TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
How do systems interact to
perform the function of regulation
in animals?
• Body systems in animals work together to keep conditions
inside their bodies as constant as possible despite changes in
external conditions.
• Animals expend energy to maintain a constant internal
environment for their cells and tissues, known as
homeostasis.
• Often homeostasis is regulated by feedback inhibition.
Feedback inhibition or negative feedback occurs when an
increase in any substance “feeds back” to stop the process that
produced the substance in the first place.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• Complex animals use several body systems to gather and
respond to stimuli in their environment.
• The nervous system collects, processes, and determines how
an animal will respond to events in its environment.
• Animals often respond to information processed in the nervous
system by moving.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
1. Predict Would an animal with a malfunctioning nervous system be able to
produce an appropriate muscle response to a predator? Explain.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• In humans, body temperature is controlled through various
feedback mechanisms.
2. Infer Why do you think moving around on a cold day helps to keep you warm?
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
How do systems interact to
perform nutrient absorption in
animals?
• Animals obtain nutrients and energy from food. The different
ways that animals obtain food depends on what they eat and
their adaptations for getting food.
• Many carnivores (animal-eaters) have specialized mouth parts
to hunt, grab, tear, and slice food.
• Herbivores (plant-eaters) typically have mouth parts adapted
for rasping, grinding, chewing, or sucking.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
3. Contrast How are the teeth of the wolf and horse adapted to their different diets?
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• Some animals digest food mainly
inside their cells and pass nutrients to
other cells by diffusion. This process is
called intracellular digestion.
• Most animals digest food outside their
cells in a digestive system and then
absorb it in a process called
extracellular digestion.
• In most animals, the digestive system
is a tube with a mouth at one end and
an anus at the other end. A digestive
tube has specialized areas where food
is broken down by enzymes as it
moves along the tube by muscular
contractions.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• Carnivores typically have short digestive tubes that produce enzymes
to break down meat. Animals don’t produce enzymes that can break
down the tough cellulose in plant tissue.
• Some herbivores, such as cattle, have a four-part stomach, each with a
special function. The largest stomach part is a pouch-like extension
called a rumen, in which bacteria digest cellulose.
• Nutrients that are absorbed through the lining of an animal’s digestive
system pass into its circulatory system and are carried to cells
throughout the body.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• In many animals, including
humans, systems interact to
regulate glucose (simple sugar)
levels. Animals get glucose from
food, and cells use the energy
stored in glucose for their life
functions.
• Insulin and glucagon are
hormones produced by the
pancreas, an organ in the
endocrine system. These
hormones help to keep the blood
glucose level stable.
4. Interpret Diagrams What two hormones regulate blood glucose levels in humans?
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
How do systems interact to
perform reproduction in animals?
• Animals undergo either asexual or sexual reproduction.
Asexual reproduction produces offspring identical to the parent.
Sexual reproduction produces offspring with genetic variations,
which may increase the ability of a species ability to adapt and
survive environmental changes.
• Proper interactions between the nervous and reproductive
systems are critical to successful reproduction. Animals’
reproductive cycles can be affected by their nervous systems’
responses to changes in length of daylight, seasons, tides, or
moon phases.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• In many animals, including humans, the endocrine system
produces hormones that regulate the activities of ovaries and
testes.
• In placental mammals, the placenta links the embryo and
mother and acts as the embryo’s organ of respiration,
nourishment, and excretion. Their blood flows past each other,
but does not mix. Oxygen and nutrients diffuse from the
mother’s blood to the embryo’s blood; carbon dioxide and
wastes diffuse from the embryo’s blood to the mother’s blood.
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
How do systems in animals
interact to defend them
from injury or illness?
• Skin, which makes up a major part of the integumentary
system, keeps many pathogens, or disease-causing
organisms, from entering the body.
• If pathogens enter the body through a cut in the skin, the
infected area reacts with an inflammatory response.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• During the inflammatory response, pathogens stimulate cells to release
histamines, which increase the flow of blood and nutrients to the
infected area.
• White blood cells from the circulatory system, called phagocytes, move
into the infected area and surround and destroy pathogens.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• The immune system can distinguish between “self” and
“foreign” cells and substances, and it can inactivate, or kill, any
foreign substance or cell that enters the body.
• Immune defenses are triggered by antigens, any foreign
substance that can stimulate an immune response.
• The immune system responds to antigens by increasing the
number of cells that attack the pathogens or by producing
proteins called antibodies.
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• There are two main cells
involved in immunity: B cells
and T cells.
• B cells are produced in red
bone marrow.
• T cells are produced in bone
marrow, but they mature in the
thymus (an endocrine gland).
B-cell
T-cell
(contd.)
TEKS 10A: Describe the interactions that occur among systems that perform the functions of regulation, nutrient
absorption, reproduction, and defense from injury or illness in animals.
• B cells discover antigens in body fluids.
• T cells are released by infected body cells or immune cells that
have encountered antigens.
• Vaccination stimulates the immune system with an antigen. The
immune system produces memory B cells and memory T cells
that quicken and strengthen the body’s response to repeated
infection.