Cells and Tissues SAP1d. Relate cellular metabolism and transport to homeostasis and cellular reproduction. SAP1e. Describe how structure and function are related in terms of cell and tissue types. Cells Founded by Robert Hooke in the late 1600s.
Cells are the building blocks of all living things, animals and plants. The human body has trillions of them. Biochemistry Cells are made up primarily of four elements carbon, oxygen, hydrogen, and nitrogen, plus trace elements. The 4 elements make up most of the cells structure.which is mostly protein.
The trace elements are important for certain cell functions. Cablood clotting, Fehemoglobin carries O 2 in blood, Ithyroid protein for metabolism, metals, Ca, Na, K, carry an electric charge (electrolytes). Na and Knerve impulses for muscle contraction Living cells are 60% water. Cells live in interstitial fluid (a dilute salt water solution), which is derived from the blood. All
exchanges between cells and blood are made through this fluid. Cells vary in size, from 2 micrometers (1/12000 of an inch) to over a meter (the nerve cell that makes your toes wiggle). Cells have different shapes, depending on their function. All cells have 3 main regions: 1. Nucleus
A. control center B. contains DNAinstructions for building proteins. C. has 3 regions: 1. nuclear envelopedouble membrane barrier 2. nucleoliwhere ribosomes are assembled a. ribosomeswhere proteins are synthesized 3. chromatinDNA and protein, when cell is not dividing. Condense to form chromosomes when it is. Parts of the Cell
2. The plasma membrane- the phospholipid bi-layer makes it impermeable to most water soluble molecules. Cholesterol makes it fluid. Plasma Membrane Proteins Enzymes Receptors for hormones Binding sites for anchoring cells to structures Protein channelspores that water and small molecules can move through.
Carrierspull things through Glycoproteinssugar groups Plasma Membrane Specializations of the Plasma Membrane 1. Microvillitiny hair like projections that increase the surface area of cells, so they can absorb more quickly. 2. Membrane Junctions A. Tight Junctionsbind cells together into leak-proof sheets
so things cant pass through space between cells. Like a zipper. B. DesmosomesAnchoring junctions that prevent cells subject to mechanical stress (ex. skin cells) from being pulled apart. Like wires. C. Gap Junctionsallow communication (heart and embryonic cells). Chemicals can pass through from one cell to another. Neighboring cells connected by connexons.hollow cylinders. Parts of the cell 3. The Cytoplasm
A. The cellular material outside the nucleus and inside the plasma membrane. B. Consists of 3 parts: 1. The cytosol- semi-transparent fluid that suspends the other elements. 2. The organellesmetabolic machinery of the cell. 3. Inclusionschemical substances that may or may not be present, depending on the specific cell type. Can be stored nutrients or cell products.
Membrane Transport Intercellular fluid inside the cell Interstitial fluidoutside the cell (contains 1000s of ingredients, including amino acids, sugars, fatty acids, vitamins, hormones, neurotransmitters, salts, and waste products. To remain healthy, cells must take the substances it needs at specific times and reject the rest. The movement of materials into and out of cells influences the internal concentrations of the molecules. So, you can see that what goes in or out will have a profound effect on the ability of cells to function properly. The ability of cells to move
materials in and out efficiently can determine whether they will live or die. How do cells control these movements? The plasma membrane is selectively permeable, allowing some substances to pass through while excluding others. (Permeable means porous or penetrable). It is the gate keeper of the cell. Movement of substances through the plasma membrane happens in two ways: 1. Passive Transport no energy input is required from the cell. It just happens (actually the kinetic energy of the particles themselves bc they
have heat--provides the energy). A. Diffusionmovement of particles from a higher concentration to a lower concentration until evenly distributed (equilibrium). (Particles will move until they are randomly distributed in space). Nonpolar and lipid soluble move through the phospholipid bilayer. (O2, CO2, fats, urea, alcohol) 1. polar, lipid insoluble substances can diffuse through the protein channels if small enough. 2. the greater the concentration difference, the faster the diffusion. Example: food coloring in water Watch video clip:
https://www.youtube.com/watch?v=6yMPpDeNwqQ Passive Transport.. 2. OsmosisMovement of water from a higher water concentration to a lower water concentration across a membrane; One molecule or ion displaces one water molecule. A. tonicityability of a solution to change the shape of a cell by altering volume of water.
