Transcript Life Functions - duncanbiology

Life Functions
1
Objectives
• Analyze the processes by which organisms
representative of the following groups
accomplish essential life functions
including:
– Unicellular protists, annelid worms, insects,
amphibians, mammals, nonvascular plants,
seed plants
– Transport, excretion, respiration, regulation,
nutrition, synthesis, reproduction, and growth
and development.
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• Transport :
Life Functions
how organisms deliver what they need to cells and
move wastes from cells to organs of excretion.
• Excretion:
how organisms get rid of their waste and balance
their fluids (pH, salt concentration, water).
• Respiration:
How organisms get oxygen from the environments
and release carbon dioxide back to the environment and how plants
exchange gases.
• Regulation: how organisms control body processes—hormones,
nervous system.
• Nutrition: how organism break down and absorb foods.
• Reproduction: sexual versus asexual, eggs, seeds, spores,
placental, types of fertilization.
• Growth and Development:
metamorphosis, development
in egg or in uterus, growth from seed or spore.
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Life Functions
Protists
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Life Functions of Protists
• The methods of transport, excretion, and
gas exchange used by protists are generally
the same at those used by cells in general:
–
–
–
–
Diffusion/osmosis
Active transport
Facilitated diffusion
Vesicular transport (endocytosis, exocytosis)
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Life Functions of Protists
• Nutrition
– Animal-like protists:
• Flagellates and Ciliates
– Ingest food via endocytosis
– Digestion is intracellular (within the cell)
– Undigested materials are eliminated by exocytosis
• Nonmotile (Sporozoans) are parasites that feed off
the cells and fluids of their hosts.
– Plant-like protists are photosynthetic
autotrophs and make their own food.
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Life Functions of Protists
• Reproduction
– Most protists reproduce asexually by cell
division (fission).
– Some may produce sexually.
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Life Functions
Animals
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Life Functions: Animals
• Transport
– Complex animals have tissues that are several
cell layers thick.
• Making exchange of materials directly with the
environment impossible.
• Oxygen and nutrients must be transported to these
body cells by a circulatory system.
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Life Functions: Animals
There are two types of circulatory systems.
• Open circulatory system
– In an open circulatory system, a heart pumps
fluids containing oxygen and nutrients through
a series of vessels out into the body cavity.
– The fluid washes across the body’s tissues,
supplying them with oxygen and nutrients.
– The fluid collects in open spaces in the
animal’s body and flows back to the heart.
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Life Functions: Animals
Open Circulatory System
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Life Functions: Animals
• Closed circulatory system
– In a closed circulatory system, a heart pumps
blood through a system of blood vessels.
– The blood vessels provide a network that
allows blood flow from the heart to all of the
body’s cells and back again.
– The blood remains in the vessels and does not
come in direct contact with the body’s tissues.
• Materials pass into and out of the blood by
diffusing through the walls of the blood vessels.
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Life Functions: Animals
Closed Circulatory System
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Life Functions
Annelid Worms
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Life Functions of Annelids
• Segmented worms have a closed
circulatory system.
– Blood carrying oxygen to and carbon dioxide
from body cells flows through vessels to reach
all parts of the body.
– The earthworm circulatory system consists of
enlarged blood vessels that are heavily
muscled.
• When these muscles contract, they help pump
blood through the system.
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Life Functions of Annelids
Earthworm Circulatory System
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Life Functions of Annelids
• Excretion
– In each segment of the worm is a pair of
excretory tubules called nephridia that remove
wastes from the blood and fluid in the body
cavity.
– The nephridia lead to exterior pores through
which the wastes are discharged.
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Life Functions of Annelids
Earthworm Excretory System
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Life Functions of Annelids
• Respiration
– Annelids that live in water breathe through
gills.
• A gill is an organ specialized for exchange of gases
under water.
– Annelids that live on land exchange oxygen
and carbon dioxide through their moist skin.
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Life Functions of Annelids
• Regulation (Nervous Control)
– An earthworm has a system of nerve fibers in
each segment.
– The nerve fibers are coordinated by a simple
brain that lies above the mouth.
– The earthworm also has a nerve cord that runs
along its belly.
