lecture 4
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Questions and Answers

Which type of muscle tissue is under involuntary control and found in the heart?

  • Epithelial tissue
  • Smooth muscle
  • Skeletal muscle
  • Cardiac muscle (correct)

    • Skeletal muscle tissue is responsible for involuntary movement.

    False

    What are the two main types of cells found in nervous tissue?

    neurons and neuroglia

    Smooth muscle tissue facilitates __________ of airways.

    <p>constriction</p> Signup and view all the answers

    Match the tissue type with its primary function:

    <p>Skeletal muscle = Voluntary movement and heat generation Cardiac muscle = Forms the heart wall Smooth muscle = Involuntary control of internal organs Nervous tissue = Coordinates and controls body responses</p> Signup and view all the answers

    Which of the following types of tissues is responsible for generating body heat?

    <p>Muscular tissue</p> Signup and view all the answers

    Epithelial tissue is specialized for exchange with only the internal environment of the body.

    <p>False</p> Signup and view all the answers

    What is the scientific study of tissues called?

    <p>Histology</p> Signup and view all the answers

    The primary connective function of connective tissue is to protect and __________ the body and internal organs.

    <p>support</p> Signup and view all the answers

    What type of junction forms leakproof connections?

    <p>Tight junctions</p> Signup and view all the answers

    Desmosomes connect adjacent cells and resist __________.

    <p>contraction</p> Signup and view all the answers

    Match the following types of tissues with their functions:

    <p>Epithelial tissue = Covers and protects the body Connective tissue = Connects organs and stores energy Muscular tissue = Generates force and body heat Nervous tissue = Detects stimuli and generates nerve impulses</p> Signup and view all the answers

    What type of cell junction anchors cells to the underlying basement membrane?

    <p>Hemidesmosomes</p> Signup and view all the answers

    What process do merocrine glands use to release their products?

    <p>Exocytosis</p> Signup and view all the answers

    Apocrine glands secrete products from the entire surface of the cells.

    <p>False</p> Signup and view all the answers

    What type of connective tissue contains mesenchymal cells?

    <p>Mesenchymal tissue</p> Signup and view all the answers

    Sebaceous glands are an example of ________ glands.

    <p>holocrine</p> Signup and view all the answers

    Match the following types of connective tissue with their descriptions:

    <p>Loose connective tissue = Contains a variety of cells and fibres, serves as packing material Dense connective tissue = Packed with protein fibres, fewer cells Adipose connective tissue = Stores energy and insulates the body Reticular connective tissue = Filters substances like lymph</p> Signup and view all the answers

    Which of the following is NOT a type of connective tissue?

    <p>Stratified squamous epithelium</p> Signup and view all the answers

    Collagen fibers are the thinnest type of fibers in the extracellular matrix.

    <p>False</p> Signup and view all the answers

    Name the process by which cells in holocrine glands release their secretions.

    <p>Rupturing</p> Signup and view all the answers

    The main component of the extracellular matrix is _________.

    <p>ground substance</p> Signup and view all the answers

    Which type of fiber in the extracellular matrix provides elasticity?

    <p>Elastic fibers</p> Signup and view all the answers

    Epithelial tissues typically have a larger number of cells compared to connective tissues.

    <p>True</p> Signup and view all the answers

    What is the primary function of macrophages in connective tissue?

    <p>Phagocytosis</p> Signup and view all the answers

    The densely packed connective tissue that is irregularly arranged is known as ________ connective tissue.

    <p>dense</p> Signup and view all the answers

    Which of the following glands is correctly paired with its secretion method?

    <p>Holocrine - secrete by cell rupture</p> Signup and view all the answers

    What types of layers can epithelial tissue have?

    <p>Simple and stratified</p> Signup and view all the answers

    The primary function of the basement membrane is to allow nutrient absorption.

    <p>False</p> Signup and view all the answers

    What are the primary functions of epithelial tissues?

    <p>Protection, secretion, absorption.</p> Signup and view all the answers

    The _____ membrane connects epithelial tissue to underlying connective tissue.

    <p>basement</p> Signup and view all the answers

    Which type of epithelium is specialized for filtration and diffusion?

    <p>Simple squamous epithelium</p> Signup and view all the answers

    Cilia in epithelial tissue assist in the secretion of mucus.

    <p>True</p> Signup and view all the answers

    Name a gland type that secretes hormones directly into the bloodstream.

    <p>Endocrine glands</p> Signup and view all the answers

    The ciliated pseudostratified columnar epithelium lines the majority of the _____ tract.

