Download Chapter 21 - Human Anatomy

Animal Anatomy and Physiology Overview
 Structural Organization of Animals
 Exchanges with the environment
 Regulating the internal environment (homeostasis)
 KEY CONCEPT! Remember how cells receive
nutrients from the outside World: osmosis,
diffusion, passive and active transport
 Even in a multicellular organism, this holds true!
 Homeostasis is the control mechanism of life
THE STRUCTURAL ORGANIZATION OF ANIMALS
• Life is characterized by a hierarchy of
organization.
• In animals,
– individual cells are grouped into tissues,
– tissues combine to form organs,
– organs are organized into organ systems, and
– organ systems make up the entire organism.
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Figure 21.1-5
Cellular level:
Muscle cell
Tissue level:
Cardiac muscle
Organ level:
Heart
Organ system level:
Circulatory system
Organism level:
Multiple organ
systems
functioning
together
Form Fits Function
• Analyzing a biological structure gives us clues
about
– what it does and
– how it works.
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Figure 21.2-3
(b) At the organ level
(a) At the organism level
(c) At the cellular level
Form Fits Function
• Biologists distinguish anatomy from physiology.
– Anatomy is the study of the structure of an
organism’s parts.
– Physiology is the study of the function of those
parts.
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Tissues
• The cell is the basic unit of all living organisms.
The only thing that is living inside of you are your
cells!
• In almost all animals, including humans, cells are
grouped into tissues.
– A tissue is an integrated group of similar cells that
performs a specific function.
– Animals have four main categories of tissue.
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Epithelial Tissue
• Epithelial tissue, also known as epithelium,
– covers the surface of the body and
– lines organs and cavities within the body.
• Cells of epithelial tissues
– are fused together,
– form a protective barrier, and
– fall off and are continuously renewed.
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Figure 21.3-3
Some examples of
organs lined with
epithelial tissue:
Heart
Lung
Stomach
Small intestine
Large intestine
Urinary bladder
Epithelial tissue
lining esophagus
Epithelial
cells
Epithelial tissue
lining small intestine
Connective Tissue
• Connective tissues have a sparse population of
cells in an extracellular matrix consisting of a
web of protein fibers within a uniform foundation
that may be liquid, jellylike, or solid.
• The structure of connective tissue is correlated
with its functions:
– to bind and
– support other tissues.
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Figure 21.4
(a) Loose
connective tissue
(b) Adipose
tissue
(c) Blood
(d) Fibrous
connective tissue
(f) Bone
(e) Cartilage
Figure 21.UN01
HIERARCHICAL ORGANIZATION OF ANIMALS
Level
Description
Cell
The basic unit of
all living organisms
Example
Muscle cell
Tissue
A collection of similar
cells performing
a specific function
Cardiac muscle
Organ
Multiple tissues
forming a structure
that performs a
specific function
Heart
Organ
system
A team of organs that
work together
Circulatory system
Organism
A living being, which
depends on the
coordination of all
structural levels for
homeostasis and survival
Person
Figure 21.UN01b
HIERARCHICAL ORGANIZATION OF ANIMALS
Level
Description
Organ
system
A team of organs that
work together
Example
Circulatory system
Organism
A living being, which
depends on the
coordination of all
structural levels for
homeostasis and survival
Person
Connective Tissue
•
•
•
•
Loose connective tissue
–
is the most widespread connective tissue,
–
binds epithelia to underlying tissues, and
–
holds organs in place.
Adipose tissue
–
stores fat,
–
stockpiles energy, and
–
pads and insulates the body.
Blood
–
is a connective tissue and
–
contains red and white blood cells suspended in a liquid called plasma.
Fibrous connective tissue
–
has a dense matrix of collagen and
–
forms tendons and ligaments.
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Connective Tissue
• Cartilage
– is strong but flexible,
– has no blood vessels, so it heals very slowly,
– functions as a flexible, boneless skeleton, and
– forms the shock-absorbing pads that cushion the ends of
bones including the vertebrae of the spinal column.
• Bone
– is a rigid connective tissue and
– has a matrix of collagen fibers hardened with deposits of
calcium salts.
