Chapter 40 Basic Principles of Form and Function

+ Chapter 40: Basic Principles of Form and Function Mrs. Valdes AP Biology

Overview: Diverse Forms, Common + Challenges n Anatomy: study of biological form of organism n Physiology: study of biological functions organism performs n Comparative study of animals reveals form and function closely correlated… you know this!

Concept 40. 1: Animal form and function + correlated at ALL levels of organization n n Body plans evolved and determined by genome Physical Constraint: ability to perform certain actions depends on animal’s shape, size, and environment n n n Environment Exchange: animal’s size and shape directly affect how it exchanges energy and materials with its surroundings n n Evolutionary convergence reflects different species’ adaptations to similar environmental challenge Physical laws impose constraints on animal size and shape occurs as substances dissolved in aqueous medium diffuse and are transported across cells’ plasma membranes n Single-celled: protist living in water has sufficient surface area of plasma membrane to service its entire volume of cytoplasm n Multicellular organisms: some have sac body plan; body walls only two cells thick, facilitating diffusion of materials n More complex organisms: highly folded internal surfaces for exchanging materials n Vertebrates: space between cells filled with interstitial fluid n allows for movement of material into and out of cells A complex body plan helps animal in variable environment to maintain stable internal environment

+Hierarchical Organization of Body Plans n Cells > Tissues > Organ System n Tissues classified into four main categories: epithelial, connective, muscle, and nervous

Epithelial Tissue + n Epithelial tissue: covers outside of body and lines organs and cavities within body n contains cells closely joined n shape of epithelial cells: n cuboidal (like dice) n columnar (like bricks on end) n squamous (like floor tiles) n arrangement of epithelial cells: n simple (single cell layer) n stratified (multiple tiers of cells) n pseudostratified (a single layer of cells of varying length)

Connective Tissue + n mainly binds and supports other tissues n contains sparsely packed cells scattered through extracellular matrix n matrix consists of fibers in liquid, jellylike, or solid foundation n Types of connective tissue fiber: n n Connective cells: n n n n n Collagenous fibers provide strength and flexibility Elastic fibers stretch and snap back to original length Reticular fibers join connective tissue to adjacent tissues Fibroblasts: secrete the protein of extracellular fibers Macrophages: involved in immune system Fibers and foundation combine to form six major types of connective tissue: Loose connective tissue: binds epithelia to underlying tissues; holds organs in place Cartilage: strong and flexible support material Fibrous connective tissue: found in tendons (attach muscles to bones) and ligaments (connect bones at joints) Adipose tissue: stores fat for insulation and fuel Blood: composed of blood cells and cell fragments in blood plasma Bone: mineralized and forms skeleton

Fig. 40 -5 c + Connective Tissue Loose connective tissue Chondrocytes Cartilage Elastic fiber Chondroitin sulfate Nuclei Fat droplets Adipose tissue Osteon 150 µm Fibrous connective tissue 30 µm 100 µm 120 µm Collagenous fiber White blood cells Blood 55 µm 700 µm Bone Central canal Plasma Red blood cells

Fig. 40 -5 d + 120 µm Collagenous fiber Elastic fiber Loose connective tissue

Fig. 40 -5 e + 30 µm Nuclei Fibrous connective tissue

Fig. 40 -5 f + 700 µm Osteon Central canal Bone

Fig. 40 -5 g + 100 µm Chondrocytes Chondroitin sulfate Cartilage

Fig. 40 -5 h + 150 µm Fat droplets Adipose tissue

Fig. 40 -5 i + 55 µm White blood cells Plasma Blood Red blood cells

+ Muscle Tissue n consists of long cells called muscle fibers, which contract in response to nerve signals n Types: n Skeletal muscle: or striated muscle, responsible for voluntary movement n Smooth muscle: responsible for involuntary body activities n Cardiac muscle: responsible for contraction of the heart

Fig. 40 -5 j + Muscle Tissue Multiple nuclei Muscle fiber Sarcomere Skeletal muscle Nucleus 100 µm Intercalated disk 50 µm Cardiac muscle Nucleus Smooth muscle Muscle fibers 25 µm

Fig. 40 -5 k + Multiple nuclei Muscle fiber Sarcomere 100 µm Skeletal muscle

Fig. 40 -5 l + Nucleus Muscle fibers 25 µm Smooth muscle

Fig. 40 -5 m + Nucleus Intercalated disk Cardiac muscle 50 µm

+ Nervous Tissue n senses stimuli and transmits signals throughout the animal n Contains: n Neurons: nerve cells, that transmit nerve impulses n Glial cells, or glia: help nourish, insulate, and replenish neurons

Coordination and Control + n Depend on endocrine system and nervous system n Endocrine system: transmits hormones to receptive cells throughout body via blood n hormone may affect one or more regions throughout body n Hormones relatively slow acting, but can have long-lasting effects n Nervous system: transmits information between specific locations n information conveyed depends on a signal’s pathway NOT type of signal n Nerve signal transmission is FAST n Nerve impulses received by neurons, muscle cells, and endocrine cells

+Concept 40. 2: Feedback control loops maintain internal environment in many animals n Animals manage internal environment by regulating or conforming to external environment n Regulator: uses internal control mechanisms to moderate internal change in face of external, environmental fluctuation n Conformer: allows internal condition to vary with certain external changes