    <p>upper respiratory</p> Signup and view all the answers

    Which type of epithelial tissue is characterized by multiple layers of flat cells?

    <p>Stratified squamous epithelium</p> Signup and view all the answers

    Goblet cells are found in ciliated simple columnar epithelium.

    <p>True</p> Signup and view all the answers

    What is the shape of cells in cuboidal epithelium?

    <p>Cube-shaped</p> Signup and view all the answers

    Stratified cuboidal epithelium is _____, meaning it is not commonly found in many areas of the body.

    <p>rare</p> Signup and view all the answers

    Match the epithelial types to their functions:

    <p>Simple squamous = Filtration and diffusion Ciliated columnar = Movement of mucus Stratified squamous = Protection from abrasion Transitional = Expansion of hollow organs</p> Signup and view all the answers

    The basal surface of epithelial cells faces the external environment.

    <p>False</p> Signup and view all the answers

    What characteristic describes epithelial cells as 'polarized'?

    <p>They have distinct apical and basal surfaces.</p> Signup and view all the answers

    Which type of dense connective tissue is characterized by packed collagen fibers and provides great tensile strength?

    <p>Dense regular connective tissue</p> Signup and view all the answers

    Elastic connective tissue provides rigidity and structure to organs.

    <p>False</p> Signup and view all the answers

    What structure do chondrocytes reside in within cartilage?

    <p>lacunae</p> Signup and view all the answers

    Hyaline cartilage provides a smooth surface between bones at _________.

    <p>joints</p> Signup and view all the answers

    Match the following types of cartilage with their characteristics:

    <p>Hyaline = Most abundant cartilage, provides smooth surfaces at joints Fibrocartilage = Strongest type of cartilage, found in intervertebral discs Elastic = Provides strength and stretch, shapes structures like the ear</p> Signup and view all the answers

    Which of the following is a function of blood?

    <p>Transports oxygen, nutrients, gases, and wastes</p> Signup and view all the answers

    Mucous membranes line cavities that are not open to the external environment.

    <p>False</p> Signup and view all the answers

    What are the cells that secrete synovial fluid in synovial membranes called?

    <p>synoviocytes</p> Signup and view all the answers

    The primary component of blood plasma is _________.

    <p>water</p> Signup and view all the answers

    Which type of connective tissue is characterized as 'uncooked egg' in appearance?

    <p>Synovial membranes</p> Signup and view all the answers

    The epidermis is the deepest layer of the skin.

    <p>False</p> Signup and view all the answers

    What type of connective tissue forms the framework for organs and supports various body structures?

    <p>areolar connective tissue</p> Signup and view all the answers

    Fibrocartilage is found at the pubic _________.

    <p>symphysis</p> Signup and view all the answers

    Match the following membranes with their functions:

    <p>Mucous membranes = Line body cavities open to the external environment Serous membranes = Lubricate and protect organs not exposed to the external environment Cutaneous membranes = Protect against abrasion and environmental damage</p> Signup and view all the answers

    Which cells are primarily responsible for detecting electrical stimuli and producing action potentials?

    <p>Excitable cells</p> Signup and view all the answers

    Study Notes

    Tissues

    • Tissues are groups of similar cells working together to perform a shared function.
    • Histology is the study of tissues.
    • Four types of human tissue:
      • Epithelial tissue
      • Connective tissue
      • Muscular tissue
      • Nervous tissue

    Epithelial Tissue

    • General Functions:
      • Covers and protects the body
      • Lines hollow organs
      • Forms glands
      • Facilitates exchange with the environment

    Connective Tissue

    • General Functions:
      • Protects and supports the body and internal organs
      • Connects organs together
      • Stores energy
      • Aids immunity

    Muscular Tissue

    • General Functions:
      • Generates force through contraction
      • Produces body heat

    Nervous Tissue

    • General Functions:
      • Detects and responds to stimuli.
      • Generates electrical signals (nerve impulses) to control muscle and gland activity.

