Chapter 33 part 2

Chapter 33: Tissues and Organs

• Embryonic Tissues: Cells from three embryonic layers migrate and differentiate to form 4 types of animal tissues and develop the alimentary canal and organs.

• Types of Animal Tissues:

  • Epithelial Tissue:

  • Covers surfaces inside and outside the body (e.g. skin, lining of gut, blood vessels).

  • Provides protection and regulates permeability.

  • Connective Tissue:

  • Supports and binds other tissues, features extracellular matrix.

  • Examples: bone, adipose (fat), cartilage.

  • Muscle Tissue:

  • Responsible for movement, identified as three types:

    • Skeletal Muscle: Striated appearance, voluntary control.

    • Cardiac Muscle: Found in the heart, involuntary control.

    • Smooth Muscle: Involuntary control, found in walls of organs and blood vessels.

  • Nervous Tissue:

  • Composed of neurons for signaling and support cells. Enables rapid responses and complex behaviors.

Chapter 33: Homeostasis

• Definition: Maintenance of stable internal conditions despite external fluctuations.

• Regulation by Systems: The endocrine and nervous systems maintain homeostasis via feedback from target organs to glands, predominantly through negative feedback.

Thermoregulation

• Mammals: Maintain a constant body temperature through metabolic and behavioral means. The hypothalamus acts as a sensor.

• Ectotherms: Body temperature fluctuates with the environment; behaviors such as basking are employed.

• Endotherms: High metabolic rates maintain constant body temperature, behaviors still play a role.

Chapter 39: Metabolism and Nutrition

Patterns of Animal Metabolism

• Metabolic Rate: Increases with mass raised to the power of rac{3}{4}. Not linear, larger animals do not necessarily have proportionately higher metabolic rates.

Nutritional Needs of Animals

1. Fuel (ATP): Energy for cellular processes; amount varies with metabolic demands.

2. Organic Materials for Biosynthesis: Includes organic carbon and nitrogen.

3. Essential Nutrients: Include amino acids, fatty acids, vitamins (e.g., A, B complex, C, D, E, K), and minerals (e.g., Ca, Fe, P, K, Zn, Mg).

Digestion Processes

• Digestion in Complex Organisms: Most animals perform extracellular digestion; breakdown products are absorbed into the bloodstream.

• Villi and Microvilli: Enhance absorptive surface area in intestines.

Water and Electrolyte Balance

• Osmoregulation: Maintaining water and electrolyte balance essential for homeostasis.

  • Osmoconformers: Match internal osmotic pressure with the environment (e.g., marine invertebrates).

  • Osmoregulators: Maintain different internal osmotic pressure using energy (e.g., freshwater and terrestrial animals).

• Terrestrial Animals: Face challenges of water loss via urine, feces, evaporation, and sweat.

• Salt Excretion: Marine birds excrete excess salt through specialized glands.

Waste Excretion

Types of Nitrogenous Waste

1. Ammonia: Toxic form excreted mostly by aquatic animals; removed or converted.

2. Urea: Less toxic; evolved for land animals to store before excretion.

3. Uric Acid: Least toxic; forms a paste, stored with minimal water loss but energetically costly to produce.

Mechanisms in Terrestrial Arthropods

• Malpighian Tubules: Filter fluids, secrete uric acid and electrolytes for osmoregulation and waste elimination.

Comparisons

• Most mammals: Excrete urea.

• Most aquatic animals: Excrete ammonia.

• Birds, insects, many reptiles: Excrete uric acid.

Integrative Questions

• Why does temperature regulation relate to nutrition and digestion?

  • Energy consumption rate relates to body temperature (Option A).

• In response to low blood sugar, the pancreas releases glucagon; in this feedback loop, the pancreas functions as the ____ (C. effector).

• Embryonic Tissues: Cells from three primary embryonic layers (ectoderm, mesoderm, and endoderm) migrate and differentiate during embryonic development to form four fundamental types of animal tissues. This process is crucial for developing various organs and systems, including the alimentary canal, which is essential for digestion and nutrient absorption.

• Types of Animal Tissues:

  • Epithelial Tissue:

    • Forms protective barriers on surfaces inside and outside the body; examples include the epidermis of the skin, the lining of the gut, and blood vessels.

    • Functions include secretion (such as in glands), absorption (such as in intestines), and sensation (as seen in sensory receptors).

    • Epithelial cells are classified by number of layers (simple or stratified) and by cell shape (squamous, cuboidal, or columnar).

  • Connective Tissue:

    • Consists of cells scattered within an extracellular matrix that gives the tissue its strength and elasticity.

    • Major types include connective tissue proper (like adipose tissue and tendons), cartilage, bone, and blood.

    • Functions include providing structural support, energy storage (as in adipose), and transporting nutrients and waste (as in blood).

  • Muscle Tissue:

    • Responsible for movement, consists of three types:

      • Skeletal Muscle:

        • Has a striated appearance, is under voluntary control, and is responsible for body movements.

        • Features multiple nuclei per cell and is attached to bones via tendons.

      • Cardiac Muscle:

        • Found exclusively in the heart, it has a striated appearance, is involuntary, and is responsible for pumping blood throughout the body.

        • Connected by intercalated discs, which facilitate synchronized contraction.

      • Smooth Muscle:

        • Involuntary muscle found in walls of organs and blood vessels, characterized by non-striated, spindle-shaped cells.

