Download Chapters 20-21

THE HIERARCHY OF
STRUCTURAL ORGANIZATION
IN AN ANIMAL
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 Anatomy—structure
 Physiology—function
 Animals consist of a hierarchy of levels or
organization
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A Cellular level
Muscle cell
A Cellular level
Muscle cell
B Tissue level
Muscle tissue
A Cellular level
Muscle cell
B Tissue level
Muscle tissue
C Organ level
Heart
A Cellular level
Muscle cell
B Tissue level
Muscle tissue
C Organ level
Heart
D Organ system level
Circulatory system
A Cellular level
Muscle cell
B Tissue level
Muscle tissue
C Organ level
Heart
D Organ system level
Circulatory system
E Organism level
Many organ systems
functioning together
Tissue
 Animals have four main categories of tissues
Muscle (20.6)
Nervous (20.7)
Structure
Connective (20.5)
Sheets of closely
packed cells
Sparse cells in
extracellular
matrix
Long cells (fibers)
with contractile
proteins
Neurons with
branching
extensions
Function
Epithelial (20.4)
Protection,
exchange,
secretion
Binding and
support of
other tissues
Movement of
body parts
Transmission of
nerve signals
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
Epithelial cells come in three shapes:
1. Squamous—like a fried egg
2. Cuboidal—as tall as they are wide
3. Columnar—taller than they are wide
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Apical surface of
epithelium
Basal
lamina
Cell
Underlying
nuclei
tissue
A Simple squamous epithelium
(air sacs of the lung)
D Pseudostratified
ciliated columnar
epithelium
(respiratory tract)
B Simple cuboidal epithelium
(kidney)
C Simple columnar epithelium
(intestine)
E Stratified squamous
epithelium
(esophagus)

Connective tissue can be grouped into six
major types
Fat
droplets
Cartilageforming
cells
C Adipose
tissue
Matrix
Cell
nucleus
Collagen
fibers
Cell
B Fibrous connective
White
tissue (forming
blood
a tendon)
cells
Collagen
fiber
Red
Elastic
blood
fibers
A Loose connective cell
tissue (under
the skin)
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D Cartilage
(at the end of a bone)
Central
canal
Matrix
Plasma
F Blood
E Bone
Boneforming
cells

Skeletal muscle causes voluntary movements

Cardiac muscle pumps blood

Smooth muscle moves walls of internal organs, such as the
intestines
Unit of
muscle
contraction
Muscle
fiber
Nucleus
Muscle
fiber
Nucleus
Junction between
two cells
Muscle fiber
Nucleus
B Cardiac muscle
A Skeletal muscle
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C Smooth muscle

Neurons carry signals by conducting electrical
impulses
Cell body
Nucleus
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
Each tissue
performs
specific
functions,
together
which make
up an organ
Small intestine
Lumen
Epithelial tissue
(columnar epithelium)
Connective tissue
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Smooth muscle
tissue (2 layers)
Connective tissue
Epithelial tissue
Lumen


