What things to animals do to maintain homeostasis?

Lecture 9 Outline (Ch. 40) Brief Organ Systems Overview Animal Size/Shape and the Environment Tissues Epithelial Connective Muscle Nervous IV. Feedback Control and Heat Balance V. Metabolic Rate and Energy Use VI. Preparation for next lecture

Overview: Diverse Forms, Common Challenges Anatomy: study of biological form of an organism Physiology: study of biological functions of an organism (a) Tuna (b) Penguin (c) Seal Evolutionary convergence: reflects different species’ adaptations to similar environmental challenge

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

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

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

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

Overview: Diverse Forms, Common Challenges Animals sizes and shapes directly affect how they exchange energy and materials with surroundings Mouth Gastrovascular cavity Exchange Exchange Figure 40.3 Contact with the environment Exchange 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells

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

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?! ;)

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

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

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.

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

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

Tissue Structure and Function Muscle Tissue 50 µm Skeletal muscle Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth Cardiac muscle Nucleus Muscle fibers 25 µm Intercalated disk Figure 40.5 Structure and function in animal tissues

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

Tissue Structure and Function Glial cells Nervous Tissue 15 µm Dendrites Cell body Axon Neuron Axons Blood vessel 40 µm Figure 40.5 Structure and function in animal tissues

Which animals tissue below is connective? Cardiac cells Glia Lining of intestines Cartilage

Tissues/Cells Included; Functions Self-Check Tissue Category Tissues/Cells Included; Functions Epithelial Connective Muscle Nervous

Feedback control loops maintain the internal environment in many animals Response: Heater turned off Stimulus: Control center (thermostat) reads too hot Room temperature decreases Set point: 20ºC increases reads too cold on Examples of negative and positive feedback? Figure 40.8 A nonliving example of negative feedback: control of room temperature

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

Feedback control loops maintain the internal environment in many animals (a) A walrus, an endotherm (b) A lizard, an ectotherm 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)

Balancing Heat Loss and Gain Balancing temperature usually involves the integumentary system Hair Epidermis Sweat pore Dermis Muscle Nerve Sweat gland Figure 40.11 Mammalian integumentary system Hypodermis Adipose tissue Blood vessels Oil gland Hair follicle

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

Energy Allocation and Use 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 Biosynthesis work Bioenergetics: overall flow of energy in an animal Determines how much food is needed due to animal’s size, activity, and environment

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

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

Energy Use 8 Shrew 7 6 5 BMR (L O2/hr) (per kg) 4 Harvest mouse 3 2 Sheep Rat Human Elephant Cat 1 Dog Horse Ground squirrel 10–3 10–2 10–1 1 10 102 103 Body mass (kg) (log scale) (b) Relationship of BMR per kilogram of body mass to body size

from temperate climate Energy Budgeting 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) 4,000 0.025-kg female deer mouse from temperate North America 8,000 4-kg female eastern indigo snake Endotherms Ectotherm 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 Energy budgets for four animals

Which animal would have the highest BMR per unit body weight? human dog mouse whale turtle

Energy Use 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

Energy Use Additional metabolism that would be necessary to stay active in winter 200 Actual metabolism Metabolic rate (kcal per day) 100 Arousals 35 Body temperature 30 25 20 Temperature (°C) 15 Figure 40.21 Body temperature and metabolism during hibernation in Belding’s ground squirrels 10 5 Outside temperature –5 Burrow temperature –10 –15 June August October December February April

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 human or a snake? Why? Explain the difference between torpor and hibernation.