Download Organization of Vertebrate Body Organization of

The Animal Body and
Principles of Regulation
Chapter 43
Organization of Vertebrate Body
Organization of Vertebrate Body
There are four levels of organization:
1. Cells
2. Tissues
3. Organs
4. Organ systems
Tissues are groups of cells that are similar in
structure and function
The three fundamental embryonic tissues are
called germ layers
-Endoderm, mesoderm and ectoderm
In adult vertebrates, there are four primary
tissues
-Epithelial, connective, muscle and
nerve
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Bodies of vertebrates are composed of
different cell types
-Humans have 210
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Organization of Vertebrate Body
Organization of Vertebrate Body
Organs are combinations of different tissues
that form a structural and functional unit
The body plan of all vertebrates is essentially
a tube within a tube
-Inner tube = Digestive tract
-Outer tube = Main vertebrate body
-Supported by a skeleton
-Outermost layer = Skin and its accessories
Organ systems are groups of organs that
cooperate to perform the major activities of
the body
-The vertebrate body contains 11 principal
organ systems
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Organization of Vertebrate Body
Inside the body are two identifiable cavities
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Organization of Vertebrate Body
Dorsal body cavity: Within skull & vertebrae
Ventral body cavity: Bounded by the rib
cage and vertebral column
-Divided by the diaphragm into:
-Thoracic cavity: Heart and lungs
-Abdominopelvic cavity: Most organs
-Peritoneal cavity: Coelomic space
-Pericardial cavity: Around the heart
-Pleural cavity: Around the lungs
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Epithelial Tissue
An epithelial membrane, or epithelium,
covers every surface of the vertebrate body
-Can come from any of the 3 germ layers
-Some epithelia change into glands
Cells of epithelia are tightly bound together
-Provide a protective barrier
Epithelia possess remarkable regenerative
powers replacing cells throughout life
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Epithelial Tissue
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Epithelial Tissue
Epithelial tissues attach to underlying
connective tissues by a fibrous membrane
-Basal surface = Secured side
-Apical surface = Free side
-Therefore, epithelia have inherent polarity,
which is important for their function
Simple Epithelium
Simple Epithelium
Two general classes
-Simple = One layer thick
-Stratified = Several layers thick
Subdivided into:
-Squamous cells = Flat
-Cuboidal cells = Cube-shaped
-Columnar cells = Cylinder-shaped
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Simple squamous epithelium
-Lines lungs and blood capillaries
Simple cuboidal epithelium
-Lines kidney tubules and several glands
Simple columnar epithelium
-Lines airways of respiratory tract and most
of the gastrointestinal tract
-Contains goblet cells: secrete mucus
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Simple Epithelium (Cont.)
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Simple Epithelium
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Simple Epithelium (Cont.)
Simple Epithelium
Stratified Epithelium
Glands of vertebrates form from invaginated
epithelia
-Exocrine glands
-Connected to epithelium by a duct
-Sweat, sebaceous and salivary glands
-Endocrine glands
-Ductless; lost duct during development
-Secretions (hormones) enter blood
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Stratified Epithelium
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Connective Tissues
Connective Tissue Proper
Derive from embryonic mesoderm
Divided into two major classes
-Connective tissue proper
-Loose or dense
-Special connective tissue
-Cartilage, bone and blood
All have abundant extracellular material
called the matrix
-Protein fibers plus ground substance
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Connective Tissue Proper
Fibroblasts produce and secrete extracellular
matrix
Loose connective tissue
-Cells scattered within a matrix that contains
large amounts of ground substance
-Strengthened by protein fibers such as:
-Collagen – Supports tissue
-Elastin – Makes tissue elastic
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Connective Tissue Proper
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Connective Tissue Proper
Adipose cells (fat cells) also occur in loose
connective tissue
-Develop in large groups in certain areas,
forming adipose tissue
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Named according to the features of their apical
cell layers
-Epidermis is a stratified squamous
epithelium
-Characterized as a
keratinized
epithelium
-Contains water-resistant keratin
-Note: Lips are covered with nonkeratinized,
stratified squamous epithelium
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Dense connective tissue
-Contains less ground substance and more
collagen than loose connective tissue
-Dense regular connective tissue
-Collagen fibers line up in parallel
-Makes up tendons and ligaments
-Dense irregular connective tissue:
-Collagen fibers have different orientations
-Covers kidney, muscles, nerves & bone
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Connective Tissue Proper
Special Connective Tissue
Connective Tissue Proper (Cont.)
