What things to animals do to maintain homeostasis?

1. What things to animals do to maintain homeostasis?

2. Lecture 9 Outline (Ch. 40) • Animal Size/Shape and the Environment • II. Tissues • Epithelial • Connective • Muscle • Nervous • IV. Feedback Control and temperature regulation • V. Metabolic Rate and Energy Use • VI. Preparation for next lecture

3. Overview: Diverse Forms, Common Challenges Anatomy: study of biological form of an organism Physiology: study of biological functions of an organism • Communication and integration • Support and movement • Regulation and maintenance • Defense • Reproduction and development

4. External environment CO2 Food O2 Mouth Animal body Respiratory system Blood 50 µm 0.5 cm Lung tissue Nutrients Cells Heart Circulatory system 10 µm Interstitial fluid Digestive system Excretory system Lining of small intestine Kidney tubules Anus Metabolic waste products (nitrogenous waste) Unabsorbed matter (feces) Overview: Diverse Forms, Common Challenges Cells bathed in interstitial fluid • More complex organisms have highly folded internal surfaces

5. Overview: Diverse Forms, Common Challenges Rate of exchange related to SA Amount of exchange related to V Mouth Gastrovascular cavity Exchange Exchange Exchange 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells

6. 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?! ;)

7. Epithelial Tissue Cuboidal epithelium Pseudostratified ciliated columnar epithelium Simple columnar epithelium Stratified squamous epithelium Simple squamous epithelium Tissue Structure and Function Note differences in cell shape and type of layering

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

9. Connective Tissue Connective tissue binds / supports other tissues • sparsely packed cells scattered in extracellular matrix • matrix - fibers in a liquid, jellylike, or solid foundation There are six main types of connective tissue.

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

11. Muscle Tissue • Muscle tissue: long cells (muscle fibers) that contract in response to nerve signals Skeletal muscle - striated, voluntary movement Smooth muscle – not striated, involuntary body activities Cardiac muscle – striated, contraction of the heart

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

13. Nervous Tissue 40 µm Dendrites Cell body Axon Glial cells Neuron Axons Blood vessel 15 µm Tissue Structure and Function • Nervous tissue senses stimuli, transmits signals • Nervous tissue contains: Neurons transmit nerve impulses Glial cells nourish, insulate, and replenish neurons

14. Self-Check

15. Response: Heater turned off Room temperature decreases Stimulus: Control center (thermostat) reads too hot Set point: 20ºC Stimulus: Control center (thermostat) reads too cold Room temperature increases Response: Heater turned on Feedback control loops maintain the internal environment in many animals Examples of negative and positive feedback?

16. Feedback control loops maintain the internal environment in many animals • Animals manage their internal environment by regulating or conforming to the external environment control center

17. 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

18. (a) A walrus, an endotherm (b) A lizard, an ectotherm Temperature Regulation • 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 non-avian reptiles)

19. Temperature Regulation • Homoeotherm: animals with constant temperature • Ex: River otter • Poikilotherm: animals with varied body temperature with environment • Ex: Largemouth bass

20. 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

21. Energy Use 103 Elephant Horse 102 Human Sheep 10 BMR (L O2/hr) (log scale) Dog Cat 1 Rat 10–1 Ground squirrel Shrew Mouse Harvest mouse 10–2 102 10–3 10–2 1 103 10–1 10 Body mass (kg) (log scale) (a) Relationship of BMR to body size

22. Energy Use 8 Shrew 7 Human average daily metabolic rate is only 1.5X BMR! 6 5 BMR (L O2/hr) (per kg) 4 Harvest mouse 3 Mouse Sheep 2 Rat Human Elephant Cat 1 Dog Horse Ground squirrel 0 10–3 103 1 10–2 10 102 10–1 Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size

23. Energy Budgeting • Torpor = physiological state with low activity and metabolism decreased – 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

24. Energy Use Additional metabolism that would be necessary to stay active in winter 200 Actual metabolism Metabolic rate (kcal per day) 100 0 Arousals 35 Body temperature 30 25 20 15 Temperature (°C) 10 5 0 Outside temperature –5 Burrow temperature –10 –15 June August October December February April

25. Things To Do After Lecture 9… Reading and Preparation: • Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms. • Ch. 40 Self-Quiz: #1, 2, 3, 4, 5, 6 (correct answers in back of book) • Read chapter 40, focus on material covered in lecture (terms, concepts, and figures!) • Skim next lecture. “HOMEWORK” (NOT COLLECTED – but things to think about for studying): • Describe the relationship between surface area and volume for a small cell compared to a large cell. Which is more efficient at exchange with the environment? • List the four types of tissues in animals – for each one, give several examples. • Define basal metabolic rate. Which would use more energy for homeostatic regulation, a small human or a large snake? Why? • Explain the difference between torpor and hibernation.