B. hypotonicsolution with lower concentration of solutes than the cell. C. hypertonicsolution with higher concentration of solutes than the cell. D. isotonicsolution with same concentration of solutes as the cell. Video clip: https://www.youtube.com/watch?v=w3_8FSrqc-I Osmosis
Diffusion vs. Osmosis Passive Transport 3. Facilitated Diffusioncarrier proteins change shape to carry large substances across the membrane; selective (glucose). Video: https://www.youtube.com/watch?v=vKGN_Zhz8 AY
4. FiltrationHydrostatic pressure forces water and solutes through a membrane (capillaries, urine). 2. Active Transportrequires energy (ATP) to move substances across the membrane. Criteria: They may be too large, lipid insoluble, move uphill or against a concentration gradient, the membrane may lack special protein carriers.
A. Active Transport (solute pumping)similar to carrier mediated facilitated diffusion. A. required protein carriers that combine reversibly with the substances to be transported across the membrane. However, it uses ATP to energize its protein carriers, which are called solute pumps. B. Amino acids, sugars, and most ions move by solute pumps against concentration (or electrical)
gradients. B. Vesicular (bulk) Transport 1. Exocytosis (out of the cell)Ex: hormone secretion, neurotransmitter release, mucus secretion, excrete wastes 2. Endocytosis (into the cell) A. Phagocytosis (cell eating)--macrophages B. Pinocytosis (cell drinking)intestinal walls https://www.youtube.com/watch?v=qasm7Mj7CYg
3. Receptor Mediated Endocytosis specific molecules are ingested into the cell. The specificity results from a receptor-ligand interaction. Receptors on the plasma membrane of the target tissue will specifically bind to ligands on the outside of the cell. An endocytotic process occurs and the ligand is ingested. Ex. Metabolism of cholesterol
Membrane Transport Membrane proteins Video Clip: Membranes and Transport https://www.youtube.com/watch?v=dPKvHrD1eS4 Cell Division New cells can be formed only by the division
of existing cells. A plant or animal starts as a single cell and grows by increasing the number of cells. The human body contains approx. 100 trillion cells, most of which are less than 1/10 mm across. Cellular Metabolism An organism acquires energy by breaking down food within its cells. It then uses this energy to maintain each cells internal
chemical environment, to build organic molecules, to grow, and to reproduce by cell division. Cell Diversity There are around 200 different cell types that vary greatly in size, shape, and function. Life begins with one cell able to divide. Different chemical signals in the embryo direct cells into specific pathways of development.
Cell DNA determines which proteins are made; cell specialization. New cells are formed throughout childhood and adolescence, although most organs are functional before birth. 1. Cells that connect body parts A. Fibroblastelongated shape that lies along cablelike fibers that it secretes. It has a lot of ribosomes and a large golgi apparatus (to make and secrete the protein building blocks of these fibers.
B. Erythrocyte (red blood cell)carries oxygen in the bloodstream. Concave disc shape, so it has extra surface area to take up oxygen and is streamlined to move easily through the blood. 2. Cell that covers and lines body organs. Epithelial cellshexagonal honeycomb shape so they can pack together in sheets. Has lots of intermediate filaments that resist
tearing. 3. Cells that move organs and body parts. Skeletal Muscle Cells Smooth Muscle Cells Elongated shape; filled with abundant contractile filaments, so they can shorten forcefully and move bones or change the size of internal organs.
4. Cells that store nutrients Fat CellsHuge spherical shape is produced by a large lipid droplet. 5. Cells that fight disease Macrophage (a phagocytic cell)Extends long pseudopods (false feet) to crawl through tissue to reach infection sites. There are many lysosomes in the cell that digest microorganisms.
6. Cell that gathers information and controls body functions Nerve Cell (neuron)long processes for receiving messages and transmitting them to other structures in the body. The processes are covered with an extensive plasma membrane, and a plentiful rough ER to synthesize membrane components.
7. Cells of reproduction Oocyte (female)-largest cell in the body contains several copies of all organelles, for distribution to daughter cells that arise when fertilized egg divides to become embryo. Sperm (male)long and streamlined, built for swimming, propelled by flagellum . What are tissues? Groups of similar cells that work together to perform a
common function. There are 4 categories: Epithelial- linings and coverings of organs and body cavities, secretory part of organs and glands, transport membranes of capillaries and alveolar sacs, and membranes which lubricate organs.--covering Connectivesupports as bone, cartilage, tendons, and ligaments, protects as the bony cavities and as protective immune cells in the blood, and stores nutrients.--support Nervouscarries information in the form of impulses throughout the body.--control
Musclecontracts to perform movements such as skeletal muscle movements, propulsion in the GI tract, and pumping blood in the heart.--movement Video Clip: https://www.youtube.com/watch?v=tKWTJ3_-1E8 4 Types of Tissue Epithelial Epithelial tissue protects your body from moisture loss, bacteria, and internal injury; form covering layers.