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Special Connective Tissue
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Special Connective Tissue
Cartilage
-Ground substance made from
characteristic glycoprotein, called
chondroitin, and collagen fibers in long,
parallel arrays
-Flexible with great tensile strength
-Found in joint surfaces and other locations
-Chondrocytes (cartilage cells) live within
lacunae (spaces) in the ground substance30
Special Connective Tissue
Bone
-Osteocytes (bone cells) remain alive in a
matrix hardened with calcium phosphate
-Communicate through canaliculi
Blood
-Extracellular material is the fluid plasma
-Erythrocytes = red blood cells
-Leukocytes = white blood cells
-Thrombocytes = platelets
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Special Connective Tissue
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Muscle Tissue
Muscle Tissue
Muscles are the motors of vertebrate bodies
-Three kinds: smooth, skeletal and cardiac
Smooth muscles are found in walls of blood
vessels and visceral organs
-Cells are mono-nucleated
Skeletal muscles are usually attached to
bone by tendons, so muscle contraction
causes bones to move
-Muscle fibers (cells) are multi-nucleated
-Contract by means of myofibrils, which
contain ordered actin & myosin filaments
-Skeletal and cardiac muscles are also
known as striated muscles
-Skeletal muscle is under voluntary control,
whereas contraction of the other two is
involuntary
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Muscle Tissue
Cardiac muscle is composed of smaller,
interconnected cells
-Each with a single nucleus
-Interconnections appear as dark lines
called intercalated disks
-Enable cardiac muscle cells to form a
single functioning unit
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Nerve Tissue
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Nerve Tissue
Cells include neurons and their supporting
cells, called neuroglia
Most neurons consist of three parts
-Cell body: contains the nucleus
-Dendrites: highly branched extensions
-Conduct electrical impulses toward the
cell body
-Axon: single cytoplasmic extension
-Conducts impulses away from cell body
Neuroglia do not conduct electrical impulses
-Support and insulate neurons and eliminate
foreign materials in and around neurons
-Associate with axon to form an insulating
cover called the myelin sheath
-Gaps, known as nodes of Ranvier, are
involved in acceleration of impulses
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Nerve Tissue
Overview of Organ Systems
Nervous system is divided into:
-Central nervous system (CNS)
-Brain and spinal cord
-Integration and interpretation of input
-Peripheral nervous system (PNS)
-Nerves and ganglia (collections of cell
bodies)
-Communication of signal to body
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Overview of Organ Systems
Communication and integration
-Three organ systems detect external stimuli
and coordinate the body’s responses
-Nervous, sensory and endocrine
systems
Regulation and maintenance
-Four organ systems regulate and maintain
the body’s chemistry
-Digestive, circulatory, respiratory
and urinary systems
Support and movement
-The musculoskeletal system consists of
two interrelated organ systems
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Defense
-The body defends itself with two organ
systems: integumentary and immune
Overview of Organ Systems
Overview of Organ Systems
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Overview of Organ Systems (Cont.)
Reproduction and development
-The biological continuity of vertebrates is
the province of the reproductive system
-In females, the system also nurtures the
developing embryo and fetus
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Overview of Organ Systems (Cont.)
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Overview of Organ Systems
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Overview of Organ Systems (Cont.)
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Overview of Organ Systems (Cont.)
Overview of Organ Systems
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Overview of Organ Systems (Cont.)
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Overview of Organ Systems
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Overview of Organ Systems (Cont.)
Overview of Organ Systems (Cont.)
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Overview of Organ Systems (Cont.)
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Homeostasis
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Homeostasis
As animals have evolved, specialization of
body structures has increased
For cells to function efficiently and interact
properly, internal body conditions must be
relatively constant
-The dynamic constancy of the internal
environment is called homeostasis
-It is essential for life
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Homeostasis
Homeostasis
To maintain internal constancy, the vertebrate
body uses negative feedback mechanisms
-Changing conditions are detected by
sensors (cells or membrane receptors)
-Information is fed to an integrating center,
also called comparator (brain, spinal cord
or endocrine gland)
-Compares conditions to a set point
-If a deviation is detected, a message is
sent to an effector (muscle or gland)
-Increase or decrease in activity brings
internal conditions back to set point
-Negative feedback to the sensor
terminates the response
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Homeostasis
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Homeostasis
Homeostasis
Homeostasis
Humans have set points for body temperature,
blood glucose concentrations, electrolyte
(ion) concentration, tendon tension, etc.
Negative feedback mechanisms often oppose
each other to produce finer degree of control
-Many internal factors are controlled by
antagonistic effectors
-Have “push-pull” action
-Increasing activity of one effector is
accompanied by decrease in the other
Antagonistic effectors are involved in the
control of body temperature
-If hypothalamus detects high temperature
-Promotes heat dissipation via sweating,
and dilation of blood vessels in skin
-If hypothalamus detects low temperature
-Promotes heat conservation via
shivering and constriction of blood
vessels in skin
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We are endothermic: can maintain a relatively
constant body temperature (37oC or 98.6oF)
-Changes in body temperature are detected
by the hypothalamus in the brain
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Homeostasis
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Homeostasis
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In a few cases, the body uses positive
feedback mechanisms to enhance a change
-These do not in themselves maintain
homeostasis
-However, they are generally part of some
larger mechanism that does!
-Examples:
-Blood clotting
-Contraction of uterus during childbirth 71
Homeostasis
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