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Cells and TissuesAnatomy and Physiology

Turner College & Career High School2015

Cellular Basis of Life

A cell is composed primarily of four elements: carbon, hydrogen, oxygen, and nitrogen plus many trace elements.

Living matter is over 60 percent water.

The major building material of the cell is protein.

Cell Structure

Cells vary in size from microscopic to over a meter in length.

Shape often reflects function.◦ For example, muscle cells have a long axis to allow shortening.

Anatomy of a Cell: Nucleus

The nucleus, or control center, directs cell activity and is necessary for reproduction.

The nucleus contains genetic material (DNA), which carries instructions for synthesis of proteins.

Anatomy of a Cell: Cytoplasm

The cytoplasm is where most cellular activities occur.

Its fluid substance, the cytosol, contains inclusions, stored or inactive materials in the cytoplasm (fat globules, water vacuoles, crystals, and the like) and specialized bodies called organelles, each with a specific function.

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Anatomy of a Cell: Organelles

Mitochondria are sites of ATP synthesis.

Ribosomes are sites of protein synthesis.

Golgi apparatus packages substances for export from the cell.

Lysosomes carry out intracellular digestion, and peroxisomes disarm dangerous chemicals in the cells.

Cytoskeletal elements function in cellular support and motion.

Centrioles play a role in cell division and form the bases of cilia and flagella.

Anatomy of a Cell: Plasma Membrane

Limits and encloses the cytoplasm and acts as a selective barrier to the movement of substances into and out of the cell.

It is composed of a bi-lipid layer containing proteins.

◦ The water-impermeable lipid portion forms the basic membrane structure.

◦ The proteins (many of which are glycoproteins) act as enzymes or carriers in membrane transport, form membrane channels or pores, provide receptor sites for hormones and other chemicals, or play a role in cellular recognition and interactions during development and immune reactions

Cell Physiology

All cells exhibit irritability, digest foods, excrete wastes, and are able to reproduce, grow, move, and metabolize.◦ Endocytosis

◦ Exocytosis

◦ Pinocytosis

Cell Physiology: Transport

Passive transport processes include diffusion and filtration.

Diffusion is the movement of a substance from an area of its higher concentration to an area of its lower concentration.

◦ It occurs because of kinetic energy of the molecules themselves.

◦ The diffusion of dissolved solutes through the plasma membrane is simple diffusion.

◦ The diffusion of water through the plasma membrane is osmosis.

◦ Diffusion that requires a protein carrier is facilitated diffusion.

Filtration is the movement of substances through a membrane from an area of high hydrostatic pressure to an area of lower fluid pressure.

◦ In the body, the driving force of filtration is blood pressure.

Cell Physiology: Diffusion

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Cell Physiology: Transport

Active transport processes use energy (ATP) provided by the cell.

In solute pumping, substances are moved across the membrane against an electrical or a concentration gradient by proteins called solute pumps.◦ This accounts for the transport of amino acids, some sugars, and most ions.

Cell Physiology: Transport

Active transport processes use energy (ATP) provided by the cell.

The two types of ATP-activated bulk transport are exocytosis and endocytosis.◦ Exocytosis moves secretions and other substances

out of cells; a membrane-bound vesicle fuses with the plasma membrane, ruptures, and ejects its contents to the cell exterior.

◦ Endocytosis, in which particles are taken up by enclosure in a plasma membrane sac, includes phagocytosis (uptake of solid particles) and pinocytosis (uptake of fluids)

Cell Physiology: Transport Cell Physiology: Osmosis

Osmotic pressure, which reflects the solute concentration of a solution, determines whether cells gain or lose water. ◦ Hypertonic solutions contain more solutes (and less

water) than do cells. In these solutions, cells lose water by osmosis and crenate.

◦ Hypotonic solutions contain fewer solutes (and more water) than do the cells. In these solutions, cells swell and may rupture (lysis) as water rushes in by osmosis.

◦ Isotonic solutions, which have the same solute-to-solvent ratio as cells, cause no changes in cell size or shape.

Cell Physiology: Osmosis Cell Physiology: Division

Cell division has two phases, mitosis (nuclear division) and cytokinesis (division of the cytoplasm).