    Cell Junction Types

    • Cell junctions act as points of contact between adjacent cells.
    • Five main types:
      • Tight junctions
      • Adherens junctions
      • Desmosomes
      • Hemidesmosomes
      • Gap junctions

    Tight Junctions

    • Function: Form leakproof connections between cells
    • Location: Stomach lining, intestinal epithelium, urinary bladder

    Adherens Junctions

    • Function: Connect adjacent cells, resist pulling forces.
    • Structure:
      • Transmembrane proteins
      • Cytoplasmic plaque
      • Microfilaments (actin)

    Desmosomes

    • Function: Connect adjacent cells, resist contraction.
    • Structure:
      • Similar to adherens junctions
      • Plaque connects transmembrane proteins to intermediate filaments.
    • Location: Epidermis, heart muscle

    Hemidesmosomes

    • Function: Anchor cells to underlying tissues.
    • Structure:
      • Transmembrane glycoproteins connect intermediate filaments to laminins in the basement membrane.
    • Location: Epidermis, anchoring skin to connective tissue

    The Basement Membrane

    • Structure: Two layers:
      • Basal lamina
      • Reticular lamina
    • Function:
      • Separates epithelial tissue from underlying connective tissue.
      • Provides a surface for epithelial attachment, migration, and growth.

    Gap Junctions

    • Function: Allow direct cell-to-cell communication through protein channels (connexons) formed by connexins.
    • Location: Nerves (electrical synapses), allowing ion flow.

    Epithelial Tissue Classification

    • Classified based on:
      • Number of layers:
        • Simple (one layer)
        • Stratified (multiple layers)
        • Pseudostratified (single layer appearing as multiple layers)
      • Shape of cells:
        • Squamous (flat)
        • Cuboidal (cube-shaped)
        • Columnar (long and rectangular).
        • Transitional (variable shape)

    Epithelial Cell Polarization

    • Polarized cells: Cells with distinct "faces" or ends.
    • Apical surface: Faces inward (organ, vessel, duct) or outward (external environment)
    • Basal surface: Faces underlying tissues (usually connective tissue)
    • Lateral surface: Faces adjacent cells.

    Surface Epithelium

    • Lines body surfaces.

    Simple Squamous Epithelium

    • Function:
      • Filtration of body fluids
      • Diffusion of nutrients and gases
    • Location:
      • Endothelium (lining blood vessels)
      • Mesothelium (epithelial layer of serous membranes)

    Simple Cuboidal Epithelium

    • Function:
      • Secretion of hormones and other substances.
      • Absorption of water and solutes
    • Location:
      • Kidney tubules
      • Thyroid gland

    Non-ciliated Simple Columnar Epithelium

    • Function:
      • Secretion of mucus
      • Absorption of nutrients.
    • Structure:
      • Contains goblet cells and gastrointestinal cells with microvilli
    • Location:
      • Digestive tract lining

    Ciliated Simple Columnar Epithelium

    • Function: Cilia on apical surface move mucus produced by goblet cells
    • Location:
      • Bronchioles
      • Oviducts

    Non-ciliated Pseudostratified Columnar Epithelium

    • Function: Absorption and secretion (e.g., saliva)
    • Structure: Single layer appears stratified due to nuclei at different depths.
    • Location:
      • Epididymis
      • Part of the male urethra

    Ciliated Pseudostratified Columnar Epithelium

    • Function: Cilia sweep mucus over the tissue surface.
    • Location:
      • Majority of the upper respiratory tract

    Stratified Squamous Epithelium (Keratinized)

    • Function: Protection from abrasion, fluid loss, UV radiation, and invasion.
    • Structure: Superficial layer can be sloughed off, and contains keratin (filamentous, insoluble protein for strength).
    • Location:
      • Epidermis (skin)

    Stratified Squamous Epithelium (Nonkeratinized)

    • Location:
      • Lining of the vagina

    Stratified Cuboidal Epithelium

    • Function: Protection from abrasion.
    • Location:
      • Sweat glands
      • Esophageal glands
      • Parts of the male urethra

    Stratified Columnar Epithelium

    • ** Function:**
      • Protection from invasion
      • Secretion (e.g., tears).
    • Location:
      • Esophageal glands
      • Conjunctiva

    Transitional Epithelium (Urothelium)

    • Function: Lines hollow organs that expand to store fluids.
    • Structure:
      • Cuboidal at rest.
      • Squamous when stretched.
    • Location:
      • Urinary bladder
      • Portions of the ureters and urethra

    Glandular Epithelium

    • Function: Secretion for body protection.
    • Types:
      • Exocrine
      • Endocrine
      • Mixed

    Exocrine Glands

    • Function: Secrete substances a short distance.
    • Secretion pathway:
      • Into ducts that carry secretions to the surface of the body or into hollow organs.

    Endocrine Glands

    • Function: Secrete hormones into the interstitial fluid, which diffuses into the blood and circulates to target tissues.
    • Hormones: Chemical messengers produced by cells that regulate homeostasis.
    • Example: Thyroxin (thyroid hormone)

    Multicellular Exocrine Glands

    • Types:
      • Merocrine
      • Apocrine
      • Holocrine

    Merocrine Glands

    • Secretion method: Exocytosis
    • Example: Most body glands, including sweat glands.

