W4 MHS1101 TISSUES

Flashcards on tissues of the body and related concepts.

Epithelial Tissue

Covers surfaces, lines passages, forms glands.

Connective Tissue

Fills spaces, supports, transports, stores energy.

Muscle Tissue

Specialized for contraction (skeletal, cardiac, smooth).

Nervous Tissue

Conducts electrical signals.

Functions of Epithelial Tissue

Physical protection, control permeability, provide sensation, produce secretions.

Characteristics of Epithelial Tissue

Polarity (apical/basal), cellularity (junctions), attachment (basement membrane), avascularity, high regeneration.

Specializations of Epithelial Tissue

Move fluids (cilia, microvilli), produce secretions, apical/basolateral surfaces.

Integrity of Epithelial Tissue Maintained By

Intercellular connections (CAMs, proteoglycans), attachment to basement membrane (basal/reticular lamina), ongoing repair (stem cells).

Gap Junctions

Rapid communication, coordination (e.g., heart).

Tight Junctions

Block passage (digestive tract).

Desmosomes

Strong connections (skin).

Hemidesmosomes

Attach to basement membrane.

Squamous (Epithelial Shape)

Flat.

Cuboidal (Epithelial Shape)

Square.

Columnar (Epithelial Shape)

Tall.

Simple (Epithelial Layers)

One layer.

Stratified (Epithelial Layers)

Multiple layers.

Simple Squamous Epithelium

Absorption/diffusion (mesothelium, endothelium).

Stratified Squamous Epithelium

Protection (skin, oral cavity).

Simple Cuboidal Epithelium

Secretion/absorption (glands, kidneys).

Stratified Cuboidal Epithelium

Rare (sweat, mammary glands).

Transitional Epithelium

Stretches (bladder).

Pseudostratified Columnar Epithelium

Typically, ciliated (respiratory tract).

Simple Columnar Epithelium

Absorption/secretion (GI tract).

Stratified Columnar Epithelium

Rare (pharynx, anus, urethra).

Glands

Clusters of epithelial cells producing secretions.

Endocrine Glands

Release hormones to blood (ductless).

Exocrine Glands

Secrete via ducts (surface).

Merocrine Secretion

Exocytosis (salivary/sweat).

Apocrine Secretion

Shedding cytoplasm (mammary).

Holocrine Secretion

Cell bursts (sebaceous glands).

Unicellular Glands

Goblet cells – mucin.

Multicellular Glands

Simple/compound ducts, tubular/acinar shape, branched.

Serous Secretion

Watery.

Mucous Secretion

Mucin.

Mixed Secretion

Mixed (both serous and mucous).

Connective Tissue Components

Specialized cells, extracellular protein fibres, ground substance (fluid).

Matrix

Fibres + ground substance, main tissue volume.

Functions of Connective Tissue

Structural support, transport, protection. Connects/supports other tissues, energy storage (triglycerides), defence (immune).

Categories of Connective Tissue

Connective tissue proper (connects/protects), fluid connective tissue (blood, lymph – transport), supporting connective tissue (cartilage, bone – strength).

Connective Tissue Proper

Connects/protects.

Fluid Connective Tissue

Blood, Lymph- Transport

Supporting Connective Tissue

Cartilage, Bone -Strength

Areolar Connective Tissue

Least specialized, supports, elastic, holds capillaries.

Adipose Tissue

Fat storage, insulation, energy.

Reticular Tissue

Support (stroma), found in liver, spleen, lymph nodes, bone marrow.

Dense Regular Connective Tissue

Parallel collagen (tendons, ligaments, aponeuroses).

Dense Irregular Connective Tissue

Interwoven collagen (dermis, organ capsules, sheaths).

Elastic Tissue

Elastic fibres (vertebral ligaments).

Fibroblasts

Most abundant, produce fibres/ground substance.

Fibrocytes

Maintain fibres.

Adipocytes

Store fat.

Mesenchymal Cells

Stem cells (repair).

Melanocytes

Pigment (melanin).

Macrophages

Engulf pathogens/debris (fixed/free).

Mast Cells

Inflammation (histamine, heparin).

Lymphocytes

Immune response (can become plasma cells).

