Transcript human body systems

B.10A: Interactions in Animals
Biological Processes and Systems
• What is the role of homeostasis in system regulation?
Part I: Systems Regulation
Your Mission: Describe the interactions that occur among
systems that perform the function of regulation.
The endocrine system is primarily responsible for regulating
many of the bodily functions that occur in animals to maintain
homeostasis, an internal balance. For example, bodies keep
calcium, salt, water, and carbohydrates balanced so that our
basic organs and cells function properly. Regulation is also necessary for growth and
development and reproduction. Several glands associated with the endocrine system,
including the pituitary, thyroid, adrenal and pancreas, are essential to regulation of
body function because they produce hormones.
Hormones are chemical substances produced in the body. Response
These have specific regulatory effects on the activity of
certain cells or a certain organ. Hormones are absorbed
into the bloodstream and transported throughout the body
via the circulatory system. Once they reach their target
cells, chemical intercellular communication occurs.
Response
Often this communication results in the action of
other body systems, such as the nervous and muscular
systems, in the process of maintaining homeostasis. An
example of this regulatory process, or feedback system,
is calcium regulation. An animal with low calcium ions Respons
in the blood will trigger an endocrine response from the e
parathyroid gland. Parathyroid hormone is released into Kidney/Bone
the bloodstream, which signals the release of calcium
and phosphate from bone in the skeletal system.
Simultaneously, the kidney is signaled to increase
Respons
calcium reabsorption for conservation and the excretion e
of phosphate through the excretory system.
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Stimuli
General
Feedbac
k Loop
Stimuli
Calcium Ions
in Blood
Stimuli
Low
Blood
Calcium
Ion
Feedbac
k Loop
Parathyroid
Gland
Stimuli
Parathyroid
Hormone
B.10A: Interactions in Animals
Biological Processes and Systems
• What is the role of homeostasis in system regulation?
Part I: Systems Regulation, continued
Your Mission: Describe the interactions that occur among systems that perform the
function of regulation.
Regulating body temperature is another example of homeostasis
important for staying healthy. Thermoregulation involves a variety
of mechanisms the used by the body to balance heat-in and
heat-out in order to keep its core temperature nearly constant.
In humans, body temperature generally stays around 37°C.
Our bodies provide different mechanisms for maintaining that
temperature, depending on whether we need to cool down or
heat up. For example, when we exercise, we sweat; and when
we are cold, we shiver.
Like regulation for other purposes, thermoregulation is coordinated among a variety of
systems. When the variable of environmental temperature makes us cold, sensors in
our epidermis, part of the integumentary system, notice the change and respond by
alerting the nervous system. The nervous system, in turn, signals the body to respond.
For example, it might signal the muscular system to shiver or signals an increase in
metabolism so that stored energy in fat is released. Both responses, whether
mechanical or metabolic, result in generating heat. Respiration provides oxygen for
either process, and the circulatory system spreads the heat through the body, raising
its core temperature.
Humans, like other mammals, are endotherms, meaning that we can produce heat
internally. But other animals, such as most reptiles, are ectotherms. They still need to
maintain homeostasis in their body temperatures, but they rely on other types of
mechanisms for thermoregulation. They must get heat, externally, that is, from the
environment. So, their body systems coordinate behaviors such as basking in the sun
to absorb heat or seeking shade to reduce heat input. Similarly to endotherms,
sensors signal the nervous system of the temperature condition, which then signals the
appropriate other systems, such as the muscular system, to move into the sun or
Complete Part I of your Student Journal before moving on.
shade.
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B.10A: Interactions in Animals
Biological Processes and Systems
• How do systems in animals interact to achieve nutrient management?
• Which systems in animals interact to achieve reproduction?
• How do systems in animals interact to protect them from injury or illness?
Part II: Nutrition, Reproduction, and Protection
Your Mission: Describe the interactions that occur among systems that perform the
function of nutrient absorption, reproduction, and defense from injury or illness.
Nutrient management is essential to the chemical processes that occur in order for
animals to carry out life processes. Such management is also very complex, as it
involves three main processes: digestion, absorption, and regulation. Furthermore,
several systems interact to perform nutrient management. These include the digestive,
nervous, muscular, endocrine, circulatory, and excretory systems.