    Apocrine Glands

    • ** Secretion method:** Exocytosis only from the apical surface.
    • Example: Mammary glands (secreting breast milk)

    Holocrine Glands

    • Secretion method: Cell rupture, releasing contents into the secretion.
    • Example: Sebaceous glands (secrete oil)

    Connective Tissues

    • General Characteristics:
      • Not usually found at body surfaces.
      • Contains nerves and blood vessels (with some exceptions).
    • Components:
      • Extracellular matrix (ECM)
      • Cells

    Extracellular Matrix (ECM)

    • Structure:
      • Protein fibers (collagen, elastic, reticular)
      • Ground substance
    • Properties: Can be liquid, solid, or gel-like.

    Connective Tissue Cells

    • ** Originate from embryonic mesenchymal cells.**
    • Types:
      • Fibroblasts (most abundant, secrete ECM of loose and dense connective tissue)
      • Macrophages (phagocytic immune cells)
      • Plasma cells (secrete antibodies)
      • Mast cells (release inflammatory chemicals)
      • Adipocytes (store triglycerides)
      • Leukocytes (white blood cells)

    ECM of Connective Tissues

    • Ground substance: Material between cells and fibers, giving the tissue its properties.
    • Protein fibers:
      • Collagen fibers (most abundant, provide tensile strength)
      • Elastic fibers (provide elasticity)
      • Reticular fibers (thin, provide support)

    Difference between Epithelial and Connective Tissue

    • Key difference: Ratio of extracellular matrix to number of cells.
      • Epithelial tissues have more cells.
      • Connective tissues have more extracellular matrix.

    Other Differences between Epithelial and Connective Tissue

    • Vascularization: Epithelial tissue is typically not vascularized (lacks blood vessels), while connective tissue is vascularized.
    • Location: Epithelial tissues often form the most superficial layer and are not covered by other tissues.

    Embryonic Connective Tissues

    • Mesenchymal tissue:

      • Contains mesenchymal cells, semifluid ground substance, and reticular fibers.
      • Develops into nearly all types of connective tissue.
      • Forms the first skeleton of the developing embryo.

    • Mucoid connective tissue:

      • Contains fibroblasts, gel-like ground substance, and thin collagen fibers.
      • Provides mechanical support to overlying tissue.
      • Found in the umbilical cord.

    Mature Connective Tissues

    • Loose connective tissue:
      • Sparsely distributed cells and fibers.
      • Types: Areolar, adipose, and reticular connective tissue.
    • Dense connective tissue:
      • Densely packed protein fibers, fewer cells than loose connective tissue.
      • Types:
        • Regular
        • Irregular
        • Elastic.

    Areolar Connective Tissue

    • Function: Supports, reinforces, provides stretch to organs, serves as packing material for body cavities.
    • Structure:
      • All three fiber types (collagen, elastic, reticular)
      • Variety of cells
      • Semifluid ground substance.

    Adipose Connective Tissue

    • Function: Insulates the body, stores energy, supports and protects internal organs.
    • Structure:
      • Contains adipocytes (store triglycerides).
      • Two types:
        • White adipose tissue (stores triglycerides in a large central droplet)
        • Brown adipose tissue (contains numerous mitochondria, involved in heat production).

    Reticular Connective Tissue

    • Function: Filters substances, forms stroma of the spleen and lymph nodes.
    • Structure:
      • Tightly woven reticular fibers
      • Fibroblasts

    Dense Regular Connective Tissue

    • Function: Provides great tensile strength.
    • Structure:
      • Packed collagen fibers
      • Sparse fibroblasts.
    • Location: Tendons, ligaments, aponeuroses.

    Dense Irregular Connective Tissue

    • Function: Resists pulling forces along any axis.
    • Structure:
      • Irregularly arranged collagen fibers
      • Few fibroblasts.
    • Location: Fasciae, pericardium.

    Elastic Connective Tissue

    • Function: Provides elasticity to organs.
    • Structure:
      • Elastic fibers
      • Few fibroblasts.
    • Location:
      • Lungs
      • Walls of elastic arteries
      • Trachea
      • Bronchial tubes.

