chapter 20: introduction to animal physiology principles of animal organization and function lecture...

Chapter 20: Introduction to Animal Physiology

Principles of animal organization and functionLecture by Jennifer Lange, Chabot College

Learning Objectives

Understand and be able to explain the following:

Why the body needs to maintain its internal environment in a dynamically constant state.

How internal temperature is maintained while exchanging heat with the environment.

How osmotic balance and solute concentrations are maintained.

Learning Objectives

Understand and be able to explain the following:

The relationship between the levels of organization of the body.

How the unique characteristics of each tissue type relate to their function.

The major tasks of each organ system.

20.1 Our bodies function best within a narrow range of internal conditions.

Take-home message 20.1

Failure to maintain a consistent internal environment can lead to many problems and can result in death.

20.2 Animals regulate their internal environment through homeostasis.

Homeostasis: maintenance of relatively constant internal chemical and physical environment in the face of constantly changing environmental factors.


The internal environment of multicellular animals is continuously influenced by their external environment.

Animals still keep many internal variables—temperature, pH, blood sugar—within a constant range.

20.3 Negative and positive feedback systems influence homeostasis.

Perturbation away from set point results in corrective action, known as negative feedback.

Regulators vs. Conformers

Non-Homeostatic Mechanism

In specific instances, perturbation can result in further movement away from setpoint, known as positive feedback.


Physiological variables have a set point to which the organism can return.

Through negative feedback, sensors detect changes in the internal environment and trigger effectors to oppose or reduce the change.


Positive feedback systems are less common than negative feedback systems.

Positive feedback systems push the body away from normal conditions and increase change in the same direction.

Thermoregulation

How is body heat generated?

20.4 Temperature control is a component of homeostasis.

Endotherms

Ectotherms

ThermoregulationIs temperature constant or fluctuating?

Both conditions are regulated.

Heat Exchange Mechanisms

Body heat is a combination of internal heat generation and exchange with the external environment through four mechanisms:1. conduction2. convection3. radiation4. evaporation

Heat Exchange Mechanisms

How do organisms adapt to heat transfer?


The control of body temperature, called thermoregulation, is an important component of homeostasis.

Body temperature is a function of internal heat production and heat transfer between an organism and its environment.


Heat transfer to and from the environment is regulated physically, behaviorally, physiologically, and at the cellular level.

20.5 Animals must balance their water content within a narrow range.

Osmoregulation: the regulation of water content and dissolved solute concentrations by balancing water gain and loss.

GAIN1. Drinking2. Eating3. Osmosis4. Cellular respiration

LOSS1. Urination2. Defecation3. Evaporation4. Osmosis

OsmoregulationLiving in air, salt water, and freshwater pose different challenges, but all organisms use one of two strategies:


Many organisms maintain their water content within a narrow range.

Organisms must be able to take up water and get rid of water and they must be able to regulate concentrations of ions in their body fluids.

Various mechanisms and strategies have evolved for coping with these challenges.

20.6 In humans, the kidney is the chief excretory organ.

The primary organ in vertebrates regulating water balance and solute concentrations is the kidney.


The kidney is the organ in vertebrates that helps maintain homeostasis by: – regulating water balance and solute

concentrations in body fluids– filtering blood– removing potentially harmful ions and

waste products, excreting them in urine.

Form Follows FunctionThis general rule applies to all levels of body organization: from the organism itself down to the cells that comprise it.


Animal bodies are highly organized, and at all levels of organization, the physical features are related to function.

In most animals, cells with similar structure and function are organized into tissue.


There are four types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue.

Tissues are often organized into organs, which serve specialized functions and can contain several types of tissue.

Organs can be organized into organ systems that accomplish highly complex tasks.

20.8 Connective tissue provides support.


The most abundant type of tissue in most animals is connective tissue.

Connective tissue is a collection of cells arranged within an extracellular matrix, usually containing collagen, that holds the cells together and gives them shape, structure, and support to other body tissues.

20.9 Epithelial tissue protects.


Epithelium is a very thin, sheet-like tissue that covers most of the exterior and interior surfaces of an animal’s body.

Epithelium acts as a barrier between the inside and outside of an organism and also aids in secretion and transport of molecules.

20.10 Muscle tissue enables movement.


Muscle tissue consists of elongated cells capable of generating force when they contract.

Skeletal muscle is responsible for generating movement.

Cardiac muscles cause the heart to pump blood.

Smooth muscle generates slower contractions that can gradually move blood, food, and other substances.


20.11 Nervous tissue transmits information.


Nervous tissue is specialized to store and transmit information.

There are two types of nervous tissue cells: (1) neurons, which can receive and transmit a signal, and (2) glial cells, which assist and provide nutrients for neurons.

20.12 Each organ system performs special tasks.

Tissues are organized into organs, which operate together in organ systems to achieve a common function.

These systems interact to support the growth and reproduction of the entire organism.


In nearly all animals, some tissues are organized into organs (such as the heart, brain, lungs, and liver).

Organs serve specialized functions and consist of multiple tissue types.


Some tissues are organized into organ systems (such as the circulatory system).

Organ systems carry out the various physiological processes necessary for the growth, development, maintenance, and reproduction of the organism.

chapter 20: introduction to animal physiology principles of animal organization and function lecture...

Documents

evaporation slide

chabot college slide

internal temperature

heat transfer

external environment

internal variablestemperature

physical environment

takehome message