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Chapter 43
The Animal Body and Principles of
Regulation
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?
Tissues: groups of cells with a common
structure and function (4 types)
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Anatomy: structure
Physiology: function
1- Epithelial: outside of body
and lines organs and cavities;
held together by tight junctions
basement membrane: dense
mat of extracellular matrix
Simple: single layer of cells
Stratified: multiple tiers of cells
Cuboidal (like dice)
Columnar (like bricks on end)
Squamous (like floor tiles)
mucous membrane
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
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Tissues, II
2- Connective: bind and support other tissues; scattered cells through matrix; 3 kinds:
A-Collagenous fibers (collagen protein) B-Elastic fibers (elastin protein) C-Reticular fibers
(thin branched collagen fibers)
Loose connective tissue: binds epithelia to underlying tissue; holds organs
1-Fibroblasts- secretes extracellular proteins 2-Macrophages- amoeboid WBC’s;
phagocytosis 3-Adipose tissue- fat storage; insulation
Fibrous connective tissue: parallel bundles of cells
1-Tendons- muscles to bones 2-Ligaments- bones to bones; joints (BOBOLI)
Cartilage: collagen in a rubbery matrix (chondroitin); flexible support
Bone: mineralized tissue by osteoblasts
Blood: liquid plasma matrix; erythrocytes (RBC’s) carry O2; leukocytes (WBC’s) immunity
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
Tissues, III
• 4- Muscle: capable of
contracting when stimulated
by nerve impulses; myofibrils
composed of proteins actin
and myosin; 3 types:
• A- Skeletal: voluntary
movement (striated)
• B- Cardiac: contractile wall
of heart (branched striated)
• C- Smooth: involuntary
activities (no striations)
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
Tissues, IV
• 3-Nervous: senses stimuli
and transmits signals from 1
part of the animal to another
• Neuron: functional unit that
transmits impulses
• Dendrites: transmit impulses
from tips to rest of neuron
• Axons: transmit impulses
toward another neuron or
effector
Organ systems
• Organ: organization of
tissues
• Mesentaries:
suspension of organs
(connective tissue)
• Thoracic cavity (lungs
and heart)
• Abdominal cavity
(intestines)
• Diaphragm (respiration)
• Organ systems…...
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Digestive-food processing
Circulatory-internal distribution
Respiratory-gas exchange
Immune/Lymphatic-defense
Excretory-waste disposal;
osmoregulation
Endocrine-coordination of body
activities
Reproductive-reproduction
Nervous-detection of stimuli
Integumentary-protection
Skeletal-support; protection
Muscular-movement; locomotion
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
Internal regulation
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Interstitial fluid: internal fluid
environment of vertebrates;
exchanges nutrients and wastes
Homeostasis: “steady state” or
internal balance
Negative feedback: change in a
physiological variable that is being
monitored triggers a response that
counteracts the initial fluctuation; i.e.,
body temperature
Positive feedback: physiological
control mechanism in which a change
in some variable triggers
mechanisms that amplify the change;
i.e., uterine contractions at childbirth
Metabolism: sum of all energyrequiring biochemical reactions
• Catabolic processes of
cellular respiration
• Calorie; kilocalorie/C
• Endotherms: bodies warmed
by metabolic heat
• Ectotherms: bodies warmed
by environment
• Basal Metabolic Rate (BMR):
minimal rate powering basic
functions of life (endotherms)
• Standard Metabolic Rate
(SMR): minimal rate
powering basic functions of
life (ectotherms)
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
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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