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Life Functions of Annelids
Earthworm
Nervous System
nerve cord
brain
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Life Functions of Annelids
• Nutrition
– Segmented worms have a complete internal
digestive tract that runs the length of the body.
– Food taken in by the mouth passes into the
esophagus.
– The food then moves through the crop, where
it can be stored.
– After that it moves through the gizzard where
it is ground into smaller pieces.
– Extracellular chemical digestion and
absorption occurs along the intestine.
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Life Functions of Annelids
Earthworm
Digestive
System
intestine
esophagus
pharynx
mouth
gizzard
crop
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Life Functions of Annelids
• Reproduction
– Most segmented worms are hermaphrodites,
• Each individual contains both sexes.
– Mating occurs when two worms join head to
tail, exchanging sperm.
– Later during egg laying, the clitellum (a
thickened glandular ring) on each worm
secretes a mucous cocoon.
• Eggs are laid within the cocoon and fertilized
externally with stored sperm as the worm
withdraws from the cocoon.
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Life Functions of Annelids
Mating Earthworms
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Life Functions
Insects
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Life Functions of Insects
• Transport
– Nutrients and other materials are transported
through the body of a grasshopper by an open
circulatory system.
• A long blood vessel with a series of muscular
“hearts” runs along the grasshopper’s back. Blood
is pumped out of the open system and bathes the
body tissues directly before returning to the heart.
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Life Functions of Insects
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Life Functions of Insects
• Excretion
– Insects have an excretory system that is
composed of units called Malpighian tubules.
– Malpighian tubules are slender, fingerlike
extensions from the arthropod’s gut that are
bathed by blood.
– Water and small particles in the blood move
through the tubules and into the gut. Metabolic
wastes remain in the gut until they exit
through the anus.
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Life Functions of Insects
• Malpighian Tubules (ant)
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Life Functions of Insects
• Respiration
– The majority of terrestrial arthropods respire
through a network of fine tubes called trachea.
– Air enters the arthropod’s body through
abdominal pores called spiracles and passes
into the tracheae, delivering oxygen
throughout the body.
– Valves that control the flow of air through the
spiracles and prevent water loss were a key
adaptation for the first arthropods that invaded
land more than 400 million years ago.
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Life Functions of Insects
• Tracheal system of a beetle
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Life Functions of Insects
• Grasshopper respiratory and circulatory
systems.
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Life Functions of Insects
• Regulation (nervous system)
– Senses
• Insects have acute senses to detect movement,
sound and chemicals.
• Antennae detect touch and chemicals in the
environment. They may also be used in
communication.
• Sensory hairs on the body may detect vibrations in
the environment.
• Eyes, simple or compound, are used to detect light
or movement.
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Life Functions of Insects
• Regulation (nervous system)
– Insects have a well developed nervous system
that processes information coming from the
sense organs.
– It consists of:
• A double nerve cord along belly.
• A brain in the head.
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Life Functions of Insects
• Grasshopper nervous system
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Life Functions of Insects
• Nutrition
– Insects have a complete digestive system with:
•
•
•
•
•
Mouth
Stomach
Intestine
Anus
Various glands that produce digestive enzymes
– Mouthparts vary and are adapted for holding,
chewing, sucking, or biting various foods.
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Life Functions of Insects
• Insect mouthparts
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Life Functions of Insects
• Anatomy of a
Grasshopper
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Life Functions of Insects
• Reproduction
– Most insect species have separate males and
females and reproduce sexually.
– Fertilization is usually internal.
– Some species, including bees, ants and wasps,
exhibit parthenogenesis, a form of asexual
reproduction in which a new individual
develops from an unfertilized egg.
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Life Functions of Insects
• Growth and Development
Insect Life Cycle
– The life cycles of most insects are complex,
and often several molts are required before the
adult stage is reached.
– During the last molt, the young insect
undergoes a dramatic physical change called
metamorphosis.
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Life Functions of Insects
• Growth and Development
Complete Metamorphosis
– Almost all insect species undergo “complete”
metamorphosis.
– In complete metamorphosis, the wingless,
wormlike larva encloses itself within a
protective capsule called a chrysalis. Here, it
passes through a pupa stage, in which it
changes into an adult.
– A complete metamorphosis is a complex life
cycle. The larvae can, however, exploit
different habitats and food sources than adults.
