Transcript Animal Structure and Function

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I. How can you describe animal characteristics?
A. Symmetry describes the general shape of an organism.
Animals exhibit one of three types of symmetry:
1. Asymmetry describes animals which cannot be
divided equally using any plane of symmetry.
For example, a sponge is asymmetrical.
2. Radial symmetry describes animals which can be
divided equally along several planes, through a central
axis. For example, a sea anemone has radial symmetry.
3. Bilateral symmetry describes animals which can
be divided equally into mirror images along only one
plane. For example, humans have bilateral symmetry.
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B. Regional terms allow scientists to specify the area of the body of an animal.
There are four basic regional terms:
1. Dorsal describes the backside of an animal. For example, the shark fin
visible from a boat is the dorsal fin.
2. Ventral describes the underside of an animal. For example, a snake
slithers on its ventral surface.
3. Anterior describes the front half of an animal, usually nearest the head.
For example, the eyes of a frog are in the anterior region.
4. Posterior describes the back half of an animal, usually nearest the tail.
For example, the udders of a cow are in the posterior region.
Dorsal
Anterior
Posterior
Ventral
C. Segmentation describes animals with groups of segments (parts) modified for
different functions. Segmentation allows a high degree of specialization, and is a
typical characteristic of insects.
III. How do different animals achieve the same life functions?
A. Energy/Food-Getting – Animals use specialized structures to
capture and ingest food.
1. Annelids (segmented worms) such as the earthworm seem
to eat their way through the soil because they suck in organic and
other material by expanding their strong pharynx
2. Insects have mouthparts adapted to handle different diets.
Mandibles are used as jaws to chew, cut, and tear food.
3. Amphibians (such as frogs) have different feeding
structures over the course of one life. Tadpoles are usually filter
feeders or herbivores. However, frogs have long, sticky tongues
to capture insects.
4. Mammals have teeth adapted to specific diets. For
example, herbivores have flat teeth for grinding, while carnivores
have sharp teeth for tearing.
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B. Energy/Nutrition - Animals need to
capture energy from other organisms because
they are heterotrophs. This requires getting food
and digesting food (nutrition). Some organisms
have a complete digestive system (a tube that
runs from mouth to anus) with functional
specialization – different parts of the system may
be adapted for various functions. Some have an
incomplete digestive system (mouth only)
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1. Annelids use a simple digestive tract that includes an
esophagus, crop (which stores food), a gizzard (which grinds
food), and an intestine (for absorption). The material that passes
through an earthworm is deposited outside the opening of its
burrow. In this way, earthworms aerate and enrich the soil.
2. Insects have a very similar digestive system to that of annelids.
3. Amphibians have a more complex digestive system. Food
enters at the mouth, moves to the esophagus, then to the stomach
containing digestive enzymes. The small intestine continues
digestion and absorption of nutrients begins, the large intestine
allows for the absorption of water. Wastes pass to the cloaca
for elimination. Accessory organs such as the liver and pancreas
secrete digestive chemicals (such as enzymes) which aid in
digestion.
4. Mammals have a very similar digestive system to that of
amphibians. However, the cloaca is absent. Wastes are stored in
the rectum until eliminated through the anus.
C.
Energy /Transport - Animals need to deliver the digested food
to the cells and move wastes from cells to organs of excretion.
1.Annelids have a closed circulatory system meaning that
blood moves through vessels. Blood is pumped throughout the
body in one direction using muscular vessels, called aortic
arches. The blood carries dissolved gases and nutrients to the
cells and picks up waste products from the cells by diffusion.
2. Insects have an open circulatory system meaning blood
(usually called hemolymph in insects) flows freely within body
cavities where it makes direct contact with all internal tissues
and organs. The “heart” is a muscular tube with holes that
depends on movement to pump out hemolymph.
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3. Fish have a closed circulatory system with two chambered heart
and single loop circulation
3. Amphibians and most reptiles , like annelids, have a closed
circulatory system. However, they have a double loop system.
The blood is pumped through a pulmonary circuit to the
lungs/skin where it is oxygenated. The blood returns to the heart,
which pumps the oxygenated blood, through a systemic circuit to
the body. The heart is three chambered with two atria (which
receive blood) and one muscular ventricle (that pumps the blood).
Because the two atria empty into one ventricle, some mixing of
oxygenated and deoxygenated blood occurs.
