Animal Form and Function: Chapter 39

• Chapter 39 discusses animal form and function.
• Learning outcomes: describe the relationship between the form and function of animal tissues, organs, and systems.
• Learning outcomes: identify the key characteristics of the four tissue types of animals.
• Learning outcomes: describe how body size affects metabolic rates and thermoregulation.
• Learning outcomes: describe how feedback loops are used to maintain homeostasis.
• Learning outcomes: compare and contrast the different methods by which animals thermoregulate.
• Homeostasis isn't equilibrium; it's dynamic equilibrium.

Introduction

• Animals are generally studied through anatomy and physiology.
• Anatomy refers to an organism's physical structure or form.
• Physiology studies how physical structures function in a living system.
• Histology studies the microscopic level, between both anatomy and physiology.

The Role of Fitness Trade-Offs

• Fitness trade-offs are inescapable compromises between traits.
• Research shows male crickets have an energy trade-off between reproductive and immune function.
• Exposing hemolymph to bacteria reveals a trade core.
• An immune system is compromised, causing a reduced reproductive fitness.
• Immune and reproduction trade-offs are common in animals.

Adaptation and Acclimatization

• Adaptation can be passed along genetically and is a reversible change.
• Acclimatization is a phenotypic change in an individual due to environmental fluctuations.
• Vasodilatation occurs when its hot outside so the body can acclimate to deal with the heat.
• The body shivers to generate heat.

Organization of Animal Bodies

• All animal cells are based on functional needs from the organism.
• All animal cells share similarities in how they exchange materials, obtain energy from organic nutrients, synthesize complex molecules, detect and respond to signals, and reproduce.
• Cells differentiate and have specialized functions.

Tissues Are Groups of Cells That Function as a Unit

• Animals are multicellular and their bodies contain specialized cells.
• A tissue is a group of similar cells working together as a unit.
• The four types of tissues are: connective, nervous, muscle, and epithelial.

Connective Tissue

• Connective tissues include loose, dense, supporting, and fluid types.

Nervous Tissue

• Many connections from other dendrites and axons exist
• Glial cells support neurons

Muscle Tissue

• There are skeletal, cardiac, and smooth muscle tissues.
• Skeletal muscle enables voluntary movement and appears striped.
• Cardiac muscle cells are branched, involuntary, and connected.
• Smooth muscle consists of tapered cells, enables involuntary movement in organ systems.

Epithelial Tissue

• Epithelial cells are composed of closely packed cells of uniform type
• They are anchored by a basement membrane and line systems
• The apical surface is the outside world
• The basal surface sits on top of extra cellular material

Organs and Organ Systems

• Organs function in multiple organ systems.
• Organs are part of larger units called organ systems, working together to perform functions.
• The small intestine is composed of muscle, nervous, connective, and epithelial tissue.
• The small intestine is part of the digestive system.
• The esophagus is a conduit that allows food to get into the stomach.
• The stomach has stratified epithelial and smooth muscle tissue.

How Does Body Size Affect Animal Physiology?

• The laws of physics affect the anatomy and physiology of living organisms.
• Body size has pervasive effects on how animals function.
• Large animals require more nutrients, produce more waste, and live longer.
• Small animals lose heat and water more rapidly.
• Surface area determines the rate at which nutrients diffuse and waste products diffuse out.
• Cell volume determines the rate at which nutrients are used and waste is generated.
• Volume is a factor of 3.

Surface area/volume relationships

• An organism that goes through a drastic increase in buddy size affects and animal's physiology.
• Surface increases increases area as volume increases
• A body size affects metabolic rate of mammals.
• Basal metabolic rate (BMR) is the rate at which an animal consumes oxygen while at rest with an empty stomach under normal temperature and moisture conditions.
• The mass specific metabolic rate decreases and babies metabolism is faster than adults
• High surface area is related to low volume. As an object enlarges, surface area increases by the power of 2, volume by the power of 3.
• High volume structures are expensive for organisms to maintain.
• Organisms create structures with a high surface area to volume ratio.

