Basic Principles of Animal Form

and FunctionChapter 40

Form and Function

• Anatomy- biological form of an organism.

• Physiology- biological function.

Size and Shape

• Development of body plan and shape is programmed by specific genes.• Ex: homeotic genes, HOX genes

Exchange with Environment

• Interstitial Fluid- fills spaces between cells of most mammals- helps exchange fluids between cells.• Circulatory Fluid (blood)- also enables

cells to obtain nutrients and get rid of wastes.

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Organization of Body Plans

• Cells – Tissues – Organs - Organ Systems

Major Tissue Types

• Epithelial

• Connective

• Muscle

• Nervous

Epithelial Tissue

• Epithelial Tissue- covers the outside of the body and lines organs and cavities within the body. • Function as a barrier against mechanical injury, pathogens, and fluid loss.

Connective Tissue

• Connective Tissue- cells scattered in an extracellular matrix.• Holds tissue and organs together and in place.

Muscle Tissue

• Skeletal Muscle- attached to bones by tendons. • Striated. Contractile units called sarcomeres are

formed by the fusion of many muscle fibers, thus cells contain multiple nuclei. Responsible for voluntary movements.

• Smooth Muscle- lacks striations. • Found in walls of digestive tract, bladder, arteries,

etc. Responsible for involuntary movements.

• Cardiac Muscle- forms the contractile wall of the heart.• Striated. Fibers connected with intercalated disks

that help synchronize muscle contraction.

Muscle Tissue

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Nervous Tissue

• Nervous Tissue- functions in the receipt, processing, and transmission of information.• Nerve cells = neurons; supporting cells =

glial cells- both work together to transmit nerve impulses.

Warm Up Exercise

1. What are the four major tissue types?

2. What are the three types of muscle tissues?

Communication and Signaling

• Two major systems are responsible for communication between cells:• Endocrine System-

signaling molecules called hormones are released into the blood stream by endocrine cells.

• Nervous System- neurons transmit signals- called nerve impulses

Communication and Signaling

• Endocrine- signal travels everywhere via blood- response is limited to cells that have a receptor for the specific hormone. Transmission may take several seconds, but duration may last hours.

• Nervous- signal travels along axon to specific location. Transmission is extremely fast and duration is extremely short.• Only four types of cells can receive nerve

impulses- other neurons, muscle, endocrine and exocrine cells.

Communication and Signaling

• Endocrine- gradual changes that affect the entire body.• Ex: growth and development,

reproduction, metabolic processes, digestion.

• Nervous- directs immediate and rapid response to the environment.• Ex: controls fast locomotion and

behavior.

Regulating and Conforming

• Regulator- uses internal mechanisms to control internal change in the face of external fluctuation.

• Conformer- allows its internal condition to change in accordance with external changes in the variable.

Homeostasis

• Homeostasis- a constant internal environment.• Includes pH,

temperature, salinity, fluids, gases, nutrients, etc.

Feedback Control and Homeostasis

• Negative Feedback- reduces the stimulus.• Brings the body back to normal and

helps restore homeostasis.

• Positive Feedback- amplifies the stimulus.• Not typically involved in homeostasis.

Alterations in Homeostasis• Regulated

Changes: puberty, menstrual cycle, etc.

• Circadian Rhythm- physiological changes that occur approx. every 24 hours.

Alterations to Homeostasis

• Acclimatization- gradual process in which an animal adjust to changes in its external environment.

Exit Slip

• Suppose you are standing at the edge of a cliff and suddenly slip- you barely manage to keep your balance and avoid falling. As your heart races, you feel a burst of energy; due in part to the surge of blood into dilated vessels in your muscles and an upward spike in the level of glucose in your blood. Why might you expect that this “fight-or-flight” response requires bot the nervous and endocrine systems?