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What things to animals do to maintain homeostasis? 1 Lecture 9 Outline (Ch. 43) I. Animal Size/Shape and the Environment II. Tissues III. Brief Organ Systems III. Feedback Control and Heat Balance IV. Metabolic Rate and Energy Use 2 Overview: Diverse Forms, Common Challenges • Anatomy: study of biological form of an organism • Physiology: study of biological functions of an organism • Evolutionary convergence: reflects different species’ adaptations to similar environmental challenge (a) Tuna (b) Penguin 3 (c) Seal Overview: Diverse Forms, Common Challenges Animals sizes and shapes directly affect how they exchange energy and materials with surroundings Mouth Gastrovascular cavity Exchange Exchange Exchange 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells 4 Overview: Diverse Forms, Common Challenges • More complex organisms have highly folded internal surfaces External environment CO2 Food O2 Mouth Respiratory system 0.5 cm 50 µm Animal body Lung tissue Nutrients Heart Cells Circulatory system 10 µm Interstitial fluid Digestive system Excretory system Lining of small intestine Kidney tubules Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) 5 Hierarchical Organization of Body Plans • Vertebrates have a “tube within a tube” structure • Levels or organiziation: smallest largest? 6 Tissue Structure and Function • Embryos have three basic tissue layers: – Ectoderm – Mesoderm – Endoderm 7 Tissue Structure and Function • Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Humans: 210 different cell types – can you name them?! ;) 8 Tissue Structure and Function Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Note differences in cell shape and type of layering 9 Tissue Structure and Function Apical surface Basal surface Basal lamina 40 µm Epithelial cells are attached to a basal lamina at their base. 10 Connective Tissue • Connective tissue mainly binds and supports other tissues • It contains sparsely packed cells scattered throughout an extracellular matrix • The matrix consists of fibers in a liquid, jellylike, or solid foundation There are six types of connective tissue. 11 Tissue Structure and Function 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 12 Muscle Tissue • Muscle tissue consists of long cells called muscle fibers, which contract in response to nerve signals • It is divided in the vertebrate body into three types: – Skeletal muscle, or striated muscle, is responsible for voluntary movement – Smooth muscle is responsible for involuntary body activities – Cardiac muscle is responsible for contraction of the heart 13 Tissue Structure and Function 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 14 Nervous Tissue • Nervous tissue senses stimuli and transmits signals throughout the animal • Nervous tissue contains: – Neurons, or nerve cells, that transmit nerve impulses – Glial cells, or glia, that help nourish, insulate, and replenish neurons 15 Tissue Structure and Function Nervous Tissue 40 µm Dendrites Cell body Glial cells Axon Neuron Axons Blood vessel 16 15 µm Self-Check Tissue Category Tissues/Cells Included; Functions Epithelial Connective Muscle Nervous 17 Organ Systems • Communication and integration – detect external stimuli, coordinate the body’s responses • Support and movement 18 Organ Systems • Regulation and maintenance – regulate and maintain the body’s chemistry 19 Organ Systems • Defense • Reproduction and development – In females, also nurtures developing embryo/fetus 20 Feedback control loops maintain the internal environment in many animals • Animals manage their internal environment by regulating or conforming to the external environment Homeostasis Effector Examples of negative and positive feedback? Stimulus: Perturbation/stress Control center Sensor 21 Feedback control loops maintain the internal environment in many animals • Thermoregulation: process by which animals maintain an internal temperature • Endothermic animals generate heat by metabolism (birds and mammals) • Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and nonavian reptiles) (a) A walrus, an endotherm (b) A lizard, an ectotherm 22 Balancing Heat Loss and Gain • Balancing temperature usually involves the integumentary system Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle 23 Balancing Heat Loss and Gain • Five general adaptations help animals thermoregulate: – Insulation – Circulatory adaptations – Cooling by evaporative heat loss – Behavioral responses – Adjusting metabolic heat production Dragonfly “obelisk” posture 24 Energy Allocation and Use External environment • Bioenergetics: overall flow of energy in an animal • Determines how much food is needed due to animal’s size, activity, and environment Animal body Organic molecules in food Digestion and absorption Heat Energy lost in feces Nutrient molecules in body cells Carbon skeletons Cellular respiration Energy lost in nitrogenous waste Heat ATP Biosynthesis Cellular work Heat 25 Heat Energy Use • Metabolic rate is the amount of energy an animal uses in a unit of time Measured by amount of oxygen consumed or carbon dioxide produced • Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature 26 Energy Use 103 BMR (L O2/hr) (log scale) Elephant Horse 102 Human Sheep 10 Cat Dog 1 10–1 Rat Ground squirrel Shrew Mouse Harvest mouse 10–2 10–3 10–2 102 1 10–1 10 Body mass (kg) (log scale) (a) Relationship of BMR to body size 103 27 Energy Use 8 Shrew BMR (L O2/hr) (per kg) 7 6 5 4 Harvest mouse 3 Mouse 2 Rat 1 Ground squirrel 0 10–3 10–2 Sheep Human Elephant Cat Dog Horse 1 10 102 10–1 Body mass (kg) (log scale) 103 (b) Relationship of BMR per kilogram of body mass to body size 28 Energy Budgeting Endotherms Reproduction 800,000 Annual energy expenditure (kcal/hr) Ectotherm Basal (standard) metabolism Thermoregulation Growth Activity 340,000 4,000 60-kg female human from temperate climate 4-kg male Adélie penguin from Antarctica (brooding) 0.025-kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake • Torpor is a physiological state in which activity is low and metabolism decreases – allows animals to save energy while avoiding difficult and dangerous conditions • Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity 29 Lecture 9 Summary 1. Overview (Ch. 43) Shape/size for multicellular animals 2. Tissues (Ch. 43) Embryonic tissue layers Four tissue types and subcategories Cells within each tissue 3. Organ System Overview (Ch. 43) Organiziation hierarchy General function 4. Homeostasis (Ch. 43) Feedback loops, negative and positive Temperature control Metabolic rate and energy use