Introduction to Animal Structure and Function Chapter 40 Introduction to Animal Structure and Function

Overview: Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organism Physiology is the study of the biological functions an organism performs (a) Tuna (b) Penguin (c) Seal

Exchange with the Environment An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings Multicellular organisms with a sac body plan have body walls that are only two cells thick, facilitating diffusion of materials More complex organisms have highly folded internal surfaces for exchanging materials In vertebrates, the space between cells is filled with interstitial fluid, which allows for the movement of material into and out of cells

Mouth Gastrovascular cavity Exchange Exchange Exchange 0.15 mm 1.5 mm (a) Single cell (b) Two layers of cells

Lining of small intestine Excretory system 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 Lining of small intestine Excretory system Kidney tubules Anus Unabsorbed matter (feces) Metabolic waste products (nitrogenous waste)

Hierarchical Organization of Body Plans Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems

Tissue Structure and Function- Epithelial Tissue Epithelial tissue covers the outside of the body and lines the organs and cavities within the body Shape: cuboidal (like dice), columnar (like bricks on end), or squamous (like floor tiles) Arrangement: simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length)

Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium

Tissue Structure and Function- Connective Tissue Connective tissue mainly binds and supports other tissues Collagenous fibers provide strength and flexibility Elastic fibers stretch and snap back to their original length Reticular fibers join connective tissue to adjacent tissues

Connective tissue contains cells, including Fibroblasts that secrete the protein of extracellular fibers Macrophages that are involved in the immune system Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Loose connective tissue binds epithelia to underlying tissues and holds organs in place Cartilage is a strong and flexible support material Fibrous connective tissue is found in tendons (attach muscles to bones) and ligaments (connect bones at joints)

Adipose tissue stores fat for insulation and fuel Blood is composed of blood cells and cell fragments in blood plasma Bone is mineralized and forms the skeleton

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

Loose connective tissue

Fibrous connective tissue

Bone

Cartilage

Adipose tissue

Blood

Tissue Structure and Function- Muscle Tissue 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

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

Multiple nuclei Muscle fiber Sarcomere 100 µm Skeletal muscle

Nucleus Muscle fibers 25 µm Smooth muscle

Nucleus Intercalated disk 50 µm Cardiac muscle

Tissue Structure and Function- 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

Nervous Tissue Neuron 40 µm Axons Blood vessel Dendrites Cell body Glial cells Neuron Axons Blood vessel 15 µm

40 µm Dendrites Cell body Axon Neuron

Glial cells and axons Glial cells Axons Blood vessel 15 µm Figure 40.5 Structure and function in animal tissues Blood vessel Glial cells and axons 15 µm

Coordination and Control Stimulus Stimulus Endocrine cell Neuron Axon Signal Hormone Signal travels along axon to a specific location. Signal travels everywhere via the bloodstream. Blood vessel Signal Axons Response Response (a) Signaling by hormones (b) Signaling by neurons

Homeostasis Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level

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 Loops in Homeostasis Negative feedback -returns a variable to either a normal range or a set point, buildup of the end product shuts the system off Positive feedback- the end product accelerates the systems further

Endothermy and Ectothermy Endothermic animals generate heat by metabolism; more active; energy expensive Ectothermic animals gain heat from external sources; less active; less energy needed

(a) A walrus, an endotherm (b) A lizard, an ectotherm

Quantifying Energy Use Metabolic rate is the amount of energy an animal uses in a unit of time Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Ectotherms have much lower metabolic rates than endotherms of a comparable size

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

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

8 Shrew 7 6 5 BMR (L O2/hr) (per kg) 4 Harvest mouse 3 2 Mouse 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

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

from temperate climate Endotherms Ectotherm 800,000 Reproduction Basal (standard) metabolism Thermoregulation Growth Activity Annual energy expenditure (kcal/hr) 340,000 8,000 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 4-kg female eastern indigo snake

from temperate climate 800,000 Reproduction Thermoregulation Basal (standard) metabolism Growth Activity Annual energy expenditure (kcal/hr) 60-kg female human from temperate climate

4-kg male Adélie penguin from Antarctica (brooding) Basal (standard) metabolism Reproduction Thermoregulation Annual energy expenditure (kcal/yr) Activity 340,000 4-kg male Adélie penguin from Antarctica (brooding)

Basal (standard) metabolism Reproduction Thermoregulation Annual energy expenditure (kcal/yr) Activity 4,000 0.025-kg female deer mouse from temperate North America

Basal (standard) metabolism Reproduction Growth Annual energy expenditure (kcal/yr) Activity 8,000 4-kg female eastern indigo snake