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Muscle Tissue
• Muscle tissue
– is the most abundant tissue in most animals,
– consists of bundles of long, thin, cylindrical cells
called muscle fibers, and
– has specialized proteins arranged into a structure
that contracts when stimulated by a signal from a
nerve. “contractile” “excitable”
– There are 3 types of muscle tissue:
– Cardiac, skeletal and smooth
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Figure 21.5
(a) Skeletal muscle
(b) Cardiac muscle
(c) Smooth muscle
Figure 21.UN01a
HIERARCHICAL ORGANIZATION OF ANIMALS
Level
Description
Cell
The basic unit of
all living organisms
Example
Muscle cell
Tissue
A collection of similar
cells performing
a specific function
Cardiac muscle
Organ
Multiple tissues
forming a structure
that performs a
specific function
Heart
Figure 21.UN02
Muscle (contracts)
Connective
(supports organs)
Epithelial (covers
body surfaces and
organs)
Nervous (relays
and integrates
information)
Muscle Tissue
•
•
•
Skeletal muscle is
–
attached to bones by tendons,
–
responsible for voluntary movements, and
–
striated because the contractile proteins form a banded pattern.
Cardiac muscle is
–
found only in heart tissue,
–
composed of cells that are branched and striated,
–
involuntary, and
–
responsible for the contraction of the heart.
Smooth muscle is
–
named for its lack of obvious stripes,
–
found in the walls of various organs such as intestines and blood vessels, and
–
involuntary.
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Nervous Tissue
• Nervous tissue
– makes communication of sensory information
possible,
– is found in your brain and spinal cord, and
– consists of a network of neurons.
• The basic unit of nervous tissue is the neuron, or
nerve cell.
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Figure 21.6
Brain
Signal-receiving
Cell body
extensions
Spinal cord
Nerve
LM
Signaltransmitting
extension
Organs and Organ Systems
• An organ consists of two or more tissues
packaged into one working unit that performs a
specific function.
• Examples include the heart, liver, stomach, brain,
and small intestines.
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Figure 21.7
Small intestine
(cut open)
Epithelial tissue
Connective tissue
(containing blood
and lymph vessels)
Smooth muscle
tissue (two layers)
Connective tissue
Epithelial
tissue
Organs and Organ Systems
•
Organ systems are teams of organs
–
that work together and
–
perform vital body functions. There are 11 organ systems in higher organisms
–
Skeletal
–
Circulatory
–
Respiratory
–
Muscular
–
Digestive
–
Urinary
–
Endocrine
–
Reproductive
–
Integumentary
–
Lymphatic
–
Nervous
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Figure 21.8a
Skeletal system:
supports body and
anchors muscles
It also plays a role in Ca
Metabolism and maintainace
Of pH
Bone
Cartilage
Figure 21.8b
Circulatory system:
transports substances
throughout body
Heart
Blood vessels
Figure 21.8c
Respiratory system:
exchanges O2 and CO2
between blood and air
And helps to maintain pH
Nasal cavity
Pharynx
Larynx
Trachea
Bronchus
Lung
Muscular system:
moves the body
And is the heating system of the body
Figure 21.8d
Skeletal muscles
Figure 21.8e
Digestive system:
breaks down food
and absorbs
nutrients
Mouth
Esophagus
Liver
Stomach
Large intestine
Small intestine
Anus
Figure 21.8f
Urinary system:
rids body of
certain wastes
Kidneys are
responsible
For monitoring
BP and
# of RBCs
Kidney
Ureter
Urinary
bladder
Urethra
Figure 21.8g
Endocrine system:
secretes hormones
that regulate body
Hypothalamus
Pituitary gland
Parathyroid gland
Thyroid gland
Adrenal gland
Pancreas
Testis (male)
Ovary
(female)
Figure 21.8h
Reproductive system:
produces gametes
and offspring
Responsible for
Homeostasis of the
Species!
