Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 31
Animal Organization and
Homeostasis
Lecture Outline
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31.1 Types of Tissue
• Tissues are:
 Collections of specialized cells organized to
perform a common function
The four tissue types are:




Epithelial
Connective
Muscular
Nervous
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Types of Tissue
• Epithelial Tissue (epithelium)




Forms a continuous layer over body surfaces
Lines body cavities
Forms glands
Epithelial cells may be connected to one another by
• Tight junctions
• Adhesion junctions
• Gap junctions
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Functions of epithelial tissue include:
Protection
Secretion
Absorption
Excretion
Filtration
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3 types of epithelial tissue
1. Simple
2. Stratified
3. glandular
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Types of Tissue
• Simple Epithelia - A single layer of cells
 Classified according to cell type:
• Squamous epithelium – flattened cells
• Cuboidal epithelium – cube-shaped cells
• Columnar epithelium – cells resembling columns
Glandular Epithelia
• - Secretes a product
 A gland can be a single epithelial cell or can contain
many cells
 Exocrine glands - Secrete products into ducts or
cavities
 Endocrine glands - Secrete products directly into the
bloodstream
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Stratified Epithelia –
Layers of cells
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Types of Epithelial Tissues in the
Vertebrates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Simple
squamous
• lining of lungs,
blood vessels
• allows diffusion
Simple cuboidal
• lining of kidney
tubules, various
glands
• absorbs molecules
basement membrane
basement membrane
(All): © Ed Reschke
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Types of Epithelial Tissues in the
Vertebrates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Simple columnar
• lining of small
intestine, oviducts
• absorbs nutrients
Pseudostratified,
ciliated columnar
• lining of trachea
• sweeps impurities
toward throat
Stratified squamous
• lining of nose,
mouth, esophagus,
anal canal, vagina
• protects
cilia
goblet cell
secretes
mucus
goblet cell
secretes
mucus
basement
membrane
basement
membrane
basement membrane
(All): © Ed Reschke
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• Connective tissue functions:




Establishing a structural framework
Transporting fluids and dissolved materials
Protecting delicate organs
Supporting, surrounding and interconnecting
tissues
 Storing energy reserves
 Defending the body from microorganisms
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• Connective tissue:
 Specialized cells
 Ground substance - Noncellular material
 Protein fibers
• Collagen fibers - contain collagen providing strength and
flexibility
• Reticular fibers – contain thinly branched collagen fibers
• Elastic fibers – contain elastin
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Three categories of connective tissue
Fibrous
Supportive
Fluid
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Types of Connective Tissue in
Vertebrates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Loose fibrous
connective
tissue
Adipose
tissue
Dense fibrous
connective
tissue
• has space
between
components.
• occurs beneath skin
and most epithelial layers.
• functions in support and binds
organs.
• cells are
filled with fat.
• occurs beneath
skin, around
heart and other organs.
• functions in insulation, stores fat.
• has collagenous
fibers closely
packed.
• in dermis of skin,
tendons, ligaments.
• functions in support.
fibroblast
50 µm
elastic
fiber
a.
50 µm
collagen
fiber
400x
collagen
fibers
nucleus
b.
nuclei of
fibroblasts
c.
(a, b); (c): © The McGraw-Hill Companies,Inc. Dennis Strete, Photographer
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Types of Connective Tissue in
Vertebrates
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hyaline
cartilage
Compact bone
• has cells in
concentric
rings.
• occurs in
bones of
skeleton.
• functions in
support and protection.
central canal
osteon
• has cells in
lacunae.
• occurs in nose;
in the walls of
respiratory
passages; at ends of bones,
Including ribs.
• functions in support and
protection.
chondrocyte
within lacunae
d.
50 µm
osteocyte
canaliculi
within a lacuna
matrix
e.
