intercellular Fluid: fluid surrounding outside of cells, very nutritious contains: Hormones Salts Waste products Sugars Vitamins Etc

Selective Permeability: when a barrier allows only SOME select substances through, wither inside or outside of the cell

Membrane Transport Definitions

Passive Transport: substances are passed across the membrane without expending energy

GREAT FOR ENERGY EFFICIENCY!!

Active Transport: when a cell uses ATP to move substances across a membrane; substances are: Too large Unable to dissolve in

fat core Moving against

concentration gradient

Membrane Transport Definitions

Isotonic Solutions: has the same solute and water concentrations as cells do

Hypertonic Solutions: contains more dissolved substances than the inside of a cell

Hypotonic Solutions: contains less dissolved substances than the inside of a cell

Histology: the study of tissues

Histology SlidesCourtesy of

The JayDoc HistoWebhttp://www.kumc.edu/instruction/medicine/anatomy/

histoweb/index.htm

Definitions

Avascular: lacking a blood supply Innervated: supplied with nerves

4 Tissue Types: names and functions

1. Epithelial Tissue: protects, secretes, absorbs and forms boundaries

2. Connective Tissue: supports and protects

3. Muscular: contracts4. Nervous: transmits impulses

Epithelial Tissue: Special Characteristics

Avascular Innervated Basement membrane: acts to reinforce

the epithelial sheet, attaches to underlying connective tissue

Cells fit closely; forms continuous sheets Apical surface: free surface exposed to

exterior or to cavity of internal organs Regenerates quickly with sufficient

nourishment

Epithelial Tissue: Classification

By cell shape By number of layers

Cell Shapes Squamous: flattened cells Cuboidal: boxlike cells Columnar: higher than wide (tall)

Epithelial Tissue: Classification

Number of layers Simple: one layer Stratified: several layers Pseudostatified: single layer but

looks like two layers Transitional: several layers of cells of

different shapes

Epithelial Tissue Types

Simple Epithelia Simple squamos

epithelium Simple cuboidal

epithelium Simple columnar

epithelium Pseudostratified

epithelium

Stratified Epithelia Stratified squamos

epithelium Stratified cuboidal and

stratified columnar Transitional epithelia

Glandular Epithelium Endocrine glands Exocrine glands

1. Simple Squamous Epithelium made up of a single layer of thin,

flattened cells suited for diffusion functions in the exchange of

gases in the lungs lines blood, lymph vessels & body

cavities

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Simple Squamos Epithelium

2. Simple Cuboidal Epithelium

consists of a single layer of cube-shaped cells with centrally located nuclei

functions in secretion and absorption in the kidneys, and glands

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Simple Cuboidal Epithelium

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3. Simple Columnar Epithelium made up of a row of elongated cells

whose nuclei are all located near thebasement membrane

may be ciliated lines the uterus, stomach, and

intestines protects underlying tissues, secretes

digestive fluids, and absorbs nutrients.

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Simple Columnar Epithelium

4. Pseudostratified Columnar Epithelium

cells appear layered due to thevarying positions of their nuclei within

NOT truly layered cilia may be present associated with goblet cells, that secrete

mucus line and sweep debris from respiratory

tubes

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Psuedostratified Epithelium

Psuedostratified Epithelium

5. Stratified Squamous Epithelium

made up of layers of flattened cells designed to protect underlying layers makes up the outer layer of skin,

lines the mouth, throat, vagina, andanal canal

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6. Stratified Cuboidal Epithelium consists of 2-3 layers of cuboidal cells lines the lumen of the mammary

glands, sweat glands, salivary glands, and the pancreas

**Several layers of cells provide greaterprotection than one single layer

STRUCTURE PERTAINS TO FUNCTION

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Stratified Cuboidal

7. Stratified Columnar Epithelium consists of several layers of cells found in the vas deferens, male

urethra, & the pharynx

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8. Transitional Epithelium designed to distend and return to its

normalsize

lines the urinary bladder this design provides distensibility and

keepsurine from diffusing back into the internalcavity

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Unstretched Transitional Epithelium

