Download Ch. 28

The Living World
Fifth Edition
George B. Johnson
Jonathan B. Losos
Chapter 28
The Animal Body and How It Moves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
28.1 Innovations in Body Design
• Several evolutionary innovations in the
design of animal bodies have led to the
diversity seen in the kingdom Animalia




radial versus bilateral symmetry
no body cavity versus body cavity
nonsegemented versus segmented bodies
protostomes versus deuterostomes
Table 28.1 Innovations in Body
Design
28.2 Organization of the Vertebrate
Body
• All vertebrates have the same general
architecture: a long internal tube that
extends from mouth to anus, which is
suspended within an internal body cavity
called the coelom
 the coelom of many terrestrial vertebrates is
divided into two parts
• thoracic cavity contains the heart and lungs
• abdominal cavity contains the stomach,
intestines, and liver
28.2 Organization of the Vertebrate
Body
• A tissue is a group of cells of the same
type that performs a particular function
• There are four general classes of tissues




epithelial
connective
muscle
nerve
Figure 28.1 Vertebrate tissue types
28.2 Organization of the Vertebrate
Body
• Organs are body structures comprised of
several different tissues grouped together
into a larger structural and functional unit
• An organ system is a group of organs
that work together to carry out an
important function
Figure 28.2 Levels of organization
within the vertebrate body
There Are 11 Principal Organ
Systems in the Vertebrate Body
•
•
•
•
•
•
skeletal
circulatory
endocrine
nervous
respiratory
immune and
lymphatic
•
•
•
•
•
digestive
urinary
muscular
reproductive
integumentary
Figure 28.3 Vertebrate body organ
systems
Figure 28.3 Vertebrate body organ
systems
28.3 Epithelium Is Protective
Tissue
• The epithelium functions in three ways
 to protect the tissues beneath them from
dehydration
 to provide sensory surfaces
• many of a vertebrate’s sense organs are modified
epithelial cells
 to secrete materials
• most secretory glands are derived from pockets of
epithelial cells
Figure 28.4 The epithelium
prevents dehydration
28.3 Epithelium Is Protective
Tissue
• Epithelial cells are classified into three
types according to their shapes
• Layers of epithelial tissue are usually one
or two cells thick but the sheets of cells
are tightly bound together
• Epithelium possesses remarkable
regenerative abilities
28.3 Epithelium Is Protective
Tissue
• There are two general kinds of epithelial
tissue
 simple epithelium is only one cell layer thick
and is important for exchanging materials
across it
 stratified epithelium is multiple cell layers in
thickness and provides for cushioning and
protection
• found in the skin, it is continuously replaced
28.3 Epithelium Is Protective
Tissue
• Pseudostratified epithelium is a special
epithelium found lining the respiratory tract
that resembles stratified epithelium
• Cuboidal epithelium has a secretory
function and often forms glands
Table 28.2 Epithelial Tissue
28.4 Connective Tissue Supports
the Body
• Connective tissue cells fall into three functional
categories
 defense (cells of the immune system)
 support (cells of the skeletal system)
 storage and distribution (blood and fat cells)
• All connective tissues share a common
structural feature
 they have an abundant extracellular material, called
the matrix, between widely spaced cells
28.4 Connective Tissue Supports
the Body
• immune cells roam the body within the
bloodstream and hunt invading
microorganisms and cancer cells
 there are two kinds of immune cells
• macrophages that engulf and digest invaders
• lymphocytes that attack virus-infected cells or
make antibodies
 these cells are collectively known as “white
blood cells”
28.4 Connective Tissue Supports
the Body
• Three kinds of connective tissue are the
principal components of the skeletal system
 fibrous connective tissue
• made up by cells called fibroblasts that secrete structurally
strong proteins in the spaces between the cells
– collagen protein is an example
 cartilage
• cartilage is firm but flexible due to its configuration of
collagen
 bone
• bone is stronger than cartilage because the collagen is
coated with calcium phosphate salt, making the tissue rigid
28.4 Connective Tissue Supports
the Body
• Some connective tissue cells are
specialized to accumulate and transport
particular molecules
 adipose tissue is made up of fataccumulating cells that contain vacuoles for
storing fat
 erythrocytes are red blood cells that
transport O2 and CO2 in blood
• in addition, the red blood cells move in the
plasma, which is a solvent for many substances
Table 28.3 Connective Tissue
28.4 Connective Tissue Supports
the Body
• The vertebrate endoskeleton is strong because
of the structural nature of bone
• Bone is a dynamic tissue that is constantly being
reconstructed
 the outer layer of bone is very dense and compact
and called compact bone
 the interior of bone has a more open lattice structure
and is called spongy bone
• red blood cells form in the marrow of spongy bone
28.4 Connective Tissue Supports
the Body
• New bone is formed in two stages
 first, osteoblasts lay down collagen fibers
along lines of stress
 then calcium minerals impregnate the fibers
• Bone is laid down in thin, concentric layers
 the layers form as a series of tubes around a
narrow central channel called a central canal
(Haversian canal)
Figure 28.5 The structure of bone
28.4 Connective Tissue Supports
the Body
• There is dynamic bone “remodeling” going
on all the time
 osteoblasts deposit bone while osteoclasts
break down bone and release calcium
• As a person ages, the backbone and other
bones tend to decline in mass
 excessive bone loss is a condition called
osteoporosis
Figure 28.6 Osteoporosis
28.5 Muscle Tissue Lets the Body
Move
• Muscle cells are the motors of the vertebrate
body