An organ system usually consists of many
organs
Each organ system has one or more functions
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A Endocrine
Hypothalamus system
Pituitary gland
Thyroid gland
Parathyroid
gland
Ovary (female)
B Skeletal
system
Bone
Adrenal
gland
Pancreas
Testis
(male)
Cartilage
C Circulatory
system
Heart
Blood
vessels
D Respiratory system
Nasal cavity
Larynx
Trachea
Bronchus
Lung
E Muscular
system
Skeletal
muscles
F Integumentary
system
Hair
Nails
Skin
G, H Lymphatic and immune systems
Thymus
Bone
marrow
Spleen
Lymph nodes
Lymphatic
vessels
K Reproductive
system
Female
Oviduct
Ovary
Uterus
Vagina
Male
Seminal vesicles
Prostate gland
Vas deferens
Penis
Urethra
Testis
Brain
Sense organ
Spinal
cord
L Nervous
system
Nerves
I Urinary
system
Mouth
Kidney
Ureter
Urinary
bladder
Urethra
J Digestive
system
Esophagus
Liver
Stomach
Small
intestine
Large
intestine
Anus
External environment
CO2 O
Food
2
Mouth
Animal
Respiratory
system
Digestive
system
Interstitial
fluid
Heart
Nutrients
Circulatory
system
Body
cells
Urinary
system
Intestine
Anus
Unabsorbed
matter (feces)
Metabolic waste
products (urine)
◦ Humpback whales strain krill from seawater
using large plates, called baleen
– Whales take a large gulp of water into their throat
– As they force water out, it is strained through
baleen plates that hang from the upper jaw
◦ Humpback whales create a net of bubbles to
concentrate the krill
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OBTAINING
AND PROCESSING
FOOD
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
Most animals have one of three kinds of diets
– Herbivores, plant-eaters—cattle, snails, sea urchins
– Carnivores, meat-eaters—lions, hawks, spiders
– Omnivores, eating both plants and other animals—
humans, roaches, raccoons, crows
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
Food is processed in four stages
–
–
–
–
Ingestion
Digestion
Absorption
Elimination
Small
molecules
Pieces
of food
Mechanical
digestion
Chemical digestion
(hydrolysis)
Nutrient
molecules
enter body
cells
Undigested
material
Food
1 Ingestion
2 Digestion
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3 Absorption
4 Elimination

Mechanical digestion breaks food down into
smaller pieces
– Smaller pieces are easier to swallow
– Smaller pieces have more surface area exposed to
digestive fluids
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◦ Chemical
digestion breaks
down large
organic molecules
into their
components
Macromolecule
Components
Proteindigesting
enzymes
Protein
Amino acids
Polysaccharide Carbohydratedigesting
enzymes
Disaccharide
Monosaccharides
Nucleic aciddigesting
enzymes
Nucleic acid
Nucleotides
Fat-digesting
enzymes
Fat
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Glycerol Fatty acids
Mouth
Pharynx
Esophagus
◦ Most animals have
an alimentary canal
with
– Mouth
Crop
Gizzard
Anus
Intestine
Dorsal fold
Earthworm
Interior of intestine
Wall of intestine
– Anus
Esophagus
– Specialized
regions
Midgut
Anus
Mouth
Crop
Gastric pouches
Grasshopper
Stomach
Mouth
Gizzard
Intestine
Esophagus
Crop
Anus
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Bird
Hindgut
HUMAN DIGESTIVE SYSTEM
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Oral
cavity
Tongue
Mouth
Pharynx
Salivary
glands
Esophagus
Liver
Esophagus
Sphincter
Stomach
Sphincter
Gallbladder
Pancreas
Small
intestine
Large
intestine
Rectum
Anus
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Small
intestine
What happens in the oral cavity, or
mouth?
Digestion begins in the oral cavity
 Teeth break up food, saliva moistens it
– Salivary enzymes begin the hydrolysis of starch
– Buffers neutralize acids
– Antibacterial agents kills some bacteria ingested
with food
 The tongue tastes, shapes the bolus of food,
and moves it toward the pharynx
 The esophagus conducts food from the
pharynx to the stomach
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Bolus of
food
Tongue
Pharynx
Epiglottis
up
Larynx
up
Larynx
Trachea
Epiglottis
down
Epiglottis
up
Larynx
down
Esophageal
sphincter
Esophagus
Sphincter contracted
Esophagus
Sphincter relaxed
Sphincter contracted

Food is moved
in waves by
smooth musclea process called
peristalsis
Esophageal sphincter
(contracted)
Bolus of
food
Bolus of
food
Muscles contract,
constricting passageway
and pushing bolus down
Muscles relax,
allowing passageway
to open
Stomach
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What do sphincters do?
◦ The lower esophageal sphincter
 Limits the upward movement of acids into the
esophagus
◦ The pyloric sphincter
– Regulates the passage of food from the
stomach to the small intestine
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What does the stomach do?

