Introduction to Animal Structure and Function AP Biology

Levels of Structural Organization Cells  Tissues  Organs  Organ Systems

Four Principle Tissue Types Epithelial tissue Epithelial tissue—covers and protects the body surface, lines body cavities, specializes in moving substances into and out of the blood Connective tissue Connective tissue—supports the body and its parts, to connect and hold them together, and to transport substances through the body

Four Principle Tissue Types Muscle tissue Muscle tissue—produces movement; specialized for contractility Nervous tissue Nervous tissue—specialized in communication between various parts of the body and in integration of their activities

Epithelial Tissue Sheets of tightly packed cells Cells held together by tight junctions Functions as a protective barrier

Dermis Cells   Keratinocyte - (90%) anchoring junctions   Melanocyte - melanin blocks UV light, shields nucleus   Langerhans cell - Macrophage Epidermal Layers   Deep layer single layer of stem cells & melanocytes division produces keratinocytes keratinocytes - anchoring junctions cells have keratin - dense "waterproof" protein nuclei break down   Top layer approx. 25 layers of flat dead cells filled with keratin continuously shed

Simple Squamous Epithelium

Simple Cuboidal Epithelium—alveoli

Stratified Squamous Epithelium—lining of the mouth

Simple Columnar Epithelium—lining digestive tract/organs

Pseudostratified Columnar Epithelium—lining trachea and bronchi cilia

Transitional Epithelium—lining urinary passages and bladder; allows for distension and evacuation

Connective Tissue Made of 3 kinds of protein fibers:   Collagenous fibers—made of collagen; nonelastic and do not tear easily when pulled lengthwise

Connective Tissue Made of 3 kinds of protein fibers:   Collagenous fibers   Elastic fibers—long threads of elastin; lends tissue resilence   Reticular fibers—thin, branched fibers composed of collagen and continuous with collagenous fibers; aids in joining connective tissue to adjacent tissues Extracellular Matrix—ground substance that is composed of a web of fibers embedded in a uniform foundation that may be liquid, jellylike, or solid

Loose Connective Tissue Holds organs in place and attaches epithelia to underlying tissues Two types of cells:   Fibroblasts— secrete proteins of the extracellular fibers   Macrophages— phagocytic amoeboid cells that function in immune defenses Has all 3 fiber types

Adipose tissue Loose connective tissue specialized to store fat Insulates the body and stores fuel molecules Each adipose cells has one large fat droplet which varies in size as fats are stored or used

Fibrous Connective Tissue Dense arrangement of collagenous fibers in parallel bundles Found in tendons (attach muscles to bone) and ligaments (attach bone to bone)

Cartilage Composed of collagenous fibers embedded in chondroitin sulfate Chondrocytes secrete collagen and chondroitin sulfate (makes cartilage strong and flexible) Cartilage makes up skeleton of vertebrate embryo—most gets replaced by bone except ears, nose, trachea, invertebral discs and ends of some bones

Growth Plate

Bone Mineralized connective tissue Osteoblasts—bone forming cells deposit collagen and calcium phosphate matrix which hardens to form hydroxyapetite Consists of repeating Haversian systems Right image: 1.Haversian Canal 2.Canaliculi 3.Lamellae 4.Lacunae

Blood Liquid extracellular matrix of plasma that contains water, salts, and proteins Blood cells made in red bone marrow near ends of long bones Cellular components:   Erythrocytes— red blood cells; transport oxygen

Blood   Leukocytes—white blood cells; immune defense neutrophils eosinophils basophil

Blood   Platelets—cell fragments; blood clotting

Nervous Tissue Senses stimuli and transmits signals from one part of the animal to another Neuron—specialized to conduct an impulse or bioelectric signal Consists of:   Cell body   Dendrites—conduct impulses to cell body   Axons—transmit signals away

Muscle Tissue Long, excitable cells capable of contraction Cell cytoplasm contains bundles of microfilaments made of the contractile proteins, actin and myosin Most abundant tissue in the body 3 types: skeletal, cardiac, and smooth

Muscle Tissue Skeletal   Attached to bones by tendons   Microfilaments aligned to form a banded (striated) pattern   Voluntary muscle movements

Muscle Tissue Cardiac   Forms the contractile walls of the heart   Ends of cells joined by intercalated disks, which relay contractile impulse between cells

Muscle Tissue Smooth   Found in walls of internal organs (digestive tract, bladder) and arteries   Spindle-shaped cells contract slowly, but can retain contracted conditions longer than skeletal muscle   Involuntary movements

Energy Input Ingestion Digestion (Hydrolysis) Absorption Catabolism (Cellular Respiration) Energy stored (ATP) Energy lost (heat) Energy used (ATP) Bioenergetics Heterotrophs harvest chemical energy from the food they ingest

Metabolism Metabolic rate—total amount of energy an animal uses per unit of time; usually measured in calories or kilocalories Determined by measuring:   Amount of oxygen used for an animal’s cellular respiration   An animal’s heat loss per unit of time Endotherms—generate own heat metabolically Exotherms—acquire heat from environment

Homeostasis--Regulating internal environment Dynamic state of equilibrium in which internal conditions remain relatively stable; steady state Depends on feedback circuits   Receptor detects internal change   Control center processes info and directs to effector to respond   Effector provides the response

Homeostasis--Regulating internal environment Positive feedback— enhances initial change in variable and response of effector Negative feedback— stops or reduces the intensity of the original stimulus Negative feedback in a thermostatic control