 they have many contractible proteins fibers, called
myofilaments, inside of them
• the proteins actin and myosin make up the myofilaments
 there are three different kinds of muscle in vertebrates
• smooth muscle
• skeletal muscle
• cardiac muscle
Table 28.4 Muscle Tissue
28.5 Muscle Tissue Lets the Body
Move
• Smooth muscle cells are long and
spindle-shaped
 each cell contains a single nucleus
 smooth muscle is the least organized of the
types of muscle tissue
 it is found in areas such as the walls of blood
vessels and the gut
28.5 Muscle Tissue Lets the Body
Move
• Skeletal muscle move the bones of the
skeleton
 skeletal muscles fuse to form one very long
fiber with the nuclei pushed out to the
periphery of the cytoplasm
 each muscle fiber consists of many
elongated myofibrils
Figure 28.7 A skeletal muscle fiber,
or muscle cell
28.5 Muscle Tissue Lets the Body
Move
• Cardiac muscle is comprised of chains of
single cells, each with its own nucleus
 these chains are organized into fibers that
branch and interconnect to form a network
 each muscle cell is coupled to its neighbors
electrically by gap junctions
• an electrical impulse passes from cell to cell
across the gap junctions, causing the heart to
contract in an orderly fashion
28.6 Nerve Tissue Conducts
Signals Rapidly
• Nerve cells carry information rapidly from
one vertebrate organ to another
• Nerve tissue is comprised of two types of
cells
 neurons are specialized for transmitting
nerve impulses
 glial cells are supporting cells that supply
neurons with nutrition, support, and insulation
28.6 Nerve Tissue Conducts
Signals Rapidly
• Each neuron is comprised of three parts
 a cell body that contains the nucleus
 dendrites that extend from the cell body and
act as antennae to receive nerve impulses
 an axon that is a single, long extension which
carries nerve impulses away from the body
• some axons can be quite long
Figure 28.8 Neurons carry impulses
28.6 Nerve Tissue Conducts
Signals Rapidly
• Neurons have three general categories
 sensory neurons
• carry electrical impulses from the body to the
central nervous system
 motor neurons
• carry electrical impulses from the central nervous
system to the muscles
 association neurons
• occur within the central nervous system and act as
a connector between the sensory and motor
neurons
Table 28.5 Nerve Tissue
28.7 Types of Skeletons
• Animals are able to move because the opposite
ends of their muscles are attached to a rigid
scaffold, or skeleton
 there are three types of skeletons in the animal
kingdom
• hydraulic skeletons are fluid-filled cavities encircled by
muscles that raise the pressure of the fluid when they
constrict
• exoskeletons surround the body as a rigid hard case to
which muscles attach internally
• endoskeletons are rigid internal skeletons to which muscles
are attached
28.7 Types of Skeletons
Figure 28.9 Earthworms have a
hydraulic skeleton
Figure 28.10 Crustaceans have an
exoskeleton
Figure 28.11 Snakes have an
endoskeleton
28.7 Types of Skeletons
• The human skeleton is made up of 206
bones
 axial skeleton
• made up of the skull, backbone, and rib cage
 appendicular skeleton
• made up of the bones of the arms and legs and the
girdles where they attach to the axial skeleton
– pectoral girdle forms the shoulder joint
– pelvic girdle forms the hip joint
Figure 28.12 Axial and appendicular
skeletons
28.8 Muscles and How They
Work
• Skeletal muscles move the bones of the
skeleton
 tendons are straps of dense connective
tissue that attach muscles to bone
• the origin of the muscle is the end of the muscle
attached to a bone that remains stationary during a
contraction
• the insertion of the muscle is attached to a bone
that moves if the muscle contracts
 bones pivot about flexible connections called
joints
Figure 28.14 The muscular system
28.8 Muscles and How They
Work
• Muscles can only pull because myofibrils
contract rather than expand
 the muscles in the movable joints of
vertebrates are attached in opposing pairs
called flexors and extensors
• when contracted they move the bones in different
directions
Figure 28.14 Flexor and extensor
muscles
28.8 Muscles and How They
Work
• All muscles contract but there are two
types of contractions
 isotonic contraction is when the muscle
shortens as it contracts
 isometric contractions is when the muscle
does not shorten when it contracts
• this would be associated with trying to lift
something extremely heavy
28.8 Muscles and How They
Work
• The sliding filament model of muscular
contraction describes how actin and
myosin cause muscles to contract
 the head of a myosin filament binds to an
actin filament
 but first, ATP is used to flex the myosin head
 when the muscle contracts, the myosin head
returns to its original shape and pulls the actin
it is attached to along with it
Figure 28.15 How myofilament
contraction works
28.8 Muscles and How They
Work
• As one after another myosin head flexes, the
myosin in effect “walks” step by step along the
actin
• The contractile unit of muscle is called a
sarcomere
 the actin filaments are anchored to one end of the
sarcomere called the z-line
 myosin is interspersed between a pair of actin
filaments connected to either end of the sarcomere
Figure 28.16 How actin and myosin
filaments interact
28.8 Muscles and How They
Work
• In vertebrate skeletal muscle, contraction
is initiated by a nerve impulse
 neurotransmitters are secreted by the neuron
to stimulate the muscle to contract by causing
Ca++ ions to enter the muscle
 access to actin by myosin is normally blocked
by a regulatory protein called tropomyosin
• in the presence of Ca++, the tropomyosin shifts
away to expose binding sites on the actin for
myosin
Inquiry & Analysis
• Do the three modes
of locomotion have
the same or different
costs?
• For any given mode
of locomotion, what is
the impact of body
size on cost of
moving?
Graph of Effect of Body Size on
Energy Costs of Motion