Acid
– pH 2
– Parietal cells secrete hydrogen and chloride ions,
which combine to make ________

Pepsinogen and HCl produce pepsin
– Pepsin production activates more pepsinogen
production—positive feedback
– Pepsin begins the chemical digestion of ________
– Acidic gastric juices mix with food to produce acid
chyme
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What prevents the gastric juices from digesting the
walls of the stomach?
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
Bacterial infections (Helicobacter pylori) in the stomach and
duodenum can produce ulcers
Bacteria
Mucous
layer of
stomach
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What does the small intestine do?

Small intestine is named for its smaller
diameter—it is about 6 meters long
Liver
Bile
Gallbladder
Stomach
Acid chyme
Intestinal
enzymes
Duodenum of
small intestine
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Pancreatic juice
Pancreas
The small intestine is the major organ of
chemical digestion and nutrient absorption



Small intestine is named for its smaller
diameter—it is about 6 meters long
Alkaline pancreatic juice neutralizes acid chyme
and its enzymes digest food
Bile, made in the liver and stored in the gall
bladder, emulsifies fat for attack by pancreatic
enzymes
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◦ Surface area for absorption is increased by
– Folds of the intestinal lining
– Fingerlike villi
Vein
with blood
en route to
the liver
Lumen of intestine
Nutrient
absorption
Epithelial
cells
Muscle
layers
Amino
Fatty
acids
acids
and
and
sugars glycerol
Lumen
Fats
Blood
capillaries
Large
circular folds
Lymph
vessel
Villi
Blood
Lymph
Nutrient
absorption
Villi
Intestinal wall
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Lumen of intestine
Nutrient absorption
into epithelial cells
Microvilli
Epithelial cells
lining villus
◦ Nutrients pass across the epithelium and into blood
◦ Blood flows to the liver where nutrients are processed
and stored
Lumen of intestine
Nutrient
absorption
Epithelial
cells
Lumen of intestine
Nutrient absorption
into epithelial cells
Microvilli
Amino
acids
and
sugars
Fatty
acids
and
glycerol
Fats
Blood
capillaries
Lymph
vessel
Blood
Lymph
Villi
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Epithelial cells
lining villus
What does the liver do?

The liver performs many functions
– Glucose is converted to glycogen and stored
– Liver synthesizes many proteins including blood
– Clotting proteins and lipoproteins that transport
fats and cholesterol
– Liver changes toxins to less toxic forms
– Liver produces bile
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Hepatitis
Transmission
Causative agent
Chronic liver
disease
Vaccine
Hepatitis A
Fecal-oral
Picornaviridae
No
Inactivated virus
Hepatitis B
Parenteral, STD
Hepadnaviridae
Yes
Recombinant
Hepatitis C
Parenteral
Filoviridae
Yes
No
Hepatitis D
Parenteral, HBV
coinfection
Deltaviridae
Yes
HBV vaccine
Hepatitis E
Fecal-oral
Caliciviridae
No
No
Large intestine??




Diarrhea occurs when too little water is
reclaimed
Constipation occurs when too much water is
reclaimed
Colon bacteria produce vitamins—biotin, vitamin
K, B vitamins
Feces are stored in the rectum and then
eliminated
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Large
intestine
(colon)
Small
intestine
Sphincter
End
of small
intestine
Appendix
Cecum
Rectum
Anus
Unabsorbed
food material


The length of the
digestive tract often
correlates with diet
Why would a
digestive tract be
longer for a
herbivore or
omnivore than a
carnivore?
Stomach
Small intestine
Cecum
Colon
(large
intestine)
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Carnivore
Herbivore
Intestine
Omasum Rumen
Esophagus
Stomach
Small intestine
Cecum
Rumen
Colon
(large
intestine)
Carnivore
Herbivore
Abomasum
Reticulum
Oral
cavity
Tongue
Mouth
Pharynx
Salivary
glands
Esophagus
Liver
Esophagus
Sphincter
Stomach
Sphincter
Gallbladder
Pancreas
Small
intestine
Large
intestine
Rectum
Anus
Small
intestine