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Life Functions of Insects
• Complete Metamorphosis
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Life Functions of Insects
• Complete Metamorphosis
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Life Functions of Insects
• Growth and Development
Incomplete Metamorphosis
– A smaller number of species develop into
adults in a much less dramatic incomplete
metamorphosis.
– In these species, the egg hatches into a
juvenile, or nymph, that looks like a small,
wingless adult.
– After several molts, the nymph develops into
an adult.
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Life Functions of Insects
• Incomplete
Metamorphosis
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Life Functions of Insects
• Incomplete Metamorphosis
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Life Functions
Vertebrates
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Life Functions of Vertebrates
• Transport
– The vertebrate circulatory system is closed
and consists of the following parts:
• Heart
• Blood
• Blood vessels
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Life Functions of Vertebrates
• Heart
– Pumps blood through lungs and body systems.
– Has two types of chambers.
• Atria—receive blood returning to the heart from
body systems.
• Ventricles—pump blood out of the heart to body
systems.
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Life Functions of Vertebrates
• Blood vessels
– Arteries
• Carry blood away from the heart to lungs or body tissues.
• Have thick, elastic walls
– Capillaries
• Smallest blood vessels
• Walls one cell thick
• Sites of materials exchange between blood and cells
– Veins
• Carry blood toward the heart
• Have thin non-elastic walls
• Have valves to prevent back flow
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Life Functions of Vertebrates
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Life Functions of Vertebrates
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Life Functions of Vertebrates
• Blood
– Includes:
• Plasma – the liquid portion of the blood composed
of water, nutrients and wastes, salts, and proteins
• Blood cells– Red blood cells – contain hemoglobin for transport of
oxygen
– White blood cells – defend the body against disease
• Platelets – cell fragments involved in blood clotting
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Life Functions of Vertebrates
Amphibians
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Life Functions of Amphibians
• Transport
– The adult amphibian’s circulatory system is
made up of two loops and a three-chambered
heart.
– In the 3-chambered heart,
• one chamber receives oxygen-rich blood from the
lungs and skin, and another receives oxygen-poor
blood from the body tissues.(these are the atria)
• Blood from both chambers then moves into the
third chamber (ventricle), which pumps blood to
the body and lungs.
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Life Functions of Amphibians
• Amphibian heart structure
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Life Functions of Amphibians
• Frog heart and double-loop circulation
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Life Functions of Amphibians
• Excretion
– Amphibians have specialized organs of
excretion, the kidneys. The function kidneys
will be discussed in detail with respect to
mammals.
• Respiration
– Adult amphibians have lungs, a key
adaptation for gas exchange on land.
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Life Functions of Amphibians
• Respiration
– A lung is an internal, baglike respiratory organ
that allows oxygen and carbon dioxide to be
exchanged between the air and the
bloodstream.
– In amphibians, the lungs are hardly more than
sacs with folds on their inner membrane that
increase their surface area.
– Many amphibians also obtain oxygen through
their thin, moist skin.
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Life Functions of Amphibians
• Amphibian Lung Structure
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Life Functions of Amphibians
• Regulation (Nervous System)
– The frog brain is about the same size as that of
a fish but has a better developed area for
smell.
– The spinal cord extends down the back and is
encased within the backbone.
• Signals conducted between the body and brain
travel along the spinal cord.
– Sense Organs
• The sense of smell, sight and hearing are well
developed.
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Life Functions of Amphibians
• Nutrition (the Digestive System)
– Most amphibians are small and so rely on
insect or other small arthropods for food.
– Their digestive system includes: pharynx,
esophagus, stomach, liver, gallbladder, small
intestine, large intestine and cloaca.
• Cloaca is a common opening for the digestive,
excretory, and reproductive systems.
– The mechanisms of digestion will be discussed
with the mammal digestive system.
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Life Functions of Amphibians
• Internal Anatomy of a Frog
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Cloaca
Life Functions of Amphibians
• Reproduction
– Amphibians depend on water to complete their
life cycle.
– Females release eggs into water and the males
deposits sperm on them externally.
• Growth and Development
– Fertilized frog eggs hatch into swimming fishlike larvae called tadpoles.