Seminal vesicles
Prostate gland
Oviduct
Vas deferens
Ovary
Uterus
Vagina
Penis
Urethra
Testis
Figure 21.8i
Integumentary
system: protects body and is
The first line of defense from
Pathogens
It is connected to the nervous
System and is responsible for
Transmitting information about
The outside world to the brain
Nail
Hair
Skin
Figure 21.8j
Lymphatic and
immune system:
defends against
disease
Thymus
Spleen
Lymph nodes
Lymphatic
vessels
Figure 21.8k
Nervous system:
processes sensory
information
and controls
Responses (motor)
Brain
Sense organ
(ear)
Spinal cord
Nerves
EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• Every organism is an open system, continuously
exchanging chemicals and energy with its
surroundings to survive.
• An animal’s size and shape affect its exchanges
with its surrounding environment.
• All living cells must be bathed in a watery solution
so that exchange of materials can occur.
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EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• The entire surface area of a single-celled amoeba
is in contact with its watery environment.
• A hydra has a body wall only two cell layers thick.
• Both layers of cells are bathed in pond water,
enabling exchange with the environment.
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Figure 21.9
Mouth
Gastrovascular
cavity
Exchange
Exchange
Exchange
(a) Single cell
(b) Two cell layers
EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• Animals with complex body forms face the same
basic problems. Every cell must
– be bathed in fluid and
– have access to resources from the outside
environment.
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EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• Complex animals have evolved extensively folded
or branched internal surfaces that maximize
surface area for exchange with the immediate
environment.
• Lungs
– have a very large total surface area and
– exchange oxygen and carbon dioxide with the air
you breathe.
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Figure 21.10
EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• Animals use three organ systems to exchange
materials with the external environment:
1. digestive,
2. respiratory, and
3. urinary.
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EXCHANGES WITH THE EXTERNAL ENVIRONMENT
• The circulatory system
– connects to nearly every organ system,
– transports needed materials from the environment
to the body’s tissues, and
– carries waste away.
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Figure 21.11
External environment
Mouth Food CO2 O2
Animal
Respiratory
system
Digestive
system
Interstitial
fluid
Heart
Nutrients
Circulatory
system
Body cells
Urinary
system
Anus
Unabsorbed matter
(feces)
Metabolic waste products
(such as urine)
REGULATING THE INTERNAL
ENVIRONMENT
• Animals adjust to a changing environment.
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Homeostasis
• Homeostasis is the body’s ability to stay relatively
unchanged even when the world around it
changes.
• The internal environment of vertebrates includes
the interstitial fluid that
– fills the spaces between cells and
– exchanges nutrients and wastes with microscopic
blood vessels.
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Figure 21.12
Animal’s internal
environment
External
environment
HOMEOSTATIC
MECHANISMS
Large external changes
Small internal changes
Negative and Positive Feedback
• Most mechanisms of homeostasis depend on a
principle called negative feedback,
– in which the results of a process inhibit that same
process,
– such as a thermostat that turns off a heater when
room temperature rises to the set point.
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Figure 21.13
Response:
Heating
stops
Thermostat
(control center)
turns heater off
Stimulus:
Room
temperature
is above set point
Room
temperature
drops
Set point:
Room temperature
20°C (68°F)
Stimulus:
Room
temperature
is below set point
Room
temperature
rises
Response:
Heating
starts
Thermostat
(control center)
turns heater on
Negative and Positive Feedback
• Less common is positive feedback,
– in which the results of a process intensify that
same process,
– such as uterine contractions during childbirth.
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Thermoregulation
• Thermoregulation is the maintenance of internal
body temperature.
– Endotherms
– such as mammals and birds
– derive the majority of their body heat from their
metabolism.
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Thermoregulation
– Ectotherms
– such as most invertebrates, fishes, amphibians,
and nonbird reptiles
– obtain body heat primarily by absorbing it from
their surroundings.
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Thermoregulation
• Humans have homeostatic mechanisms that aid in
thermoregulation, which
– cool or
– heat the body.
• Fever
– is an abnormally high internal body temperature
and
– usually indicates an ongoing fight against infection.