There are 2 types of epithelial cells: A. Covering and lining epithelium covers or lines almost all of your internal and external body surfaces; ex. Outer layer of skin and organs, internal surface lining of your lymph vessels and digestive tract. B. Glandular epithelium secretes hormones or other products such as stomach acid, sweat, saliva, and milk. Functions: Protection, Absorption, Filtration, Secretion Epithelial Song
6 Characteristics of Epithelial Cells 1. Tightly Packed; Specialized contacts desmosomes and tight junctions hold cells together. 37 2. Cells have one free surface. Apical surface faces bodys exterior or a cavity.
3. Exposed surface may be slickothers have cilia or microvilli. 4. Lower surface rests on basement membrane. (Supported by connective tissue) Epithelial Connective
5. Cells have no blood supply of their own and depend on underlying connective tissue for food and oxygen. 6. Reproduce readily. --cells are highly mitotic. Video Clip: Epithelia https://www.youtube.com/watch?v=Ucgm0qX4T0k Epithelial Cells
There are many types of epithelial cells. They are found on all body surfaces inside and out. Each epithelial cell is given two names. The first name indicates the number of cell layers and the second describes the shape of the cell. Number of Layers: Simple, Stratified Simpleonly one cell layer thick Stratifiedmore than one cell layer thick Cell Shape: Squamous, Cuboidal, Columnar Squamousflat and tile-like; like a fried egg
CuboidalSpherical nuclei Columnarrectangular with elongated nuclei Epithelial Cell Shapes Squamous- flat and tile-like Cuboidalspherical nucleus Columnarelongated nuclei
Classified as simple or stratified by number of layers EpithelialNumber of Layers Simple Stratified
Epithelial Tissue Epithelial Tissue Simple Epithelia: absorption, secretion, and filtration. Too thin for protection. Simple Squamous: Single layer of flattened cells resting on basement membrane, disc shaped central nuclei. Fit closely together like floor tiles.
Allows passage of materials (diffusion/filtration). Found in air sacs of the lungs (alveoli), walls of capillaries (nutrients and gases pass between tissues and blood), lining of heart Also form serous membranes, the slick membranes that line interior body cavities. Simple Squamous Simple Epithelial Tissues
Simple Cuboidal: One layer of cuboidal cells resting on a basement membrane. Common in glands and their ducts (ex. salivary gland and pancreas). Forms the walls of the kidney tubules and covers the surface of ovaries; parts of the eye and thyroid. Secretion and absorption.
Simple cuboidal Simple Epithelial Tissues Simple Columner: Single layer of tall cells that fit close together; oval nuclei. Contain goblet cells, mucus secreting cells. Absorption, secretion, propel secretion (mucus, enzymes) Lines the entire length of digestive tract, from
stomach to anus, gallbladder, uterus Epithelial membranes that line body cavities and open to the body exterior are called mucous membranes. Simple Epithelial Tissues Pseudostratified Columnar Epithlium: All of the cells rest on the basement membrane, but some of its cells are shorter than others, and their nuclei appear at different heights above the
basement membrane. This gives the false impression that it is stratified. Function: Absorption and secretion. A ciliated variety lines most of the respiratory tract. The mucus produced by the goblet cells in this epithelium traps dust and other debris, and the cilia propel the mucus upward and away from the lungs. Stratified Epithelial Tissues2 or more layers; more durable. Primary function is to protect.
Stratified Squamous: Most common stratified epithelium. Several layers of cells; surface cells full of keratin (dead). The cells at the free edge are squamous, but those close to basement membrane are cuboidal or columnar. Esophagus, mouth, and outer portion of the skin. Stratified Epithelial Tissues
Stratified Cuboidal: Usually 2 layers with (at least) the surface being cuboidal. They protect areas such as the ducts of sweat glands, mammary glands, and salivary glands. Stratified Columnar: Surface cells are columnar, but basal cells vary in size and shape. Also found in the ocular conjunctiva of the eye, in parts of the pharynx and anus, the females uterus,
the male uretha and vas deferens, and intralobular ducts in salivary glands. Transitional Epithelium A highly modified, stratified squamous epithelium that forms the lining of only a few organs: the urinary bladder, the ureters, and part of the urethra. All of these are part of the urinary system and subject to stretching. Basal layer are cuboidal or columnar; those of free surface vary in appearance.