– Tadpoles develop into adult frogs through the
process of metamorphosis.
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Life Functions of Amphibians
• Life Cycle of a Frog
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Life Functions of Amphibians
• Life Cycle of a Frog
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Life Functions
Mammals
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Life Functions of Mammals
• Transport
– Mammals have a
four-chambered
heart and doubleloop circulatory
system.
– In this system,
oxygen-rich and
oxygen-poor
blood are kept
completely
separate.
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Life Functions of Mammals
• Excretion
– Excretion is the process that rids the body of
toxic chemicals, excess water, salts, and
carbon dioxide while maintaining osmotic and
pH balance.
– The lungs, the kidneys, and the skin all
function as excretory organs.
– In the liver, ammonia is converted to a less
toxic nitrogen waste called urea, which is
transported to the kidneys, then removed from
the blood
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Life Functions of Mammals
• Organs of Excretion
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Life Functions of Mammals
• Excretory System
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Life Functions in Mammals
• Excretion
Kidneys
– The kidneys are a pair of bean-shaped, reddish
brown organs located in the lower back.
– The kidneys regulate the amount of water and
salts contained in blood plasma. They play a
vital role in maintaining homeostasis.
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Life Functions of Mammals
• Excretion
Kidneys
– Each kidney is composed of blood-filtering
units called nephrons. The kidneys filter out
toxins, urea, water, and mineral salts from the
blood. The body reabsorbs useful molecules
and water.
– Urine is formed from the remaining water,
urea, and salts. Ureters are tubes that carry the
urine from the kidney to the urinary bladder.
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Life Functions of Mammals
• Human Kidney Structure
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Life Functions of Mammals
• Excretion
– The ureters direct the urine into the urinary
bladder, a hollow, muscular sac that stores
urine.
– Urine leaves the bladder and exits the body
through a tube called the urethra. The
elimination of urine from the body through the
urethra is called urination.
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Life Functions of Mammals
• Respiration
– During aerobic respiration, cells must take in
oxygen to oxidize glucose and make ATP.
– Cells must also release carbon dioxide, a waste
product of aerobic respiration.
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Life Functions of Mammals
The Path of Air
– From the nose, air passes through a muscular
tube in the upper throat called the pharynx.
The air flows through a passageway for air
called the larynx.
– Air then passes into the trachea. The trachea
divides into two smaller tubes, the bronchi,
which lead to the lungs. Within the lungs, gas
exchange occurs in clusters of tiny sacs called
alveoli.
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Life Functions of Mammals
• Human Respiratory System
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Life Functions of Mammals
• Alveoli
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Life Functions of Mammals
• Gas Exchange in the Lungs
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Life Functions of Mammals
• Gas Transport
– In the lungs, hemoglobin molecules in the
blood pick up oxygen. The blood travels to the
heart, then to the rest of the body.
– In body tissues, oxygen diffuses into the cells
for use during aerobic respiration. Carbon
dioxide diffuses from the cells into the blood.
In the lungs, carbon dioxide is released.
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Life Functions of Mammals
O2 and CO2 in the
blood
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Life Functions of Mammals
• Regulation (Nervous System)
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Life Functions of Mammals
• The nervous system consists of cells and
organs that:
– Detect stimuli in the internal and external
environment.
– Control and coordinate responses.
– Integrate the activities of organ systems.
• The basic functional unit of the nervous
system is the nerve cell or neuron.
• Neurons are specialized cells that transmit
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information throughout the body.
Life Functions of Mammals
• Neurons carry information by conducting
electrical signals called nerve impulses.
• Structure of a neuron:
– Dendrites – often short, numerous extensions
from the cell body that receive information
from other cells.
– Cell Body (soma) – the largest part of the cell,
it contains the nucleus, most of the organelles
and most of the cytoplasm.
– Axon – long, slender process that conducts
impulses away from the cell body.
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Life Functions of Mammals
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Life Functions of Mammals
• Nervous tissue consists of neurons and
supporting cells.
• A nerve is a bundle of axons.
• The nervous system is divided into two
structural components
– Central nervous system
• Brain
• Spinal cord
– Peripheral nervous system
• Nerves and sensory structures outside the central
nervous system.