Stretched Transitional Epithelium

9. Glandular Epithelium made up of cells designed to

produce andsecrete substances into ducts or into bodyfluids

Exocrine Glands: secrete products into ducts

Endocrine Glands: secrete products into blood

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Connective Tissue: Special Characteristics

Living cells surrounded by a matrix Some vascularized, others not Vary in rigidity: solid --- liquid

Types of Connective Tissues

Areolar Tissue Adipose Tissue Dense Connective

Tissue

Cartilage Hyaline cartilage Elastic cartilage Fibrocartilage

Bone Blood

Major Connective Tissue Cell TypesA. Fibroblasts: the most common cell typea large, fixed, star-shaped cell; secretesfibersB. Macrophages: wanderers, function as scavenger cells; defend against infectionC. Mast cells: large and located near

bloodvessels; release heparin (anticoagulant)and histamine (promotes inflammation).

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1. Areolar Tissue: loose connectivetissue forms delicate, thin membranes

throughout the body binds body parts together Example: skin and underlying organs majority of the cells are

fibroblasts separated by a gel-like groundsubstance that contains collagenous (tough) and elastic fibers (stretchy)

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Areolar Tissue

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2. Adipose Tissue loose connective tissue designed to store fat found beneath the skin, around joints,

padding the kidneys and other internal organs

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3. Dense Connective Tissue consists of densely packed

collagenous fibers very strong relatively avascular found as part of tendons and ligaments

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Dense Connective Tissue

4. Cartilage rigid connective tissue; provides a

supportive framework for various structures

avascular; heals slowly chondrocytes: cartilage cells 3 types:A. Hyaline cartilage: white with abundant

fine collagen fibers; found at the ends of bones;

supports respiratory passages

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B. Elastic cartilage: with elastic fibers;provides a framework for the external ears

andparts of the larynx

C. Fibrocartilage: with many collagenousfibers; a tough tissue; provides a shockabsorbing function in intervertebral disks and

in the knees & pelvic girdle

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Hyaline Cartilage

5. Bone the most rigid connective tissue, holds deposits of mineral salts and

collagen within the matrix bone internally supports the body,

protects, forms muscle attachments, and is the site for blood cell formation

Osteocytes: bone cells Highly vascularized-heals well

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Bone

6. Blood composed of cells suspended in a

liquid matrix calledplasma

functions to transport substances throughout the body

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Muscle Tissue: Special Characteristics

Highly cellular Well vascularized Muscle cell=muscle fiber

Muscle Tissue Types

1. Skeletal Muscle2. Cardiac Muscle3. Smooth Muscle

1. Skeletal Muscle Tissue attached to bone Voluntary: controlled by conscious

effort the cells are long and cylindrical,

striated, have many nuclei

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2. Smooth Muscle Tissue lacks striations, is uni-nucleate, and

consists of spindle-shaped cells involuntary muscle: controlled

subconsciously found in the walls of internal organs,

and in the digestive tract, blood vessels, and urinary bladder

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Smooth Muscle

3. Cardiac Muscle Tissue found only in the heart consists of branching fibers that are connected to each other with intercalated

disksinvoluntary muscle has a single nucleus in

eachcell but appears striated

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Cardiac Muscle

Nervous Tissues: Nervous tissues are found in the

brain,spinal cord, and nerves

Neurons, or nerve cells, conduct

nervous impulses while helper cells, orneuroglia, support and nourish the neurons

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Tissue Repair: occurs in phases

Phase 1 Inflammation: a local response to cellular injury marked by: Redness Heat Pain Swelling Loss of function

Designed to protect, localize and rid body of injurious agents

Tissue Repair: occurs in phases

Phase 2 Regeneration: replacement of destroyed tissue with same kind of tissue (48 hours- 6 weeks)

Phase 3 Fibrosis: proliferation of fibrous connective tissue (scar tissue) Fibers deposit randomly (48 hours – 6

weeks) Scar tissue is strong but inflexible and

cannot perform normal tissue tasks

Tissue Repair: occurs in phases

**Whether tissue regenerates or scar tissue forms is dependant on severity of injury and the type of tissue damaged

Phase 4 Remodeling/Maturation: the realignment of fibers (3 months to 2 years)