(d, e): © Ed Reschke
320x
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Fibrous Connective Tissue
 consist of:
• Fibroblast cells
• A matrix containing collagen and elastic fibers
 Loose fibrous connective tissue
• Allows organs to expand
 Adipose tissue
• Stores energy
• Insulates the body and provides padding
 Dense fibrous connective tissue
• Strong connective tissue
• Tendons – connect muscle to bone
• Ligaments – connect bones to other bones at joints
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Diagram of Fibrous Connective
Tissue
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Adipose cell:
stores fat
Stem cell: divides to
produce other types
of cells
Collagen fiber:
unbranched, strong
but flexible
Ground
substance: fills
spaces between
cells and fibers
Elastic fiber:
branched and
stretchable
Fibroblast: divides to
produce other types
of cells
Reticular fiber:
branched, thin, and
forms network
White blood cell:
engulfs pathogens
or produces antibodies
Blood vessel
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Supportive Connective Tissue
 Cartilage
• Classified according to type of collagen and elastic fibers
found in the matrix (hyaline cartilage, elastic cartilage,
fibrocartilage)
• Cartilage cells lie in small chambers (lacuna) in the matrix
 Bone
• Matrix is inorganic salts deposited around protein fibers
• Bone cells are located in lacunae
• Lacunae arranged in concentric circles within osteons around
tiny tubes (central canals)
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Fluid Connective Tissues
 Blood
• A connective tissue in which cells are embedded in a liquid
matrix (plasma)
– Red blood cells – oxygen transport
– White blood cells – immune response
– Platelets – involved in the clotting process
• Functions
– Transports nutrients and oxygen to cells
– Removes carbon dioxide and other wastes
 Lymph
• A fluid connective tissue located in lymphatic vessels
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Blood, a Liquid Tissue
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plasma
white blood cells
(leukocytes)
red blood cells
(erythrocytes)
a. Blood sample
after centrifugation
white blood cell
platelets
red blood cell
plasma
b. Blood smear
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Muscular (contractile) Tissue
 Contractile cells containing actin and myosin
filaments
 Cells are called muscle fibers
 Three types of muscle tissue:
• Skeletal Muscle
– Voluntary - Long, striated fibers, multinucleated
• Smooth (visceral) Muscle
– Involuntary - No striations
• Cardiac Muscle
– Striated, but mostly involuntary
– Cells are bound to each other by intercalated disks
– Relies on pacemaker cells for regular contraction
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Muscular Tissue
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Skeletal muscle
• has striated cells
with multiple nuclei.
• occurs in muscles
attached to skeleton.
• functions in voluntary
movement of body.
striation
Smooth muscle
• has spindle-shaped
cells, each with a
single nucleus.
• cells have no striations.
• functions in movement of
substances in lumens of body.
• is involuntary.
• is found in blood vessel walls and walls
of the digestive tract.
nucleus
smooth muscle cell
a.
b.
nucleus
400
Cardiac muscle
• has branching,
striated cells, each
with a single nucleus.
• occurs in the wall of
the heart.
• functions in the pumping
of blood.
• is involuntary.
intercalated disk nucleus
250
c.
a, c: © Ed Reschke; b: © McGraw-Hill Higher Education, Dennis Strete, photographer
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Nervous system (functions):
 Sensory input
• Sensory receptors detect changes
• Transmit information to the spinal cord and brain
 Data integration
• Spinal cord and brain integrate data
• Decision is made regarding appropriate response
 Motor output
• Response is transmitted to effector (gland or
muscle)
• Effector initiates the actual response
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Nervous Tissue
 Conducts electrical impulses
 Conveys information from one area to another
 Nervous tissue includes:
• Neurons
– Transmit information
– Consist of dendrites, a cell body, and an axon
– Outside the brain and spinal cord, fibers bound by
connective tissue form nerves.
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Nervous Tissue
 Neuroglia
• Support and nourish neurons
• Neuroglia in brain include
– Microglia
– Astrocytes
– Oligodentrocytes
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Neurons and Neuroglia
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dendrite
Neuron
nucleus
cell body
axon
Microglia
Astrocyte
Oligodendrocyte
myelin sheath
axon
b. Micrograph of a neuron
Capillary
a. Neuron and neuroglia
200×
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b: © Ed Reschke
Regenerative Medicine
• In humans, axons outside the brain and
spinal cord can regenerate, but not those
inside these organs.
• Injured neurons in CNS degenerate
 Permanent loss of nervous function.
• In cold-water fishes and amphibians axon
regeneration in the CNS does occur.
 Several proteins play role in axon
regeneration
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Creating a New Type of
Salamander for Limb Regeneration
31.2 Organs, Organ Systems,
and Body Cavities
• Organ
 Composed of two or more tissue types
working together for a particular function
• Organ System
 Composed of various organs that cooperate
to carry out a general process
• Ex: the digestion of food
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Body Cavities
1.Dorsal cavity (toward the back)
• Contains the cranial cavity and the vertebral canal
• The brain is in the cranial cavity, and
• The spinal cord is in the vertebral canal
2. Ventral cavity (toward the front) is divided
into
• The thoracic cavity (includes heart and lungs),
• The abdominal cavity (most other internal organs),
and
• The pelvic cavity (certain reproductive organs)
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Mammalian Body Cavities
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Cranial
cavity:
contains brain
Thoracic
cavity:
contains heart,
lungs, and
esophagus
Ventral
cavity
diaphragm
Abdominal
cavity:
contains stomach,
liver , spleen,
pancreas,
and intestines
Pelvic
cavity:
contains certain
reproductive
organs
a.