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Life Functions of Mammals
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Life Functions of Mammals
• The Endocrine
System
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Life Functions of Mammals
• The endocrine system regulates body
functions through the production of
hormones.
• Hormones are substances secreted by cells
that act to regulate the activity of other
cells in the body.
• The functions of hormones include the
following:
– Regulate growth, development, behavior and
reproduction.
– Coordinate the production, use and storage of
energy.
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– Maintain homeostasis
Life Functions of Mammals
• The endocrine system
consists a number of
recognizable
endocrine glands and
tissues scattered
throughout the body.
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Life Functions of Mammals
• The hypothalamus is an
area of the brain that
coordinates the activities
of the nervous and
endocrine systems.
• It controls many body
functions by using
hormones to
communicate with the
pituitary gland.
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Life Functions of Mammals
• The pituitary gland secretes
many hormones that control
other endocrine glands.
• The secretions of these
hormones is directed by
hormonal signals from the
hypothalamus.
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Life Functions of Mammals
• The thyroid gland is located in the neck,
just below the larynx.
• Thyroid hormones are primarily involved
in the regulation of metabolic rate in the
body.
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Life Functions of Mammals
• The parathyroid glands are
located within the thyroid
glands.
• Parathyroid hormone (PTH)
helps to regulate the levels of
calcium in body fluids.
– If blood calcium levels get too
low, the parathyroid gland is
stimulated to release PTH.
– The effect of PTH is to raise
calcium levels
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Life Functions of Mammals
• The pancreas contains clusters of
specialized cells called islets of
Langerhans that secrete endocrine
hormones.
• The hormones are: insulin and glucagon
• These hormones help regulate blood
glucose levels
– Insulin stimulates body cells to take up
glucose thereby lowering levels in the blood.
– Glucagon has the opposite effect, by causing
the liver to release glucose into the blood. 97
Life Functions of Mammals
• The Adrenal Glands are located above the
kidneys.
• One of the chief functions of adrenal
hormones is to prepare the body for “fight
or flight” responses in time of stress.
• The hormones epinephrine and
norepinephrine (sometimes called
adrenaline) cause increased heart rate,
blood pressure, and blood glucose levels.
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Life Functions of Mammals
• Nutrition (The Digestive System)
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Life Functions of Mammals
• Functions:
– Ingestion of water and food
– Chemical digestion and absorption
– Elimination of food residues
• Includes:
–
–
–
–
–
–
–
Mouth (tongue, teeth, salivary glands)
Esophagus
Stomach
Small intestine
Large intestine
Liver and gall bladder
Pancreas
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Life Functions of Mammals
• Mouth
– Chewing accomplishes physical breakdown of
food
– Tongue move food over teeth, mixes it with
saliva, and pushes it to throat for swallowing
– Salivary glands secrete saliva, which
• moistens and softens the food
• contains enzymes the begin the breakdown of
starch
• contains mucus for lubrication
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Life Functions of Mammals
• The esophagus
– Transport food from throat to stomach
– Uses wavelike muscle contractions called
peristalsis.
• Stomach
– Temporarily stores food
– Churning further contributes to physical
breakdown
– Gastric juices contain enzymes and acids that
begin the chemical breakdown of proteins 102
Life Functions of Mammals
• Small Intestine
– Most nutrient digestion a absorption occur
here
– Enzymes from pancreas and bile from liver
contribute to the chemical digestion of
carbohydrates, lipids, and proteins
– Finger-like projections of digestive epithelium
increase surface area for absorption of
digested nutrients.
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Life Functions of Mammals
• Villi in the Small Intestine
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Life Functions of Mammals
• Cross Section of the Small Intestine
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Life Functions of Mammals
• Large Intestine
– Absorbs water
– Microbes here synthesize vitamins K and B
– Undigestible wastes are compacted into feces
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Life Functions of Mammals
Reproduction
• All mammals reproduce sexually through internal
fertilization.
• Mammals are divided into three subclasses based
on their method of reproduction.
– Monotremes (egg-laying mammals): There are only
three surviving species of montremes (2 spiny
anteaters and the platypus)
– Marsupials (pouched mammals): have a short period
of development inside the mother’s body. After that,
they experience a period of development inside a
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pouch on the outside of the mother’s body.
