Transcript Unit 1 – Chemical Basis of Life

Unit 4 – Animal Systems
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This unit will focus on human systems
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In unicellular (single-celled) organisms, the single cell
performs all life functions - it functions independently.
However, multicellular (many celled) organisms have
various levels of organization within them. Individual cells
may perform specific functions and also work together for
the good of the entire organism. The cells become
dependent on one another.
Multicellular organisms have the following 5 levels of
organization ranging from simplest to most complex:
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levels of organization:
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cells → tissues → organs → organ systems → organism
Level 1 - Cells
 Are
the basic unit of structure and
function in living things.
 May serve a specific function within
the organism
 Examples- blood cells, nerve cells,
bone cells, etc.
Level 2 - Tissues
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Made up of cells that are similar in structure and
function and which work together to perform a
specific activity
Examples - blood, nervous, bone, etc.
Humans have 4 basic tissues: connective,
epithelial, muscle, and nerve.
Level 3 - Organs
 Made
up of tissues that work together
to perform a specific activity
 Examples - heart, brain, skin, etc.
Level 4 – Organ Systems
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Groups of two or more tissues that work
together to perform a specific function for the
organism.
Examples - circulatory system, nervous system,
skeletal system, etc.
The Human body has 11 organ systems circulatory, digestive, endocrine, excretory
(urinary), immune (lymphatic), integumentary,
muscular, nervous, reproductive, respiratory, and
skeletal.
Level 5 - Organism
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Entire living things that can carry out all basic
life processes. Meaning they can take in
materials, release energy from food, release
wastes, grow, respond to the environment, and
reproduce.
Usually made up of organ systems, but an
organism may be made up of only one cell such
as bacteria or protist.
Examples - bacteria, amoeba, mushroom,
sunflower, human
Chapter 28, questions 1-2, p856
How does the process of cell determination differ
from the process of cell differentiation?
1.
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2.
In cell determination, stem cells commit to becoming a certain type
of cell, such as a muscle cell. In cell differentiation, cells develop
the actual structures and functions that make them specialized cells.
Briefly define and give an example of each of the five
levels of organization in multicellular organisms.
- A cell is the smallest unit of life (example: neuron). A tissue
is a group of similar cells that work together to perform a
specialized function (example: nerve tissue). Organs
consist of two or more types of tissues that function
together (example: brain). Organ systems consist of two
or more organs working together (example: nervous
system).
3.
What organ systems must work together to bring
oxygen to the body’s cells?
- The respiratory system brings oxygen into the body. Part of
the muscular system coordinates the movement of the
lungs. The circulatory system picks up oxygen from the
lungs and delivers it to body cells.
4.
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A cell has undergone determination to become an
endocrine gland cell. If it is transplanted to a leg
muscle, what do you think would happen to this cell?
Because determination is usually not reversible, the
cell and its daughter cells will continue to develop as
endocrine cells.
Question 5, p856
In the spring, tadpoles lose their tails as part of
their life cycle. At a certain stage in
development, the human fetus acquires
individual fingers and toes. What occurs in
some cells of both species to explain these
changes?
5.
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Both are examples of programmed cell death, or
apoptosis
Questions 1-2, p861
1.
2.
A system to maintain homeostasis must have at least four
parts that function together. Name these parts and briefly
explain what each one does.
Sensors gather information. A control center analyzes and
compares the information to the desired value.
Communication systems send messages from the control
center to regulate the change. Targets receive and respond
to the message.
What is the main difference between the way negative
feedback and positive feedback mechanisms regulate change
in the body.
- Negative feedback loops counteract change to return to a set
point, while positive feedback loops accelerate change away
from a set point.
3.
When a newborn baby nurses, the mother’s body is
stimulated to produce milk. What would happen to
the milk supply if the mother chose to bottle feed
rather than breast feed?
- A baby nursing creates a positive feedback loop that causes
the mother’s body to lactate. Bottle feeding eliminates the
stimulus.
4.
Suppose you go on a long hike in hot weather.
Describe a possible negative feedback loop that
would keep your body from overheating.
- Sensors would detect a rise in body temperature, increasing
blood flow to the skin, activating sweat glands, and
increasing heart and breathing rates.
5.
Reptiles regulate their body temperature by
changing their environment. A snake, for
instance, must lie in the sunlight to warm its
body. Mammals, on the other hand, can
regulate their internal environment to gain or
lose heat. How might this ability give
mammals an advantage over reptiles?
- Mammals can live in a wider range of habitats and
tolerate rapid changes in external conditions.
Questions 1-2, p865
Why do organ systems in the body need to work so
closely together?
1.
- All body systems contribute to maintenance of homeostasis.
What happens in one system may require response from
another.
Explain why a long-term disruption of homeostasis
can often be more damaging to the body than a short
term disruption is.
2.
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Long-term disruption can produce a type of chain
reaction in which more and more organ systems are
affected over time. The result can be permanent damage
to organs and possibly death.
3.
4.
Why would giving synthetic insulin to people with Type 1
diabetes restore their glucose homeostasis?
- In Type 1 diabetes, no insulin is made. When synthetic insulin
is given to people with Type 1 diabetes, glucose can enter
cells, so blood sugar levels return to normal.
If you lived in Alaska for the whole year, what changes might
occur in your calcium and phosphorus levels during the winter
versus the summer?
During the winter months, because there is little sunlight, and
your skin is fully covered with clothing, you would be
exposed to very little UV light. As a result, you would
produce less vitamin D, and calcium and phosphorus levels
in your body would decrease. In summer, your skin would
be exposed to sunlight far more often. The increase in
vitamin D production would result in an increase in calcium
and phosphorus levels.
Question 5, p865
5.
Some animals can store more glucose – in the
form of glycogen – in their bodies than can
other animals. What might be the evolutionary
advantage of having these extra energy stores?
- Answer may include the development of more
efficient cellular metabolism, the ability to survive
on a irregular food supply, or the ability to mobilize
extra glucose rapidly to provide energy in fight-orflight situations.