Unstretched: membrane is many-layered, superficial cells are rounded and dome-like. Stretched and full: epithelium thins, surface flatten and become squamous-like. The ability of transitional cells to slide past one another and change their shape (transitions) allows the ureter wall to stretch as greater volume of urine flows through the tubelike organ. Thus, more urine can be stored. Transitional Epithelium
10 or more layers of cuboidal cells Able to withstand tension changes/stretching Cells flatten when organ stretched Bladder Glandular Epithelium
A gland consists of one or more cells that make and secrete a particular product. The product is called a secretion, and typically contains protein molecules in an aqueous solution. Glandular Epithelium A. Endocrine glands Lose their connection to the surface (duct); often called duct-less glands. Their secretions (all hormones) diffuse directly into the blood
vessels that weave through the glands. Ex: thyroid, adrenals, and pituitary. Glandular Epithelium B. Exocrine glands Retain their ducts, and their secretions empty through the ducts to the epithelial surface. Can be internal or external. Sweat and oil glands, liver, and pancreas. Connective Tissue
Connects body parts. Found everywhere in the human body; most abundant and widely distributed type of tissue. Functions: protecting, supporting, and binding together. Characteristics: 1. Variation in blood supply. (Most vascular, except tendons and ligaments, making them slow to heal; cartilage are avascular.) 2. Cells have extracellular matrixnonliving substance found outside the cells. Vascularized: have good blood supply
Connective Tissue Binds, supports, protects, insulates, and transports 64 Extracellular Matrix The extracellular matrix is produced by the connective
tissue cells then secreted to their exterior. It is made of a structure-less ground substance and fibers. Ground Substance Unstructured Serves as glue (allows connective tissue cells to attach themselves to a matrix) Holds a lot of fluids Nutrients can diffuse between blood and cells
Structural Elements Ground substance fluid, proteins Fibers Collagen tough and strong (stronger than steel) Elastic stretchy (rubber band) Reticular network of
thin fibers (support tissues of organs, allow more give than collagen) 66 Connective tissue generally provides structure and support to the body. A. Bone B. Cartilage--(Hyaline, elastic, fibrocartilage)
C. Dense or Fibrous connective tissuealso holds body parts together, buts its structure is more rigid. Found in ligaments, tendons, cartilage, and bone. D. Loose connective tissueholds structures together. Ex. Holds the outer layer of skin to underlying muscle tissue. Found in fat layers, lymph nodes, and red bone marrow. E. Blood Bone Tissue:Osseous Tissue
Supports, protects, stores, produces Hard, calcified, a lot of collagen, vascular Support, protect, lever for muscles to act on, stores calcium/minerals, marrow produces blood Two types: compact bone and spongy bone. 68 Cartilage
Cartilage consists of a dense matrix of collagen fibers and elastic fibers embedded in a rubbery ground substance. The matrix is produced by cells called chondroblasts, which become embedded in the matrix as chondrocytes. The surface of most of the cartilage in the body is surrounded by a membrane of
dense irregular connective tissue called perichondrium. Cartilage contains no blood vessels or nerves (except in the perichondrium). 69 1. Hyaline (glassy) Cartilage Supports, cushions, and provides flexibility.
Most abundant Abundant collagen fibers hidden by a rubbery matrix with glassy (shiny), blue-white appearance. Provides smooth surfaces, enabling tissues to move/slide easily over each other, facilitating smooth movement at joints; Supporting structures of larynx (voice box), attaches to ribs of the
breastbone, covers the ends of many bones forming joints, bronchi, bronchial tubes, nose, trachea. The skeleton of a fetus is largely hyaline cartilage, but it is bone by birth. 70 2. Elastic Cartilage
More elastic fibers. Provides support to surrounding structures and helps to define and maintain shape. Flexibility/structure External ear, auditory tubes, epiglottis (lid on top of larynx) 71 3. Fibrocartilage
Similar to hyaline but more fibrous Absorbs shock, compressible Strongest and most durable Between vertebrae, meniscus of knee
72 Dense Connective (or dense fibrous) Has collagen fibers as main matrix element Crowded between the collagen fibers are rows of fibroblasts that manufacture the building blocks of fibers. Lots of fibers, few cells. 73
Dense Regular Dense connective tissue: dense regular Parallel collagen fibers Attaches muscle to bone Attaches bone to bone Withstands stress Tendons, ligament Dense Irregular
Irregularly arranged collagen fibers Withstands great tension, strong, can move in many directions Skin, digestive tract, joints 1. Loose Connective Areolar Most abundant CT Most widely distributed CT. Soft, pliable,gel-like cobwebby
tissue that cushions and protects the organs it wraps. Lots of empty space. Binds skin to muscles, around organs, surrounds capillaries and nerves. Lots of fibroblasts, macrophages Several Functions Protection/cushion/support/binding/elasticity Functions as a universal packing tissue and connective tissue glue because it helps to hold the internal organs together and in their proper positions.