◦ Mitosis begins after DNA has been replicated; it consists of four stages: prophase, metaphase, anaphase, and telophase. The result is two daughter nuclei, each identical to the mother nucleus.

◦ Cytokinesis usually begins during anaphase and progressively pinches the cytoplasm in half.

◦ Mitotic cell division provides an increased number of cells for growth and repair.

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Cell Physiology: Protein Synthesis

Protein synthesis involves both DNA (the genes) and RNA. ◦ A gene is a segment of DNA that carries the instructions for building one protein. The information is in the sequence of bases in the nucleotide strands. Each three-base sequence (triplet) specifies one amino acid in the protein.

◦ Messenger RNA carries the instructions for protein synthesis from the DNA gene to the ribosomes. Transfer RNA transports amino acids to the ribosomes. Ribosomal RNA forms part of the ribosomal structure and helps coordinate the protein building process.

BODY TISSUES

Body Tissues

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

Four major types

◦ Epithelial tissue

◦ Connective tissue

◦ Muscle tissue

◦ Nervous tissue

Epithelial Tissues

Epithelial Tissues

Special characteristics◦ One free surface or edge

◦ No blood supply (avascular)

◦ Classified by number of layers and shape of cells

Simple – one layer

Stratified – more than one layer

Squamous – flat

Cuboidal – cube-shaped

Columnar – column-shaped

Epithelial Tissue

Sheets of cells Specialized contacts/cell junctions (see below) Basal lamina: protein scaffolding secreted by

epithelial cells Basement membrane: reticular fibers (crossed

collagen network) that supports epithelium--really associated connective tissue

Connective tissue support Nutrients from capillaries in underlying

connective tissue Nerves pass through Easily regenerates E.g. skin, lining of gut, mucous membranes

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Simple Squamous Epithelium

One layer.

Thinnest tissue of the body.

Allows transport across membranes.

Flat cells: Lungs, capillary walls.

Secretes fluid in serous membranes.

Lines cardiovascular system.

Covers organs.

Forms glomerular capsules in kidney.

Simple Squamous Epithelium

Line organs

◦ Heart

◦ Alveoli

◦ Bowman’s capsule

Functions

◦ Absorption

◦ Exchange of materials

◦ Filtration

◦ Secretion

Simple Cuboidal Epithelium

One layer

Cube-shaped cells Ovary, thyroid gland, kidney tubules, pancreas, salivary

glands

Simple Cuboidal Epithelium

Forms secretory, tubules and ducts of exocrine glands

Covers surface of ovary

Lines interior of eye

Absorption and secretion

Simple Columnar Epithelium

One layer.

Tall, column-shaped cells.

Round to oval nuclei.

Non-ciliated in the GI tract as stomach and intestinal lining.

Ciliated portions of respiratory and genitourinary tract.

Simple Columnar Epithelium

Absorption of digestive products.

Secretion of mucus, enzymes.

Ciliated type propels mucus along apical surfaces.

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Pseudostratified Columnar

One layer.

Column-shaped cells, differing heights.

Major lining of respiratory tract.

Function: secretion and movement of mucus to remove particulate matter.

Stratified Squamous Epithelium

Thick membrane, several layers.

Basal cells are cuboidal or columnar.

Surface cells are squamous in keratinized.

Basal cells are active in mitosis.

Protects underlying tissues.

Stratified Cuboidal Epithelium

Generally two or more layers.

Cube-shaped cells.

Function: Protection.

Location: Largest ducts of sweat glands, mammary glands, salivary glands.

Transitional Epithelium

Epithelium is 4-5 cells deep.

Stretched, the superficial cells become squamous.

Lines the urinary tract, allows expansion.

Epithelial Tissues

Type Cell shape Example

Squamous Squashed Endothelium (lines blood

vessels), mesothelium

(serous lining of celom)

Cuboidal

Cubed Walls of glands

Columnar Columns Lining of gut tube;

sometimes with cilia like

lining of uterine tube

Pseudo-stratified Flat cells give rise

to columns

With cilia in respiratory

tubes to move

mucous/particles out of

lungs

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Glands

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

Exocrine Glands

◦ Secrete substance onto body surface or into body cavity.