Microphages

Phagocytic WBCs (neutrophils, eosinophils).

Collagen Fibres

Strong, unbranched (tendons/ligaments).

Reticular Fibres

Network (support, sheaths).

Elastic Fibres

Stretch, recoil (vertebrae).

Functions of Blood

Transport gases, nutrients, wastes, hormones. Regulate pH, ions. Restrict fluid loss. Defend against toxins/pathogens. Stabilize temperature.

Plasma

55% of blood, mostly water, proteins, solutes.

Formed Elements

Red cells (erythrocytes), white cells (leukocytes), platelets (thrombocytes).

Red Blood Cells

99.9% of formed elements. Biconcave, no nucleus/mitochondria/ribosomes. Filled with hemoglobin (binds O₂/CO₂). Live ~120 days.

Surface Antigens

A, B, Rh (D).

Type A Blood

A antigen, anti-B antibody.

Type B Blood

B antigen, anti-A antibody.

Type AB Blood

A/B antigens, no antibodies.

Type O Blood

No antigens, both antibodies.

Rh+ Blood

D antigen present.

Rh- Blood

D antigen absent.

Agglutinogens

RBC antigens.

Agglutinins

Plasma antibodies (attack foreign antigens).

Transfusion Reaction

Incompatibility causes agglutination/hemolysis.

Universal Donor

O- (still risk due to other antigens).

White Blood Cells

Defence (pathogens, toxins, abnormal cells). Neutrophils, eosinophils, basophils, monocytes, lymphocytes. Can migrate from bloodstream, amoeboid movement, chemotaxis, some phagocytic.

Platelets

Cell fragments, clotting, patch damaged vessels, reduce break size. Circulate 9–12 days, stored in spleen.

Cartilage

Shock absorption, protection. Matrix: firm gel with chondroitin sulphates. Cells: chondrocytes in lacunae, avascular, antiangiogenesis factor (no blood vessels). Perichondrium: Outer fibrous/inner cellular.

Hyaline Cartilage

Most common, tough, flexible, reduces friction (joints, ribs, sternum, trachea).

Elastic Cartilage

Flexible, supports (ear, epiglottis).

Fibrocartilage

Durable, prevents bone contact (joints, pubic bones, vertebrae).

Bone (Osseous Tissue)

Weight support, rigid (calcium salts), resists shattering (collagen). Cells: osteocytes in lacunae, organized around central canals (blood supply). Periosteum: Covers bone (fibrous/cellular layers). Bone structure: 1/3 organic (collagen/proteins), 2/3 inorganic (hydroxyapatite, minerals). Spongy bone: Lattice structure, red marrow, strength with less weight.

Osteogenic Cells

Stem cells, create other bone cells.

Osteoblasts

Build bone, form matrix, produce osteocalcin.

Osteocytes

Former osteoblasts, maintain matrix, act as strain sensors, in lacunae connected by canaliculi.

Osteoclasts

Dissolve bone (resorption), large, multinucleate, ruffled border.

Ossification/Osteogenesis

Bone formation in fetus/infant. Intramembranous: Flat bones (skull, clavicle). Endochondral: Most other bones (cartilage model replaced by bone).

Bone Remodeling

Continuous absorption/deposition (10%/year), repairs, reshapes, releases minerals. Wolff’s law: Bone structure adapts to mechanical stress.

Bone Physiology

Active tissue: Exchanges minerals with fluids, impacts body systems.

Mineral Deposition (Mineralization)

Ca²⁺, phosphate deposited in bone by osteoblasts.

Resorption

Osteoclasts dissolve bone, release minerals.

Calcitriol

Increases blood Ca²⁺ (vitamin D).

Calcitonin

Lowers blood Ca²⁺ (thyroid, inhibits osteoclasts, stimulates osteoblasts; important in children).

Parathyroid Hormone (PTH)

Raises blood Ca²⁺ (increases osteoclasts, kidney reabsorption, activates calcitriol, inhibits osteoblasts).

Hypocalcaemia

Low Ca²⁺, excitable nerves/muscles, risk in pregnancy/lactation.

Hypercalcaemia

High Ca²⁺, weak muscles, cardiac issues.