It provides water and salt for surrounding tissue. Fights infectionswelling, puffiness of skin is due to macrophages. 76 2. Loose Connective Adipose Tissue/ FAT Each adipocyte cell is filled with a single, large droplet of fat. Its
cytoplasm, nucleus, and other components are pushed toward the edges of the cell. Storage for excess food Insulates body and protects it from bumps, heat, and cold. Protects some organs: kidneys and eyeballs and found in thick layer under skin.
77 3. Loose Connective Reticular Tissue Network of reticular fibers in a loose ground substance Form a soft skeleton that supports other cells (white blood cells, macrophages) Lymphoid organs lymph nodes, bone marrow, spleen 78
Blood No ground substance or fibers Blood cells surrounded by nonliving, fluid matrix called blood plasma. Erythrocytes Leukocytes Thrombocytes Transportation for cardiovascular system, carrying nutrients, waste, gases, etc.
79 Recap of Connective Tissue Muscle It contracts and expands, moves bones and organs. Made of muscle fibers. A. Skeletal (striated) muscles 1. Attached to skeleton. 2. Controlled voluntarily.
3. Causes gross body movement. B. Cardiac Muscle 1. Found in the heart. 2. Involuntary. C. Smooth (involuntary) muscle 1. lines the walls of blood vessels and certain organs such as the digestive and urogenital tracts. 2. Contracts much more slowly than other muscle types.
3. Involuntary. 3 Types of Muscle Tissue Skeletal attached to bones Smooth walls of organs, blood vessels, etc. Cardiac - heart 82
Skeletal Muscle Control voluntary motion. Attached to the skeleton. When they contract, they pull on bones or skin, resulting in gross body movements or changes in facial expression. The cells are long and narrow, multinucleate, and
have obvious striations (stripes). Because they are elongated to provide a long axis for contraction, they are often called muscle fibers. 83 Smooth Muscle Function propulsion
No striations (aka visceral) 1 nuclei and are spindle shaped (pointed at each end) Tightly packed into a sheet Involuntary Found in walls of hollow organs, such as stomach, uterus, and blood vessels.
85 Cardiac Muscle Only in the heart; propels blood through blood vessels. Involuntary Striated, one nucleus Relatively short, branching cells that fit tightly together (like clasped fingers) at junctions
called intercalated disks. They contain gap junctions that allow ions to pass freely from cell to cell, resulting in rapid conduction of electrical impulses across the heart. 86 Nervous
Forms the nervous system, which is responsible for coordinating the activities and movements of your body through its network of nerves. Includes the brain, spinal cord, and nerves that branch off of those two key parts. A. Neuronsbasic structural unit of CNS. Each cell consists of the cell body, dendrites, and axon. B. Neuroglia (glial cells)insulate and protect the delicate neurons or anchoring neurons to blood vessels. Functions: irritability and conductivity Neurons receive and conduct electrochemical messages
from one part of the body to another. What is Nervous Tissue? Their cytoplasm is drawn out into long processes (extensions), as much as 3 feet in the leg, which allows a single neuron to conduct an impulse over long distances in the body. 88
Tissue Repair 1. Inflammation Tissue DRAMA! Injured cell releases chemicals Chemicals cause tissue to dilate more permeable White blood cells/plasma/antibodies seep into area Construct a clot
Tissue Repair 2. Organization restores blood supply Clot is replaced by granulation tissue (delicate pink tissue that contains capillaries) Granulation tissue bleeds easily (pick at a scab) Produce growth factors Becomes scar tissue (highly resistant to infection bacteria inhibiting substances) Tissue Repair
Regeneration/fibrosis Epithelium regenerates Scar may be visible or invisible
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