1 What things to animals do to maintain homeostasis?

2 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

3 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 (c) Seal

4 Exchange 0.15 mm (a) Single cell 1.5 mm (b) Two layers of cells Exchange Mouth Gastrovascular cavity Animals sizes and shapes directly affect how they exchange energy and materials with surroundings Overview: Diverse Forms, Common Challenges

5 0.5 cm Nutrients Digestive system Lining of small intestine Mouth Food External environment Animal body CO 2 O2O2 Circulatory system Heart Respiratory system Cells Interstitial fluid Excretory system Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste) Kidney tubules 10 µm 50 µm Lung tissue More complex organisms have highly folded internal surfaces Overview: Diverse Forms, Common Challenges

6 Levels or organiziation: smallest  largest? Hierarchical Organization of Body Plans Vertebrates have a “tube within a tube” structure

7 Embryos have three basic tissue layers: –Ectoderm –Mesoderm –Endoderm Tissue Structure and Function

8 Tissues are classified into four main categories: epithelial, connective, muscle, and nervous Tissue Structure and Function Humans: 210 different cell types – can you name them?! ;)

9 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 Tissue Structure and Function

10 Apical surface Basal surface Basal lamina 40 µm Tissue Structure and Function Epithelial cells are attached to a basal lamina at their base.

11 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.

12 Connective Tissue Collagenous fiber Loose connective tissue Elastic fiber 120 µm Cartilage Chondrocytes 100 µm Chondroitin sulfate Adipose tissue Fat droplets 150 µm White blood cells 55 µm Plasma Red blood cells Blood Nuclei Fibrous connective tissue 30 µm Osteon Bone Central canal 700 µm Tissue Structure and Function

13 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

14 Muscle Tissue 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth muscle Cardiac muscle Nucleus Muscle fibers 25 µm Nucleus Intercalated disk Tissue Structure and Function

15 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

16 Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm Tissue Structure and Function

17 Self-Check Tissue CategoryTissues/Cells Included; Functions Epithelial Connective Muscle Nervous

Organ Systems 18 Communication and integration –detect external stimuli, coordinate the body’s responses Support and movement

19 Organ Systems Regulation and maintenance –regulate and maintain the body’s chemistry

Reproduction and development –In females, also nurtures developing embryo/fetus 20 Organ Systems Defense

21 Feedback control loops maintain the internal environment in many animals Animals manage their internal environment by regulating or conforming to the external environment Homeostasis Stimulus: Perturbation/stress Effector Control center Sensor Examples of negative and positive feedback?

22 Feedback control loops maintain the internal environment in many animals Thermoregulation: process by which animals maintain an internal temperature (a) A walrus, an endotherm (b) A lizard, an ectotherm Endothermic animals generate heat by metabolism (birds and mammals) Ectothermic animals gain heat from external sources (invertebrates, fishes, amphibians, and non- avian reptiles)

23 Epidermis Dermis Hypodermis Adipose tissue Blood vessels Hair Sweat pore Muscle Nerve Sweat gland Oil gland Hair follicle Balancing Heat Loss and Gain Balancing temperature usually involves the integumentary system

24 Five general adaptations help animals thermoregulate: –Insulation –Circulatory adaptations –Cooling by evaporative heat loss –Behavioral responses –Adjusting metabolic heat production Balancing Heat Loss and Gain Dragonfly “obelisk” posture

25 Bioenergetics: overall flow of energy in an animal Determines how much food is needed due to animal’s size, activity, and environment Organic molecules in food External environment Animal body Digestion and absorption Nutrient molecules in body cells Carbon skeletons Cellular respiration ATP Heat Energy lost in feces Energy lost in nitrogenous waste Heat Biosynthesis Heat Cellular work Energy Allocation and Use

26 Metabolic rate is the amount of energy an animal uses in a unit of time Energy Use 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

27 Shrew Harvest mouse Mouse Ground squirrel Rat Cat Dog Sheep Human Horse Elephant Body mass (kg) (log scale) BMR (L O 2 /hr) (log scale) (a) Relationship of BMR to body size 10 –3 10 –2 10 – Energy Use

–1 10 –2 10 – Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size BMR (L O2/hr) (per kg) Shrew Harvest mouse Mouse Rat Ground squirrel Cat Sheep Dog Human Horse Elephant Energy Use

29 Annual energy expenditure (kcal/hr) 60-kg female human from temperate climate 800,000 Basal (standard) metabolism Reproduction Thermoregulation Growth Activity 340,000 4-kg male Adélie penguin from Antarctica (brooding) 4, kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake EndothermsEctotherm Energy Budgeting 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

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