Life Functions of Mammals
– Placental mammals:
• give birth to young that have developed inside the
mother’s uterus until their body systems are fully
functional.
• During development the young receive
nourishment through the placenta.
• The placenta is an organ made of uterine and
embryonic tissues that passes nutrients and oxygen
to and removes wastes from the developing
embryo.
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Life Functions of Mammals
The Reproductive System:
• The Male Reproductive System consists of:
– Internal organs including
•
•
•
•
Testis
Epididymus
Vas deferens
Seminal vesicles
• Prostate gland
• Bulbourethral glands
• Urethra
– External organs including
• Penis
• Scrotum
• Urethra
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Life Functions of Mammals
• Testes
– Located in the scrotum
• Scrotum is an external skin pouch that helps
regulate the temperature of the testes
– Produce sperm
– Contain cells that secrete testosterone
hormones necessary to maintain male
secondary sex characteristic.
• Epididymus
– Coiled tube on testis where sperm finish
maturing and become able to move.
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Life Functions of Mammals
• Vas deferens
– Tube through which sperm move to reach the
urethra.
• Seminal vesicles
– Produces a sugary fluid that sperm use for
energy. It is slightly alkaline to neutralize
acids in prostate fluid and the vagina.
• Prostate gland
– Produces a slightly acid fluid that contributes
20-30% of semen volume.
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Life Functions of Mammals
• Bulbourethral gland
– Secrete a thick, alkaline mucus
– Helps neutralize urinary acids in urethra and
lubricates the glans (tip of the penis)
• The secretions of the seminal vesicle,
prostate, and bulbourethral gland mixed
with sperm form the semen.
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Life Functions of Mammals
• The urethra passes through the penis.
• The penis deposits the semen into the
female reproductive system.
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Life Functions of Mammals
The Male Reproductive System
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Life Functions of Mammals
• The Female Reproductive System consists
of :
– Ovaries
– Oviducts
– Uterus
– Vagina
• Ovaries
– Produce eggs (ova)
– Secrete hormones (estrogen, progesterone)
• Maintain female secondary sex characteristics
• Regulate menstrual cycle
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Life Functions of Mammals
• Oviducts provide a passageway through
which ovum moves toward uterus.
• Uterus—hollow, muscular organ within
which development takes (if egg has been
fertilized)
• Vagina—muscular tube that leads from
uterus to outside of body.
– Receives the penis during sexual intercourse
– Serves as “birth canal” during labor and
delivery.
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Life Functions of Mammals
Female Reproductive System
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Life Functions of Mammals
Fertilization
• If sperm are present in the female
reproductive system within a few days
after ovulation, fertilization may occur.
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Life Functions of Mammals
Cleavage and Implantation
• In the first week after fertilization, the zygote
undergoes a series of internal divisions known as
cleavage.
• Cleavage continues as the embryo moves toward
the uterus. By the time it reaches the uterus, the
embryo is a hollow ball of cells.
• About six days after fertilization, the embryo
burrows into the lining of the uterus in an event
called implantation.
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Life Functions of Mammals
Early Zygote Development
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Life Functions of Mammals
Pregnancy
• Human development takes about 9
months—a period known as gestation, or
pregnancy.
• The 9 months of pregnancy are often
divided into three trimesters, or 3-month
periods.
• For the first 8 weeks of pregnancy, the
developing human is called an embryo.
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Life Functions of Mammals
First Trimester
• In the second week after fertilization the
embryo grows rapidly.
• Embryonic membranes interact with the
uterus to form the placenta.
• The placenta is the structure through with
the mother nourishes the embryo.
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Life Functions of Mammals
Structure of the Placenta
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Life Functions of Mammals
• By the end of the fourth week, all the
major organs begin to form and the heart
begins to beat.
• From the eighth week until childbirth the
developing human is called a fetus.
• A fetus has recognizable body features.
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Life Functions of Mammals
Second and Third Trimesters
• During these trimesters, the fetus grows
rapidly as its organs become functional.
• By the end of the third trimester, the fetus
is able to exist outside the mother’s body.
• After about 9 months of development, the
fetus leaves the mother’s body in a
process called labor.
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Life Functions of Mammals
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