Adaptations that increase surface area

• Adaptations increase surface area.
• Gills have huge surface area but small volume
• Structures that increase surface area include gill lamellae neuron dendrites
• Folding maximizes the intestine's ability to absorb solutes.

Homeostasis

• Homeostasis occurs as a constant set of functional reactions.
• Perspiring and drinking water are both mechanisms that help achieve homeostasis.

Homeostasis

• Homeostasis maintains a stable internal environment.
• Some animals are conformers: maintaining the same composition as the environment and needing less energy.
• Others are regulators: working to maintain a different body than the environment and requiring more energy.
• Some animals can be both regulators and conformers.
• Homeostatic control systems have a "set point", they monitor particular variable (sensor), integrator, signals, and effector.
• An examplary control system is the maintenance of body temperature in mammals.

Homeostatic control systems

• Regulatory activities happen to occur
• Temperature affects chemical reactions, protein function and plasma membranes.
• The rate of chemical reactions doubles or even triples for every 10 °C increase in body temperature.
• The body has a built-in temp range for chemical reactions and an effector for skeletal muscle.

Thermoregulatory Strategies

• Thermoregulatory Strategies indicate deep tissue sensors sense whether its cold.
• When its cold redirect heat to brain + heart
• Humans are able to sweat with thermoregulatory strategies.
• An endotherm produces adequate heat its own tissue.
• An ectotherm relies on heat gained from the environment.
• Homeotherms keep their body temperature constant
• Poikilotherms allows their body temperature to change depending on environmental conditions

Thermoregulation

• Humans are endothermic homeotherms
• Many animals lie somewhere between endothermic and ectothermic
• Some animals may permit themselves to be at a broader range in temperature during the day, like African elephants.
• Some animals can change how they thermoregulate
• Honeybees use heat to kill predators.

Organisms exchange heat

• Walruses are endothermic while lizards are ectothermic.
• Organisms exchange heat by four physical processes; radiation, conduction, convection, and evaporation.
• limited ratio causes animals to lose heat easily, reduce metabolic rate, and tolerate the low tempm making them a Torpor.

Mechanisms of Heat Exchange

• Conduction is the direct transfer of heat between bodies in contact.
• Convection is a special case of conduction in which heat is exchanged between a solid and a liquid or gas rather than between two solids.
• Radiation is the transfer of heat between two bodies that are not in direct physical contact.
• Evaporation is the phase exchange that occurs when liquid water becomes a gas.
• Animals seek sunny spots or shade.
• It is important to retain heat and not risk losing water.

Mechanisms of thermoregulation

• The mechanisms of thermoregulation are the integumentary system, insulation, circulatory adaptations, cooling by evaporative heat loss, behavioral responses, and adjusting metabolic heat production.
• Insulation is where the organism needs to eat and be meta-bolically demanding to breathe
• The cold in lot of water = risk losing heat

Circulatory adaptations

• Circulatory adaptations enable vasodilation to increase blood flow to surface areas or enable vasoconstriction to reducing heat lost.

Behavioral adaptations

• Circulatory adaptations are countercurrent and move in one direction
• Adaptations include muscle activity, shivering thermogenesis, and nonshivering thermogenesis to create heat.

Disadvantages of endothermy

• Must consume larger amounts of food
• They risk overheating during activity
• Often restricted to environments where water is plentiful
• migrate to another area so they can get water

Feedback mechanisms for homeostasis

• Feedback mechanisms for homeostasis minimize major disturbances to the internal environment. *Homeostatic feedback loops are negative.

Feedback

• In negative feedback loops, the regulated bring about responses that move the opposite direction.
• Positive feedback loops result in something that is less common and push the temp further out of range
• Can result in fever or killing cot bacteria/virus
• Osmoregulation maintains internal fluid balance in aquatic/terrestrial animals.