Bio II lecture Chapter 40 Basic Principles of Animal Form and Function

Natural Selection

• operates by favoring variations that enhance an organism's relative fitness, improving their survival prospects in challenging environments.

Biological Hierarchies

• The organization within an animal's body ranges from simple structures like cells to complex systems such as organ systems, each playing a vital role in maintaining life.

Convergent Evolution

• Similar adaptations often occur in unrelated species who face analogous environmental pressures, exemplified by swimming species that develop comparable body shapes for efficient movement.

Homeostasis

• the maintenance of stable internal conditions despite fluctuations in external environments, a critical process for survival. Ex. regulation of body temperature and solute concentrations, which are vital for the optimal functioning of biological systems.

Negative Feedback

• This mechanism serves to counteract changes from a set point, maintaining homeostasis.

Positive Feedback

amplifies physiological changes, pushing the system further away from its starting point.

Set Point

The homeostatic control system in animals

maintains a variable at or near a particular value

Stimulus

A fluctuation above or below the set point

Sensor

• Structure that detects changes in the body or its environment

Response

Physiological activity that helps return the variable to the set point.

Regulated Changes

An alteration in Homeostasis where an organism actively adjusts its internal state in response to environmental changes

Circadian Rhythm

A set of physiological changes that occur roughly every 24 hours.

Tissue Hierarchy

The complex structure of living organisms is organized into tissues, which are further organized into organs, culminating in comprehensive organ systems responsible for specific physiological functions

Epithelial Tissue

• these tissues cover body surfaces and are involved in protective barriers, absorption, and secretion processes.

Connective Tissue

This category includes various tissues that bind organs together, store energy, and provide structural support (e.g., bones and cartilage)

Muscle Tissue

Responsible for movement, this type of tissue comprises three types: skeletal (voluntary movement), cardiac (involuntary movement of the heart), and smooth (involuntary movements in organ systems).

Nervous Tissue

Essential for signal transduction and coordination, composed of neurons that transmit impulses and glial cells that support neuronal function.

Endocrine System and Nervous System

The Two Major Control Systems

Endocrine System

• network of glands throughout the body that produce and secrete hormones directly into the bloodstream

Nervous System

a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body

Hormones

• Signaling molecules that are broadcast throughout the body by the endocrine system

Nerve Impulses

Signals that travel to specific target cells along communication lines consisting mainly of axons.

Regulator

An animal that uses internal mechanisms to control internal change in the face of external fluctuation

Conformer

• An animal that allows its internal condition to change in accordance with external changes in the particular variable

Thermoregulation

•  Process by which animals maintain their body temperature within a normal range.

Endothermic (warm-blooded)

• Using metabolic heat for temperature regulation ex. humans
  and other mammals, as well as birds.

Ectothermic (cold- blooded)

• Animals that gain most of their heat from external sources ex. amphibians, many nonavian reptiles and fishes, and most invertebrates

• True

• Ectotherms generally need to consume much less food than endotherms of equivalent size—an advantage if food supplies are limited.

Poikilotherms

an organism that cannot regulate its body temperature except by behavioral means such as basking or burrowing

homeotherms

an organism that maintains its body temperature at a constant level, usually above that of the environment, by its metabolic activity

Radiation

• the emission of electromagnetic waves by all objects warmer than absolute zero. Here, a lizard absorbs heat radiating from the distant sun and radiates a smaller amount of energy to the surrounding air.

Evaporation

• the removal of heat from the surface of a liquid that is losing some of its molecules as gas.

Convection

• the transfer of heat by the movement of air or liquid past a surface, as when a breeze contributes to heat loss from a lizard‘s dry skin or when blood moves heat from the body core to the extremities.

Conduction

• the direct transfer of thermal motion (heat) between molecules of objects in contact with each other, as when a lizard sits on a hot rock.

Integumentary System

• Outer covering of the body, consisting of the skin, hair, and nails

Insulation

• Reduces heat flow between an animal's body and its environment.

  • Found at body surface: hair and feathers;

  • Found beneath surface: layers of fat (adipose tissue).

Oily Substances

something animals secrete to repel water, protecting insulating properties of feathers/fur

Adjustable Insulating Layers

Ex. Land mammals and birds can raise fur or feathers in cold to trap additional air and increase insulation effectiveness.

• Humans rely primarily on fat for insulation; experience "goose bumps" as a vestige of hair raising.

Vasodilation

• Increases blood flow to the skin, enhancing heat loss via radiation and convection.

Vasoconstriction

Reduces blood flow to conserve body heat.

Countercurrent Exchange

• Allowed by adjacent arteries and veins, this process keeps warm blood from losing heat to the environment.

Behavioral Responses

how an organism changes its activity in reaction to a stimulus. Ex. When cold, they seek warmth by orienting toward heat sources and increasing exposure of body surface to heat.

• When hot, they engage in behaviors such as bathing, moving to cooler areas, or adjusting their orientation to minimize sun exposure.

Thermogenesis

• Ability to vary heat production to match heat loss.

Nonshivering Thermogenesis

• Endocrine signals in some mammals cause mitochondria to produce heat instead of ATP when cold.

• Brown fat tissue: specialized for rapid heat production, containing extra mitochondria; found in mammals, especially infants (5% of body weight in human infants).

Acclimatization in Thermoregulation

a short-term physiological adjustment that helps the body regulate temperature. ex. Grow thicker fur in winter.

• Shed fur in summer.

hypothalamus

location for Sensors for thermoregulation and controls the circadian clock

Fever

• Elevated body temperature during bacterial and viral infections.

Autotrophs

• Harness light energy to build organic molecules. an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

Heterotrophs

• Obtain chemical energy from food (e.g., animals)

Metabolic Rate

• measures total energy expenditure over a specified time frame, is influenced by several factors, including an animal's size, environmental temperature, age, and activity level.

Basal Metabolic Rate (BMR)

 the minimum metabolic activity level while at rest

Standard Metabolic Rate (SMR)

pertains to the metabolic rate of a fasting, non-stressed ectotherm at rest at a particular temperature.

True

• Larger animals have more body mass and require more chemical energy.

True

• Energy expenditure per gram of body mass is INVERSELY related to body size.

Torpor

• A physiological state of decreased activity and metabolism to conserve energy during difficult conditions.

Hibernation

• Long-term torpor as an adaptation for winter cold and food scarcity.

Estivation

• Summer torpor that allows animals to survive high temperatures and scarce water conditions.