Vertebral
cavity:
contains
spinal cord
Dorsal
cavity
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Mammalian Body Cavities
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Thoracic cavity:
contains esophagus,
heart, and lungs
Abdominal cavity:
contains digestive
and other organs
Pelvic cavity:
contains reproductive
and other organs
b.
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31.3 The Integumentary System
• Functions of skin
 Covers and protects underlying body regions
 Regulates body temperature, and
 Contains sensory receptors
• Skin and its derivatives make up the
integumentary system
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Regions of the Skin
 Epidermis
 Dermis
 Subcutaneous Layer
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- Outer, thinner region
Stratified squamous epithelium
New cells are pushed outward,
become keratinized, and are
sloughed off
Melanocytes produce melanin
(pigment)
UV radiation can cause mutations in
the DNA of skin cells, leading to skin
cancer.
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 Dermis - Deeper and thicker than epidermis
• Fibrous connective tissue containing elastic and collagen
fibers contains:
– Receptors
– Nerve fibers
– Blood vessels
 Subcutaneous Layer - Loose, connective tissue
located below dermis
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The Integumentary System
• Accessory Structures of Human Skin:
 Nails
 Hair follicles
 Hair follicles
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Nails
Grow from nail root and form
protective covering of distal
portion of fingers and toes
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Hair follicles
Begin in the dermis and continue through
the epidermis
Contain oil glands (sebaceous glands)
which secrete sebum
Lubricates the hair within the follicle as
well as the skin
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Hair follicles
Begin in the dermis and continue through
the epidermis
Contain oil glands (sebaceous glands)
which secrete sebum
Lubricates the hair within the follicle as
well as the skin
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Human Skin Anatomy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
hair shaft
sweat pore
melanocytes
Epidermis
sensory receptor
capillaries
oil gland
arrector pili muscle
Dermis
free nerve endings
hair follicle
hair root
sweat gland
artery
vein
Subcutaneous layer
nerve
adipose tissue
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The Epidermis
flattened and
dead cells
Epidermis
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b. Basal cell
carcinoma
cells undergoing
keratinization
dermal
projection
a. Photomicrograph of skin
Dermis
stem cells
and melanocytes
c. Melanoma
a: © John D. Cunningham/Visuals Unlimited; b: © Ken Greer/Visuals Unlimited; c: © James Stevenson/SPL/Photo Researchers, Inc.
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31.4 Homeostasis
• The organ systems of the human body
contribute to homeostasis:
 The ability of an organism to maintain a relatively
constant internal environment
 Animals vary to the degree in which they can regulate
internal variables.
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The organ systems of the human body
contribute to homeostasis
1.The digestive system
• Takes in and digests food
• Provides nutrient molecules that replace used nutrients
2.The respiratory system
• Adds oxygen to the blood
• Removes carbon dioxide
3.The liver and the kidneys
• Store excess glucose as glycogen
• Later, glycogen is broken down to replace the glucose used
• The hormone insulin regulates glycogen storage
4.The kidneys
• Under hormonal control as they excrete wastes and salts
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Homeostasis
• Homeostatic Control
 Partially controlled by hormones
 Ultimately controlled by the nervous system
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Negative feedback
 is the primary homeostatic mechanism that keeps a
variable close to a set value
• Sensor detects change in environment
• Regulatory center initiates an action to bring the conditions
back to normal
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Regulation of Room Temperature
Using Negative Feedback
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Control center
sends data to
thermostat
68°F set point
directs furnace
to turn off
Sensor
70°F
too hot
furnace off
negative feedback
and return to
normal temperature
stimulus
Homeostasis
negative feedback
and return to
normal temperature
stimulus
Sensor
furnace on
66°F
too cold
Control center
directs furnace
to turn on
sends data to
thermostat
68°F set point
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Regulation of Body Temperature by
Negative Feedback
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Control center
sends data to
control center
directs response
to stimulus
98.6°F set point
Sensor
Effect
Blood vessels dilate;
sweat glands secrete.
negative feedback
and return to normal
temperature
stimulus
Normal body temperature
negative feedback
and return to normal
stimulus
Effect
Blood vessels constrict;
sweat glands are inactive.
Sensor
Control center
directs response
to stimulus
sends data to
control center
98.6°F set point
Positive feedback
• is a mechanism that brings about an ever
greater change in the same direction
 Childbirth process
• Positive Feedback
 Does not result in equilibrium
 Does not occur as often as negative feedback
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Positive Feedback
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2. Signals cause pituitary gland to
release the hormone oxytocin.
As the level of oxytocin increases,
so do uterine contractions
until birth occurs.
pituitary gland
+
+
1. Due to uterine contractions,
baby’s head presses on
cervix, and signals are
sent to brain.
uterus
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