Download Structure and Function in Living Systems Chapter 8: Systems in

Structure and
Function in Living
Systems
Chapter 8: Systems in Organisms
8.1: Systems help organisms meet their needs
8.2: Plants have several levels of organization
8.3 Animals have several levels of organization
8.4 Human health depends on a balance among systems
Systems help organisms
meet their needs
 Groups of people working at the restaurant are
each doing something different in order to
produce and serve the meals.
 In a complicated process like this one, it helps to have different
people doing different tasks at the same time. If everyone made
salads, for example, how do you think the process would fail?
Living things have common needs
 All organisms require:
 Energy
 Water and other materials
 Living space
 Plants use energy in sunlight, live where they can receive enough
sunlight…and survive
 Animals live where they can find protection and materials
 Organisms are found everywhere, and have structures that allow
them to use energy and materials and to find living space
 Single celled organisms have structures to grow, respond to
environment, and reproduce
 Multicellular organism have structures as well, but made of specialized
cells
Multicellular organisms have
organ systems
 As plants and animals develop, their cells specialize
(differentiate)
 Same cell type = same job
 Different cell type = different job
Levels of Organization
 Cells
 animals: skin cells, nerve cells, and muscle cells
 Tissue
 Group of many similar cells
 Work together to perform a particular function
 Skin tissue: provide protection
 Nerve tissue: carries signals
 Muscle tissue: provides movement
Levels of Organization
 Organ
 Two or more types of tissue that work together to carry out a function

Brain
 Lungs
 Heart: muscle tissue contracts at a signal from nerve tissue

Pumps blood to lungs and body
 Organ system
 Group of organs working together to perform a function

Circulatory system: heart pumps blood through blood vessels
 Blood transports nutrients to rest of body, carries back wastes
 Cells  tissues  organs  organ systems  _____________
How an Organ System Works
 Circulatory system: heart pumps blood that vessels carry
 Failure of one can cause failure of the whole
 Digestive system: breaks down food to release nutrients
 Food travels through mouth, esophagus, stomach, small intestine, and large
intestine
 Pancreas, liver, and gall bladder, release chemicals
 Smooth operation: food chewed, mixed with saliva  strong stomach muscles
mix some more, chemicals break down food  small intestine, nutrients are
absorbed, passed to blood  large intestine, water and other nutrients are
absorbed  waste material compacted and moved through…
 Failures:



Acids in stomach may back up
Large intestine causing pain, fever, nausea, vomiting
malnutrition
How an Organ System Works
Organs and systems respond to
changes in conditions
 …to help organisms meet their needs
 Examples:
 Plant Responses to Stimuli
 Animal Responses to Stimuli
 Stimulus: something that causes a response from an
organism
Plant Responses to Stimuli
 Plants grow and move in response
to:
 Ex: light, gravity, moisture,
temperature, and touch
 Leaves are the organs that hold
the chloroplasts in position to
capture sunlight
 Many plants move their leaves
during the day in response to
changes in light
 Broad flat leaves presented to
sun early and late in the day,
vertical at mid-day to prevent
over-heating damage
 leaf movements are caused by
changes in the cells of the joint
where the leaf meets the stem
Figure 1. Cross-section through a typical
leaf illustrating types of cells and also the
intracellular organelles called chloroplasts,
where photosynthesis takes place. The
cuticle is a waxy coating, layers of cells
(epidermis, palisade and spongy mesophyll)
and vascular bundles (xylem and phloem,
which are specialized cells) that transport
water and nutrient solution. The stoma
(plural: stomata) is a pore that allows the
entry of air and therefore CO2 into the leaf
(image source: Oregon State, botany)
Plant Responses to Stimuli
 Stems are the organ that supports a plant
 Plants “bend to the light”
 A hormone, or chemical messenger, called auxin is produced in the
growing tip of the stem
 Auxin flows down the dark side of the stem, collects in the cells causing
them to grow faster than the light side
Phototropism 1
Phototropism 2
Plant Responses to Stimuli
 Venus flytrap
 grows in areas where the soil lacks materials
that the plant needs
 Get important nutrients from insects
 relies on the stimulus of touch
 leaves of the Venus flytrap fold in the middle,
have long teethlike spines around the edges
 Insect lands, two sides of the leaf fold
together, form a trap
Animal Responses to Stimuli
 New environment or a change of season
 Some frogs, fish, and octopi are able to change the
color and patterns of their skin to blend in with new
surroundings
 An adaptation to hide from predators and their prey!
 Chameleons change color in response to mood,
temperature, and light (not usually to a change in
environment)
 can communicate anger or willingness to mate
 Due to several layers of specialized cells in the skin of
these organisms
Chamelon 1
more info
Animal Responses to Stimuli
 Hibernation - a sleeplike state that lasts for an extended time
period
 Body systems slow down
 the animal needs less energy to survive.
 raccoons, skunks, woodchucks, chipmunks, hamsters, hedgehogs,
bats, and bears
 Bears:





Before hibernation, eat rich foods – put on weight – curl into ball
Heartbeat slows from 40-50 bpm to 8
Metabolism (chemical reactions in their cells and organs) slows
Require less oxygen
Up to 100 days
hibernation
1.
Without a nucleus, a red blood cell cannot store DNA or direct cellular activities. Without
mitochondria, a red blood cell cannot release the chemical energy stored in sugars. Explain why
both of these consequences are acceptable for cells in a multicellular organism such as humans,
but would be fatal for a Paramecium.
2.
Explain why specialized cells, such as red blood cells, are a necessary characteristic of multicellular
organisms.
1.
Without a nucleus, a red blood cell cannot store DNA or direct cellular activities.
Without mitochondria, a red blood cell cannot release the chemical energy stored in
sugars. Explain why both of these consequences are acceptable for cells in a
multicellular organism such as humans, but would be fatal for a Paramecium.
2.
Explain why specialized cells, such as red blood cells, are a necessary characteristic of
multicellular organisms.
1.
Multicellular organisms continually make new red blood cells
to replace old red blood cells as they die. A Paramecium,
however, is a single-celled organism that would not be able to
survive and reproduce without a nucleus or mitochondria.
2.
Because multicellular organisms are large, many of their cells
are far away from one another or from the outside of the
organism where oxygen can be obtained and wastes such as
carbon dioxide can be released. Therefore, multicellular
organisms must have specialized cells to efficiently perform
the tasks necessary for survival and reproduction.