4. Mammals have a closed circulatory system and a four
chambered heart which is fully divided into two halves. Blood
circulates through two loops/circuits. Oxygenated blood from the
lungs is kept separated from the deoxygenated blood
from the rest of the body.
D. Energy / Respiration - Animals need to use the digested,
delivered food for cellular respiration in order to produce ATP
for cellular energy. Aerobic organisms must get oxygen from
the environment and release carbon dioxide back to the
environment due to cellular respiration.
1. Annelids obtain oxygen from their environment by
diffusion through their moist skin and into the blood stream.
They eliminate carbon dioxide in the same way.
2. Insects have no single major respiratory organ. A system of
tracheal tubes exchange respiratory gases directly with
individual cells using either diffusion or changes in internal
pressure produced by body movement. Openings on the
surface of the body called spiracles (which can be opened or
closed by valves to prevent water loss) lead to the tubular
tracheal system.
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3. Amphibians
in their larval form (tadpoles) obtain
oxygen from the water by diffusion
through their
skin and gills, directly into the blood stream. Adult
amphibians may also obtain oxygen by diffusion through
their skin and the lining of their mouths.
However,
adult amphibians also have lungs which help with gas
exchange in a terrestrial environment. The lungs may
also have small sacs called alveoli, which are wrapped
in small blood vessels. This allows for diffusion of
gases between the lungs and the blood stream.
4. Mammals rely on well developed lungs composed of
numerous alveoli for the exchange of gases.
F. Excretion – Processes such as synthesis and digestion produce waste products that
may be toxic to the animal’s body. Unless removed, waste products disrupt
homeostasis. Excretory structures help animals to balance chemicals (such as
pH, glucose concentration and water).
1. Annelids have two excretory structures, called nephridia, per segment. The
nephridia gather wastes from the body cavity and surrounding blood vessels.
The waste is excreted through a pore in the following segment.
2. Insects eliminate wastes by collecting circulatory fluid in long spaghetti-like
tubules called Malpighian tubules, which extend throughout most of the
abdominal cavity. The tubules remove nitrogenous wastes from the hemolymph
and convert it to uric acid. The ability to conserve water by excreting solid uric
acid has enabled insects to colonize very arid environments.
3. Amphibians use organs called kidneys that are composed of nephrons to
filter wastes from blood. This waste, called urine, passes to tubes called ureters,
which lead to the cloaca. Urine may be stored in a urinary bladder or passed
immediately.
4. Mammals also rely on two kidneys composed of nephrons to filter wastes
from the blood. From each kidney there is a ureter tube which leads to the
urinary bladder. The urine is then expelled from the body through the urethra.
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I.
Regulation – Animals must control necessary body
processes (such as metabolism) using the nervous system
and endocrine system (which produces hormones).
Hormones are chemical messengers that can control target
cells or tissue.
1. Annelids have an anterior “brain” with ganglia
extending to each body segment. A ganglion is a cluster
of interconnected neurons (nerve cells) that process
information and control movement. The nerves are used
to coordinate muscle contractions for movement.
Earthworms have numerous light-, chemo-, and touchsensitive cells near the end of the body. Hormones are
involved in growth, regeneration, and reproduction.
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2. An
insect’s nervous system is composed of neurons within the
body. These cells are grouped in bundles called ganglia and
nerves. Insects have a relatively simple central nervous system with
a “brain” linked to nerve cord that consists of paired ganglia.
Insects use special cells in the body to produce hormones which
regulate processes such as molting and metamorphosis.
3, Amphibians have a more complex central nervous system. Areas
of the brain are specialized to regulate certain processes, such as
the olfactory bulb (smell), optic lobes (vision), cerebrum (voluntary
activity), cerebellum (coordinates body movement), and medulla
oblongata (regulate organ function). Like insects, amphibians have
developed sense organs . Like all vertebrates, amphibians have an
endocrine system that works with the nervous system to maintain
internal conditions, react to stimuli, and regulate growth and
development.
4. Mammals have the most highly developed nervous
system. The system is divided into a central nervous system
(composed of the brain and spinal cord) and the peripheral
nervous system (composed of nerves and sensory
receptors). In addition to specialized areas of the brain, the
brain is larger and can coordinate and store more
information. The increase in complexity leads to more
advanced sensory ability, communication, and learning.