        • Controls movements like peristalsis in the digestive tract and vasodilation in blood vessels.

  • Nervous Tissue:

    • Composed of neurons, which transmit signals, and glial cells, which support and protect neurons.

    • Enables rapid responses to stimuli and coordination of complex behaviors essential for survival, such as reflexes and sensory processing.

Chapter 33: Homeostasis

• Definition: Homeostasis is the ability of an organism to maintain stable internal conditions (e.g. temperature, pH, hydration levels) despite changes in the external environment. This balance is critical for the survival of cells and the organism as a whole.

• Regulation by Systems: The endocrine and nervous systems interact to maintain homeostasis primarily through negative feedback mechanisms. Hormones and nerve impulses convey information between various organs and tissues, allowing adjustments to maintain equilibrium.

Thermoregulation

• Mammals: exhibit endothermy, allowing them to maintain a constant body temperature through metabolic and behavioral means. The hypothalamus acts as a thermostat, detecting temperature changes and activating mechanisms to cool or heat the body.

• Ectotherms: (e.g., reptiles, amphibians) depend on external environmental conditions to regulate their body temperature. They exhibit behaviors such as sun basking or seeking shade to achieve optimal thermal conditions.

• Endotherms: (e.g., birds and mammals) possess high metabolic rates that generate heat to maintain constant body temperature, though behavioral adaptations, like seeking shelter in extreme temperatures, also play a role in achieving homeostasis.

Chapter 39: Metabolism and Nutrition

Patterns of Animal Metabolism

• Metabolic Rate: Refers to the energy expenditure per unit time, which increases with mass raised to the power of rac{3}{4} according to the Kleiber's law. This means larger animals consume relatively less energy per gram of body mass compared to smaller animals due to differences in physiological needs and scaling.

Nutritional Needs of Animals

1. Fuel (ATP):

   • Provides energy for cellular processes and varies significantly with the metabolic demands of the organism, including activity level, growth, and reproduction.

2. Organic Materials for Biosynthesis:

   • These include organic compounds containing carbon and nitrogen, which are essential for the synthesis of proteins, nucleic acids, and other cellular components.

3. Essential Nutrients:

   • Must be obtained from the diet as the body cannot synthesize them. They include:

     • Amino Acids: Building blocks of proteins (e.g., lysine, methionine).

     • Fatty Acids: Essential for cell membrane structure and function (e.g., omega-3 and omega-6 fatty acids).

     • Vitamins: Organic molecules necessary for various biochemical functions (e.g., A for vision, B complex for metabolism, C for antioxidant functions, D for calcium absorption, E for cell protection, K for blood clotting).

     • Minerals: Inorganic elements required for structure and function (e.g., calcium for bones, iron for hemoglobin, potassium for nerve function).

Digestion Processes

• Digestion in Complex Organisms: Most animals utilize extracellular digestion, involving the breakdown of food outside individual cells, with enzymes secreted into a digestive cavity. The resulting small nutrient molecules are then absorbed into the bloodstream through cellular structures.

• Villi and Microvilli:

  • Tiny projections in the intestines that exponentially increase the surface area for absorption, enhancing the efficiency of nutrient uptake.

Water and Electrolyte Balance

• Osmoregulation:

  • The process of maintaining water and electrolyte balance is crucial for homeostasis.

    • Osmoconformers: These animals, like marine invertebrates, match their internal osmotic pressure with that of their environment, allowing for minimal energy expenditure on osmoregulation.

    • Osmoregulators: These organisms (e.g., freshwater and terrestrial animals) actively maintain their internal osmotic pressure using energy, which is key to survival in varied environments.

• Terrestrial Animals: Face challenges related to water loss due to urine production, evaporation through skin and lungs, and sweating. They have developed various adaptations to minimize these losses, such as concentrated urine.

• Salt Excretion: Marine birds possess specialized glands that allow them to excrete excess salt, adapting to their saline environment without harming their physiological functions.

Waste Excretion

Types of Nitrogenous Waste

1. Ammonia:

   • Highly toxic and primarily excreted by aquatic animals through diffusion; being water-soluble allows for quick removal from the body.

2. Urea:

   • Less toxic nitrogenous waste, synthesized in the liver from ammonia; facilitates storage and is excreted in urine, conserving water. Evolved as an adaptation for land animals.

3. Uric Acid:

   • The least toxic form, precipitates into a semi-solid paste that conserves water and minimizes energy costs; seen in birds, insects, and many reptiles.

Mechanisms in Terrestrial Arthropods

• Malpighian Tubules: These structures filter body fluids, secrete uric acid, and help with osmoregulation and waste elimination, allowing for efficient nitrogenous waste management and water conservation.

Comparisons

• Most mammals: typically excrete urea due to its balance of toxicity and water conservation.

• Most aquatic animals: primarily excrete ammonia, taking advantage of their surrounding water to dilute this toxic substance.

• Birds, insects, and many reptiles: favor uric acid due to its ability to conserve water in their often arid environments, despite the energy cost of production.

Integrative Questions

• Why does temperature regulation relate to nutrition and digestion?

  • Energy consumption rate directly correlates with body temperature; maintaining a stable temperature requires energy, which influences dietary needs and digestion efficiency (Option A).

• In response to low blood sugar, the pancreas releases glucagon; in this feedback loop, the pancreas functions as the effector (C).