◦ Ducts.

◦ Salivary, mammary, pancreas, liver.

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.

◦ No ducts.

Connective Tissue

Common characteristics◦ Protect, support, and bind together body tissues

◦ Well vascularized

◦ Usually connective tissue is a few cells with a lot of matrix (substance surrounding the cells)

◦ Classified by

Number of cells

Types of matrix

Loose Connective Tissue

Beneath dermis of skin, digestive tract, respiratory, urinary tract, between muscles, around blood vessels, nerves, joints.

Cushions organs, provides support.

Loose Reticular Connective

The supportive tissue of lymph nodes, glands, organs, and bone marrow, reticular connective tissue is not that obvious.

Small, branching, collagen fibers that form the reticular connective tissue are usually hidden from view by the numerous lymphatic, epithelial, or bone marrow cells anchored to them.

Adipose Tissue

Deep to the skin.

Cells filled with fat have nucleus pushed to the periphery.

Padding around eyes, kidneys.

Cushions, insulates, stores energy reserves.

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Dense Connective Tissue

Between skeletal muscles and skeleton (tendons).

Between bones (ligaments).

Covering skeletal muscles.

Provides firm attachment.

Reduces friction.

Dense Elastic Tissue

Allow recoil of tissue following stretching

Maintain flow of blood through arteries.

Location: Walls of large arteries, lungs, Trachea, vocal cords

Osseous Tissue

Hard, calcified matrix containing many collagen fibers.

Bones support and protection.

Stores calcium, minerals, fat.

Marrow site for blood cell formation

Cartilage

Hyaline Cartilage

Also called gristle.

It is shiny, slippery, firm, translucent, and bluish-gray in color.

It is simple in structure, with no nerves or blood vessels.

It has high elasticity and helps cushion and protect bones.

Scattered chondrocytes.

Solid matrix:◦ Ends of long bones, nose, ribs, tracheal rings, fetal

skeleton.

Fibrocartilage

Type of cartilage which is very rich in type I collagen, and found in areas such as the meniscus of the knee, the pubic symphysis, and the vertebral discs.

This type of cartilage is especially strong and durable, so it appears in areas where these traits are needed.

Characterized by the bundles of tough collagen.

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Elastic Cartilage

Elastic cartilage is found in the epiglottis, larynx, and the outer ear.

As its name suggests, elastic cartilage is significantly more pliable than either hyaline or fibrocartilage.

Comprised of elastic fibers and collagen.

Network of elasticity forms a solid matrix, protecting itself from rupture and similar fates.

◦ This matrix of fibers lends the part a significant flexibility, and this means it can withstand repeated instances of bending.

Muscle Tissue

Muscle tissue is made of "excitable" cells that are capable of contraction.

Of all of the different tissue types (muscle, epithelial, connective, and nervous), muscle tissue is the most abundant in most animals.

Muscle tissue contains numerous microfilaments composed of actin and myosin, which are contractile proteins.

Skeletal Muscle Tissue

Allows for physical movements of all sorts.

Usually function in pairs, & control is voluntary.

Striated, meaning one can find alternating bands of dark and light crossing the width of the muscle fibers

Attached to the skeleton, usually by tendons.

Cardiac Muscle Tissue

Cells are short, branched & striated.

Single nucleus.

Cylindrical, branching, intercalated disks.

Involuntary.

Pumps blood through heart and blood vessels.

Smooth Muscle Tissue

Walls of internal organs and blood vessels.

Contracts viscera and blood vessels.

Spindle-shaped, tapered ends.

One nucleus.

Involuntary.

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Nervous Tissue

Function: Conduction of nervous impulses.

Neurons: Irritability and conductivity.

Neuroglial cells: support cells.

Blood

Red & white blood cells in fluid matrix (plasma).

Transport of respiratory gases, nutrients, wastes, other substances.

Contained withinblood vessels

Tissue Repair

Structure of Cancer Cells Development of Cancer

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Development of Cancer