Cells and Tissues Anatomy of the Generalized Cell

Cells and Tissues

Anatomy of the Generalized Cell · All cells share general structures · Carry out all chemical activities needed to sustain life. · Cells are the building blocks of all living things

Cell Diversity · Cells are not all the same · Structure reflects function

Cell Diversity

Cell Diversity

Cellular Physiology: Membrane Transport · Membrane Transport – movement of substance into and out of the cell · Transport allows the cells to maintain homeostasis micro. magnet. fsu. edu

· The plasma membrane allows some materials to pass while excluding others · This permeability includes movement into and out of the cell · Transport is by two basic methods · Passive transport · No energy is required · Active transport · The cell must provide metabolic energy

Passive Transport Processes · Diffusion · Particles tend to distribute themselves evenly within a solution · Movement is from high concentration to low concentration, or down a concentration gradient Figure 3. 8

Passive Transport Processes · Types of diffusion · Osmosis – simple diffusion of water · Highly polar water easily crosses the plasma membrane · Facilitated diffusion (glucose) · Substances require a protein carrier for passive transport

Diffusion through the Plasma Membrane

Passive Transport Processes · Filtration · Water and solutes are forced through a membrane by fluid, or hydrostatic pressure · A pressure gradient must exist · Solute-containing fluid is pushed from a high pressure area to a lower pressure area

Active Transport Processes (ATP) · Transport substances that are unable to pass by diffusion · They may be too large · They may not be able to dissolve in the fat core of the membrane · They may have to move against a concentration gradient · Two common forms of active transport · Solute pumping · Bulk transport

Active Transport Processes · Solute pumping · Amino acids, some sugars and ions are transported by solute pumps · ATP energizes protein carriers, and in most cases, moves substances against concentration gradients

Active Transport Processes

Active Transport Processes · Bulk transport · Exocytosis · Moves materials out of the cell · Material is carried in a membranous vesicle · Vesicle migrates to plasma membrane · Vesicle combines with plasma membrane · Material is emptied to the outside

Active Transport Processes

Active Transport Processes · Bulk transport · Endocytosis · Extracellular substances are engulfed by being enclosed in a membranous vescicle · Types of endocytosis · Phagocytosis – cell eating · Pinocytosis – cell drinking

Active Transport Processes

Cellular Disease • Abnormal cells can disrupt the internal environment of the body • Cell Transport disorders ▫ Cystic fibrosis(CF)- condition in which Chlorine is altered and it causes abnormal secretion of sweat, mucus and pancreatic juice. ▫ Duchenne Muscular Dystrophy (DMD)Membranes leaks excess Calcium. This triggers chemical reactions that destroy muscles.

Cellular Disease • Cell membrane disorders ▫ Diabetes mellitus (type 2)- number of insulin membrane receptors is reduced as a result of obesity • Cell Reproduction ▫ Cancer- abnormal cell growth that forms tumors which can potentially impair health • DNA and Protein synthesis ▫ Sickle cell anemia- abnormal hemoglobin ▫ Metabolism problems

Tissues When cells come together

Body Tissues · Tissues- Groups of similar cells that perform a common function · Matrix- non-living intercellular material · Four primary types · Epithelium · Connective tissue · Muscle tissue · Nervous tissue

Epithelial Tissues Locations · Membranous · Body coverings · Body linings · Glandular tissue Functions · Protection · Absorption · Filtration · Secretion · Sensory Characteristics · Cells close together · Cells have free apical surface · Limited matrix · Bottom surface is basement membrane · Avascular – no blood supply · Regenerate easily

Classification of Epithelium 1. Based on # of cell layers · Simple – one layer · Stratified – more than one layer 2. Shape of cells · Squamous – flattened · Cuboidal – cube-shaped · Columnar – column-like

Type of Simple Epithelium 1. Simple squamous · Single layer of flat cells · Usually forms membranes · Lines body cavities · Lines lungs and capillaries

2. Simple cuboidal · Single layer of cube-like cells · Common in glands and their ducts · Forms walls of kidney tubules · Covers the ovaries

3. Simple columnar · Single layer of tall cells · Often includes goblet cells, which produce mucus · Lines digestive tract

4. Pseudostratified · Single layer, but some cells are shorter than others · Often looks like a double cell layer · Sometimes ciliated, such as in the respiratory tract · May function in absorption or secretion

