Human Body Systems - Fall River Public Schools

Human Body Systems
Body Organization and Homeostasis
Objectives
• Describe how the human body is organized
• Explain homeostasis
Organization of the Body
• Every cell in the human
body is both an
independent unit and
an interdependent part
of a larger community
(the entire organism)
– In other words, each cell
is its own living thing,
but each cell works with
other cells in order to
maintain a larger, more
complex organism
Organization of the Body
• The levels of organization
in a multicellular organism
include:
–
–
–
–
Cells
Tissues
Organs
Organ systems
Cells
• A cell is the basic unit of
structure and function
in living things
• Specialized cells
perform a particular
function
Tissues
• A tissue is a group of cells that perform a single
function
• There are 4 basic types:
– Epithelial tissue includes glands and tissues that cover
interior and exterior body surfaces
– Connective tissue provides support for the body and
connects its parts
– Nervous tissue transmits nerve impulses throughout
the body
– Muscle tissue works with bones to enable the body to
move
Tissues
Organs
• An organ is a group of
tissues that work
together to perform a
single function
• For example, in the eye,
epithelial tissue,
nervous tissue, muscle
tissue, and connective
tissue all work together
for a single function sight
Organ Systems
• An organ system is a
group of organs that
perform closely related
functions
• Example: the brain is an
organ in the nervous
system
Nervous System
• Brain, spinal cord,
peripheral nerves
• Recognizes and
coordinates the body’s
response to changes in
its internal and external
environments
Integumentary System
• Skin, hair, nails, sweat
and oil glands
• Serves as a barrier
against infection and
injury
• Helps to regulate body
temperature
• Provides protection
against the sun’s UV
rays
Skeletal System
• Bones, cartilage,
ligaments, tendons
• Supports the body
• Protects internal organs
• Allows movement
• Stores mineral reserves
• Provides a site for blood
cell formation
Muscular System
• Skeletal muscle, smooth
muscle, cardiac muscle
• Works with skeletal
system to produce
voluntary movement
• Helps to circulate blood
and move food through
the digestive system
Circulatory System
• Heart, blood vessels, blood
• Brings oxygen, nutrients, and
hormones to cells
• Fights infection
• Removes cell wastes
• Helps to regulate body
temperature
Respiratory System
• Nose, pharynx, larynx,
trachea, bronchi,
bronchioles, lungs
• Provides oxygen needed for
cellular respiration and
removes excess carbon
dioxide from the body
Digestive System
• Mouth, pharynx,
esophagus, stomach,
small and large
intestines, rectum
• Converts foods into
simpler molecules that
can be used by cells of
the body
• Absorbs food
• Eliminates wastes
Excretory System
• Skin, lungs, kidneys,
ureters, urinary bladder,
urethra
• Eliminates waste products
from the body in ways that
maintain homeostasis
Endocrine System
• Hypothalamus, pituitary,
thyroid, parathyroids,
adrenals, pancreas, ovaries
(in females), testes (in
males)
• Controls growth,
development, and
metabolism
• Maintains homeostasis
Reproductive System
• Testes, epididymis, vans
deferens, urethra, and
penis (males)
• Ovaries, Fallopian tubes,
uterus, and vagina
(females)
• Produces reproductive
cells
• In females, nurtures and
protects developing
embryo
Lymphatic/Immune System
• White blood cells, thymus,
spleen, lymph nodes, lymph
vessels
• Helps protect the body from
disease
• Collects fluid lost from blood
vessels and returns the fluid
to the circulatory system
Homeostasis
• Homeostasis means “keeping things in balance”
• Homeostasis is the process by which organisms keep
internal conditions relatively constant despite changes
in external environments
• Feedback inhibition is the process in which a stimulus
produces a response that opposes the original stimulus
• To maintain homeostasis, all of the organ systems must
be integrated at all times
– For example, if the nerves sense that the temperature
drops, the brain sends signals to the body to increase cell
activity, which produces heat to increase the body’s
temperature
Review Questions
• What are the levels of organization in the
human body from smallest to largest?
– Cells, tissues, organs, and organ systems
• What is homeostasis?
– Homeostasis is the process by which organisms
keep internal conditions relatively constant
despite changes in external environments