Transcript ch. 38 Introduction to Body Structure-notes-ppt

Introduction to Body Structure
Ch. 38
Biology
Ms. Haut
Levels of Structural Organization
• Cell—smallest functional unit
• Tissue—group of similar cells performing a
common function
• Organ—combination of 2 or more tissues
that work together
• Organ system—combination of 2 or more
organs working together to perform a
common function
Epithelial Tissue
• Lines most
body
surfaces—
inside and
out
• Protects
other tissues
from
dehydration
and physical
damage
Nervous Tissue
• Consists of nerve cells (neurons)
• Carries messages throughout the body
Connective Tissue
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•
•
•
•
•
Support, protect, and insulate the body
Fat
Cartilage
Bone
Tendons
blood
Muscle Tissue
• Skeletal
– Voluntary—can control contractions
– Moves bones in trunk and limbs
• Smooth
– Involuntary—can’t control contractions
– Slow, long-lasting contractions
– Line blood vessels and digestive tract
• Cardiac
– Involuntary
– Found only in the heart
Skeletal Muscle
Smooth Muscle
Cardiac Muscle
Body Cavities
• House and protect
major internal
organs
• Organs suspended
in fluid that
supports their
weight
Endothermy
• Mammals are endothermic
– Have ability to maintain a constant internal
body temperature
• Humans maintain a body temp. of 38C (99F )
– The body uses a lot of energy to maintain a
stable internal condition (homeostasis)
Skeletal System
• Functions to support the body
• Two Main Parts
– Axial skeleton
• Bones of the skull, spine, ribs, and sternum
– Appendicular skeleton
• Forms the appendages (limbs)
• Bones of the arms, legs, pelvis, and shoulder
Bone Structure
Bone Growth
• In early development the skeleton is made
mostly of cartilage
– Serves as template for bone formation
• Cartilage is gradually replaced by bone as
calcium and minerals are deposited
• New bone cells (osteocytes) are added in
layers around hollow channels (Haversian
canals) which contain blood vessels
Compact Bone
Concentric rings of bone
surround the Haversian
canals
Longitudinal Growth occurs
along the Growth Plate in Bones
Importance of Calcium:
Got Milk?
• Almost all of the body's calcium
(99%) is present in the bones and
teeth. The remaining 1% is found in
the blood and some nerve cells
• The amount of calcium in the blood must remain at
a steady level
• If your calcium intake is inadequate, the body uses
the 'stored' bone calcium to maintain the blood
calcium.
– This mobilization of bone calcium can lead to
osteoporosis, i.e., a reduction in the amount of calcium
in the bone leading to weak and thin bones.
Joints Fasten
Bones
Together
• Pads of cartilage
cushion the ends of
the bones of a joint
• Bones of a joint are
held together by
ligaments (connective
tissue)
Muscular System
• Skeletal muscles
move the body
• Muscles are
attached to bones
by tendons
• Muscles typically
work in opposing
pairs
Opposing Muscle Pairs
Muscles Move
Skeletal Parts
• Skeletal Muscle
– Each muscle fiber is a single
cell with many nuclei
– Each fiber is composed of a
bundle of myofibrils which
contain myofilaments
• Thin filaments—actin
• Thick filaments—myosin
– Striated appearance due to
sarcomeres (basic functional
unit)
Muscle Contractions:
“Sliding-Filament
Model”
• Thin and thick filaments of
the sarcomere slide past
one another to shorten the
length of the muscle
Cyclic Interaction Between Actin and
Myosin in Muscle Contraction
Sliding-Filament Model
Integumentary System
•
•
•
•
Skin, hair, and nails
Skin is the largest organ of the body
Protects the body from injury
Provides 1st line of defense against disease
Skin has 2 Distinct Layers
• Epidermis
– Outermost layer
– Made up of several layers
of epithelial cells
– Flattened, dead cells that
contain keratin (protein that
waterproofs skin)
– Damaged cells replaced by
cells below
– Inner layer contains
melanin—absorbs UV
radiation
Skin has 2 Distinct Layers
• Dermis
– Functional layer of skin
– Presence of connective
tissue makes it tough and
elastic
– Contains nerve cells, blood
vessels, and hair follicles
– Nerve cells sense
temperature and pain
– Blood vessels responsible
for regulating temperature
– Sweat glands—evaporation
of sweat from skin cools
body
Acne
• Chronic inflammatory condition that involves the
skin’s oil-producing glands
• Oil glands release sebum (oily secretion that
lubricates the skin)
– Released through ducts (exocrine glands)
• Acne results from the duct pores being clogged
with oil, dirt, and bacteria
• Surrounding tissue gets infected and inflamed, and
pores accumulate pus, producing pimples
Skin Cancer
• Results from genetic
mutations from
overexposure to UV
radiation
• Carcinoma—originates
in cells without melanin
– Can be treated early on
• Malignant melanoma—
mutation occurs in
melanin producing cells
– Grow quickly and spread
easily