Types of Stratified Epithelium 1. Stratified squamous · Cells at the free edge are flattened · Found as a protective covering where friction is common · Locations · Skin · Mouth · Esophagus

2. Stratified cuboidal · Two layers of cuboidal cells 3. Stratified columnar · Surface cells are columnar, cells underneath vary in size and shape Both are: · Found mainly in ducts of large glands Rare in human body

Glands (side note) Gland – one or more cells that secretes a particular product 2 types 1. Endocrine gland · Ductless · Secretes hormones 2. Exocrine gland · Empty through ducts to surface · Include sweat and oil glands

4. Transitional epithelium (Back to Types of Stratified Epithelium) · Shape of cells depends upon the amount of stretching · Lines organs of the urinary system

Connective Tissue Location Characteristics · Found everywhere in the body · Variations in blood supply Functions · Connects · Supports · Transports · Protects · Some tissue types are well vascularized · Some have poor blood supply or are avascular · Extracellular matrix · Non-living material that surrounds living cells

Connective Tissue Types 1. Bone (osseous tissue) · Bone cells in lacunae (cavities) · Hard matrix of calcium salts · A lot of collagen fibers · Protect & supports body

Connective Tissue Types 2. Hyaline cartilage · Most common cartilage · Lots of collagen fibers · Rubbery matrix · Fetal skeleton & ribs

Connective Tissue Types 3. Elastic cartilage · Provides elasticity · found in external ear, epiglottis, & trachea

Connective Tissue Types 4. Fibrocartilage · Highly compressible · forms cushion-like discs between vertebrae

Connective Tissue Types 5. Dense · Main matrix element is collagen fibers · Cells are fibroblasts · Tendon – muscle to bone · Ligaments – bone to bone

Connective Tissue Types 6. Areolar · Most widely distributed · Soft, pliable tissue · Contains all fiber types · Can soak up excess fluid · Think “airy”

Connective Tissue Types 7. Adipose · Similar to areolar with fat globules · Many cells contain large lipid deposits · Functions - Insulates body - Protects organs - Fuel storage

Connective Tissue Types 8. Reticular · Delicate network of interwoven fibers · Forms stroma (internal supporting network) of lymphoid organs - Lymph nodes - Spleen - Bone marrow

Connective Tissue Types 9. Blood · Blood cells surrounded by fluid matrix · Fibers are visible during clotting · Functions as the transport vehicle for materials

Muscle Tissue · Function = produce movement · 3 types - Skeletal muscle Ømove muscles of skeleton - Cardiac muscle Øonly found in heart - Smooth muscle Øfound in organs & vessels

Muscle Type of Control? Striations? How many nuclei? Skeletal Voluntary Yes Many per cell Cardiac Involuntary Yes & 1 per cell intercalated disks Smooth Involuntary No 1 per cell

Nervous Tissue · Neurons and nerve support cells · Function = send impulses to other areas of the body - Irritability – able to respond to stimuli - Conductivity – conducts messages

Tissue Repair · Regeneration · Replacement of destroyed tissue by the same kind of cells · Fibrosis · Repair by dense fibrous connective tissue (scar tissue) · Determination of method · Type of tissue damaged · Severity of the injury

Events in Tissue Repair · Capillaries become very permeable · Introduce clotting proteins · Wall off injured area · Formation of granulation tissue · Regeneration of surface epithelium

Regeneration of Tissues · Tissues that regenerate easily · Epithelial tissue · Fibrous connective tissue and bone · Tissues that regenerate poorly · Skeletal muscle · Tissues that are replaced largely with scar tissue · Cardiac muscle · Nervous tissue within the brain and spinal cord

Tissue Type Epithelial Connective Muscle Nerve Cell Shape Flattened, cuboidal, columnar Irregular or round Elongated Cell appendages branched Cell Arrangement Single multilayered Scattered in matrix In sheets or bundles Isolated or networked Location Body covering or lining organs or cavities Supports other organs Lining internal organs, make skeletal muscles Concentrated in brain and spinal cord + all over the body Surface Feature of Cells Cilia, microvilli - - - Matrix Type Basement membrane Varied – protein fibers + liquid, gelatinous, firm to calcified - - Matrix Amount Minimal Extensive Absent Unique Feature No direct blood supply, except for glands Cartilage has no blood supply Can generate electrical signals, force and movement Can generate electrical signal