Digestion begins when the body ingests food.
Food particles are then broken down into
smaller molecules through the process of
hydrolysis. The pancreas is one endocrine
gland that aids this process by secreting
digestive enzymes. It also produces hormones,
such as insulin, which is crucial to regulating
fat and carbohydrate metabolism in the body.
The nervous system controls the involuntary
muscular contractions that occur in the esophagus,
stomach, and intestines that keep things moving
Digestiv
along.
e System
Circulatory
System
The next step in nutrient management is absorption.
Once the smaller molecules enter the large intestine, they pass over intestinal villi.
Here, nutrients are absorbed into capillaries of the circulatory system and moved
throughout the body to be utilized or stored. Nutrients in the bloodstream are
monitored by sensors of the nervous system to keep tabs on the body’s the internal
balance. As needed, these sensors trigger responses from the endocrine system to
regulate the excess or deficiency of nutrients within the bloodstream. As food moves
through the digestive system, waste gets collected and is eventually released through
the excretory organs.
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B.10A: Interactions in Animals
Biological Processes and Systems
• How do systems in animals interact to achieve nutrient management?
• Which systems in animals interact to achieve reproduction?
• How do systems in animals interact to protect them from injury or illness?
Part II: Nutrition, Reproduction, and Protection, continued
Your Mission: Describe the interactions that occur among systems that perform the
function of nutrient absorption, reproduction, and defense from injury or illness.
Reproduction also involves a variety systems and is generally regulated by the
endocrine system. Most mammals mate according to the female estrous cycle, in
which the female’s ovary regulates hormones that trigger the release of an egg for
fertilization. These hormonal changes are vital to successful reproduction. Once the
egg is fertilized in the uterus, more hormones are released that regulate the
development of the fetus.
In humans, the zygote (fertilized egg) implants into the wall of the uterus. The zygote
will develop into a fetus during a gestational period of 9-10 months. When the birth
process begins, the fetus presses against the cervix sending nerve impulses to the
brain. The
nervous system then signals the pituitary gland of the endocrine system to release the
hormone oxytocin into the circulatory system via the bloodstream. This action
stimulates the muscular system to contract in the smooth muscle of the uterus.
Many factors effect an organism’s
ability to reproduce. Changes in
daylight and temperature can
be detected in the nervous
system by receptors in the brain;
these receptors then use this
information to regulate the body’s
hormone levels. Even slight variations
in these hormones can impact the
overall success of reproduction.
While the endocrine system is paramount
to the process of reproduction, the
entire process is delicately balanced
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among the performance of multiple body systems.
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B.10A: Interactions in Animals
Biological Processes and Systems
• How do systems in animals interact to achieve nutrient management?
• Which systems in animals interact to achieve reproduction?
• How do systems in animals interact to protect them from injury or illness?
Part II: Nutrition, Reproduction, and Protection, continued
Your Mission: Describe the interactions that occur among systems that perform the
function of nutrient absorption, reproduction, and defense from injury or illness.
The integumentary system is any human or animal’s primary line of defense from the
outside world, forming a barrier between the more vulnerable inside of an organism
and any bacteria, viruses, or other pathogens that are encountered. In mammals, hair
is also an important structure of the integumentary system that works to protect them
from environmental conditions, helping in thermoregulation, and repelling dirt and rain.
The skeletal system of many animals is also highly specialized to provide protection
from injury, especially to the vital organs, such as the heart, liver, and lungs. In some
animals, parts of the skeletal system have evolved into highly protective “armor”, such
as in the tortoise, whose rib cage is what forms its shell. The muscular system also
helps protect from injury by responding to stimuli so that the body moves away from
harm. A muscle
also protects bone from injury, for example, by absorbing an impact; the muscle may
suffer a bruise, but the bone remains unbroken.
Organisms are also equipped with defenses on
a microscopic level, launched by the immune
system. The immune system defends against
pathogens, such as bacteria and viruses. When
a foreign invader is detected in the body, the
immune system is triggered. This response
involves an intricate process of cellular
communication (illustrated in the diagram on
right) that requires the help of the nervous,
endocrine, and circulatory systems. Depending
on the foe, anti-bodies or other defenses, are
activated and targeted to overcome the invader.
Complete Part II of your Student Journal before moving on to the activity.
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