Chapter 43

The Animal Body and Principles of Regulation

Max Ammendolea Greg Raube

Organization of the Vertebrate Body

• There are levels of organization in the vertebrate body

-cells

-tissues

-organs

-organ systems

Tissues are groups of cells of a single type and function

• Early in development, the cells of the growing embryo differentiate into the three fundamental embryonic tissues called germ layers

-endoderm

-mesoderm

-ectoderm

• Four principal kinds of tissues in adult vertebrates

-epithelial, connective, muscle, and nerve tissue

• Organs and organ systems provide specialized functions

-organs are body structures composed of several different types of tissues that form a structural and functional unit

-organ system is a group of organs that cooperate to perform the major activities of the body

• The general body plan of vertebrates is a tube within a tube, with internal support

• Vertebrates have both dorsal and ventral body cavities

-dorsal cavity is cranium and vertebrae

-ventral: thoracic (pericardial, pleural) cavity and abdominopelvic (peritoneal) cavity

Epithelial Tissue

• Rows of cells exposed to open area and anchored down by a basement membrane to connective tissue

• Three types of epithelial cell structures

-squamous, cuboidal, and columnar

• Classified as simple or stratified

• Function in protection, transport, and secretion

-examples?

Connective Tissue

• All CT are widely spaced apart cells in a matrix of extracellular material

• CT function in protecting (bone), support (cartilage), food storage (fat or adipose tissue)

• CT can be either proper or special

CT Proper May Be Either Loose or Dense

• Fibroblast cells produce and secrete the extracellular matrix (collagen and elastin fibers)

• Loose CT consists of cells scattered within a matrix that contains a large amount of fluid material and fibers. They provide support, insulation, food storage, and nourishment for epithelium

-Adipose tissue is fat tissue

• Dense CT has a lot more collagen than Loose CT making it structurally stronger. They provide flexible, strong connections

-tendons of muscles

Special CT have unique characteristics

• Cartilage provides flexible support and is a shock absorber (intervertebral disks)

• Bone protects internal organs and provides rigid support for muscle attachment

• Blood functions as highway of immune system and primary means of communication between organs

Muscle Tissue

• Muscles are the motors of the vertebrate body

• Three types

-skeletal: voluntary, moves the body

-smooth: involuntary, control most actions of organs

-cardiac: involuntary, controls the heart

Nerve Tissue

• Composed of nerve cells (neurons) and their supporting cells (neuroglia) that are specialized to produce and conduct electrochemical events (impulses)

• Two divisions of the nervous system coordinate activity

-central nervous system (CNS): the brain and spinal cord

-peripheral nervous system (PNS): nerves and ganglia, collections of neuron cell bodies

Overview of the Vertebrate Organ Systems

• Organ systems are approached by placing them in the following functional groupings: communication and integration, support and movement, regulation and maintenance, defense, and reproduction and development

-Communication and integration sense and respond to the environment (nervous, sensory, and endocrine system)

-Skeletal support and movement are vital to all animals (musculoskeletal system)

-Regulation and maintenance of the body’s chemistry ensures continued life (digestive, circulatory, respiratory, and urinary)

-The body can defend itself from attackers and invaders (integumentary and immune system)

-Reproduction and development ensure the continuity of species (reproductive system)

Homeostasis

• The dynamic constancy of the internal environment

• Negative feedback mechanisms keep values within range

-hypothalamus is the body’s thermostat

• Antagonistic effectors act in opposite directions

• Positive feedback mechanisms enhance a change

-less common and have specialized functions in body

The Evolution of Organ Systems

• The digestive system

-Sponges flipped their stomachs inside out and ate stuff

-earth worms obtained a one way digestive tract

-vertebrates developed specialized organs for their digestive tracts

The Respiratory System

• The respiratory system

-fishes have gills and let O2 diffuse in

-amphibians breathe in cutaneously and have lungs

-reptiles have straight up lungs

-birds are weird and have a bunch of air sacs

-mammals have well developed lungs

The Heart

• Fish have a 2 chambered heart• Amphibians have a 3 chambered heart• Reptiles have a 3 and a half chambered heart• Mammals have a 4 chambered heart

The Brain

• Cephalization and the development of a brain were important steps in animal evolution

-the concentration of the nervous system toward the anterior end of the organism

• the flat worms were the first to cephalize

• efficient response to a stimulus (during movement sensory organs encounter the environment first

• Ectoderm gives rise to the nervous system

-development of notochord

-neural tube develops into brain

-spinal column/vertebrae/cranium protect the CNS

-notochord signals or directs the development of neural tube

THE END