Animal Structure and Function

Functional Anatomy Animal adaptations evolved through time by natural selection. Can also adapt over short periods of time. Chemical energy needed for searching for food, generating body heat, regulating internal temperature, etc..

Bioenergetics - how organisms obtain, process, and use their energy resources. All animals have correlation between form (anatomy) and function (physiology).

Tissues make up organs, organs  organ systems  organisms. Tissues - groups of cells with common structure and function. 4 types of tissues: epithelial, connective, muscle, nervous.

1 Epithelial – covers body, lines organs and cavities in body. Cells joined tightly together. Prevents fluid loss, invasion of microorganisms. Attached to underlying tissue by basement membrane.

A Simple epithelium – single-layered. B Stratified – multi-layered. Shapes – cuboidal, columnar, sqamous (flattened) Glandular – secretes fluid – can line respiratory system (produces mucous)

2 Connective tissue – binds, supports other tissue. Cells scattered throughout matrix. Matrix made of fibers. 3 types of fibers – 1 collagenous (collagen – tough), 2 elastic (elastin, flexible), 3 reticular (thin and branched – connect to adjoining tissues)

Reticular fibers

Major types - loose connective tissue, adipose tissue, fibrous connective tissue, cartilage, bone, and blood. A Loose connective - packing materials, holding organs in place. 2 cell types – 1 Fibroblasts (secrete proteins), 2 Macrophages (engulf bacteria)

B Adipose - insulates body, stores fuel as fat molecules. Contains large fat droplet that swells when fat is stored, shrinks when body uses fat as fuel.

C Fibrous connective - forms tendons (muscles to bones) and ligaments (bones to bones at joints) D Cartilage - flexible supports in certain locations, such as the nose, ears, and vertebral disks. Chondrocytes secrete collagen.

E Bone - mineralized connective tissue. Osteoblasts deposit a matrix of collagen. Bones consists of repeating units called osteons – has nerves and blood vessels.

F Blood - matrix liquid (plasma) has water, salts, variety of dissolved proteins. Suspended in plasma erythrocytes (red blood cells – carry oxygen), leukocytes (white blood cells – fight invaders) cell fragments (platelets – clotting)

3 Nervous - senses stimuli, transmits signals from one part of animal to another; functional unit – neuron Consists of cell body, 2+ extensions (dendrites + axons) Dendrites transmit nerve impulses from tips toward rest of neuron. Axons impulses toward another neuron or effector (muscle cell)

4 Muscle – composed of muscle fibers capable of contracting when stimulated by nerve impulses. Fibers consist of contractile proteins actin and myosin. 3 types – skeletal, cardiac, smooth.

A Skeletal – responsible for voluntary movement; striated. B Smooth – no striations; found in walls of digestive tract, urinary bladder, arteries, other internal organs – involuntary. C Cardiac – striated and branched; forms walls of heart muscle. Cells joined by intercalated discs; involuntary.

Functional Anatomy Tissues organized into organs. Mammals – thoracic cavity – lungs, heart – separated from abdomen by diaphragm. Tissues can be arranged in layers. Organ systems carry out major body functions.

Body Plans Animal’s size and shape - body plans. Physical requirements constrain natural selection. Laws of hydrodynamics constrain shapes possible for aquatic organisms that swim very fast.

Animals shape, size, determine how animal exchanges materials with surroundings. Protist living in water – plasma membrane large to exchange materials through diffusion. Multicellular organisms – many smaller cells able to exchange materials through each one.

Flat body – maximizes exposure to surroundings; prevents internal complexity. Most animals complex – cells small compared to volume. Allows animal to not be tied to land. Internal organs can regulate body.

Regulating Internal Environment Internal environment of vertebrates – interstitial fluid. Exchanges nutrients and wastes. Animals maintain homeostasis (internal balance) even when external environment changes.

Major internal changes are programmed to occur, such as during pregnancy. Homeostatic control system has 3 parts: receptor, control center, effector. 1 Receptor – detects change in environment. 2 Control center – processes change. 3 Effector – directs response.

Two types – 1 Negative feedback control – change causes reaction in opposite direction. Fever – causes body to sweat to bring temperature down. 2 Positive – change causes reaction in same direction. Labor – release in oxytocin increases uterine contractions.

Regulated change important to survival. Can by cyclical (hormones), or reactive (fever) Internal regulation expensive in energy.

Bioenergetics Chemical energy needed for growth, repair, regulation, reproduction. Food digested through hydrolysis, nutrients absorbed by cells. ATP use creates heat that is lost to environment. Energy left over – used for bioenergetics.

Bioenergetics - synthesis of storage material, production of reproductive structures, including gametes. Flow of energy through animal – sets limits on growth, behavior, reproduction, energy needs.

Amount of energy used in given time – metabolic rate. Measured in calories. Metabolic rate can be determined by measuring amount of heat produced. 2 metabolic strategies used by animals.

1 Endothermic – birds, mammals - maintain body temperature at certain level with heat generated by metabolism. High-energy strategy – allows for intense activity. 2 Ectothermic – reptiles, amphibians - do not produce enough metabolic heat to effect body temperature. Need less energy.

Amount of energy needed to maintain homeostasis inversely proportionate (per gram) to size. Each gram of a mouse consumes more energy than elephant. Smaller animal – higher metabolic rate to deliver oxygen, energy.

Metabolic rate of nongrowing endotherm at rest, with empty stomach, experiencing no stress - basal metabolic rate (BMR) Metabolic rate of resting, fasting, nonstressed ectotherm - standard metabolic rate (SMR).

Behavior above BMR or SMR consumes energy. Maximal BMR determines amount of energy expended. Ectotherms cannot do long, intense activity. BMR of human much higher than SMR of alligator.

Factors influence BMR - age, sex, size, body and environmental temperatures, quality and quantity of food, activity level, oxygen availability, hormonal balance, time of day. How energy used varies among species. Endotherms need more energy; smaller animals need more energy.

Human female spends large fraction of energy budget for BMR, relatively little for activity and temperature regulation. Male penguin spends larger fraction of energy expenditures for activity - must swim to catch food.