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Figure 21.14
Skin
Sweat
gland
Response:
1. Blood
vessels dilate
2. Sweat is
produced
Control center
in brain activates
cooling
mechanisms
Stimulus:
Body
temperature
is above set point
Body
temperature
drops
Set point:
Body temperature
near 37°C (98.6°F)
Stimulus:
Body
temperature
is below set point
Body
temperature
rises
Skin
Response:
1. Blood vessels
constrict
2. Person shivers
3. Metabolic rate
increases
Control center
in brain activates
warming
mechanisms
Osmoregulation
• Living cells depend on a precise balance of
– water and
– solutes (dissolved substances).
• Osmoregulation is the control of the gain or loss
of
– water and
– dissolved solutes, such as the ions of NaCl and
other salts.
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Osmoregulation
• Osmoconformers
– have internal and external environments with
similar solute concentrations and
– include most marine invertebrates.
• Osmoregulators
– actively regulate their water loss or gain and
– include freshwater animals, most marine
vertebrates, and all land animals.
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Figure 21.16
Osmoconformer
Osmoregulator
Homeostasis in the Urinary System
• The human urinary system
– plays a central role in homeostasis,
– forms and excretes waste-carrying urine, and
– regulates the amount of water and solutes in body
fluids.
• In humans, the two kidneys
– are the main processing centers and
– contain many fine tubes called tubules and an
intricate network of capillaries.
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Homeostasis in the Urinary System
• As blood circulates through the kidneys,
– a fraction of it is filtered and
– plasma enters the kidney tubules, forming filtrate.
• Filtrate contains
– valuable substances that need to be reclaimed (such as
water and glucose) and
– substances to be eliminated, such as urea.
• The human urinary system includes
– the circulatory system,
– the kidneys,
– nephrons, the functional units within the kidneys, and
– the urinary bladder, where urine is stored.
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Figure 21.17
(b) Kidney
(a) Urinary system
(c) A nephron and
collecting duct
Homeostasis in the Urinary System
• Nephrons
– carry out the functions of the urinary system,
– consist of a tubule and its associated blood
vessels, and
– number more than a million in a kidney.
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Figure 21.17c
Filter
Branch of
renal artery
Tubule
Collecting
duct
Branch of
renal vein
To ureter
(c) A nephron and collecting duct
Homeostasis in the Urinary System
• Nephrons perform four key functions.
1. Filtration, forcing water and other small
molecules
from the blood to form filtrate
2. Reabsorption of water and valuable solutes back
into the blood
3. Secretion of certain substances, such as ions and
drugs, into the filtrate
4. Excretion of urine from the kidneys to the outside
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Figure 21.18
Filtration
Reabsorption
Renal artery
Secretion
Filtrate
Renal vein
Capillaries
Tubule
Excretion
Urine
Figure 21.UN04
Blood
Capillaries
Filtration
Water and small molecules
enter the tubule.
Tubule
Reabsorption
Water and valuable solutes
are returned to the blood.
Secretion
Specific substances are
removed from the blood.
Urine
Excretion
Urine exits the body.
Homeostasis in the Urinary System
• Hormonal control of the nephrons allows the body
to control its internal concentration of
– water and
– dissolved molecules.
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Homeostasis in the Urinary System
• Kidney failure can be caused by
– injury,
– illness, or
– prolonged use of pain relievers (including over-thecounter medicines such as aspirin), alcohol, or
other drugs.
• One option for treatment of kidney failure is
dialysis, filtration of blood by a machine that
mimics the action of a nephron.
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Figure 21.19
Line from artery
to apparatus
Pump
Line from
apparatus
to vein
Tubing made of a
selectively permeable
membrane
Dialyzing
solution
Fresh dialyzing
solution
Used dialyzing
solution (with urea
and excess salts)
Evolution Connection:
Adaptations for Thermoregulation
• A major anatomical adaptation in mammals and
birds is insulation, consisting of
– hair (fur),
– feathers, or
– fat layers.
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Evolution Connection:
Adaptations for Thermoregulation
• Some adaptations are physiological, such as
– changes in metabolic rate,
– shivering, or
– panting and sweating.
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Figure 21.20
METHODS OF THERMOREGULATION
Anatomical Adaptations
(such as hair, fat,
and feathers)
Physiological
Behavioral Adaptations
Adaptations
(such as bathing,
(such as panting,
basking, hibernating,
shivering, and sweating)
and migrating
Fat
Hair
Panting
Bathing