    Supporting Connective Tissues: Cartilage

    • Function:
      • Provides smooth surfaces between bones (hyaline cartilage)
      • Resists compression (all types of cartilage)
    • Structure:
      • Thick collagen fibers in a gel-like ground substance.
    • Cells: Chondrocytes (fibroblasts) reside in lacunae.
    • Vascularization: Not vascularized, heals slowly.
    • Perichondrium: Layer of new chondrocytes containing blood vessels that covers some types of cartilage.

    Types of Cartilage

    • Hyaline cartilage:
      • Most abundant type, forms the fetal skeleton before ossification.
      • Found at joints.
    • Fibrocartilage:
      • Strongest type, lacks a perichondrium.
      • Found at the pubic symphysis, intervertebral discs, and menisci (knee joints).
    • Elastic cartilage:
      • Provides strength and stretch.
      • Found in the auricle, eustachian tubes, and epiglottis.

    Bone Tissue

    • Types: Compact and spongy.
    • Compact bone:
      • Consists of repeating osteons, which are rings of calcified ECM with:
        • Lacunae containing osteocytes (bone cells)
        • Central canal (contains blood vessels and nerves)

    Liquid Connective Tissues

    • Blood:
      • Liquid ECM (blood plasma) containing blood cells, transporting oxygen, nutrients, gases, wastes, immune cells, hormones, and platelets.
    • Lymph:
      • Liquid tissue with varying composition depending on location.
      • Less protein than blood plasma.
      • Composition:
        • Lymphocytes (exiting lymph nodes)
        • Dietary fats (exiting the small intestine)

    Anatomical Membranes

    • Types:
      • Mucous membranes
      • Serous membranes
      • Cutaneous membranes (skin).
    • Structure: Usually contain an epithelial layer and connective tissue, except for synovial membranes.

    Mucous Membranes

    • Function:
      • Line body cavities open to the external environment.
      • Protect the body from invaders and fluid loss.
      • Secrete enzymes for digestion and absorption.
    • Structure:
      • Variable epithelial layer
      • Connective tissue (lamina propria)

    Serous Membranes

    • Function:
      • Line internal body cavities and organs not exposed to the external environment.
      • Lubricate organs and walls.
    • Structure:
      • Areolar connective tissue covered by mesothelium (secretes serous fluid).

    Cutaneous Membranes (Skin)

    • Function: Protection from abrasion, UV radiation, and invasion
    • Structure:
      • Epidermis (keratinized stratified squamous epithelium)
      • Dermis (dense irregular and areolar connective tissue)

    Synovial Membranes

    • Function: Line and lubricate joints, nourish cartilage.
    • Structure:
      • Contains only connective tissue.
      • Synviocytes (secrete synovial fluid)
      • Layers of areolar and adipose connective tissue.

    Muscular and Nervous Tissues

    • Excitable cells: Detect electrical stimuli and respond by producing action potentials.

    Muscular Tissue

    • Function:
      • Contraction to move bones
      • Generates heat
    • Structure:
      • Made of muscle fibers (myocytes).
    • Types:
      • Skeletal
      • Cardiac
      • Smooth

    Nervous Tissue

    • Function:
      • Detects and responds to stimuli.
      • Generates nerve impulses.
    • Primary cell type: Neuron.
    • Supporting cells: Neuroglia.### Skeletal Muscle Tissue
    • Long, multinucleate, striated tissue
    • Responsible for voluntary movement, maintaining posture, and generating heat
    • Attaches to bones via tendons

    Cardiac Muscle Tissue

    • Branched, striated fibres with a single nucleus
    • Cells joined by gap junctions for rapid electrical signal conduction
    • Under involuntary control
    • Collectively forms the myocardium or heart wall

    Smooth Muscle Tissue

    • Long, nonstriated fibres in an irregularly-shaped cell with a single nucleus
    • Cells joined by gap junctions to coordinate involuntary muscle contractions
    • Facilitates peristalsis, constriction of airways, contractions of the urinary bladder and gallbladder

    Nervous Tissue

    • Comprised of two types of cells: neurons and neuroglia
    • Neurons consist of a cell body, dendrites, and an axon and generate electrical signals
    • Neuroglia do not generate electrical impulses but synthesize myelin, a coating of neuronal axons, to increase electrical signal transmission speed

    Summary of Tissue Types

    • Tissues are composed of cells and extracellular matrix (ECM)
    • Epithelial tissues cover and line the body, able to secrete/absorb substances and protect from mechanical injury
    • Connective tissues join epithelial tissues to deeper tissues and support the body
    • Muscular tissue moves the body and generates heat
    • Nervous tissue coordinates and controls the body's response to stimuli

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