Homeostasis n+ Maintain “steady state” or internal balance regardless of external environment n Humans: body temperature, blood p. H, and glucose concentration n Mechanisms: moderate changes in internal environment n n For given variable, fluctuations above/below set point serve as stimulus that are detected by sensor and trigger response n response returns the variable to the set point Feedback Loops: n n Negative feedback n Helps return variable to either normal range or a set point n Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off Positive feedback n occur in animals, but do not usually contribute to homeostasis n Set points and normal ranges change with age or show cyclic variation n Acclimatization: homeostasis can adjust to changes in external environment

Concept 40. 3: Homeostatic processes for + thermoregulation involve form, function, & behavior Thermoregulation: process by which animals maintain internal temperature within tolerable range n Endotherm: animal generates heat by metabolism; Ex: birds and mammals n active at a greater range of external temperatures n more energetically expensive n Homeotherm: body temperature relatively constant n Ectotherm: animal gains heat from external sources; include most invertebrates, fishes, amphibians, and non-avian reptiles n tolerate greater variation in internal temperature, while endotherms are n Poikilotherm: body temperature varies with its environment, n

+ Balancing Heat Loss & Gain Organisms exchange heat by : • • • conduction convection radiation evaporation Heat regulation in mammals involves integumentary system: • • skin hair nails General adaptations: • n n n Insulation Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production

+ Insulation n Major thermoregulatory adaptation in mammals and birds n Ex: Skin, feathers, fur, and blubber n Reduce heat flow between an animal and its environment

+ Circulatory Adaptations n Regulation of blood flow near body surface significantly affects thermoregulation n Many endotherms and some ectotherms alter amount of blood flowing between body core and skin n Vasodilation: blood flow in skin increases increase heat loss n Vasoconstriction: blood flow in skin decreases decrease heat loss n Countercurrent exchange: important mechanism for reducing heat loss; transfer heat between fluids flowing in opposite directions n arrangement of blood vessels in marine mammals and birds n Some bony fishes and sharks n Many endothermic insects use to maintain high temperature in thorax

+ Cooling by Evaporative Heat Loss n Animals lose heat through evaporation of water in sweat n Panting increases cooling effect in birds and many mammals n Sweating/bathing moistens skin, helping cool animal down

+Behavioral Responsesand n Endotherms ectotherms use behavioral responses to control body temperature n Terrestrial invertebrates have postures to minimize or maximize absorption of solar heat n Ex: Dragonfly obelisk to minimize sun exposure

Adjusting Metabolic Heat Production + n Some animals regulate body temperature by adjusting rate of metabolic heat production n Heat production increased by muscle activity like moving or shivering n Some ectotherms shiver to increase body temperature

+Acclimatization in Thermoregulation n Birds and mammals vary insulation to acclimatize to seasonal temperature changes n Temps subzero: some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells n Thermoregulation: controlled by hypothalamus n Hypothalamus: triggers heat loss or heat generating mechanisms n Fever: result of change to set point for biological thermostat

Concept 40. 4: Energy requirements related to + animal size, activity, and environment Bioenergetics: overall flow and transformation of energy in an animal n determines how much food animal needs n relates to animal’s size, activity, and environment n Energy Allocation and Use n Animals harvest chemical energy from food n Food ATP Cellular Work n After needs of staying alive met, remaining food molecules used in biosynthesis n Biosynthesis: includes n body growth and repair n synthesis of storage material such as fat n production of gametes n

Quantifying Energy Use + n Metabolic rate: amount of energy animal uses in unit of time n One way to measure: determine amount of oxygen consumed OR carbon dioxide produced n affected by many factors besides whether an animal is an endotherm or ectotherm n size n activity n Basal metabolic rate (BMR): metabolic rate of endotherm at rest at “comfortable” temperature n Standard metabolic rate (SMR): metabolic rate of ectotherm at rest at specific temperature n Both rates assume nongrowing, fasting, and nonstressed animal n Ectotherms have lower metabolic rates than endotherms of comparable size

+ Size and Metabolic Rate n Metabolic rate per gram inversely related to body size among similar animals n Higher metabolic rate of smaller animals higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal

+Activity and Metabolic Rate n Maximum metabolic rate animal can sustain inversely related to duration of the activity

+ Energy Budgets n Different species use energy and materials in different ways depending on environment n Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction

+Torpor and Energy Conservation n Torpor: physiological state in which activity is low and metabolism decreases n enables animals to save energy while avoiding difficult and dangerous conditions n Hibernation: long-term torpor; adaptation to winter cold and food scarcity n Estivation: summer torpor; enables animals to survive long periods of high temperatures and scarce water supplies n Daily torpor: exhibited by many small mammals and birds; seems adapted to feeding patterns

+ You should now be able to: 1. 2. 3. 4. 5. 6. 7. Distinguish among the following sets of terms: collagenous, elastic, and reticular fibers; regulator and conformer; positive and negative feedback; basal and standard metabolic rates; torpor, hibernation, estivation, and daily torpor Relate structure with function and identify diagrams of the following animal tissues: epithelial, connective tissue (six types), muscle tissue (three types), and nervous tissue Compare and contrast the nervous and endocrine systems Define thermoregulation and explain how endotherms and ectotherms manage their heat budgets Describe how a countercurrent heat exchanger may function to retain heat within an animal body Define bioenergetics and biosynthesis Define metabolic rate and explain how it can be determined for animals