Like amphibians, mammals depend on an endocrine system
to work with the nervous system and release hormones for
regulation.
IV.
How does the form of structures affect their function?
A. Microvilli in the Small Intestine
1. The purpose of the small intestine is to absorb
nutrients. The food has been chewed in the mouth,
broken down by enzymes in the mouth and stomach,
processed by peristalsis (movement through the
esophagus) and churned in the stomach. The small
intestine must now absorb the products of digestion into
the blood stream for delivery to cells.
2. Microvilli in the small intestine are finger-like
projections that increase surface area. Increasing surface
area allows more physical space for absorption of the
nutrients, increasing the efficiency of digestion.
3. Diagram of Microvilli
B. Chambers of the Vertebrate Heart
1.The purpose of the heart is to pump blood to and
from the lungs and then throughout the body. Blood acts
as the vehicle for many things in our body (such
as nutrients, wastes, and hormones) and the circulatory
system is the “highway” for this vehicle. One of the
major functions of blood is to deliver oxygen to the
cells and to remove carbon dioxide from the cells. In a
vertebrate’s body, there is blood which contains oxygen
(oxygenated blood) which must be delivered to the
cells and blood which does not (deoxygenated blood)
which is sent to the lungs.
2. A heart contains chambers which separates the deoxygenated
blood from the oxygenated blood. By separating the blood, the
heart can more efficiently deliver the correct blood to the correct
location.
a. Fish have a simple two-chambered heart.
b. Amphibians and most reptiles have a three-chambered heart.
c. Crocodiles, aves, and mammals have a four-chambered heart.
3. The heart is composed of muscle to provide strength as it pumps
the blood through the circulatory system. The chamber which must
send the blood to the entire body (left ventricle) has a much thicker
layer of muscle. This allows that chamber to better perform its
function.
4. Diagram of a four-chambered heart
C. Alveoli in the lungs
1. The purpose of the lungs is gas exchange.
Oxygen is taken in and carbon dioxide is released.
The oxygen is needed for cell respiration (which
makes ATP to use for cell energy) and the carbon
dioxide is a waste product produced during cell
respiration. The oxygen has to enter the blood
supply, and the carbon dioxide has to be removed
from blood.
2. The diffusion of gas happens best across a thin, moist membrane.
Air enters the body through the nose and mouth, moves through the
trachea into the lungs via the bronchi and then into smaller tubes
called bronchioles. At the end of each bronchiole, a structure called
the alveoli provides a very thin (one cell thick) and moist membrane
surrounded by capillaries (some with deoxygenated blood and some
with oxygenated).
3. Diagram of alveoli
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D. Kidney Structure
1. The purpose of kidneys is to remove wastes from blood,
maintain blood pH, and
regulate water content of blood. Kidneys form urine
(result of filtration) which can be passed from the body.
2.Kidneys are composed of many smaller units called
nephrons. As the fluid part of blood (containing waste) is
pushed into a nephron (called the “filitrate”), the nephron
removes urea, excess water, and other waste products.
The clean, filtered blood leaves the kidney through the
renal vein and returns to circulation.
3. The nephron is composed of a looping tube that provide
a great deal of surface area for diffusion and active
transport of molecules into and out of the filtrate as urine
is formed.
E. Neuron Structure
1. The purpose of the nervous system is to sense, process,
and respond to stimuli. The
basic structure which
allows the nervous system to perform its function is the
neuron (nerve cell). In less complex animals, the
nervous system may consist of a nerve net or small
clusters of nerves called ganglion. More complex animals
have a central processing center (a brain) in addition to
the neurons.
2. A neuron uses chemicals (called neurotransmitters) or
electricity to send a message to the next neuron in the
chain. The shape of a neuron allows it to quickly receive
a message through branched dendrites which “charges”
the axon to release a message through the axons for the
next neuron.
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3. Sensory receptor neurons are usually associated with
structures specialized for receiving a specific type of
stimuli (ex. tastebuds). Interneurons transmit this
“message” to a processing center (such as the brain). A
motor neuron activates a muscle cell to respond to the
stimuli.
4. Diagram of a Neuron
Axon
Axon terminals
Dendrites
Endocrine control
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Hormones – chemicals that are produced by
the endocrine gland and released directly
into the bloodstream.
Some Endocrine Glands:
Pituitary
Thyroid
Adrenals
Pancreas
Testes
Ovaries