Human Physiology
Human physiology is the study of how the human body works.
It looks at how the body’s organs, systems, tissues, cells, and molecules
perform the chemical and physical tasks that keep us alive. Physiology is a
part of biology that connects the body's structure (anatomy) with the study of
chemicals and molecules (biochemistry and molecular biology). By understanding
physiology, we learn how the body functions normally and how it reacts to
changes inside and outside the body.
Homeostasis
Our body can keep a steady internal environment even when
the outside world changes. For example, it keeps body temperature, blood
acidity (pH), and blood sugar levels stable.
Body Systems
The Digestive System
The digestive system is important for health because it turns food into the parts our body uses to build and keep itself going. It takes in food, breaks it down into smaller parts (nutrients), absorbs the nutrients into the blood, and then removes the waste that can't be used.
Breathing and Respiration
In animals, the body
uses special organs to collect air, and in humans, the respiratory system does
this. Breathing helps bring in air with oxygen and get rid of carbon dioxide.
The body also moves air and regulates how much we breathe. There are different
volumes of air involved in breathing, and some problems like asthma, emphysema,
and work-related lung issues can affect this system.
Body Fluids and Circulation
Living cells need
food, oxygen, and other important things, while waste and toxins need to be
removed for the body to stay healthy. The body uses special ways to move these
things around. Simple creatures like sponges and jellyfish use water to move
things through their bodies. In more complex animals, like humans, blood and
lymph (a special type of fluid) carry these substances.
Excretory Products and Their Elimination
Animals collect
different waste materials like ammonia, urea, uric acid, carbon dioxide, water,
and ions like sodium, potassium, chloride, and others. These come from the
body’s normal processes and from eating too much. These wastes need to be
removed, either fully or partly. The major nitrogen-based wastes are ammonia,
urea, and uric acid. Ammonia is the most harmful and needs a lot of water to
get rid of, while uric acid is less harmful and can be removed with less water.
Locomotion and Movement
Movement is a key
part of both plants and animals. Locomotion is when the body moves from one
place to another, like walking, running, climbing, flying, or swimming. These
movements are often for finding food, shelter, mates, a good place to live, the
right weather, or escaping danger. Not all movements are locomotion, but all
locomotion is a type of movement.
Neural Control and Coordination
To keep the body balanced and functioning properly, the
different parts of the body must work together. Coordination is when different
body parts and systems work with each other. For example, when you exercise,
your muscles need more energy, so your body increases oxygen supply by
breathing faster, beating the heart faster, and more blood flows through the
body.
Chemical Coordination and Regulation
The nervous system
and the endocrine system work together to control the body’s functions. The
nervous system controls things quickly and precisely but only for a short time,
while the endocrine system acts slowly and over a longer period.
Not all body cells are connected to nerves, so hormones are used to control the
functions that are not directly controlled by the nervous system.
The Immune System
The immune system is made up of organs, cells, and proteins
that help protect the body from infections and keep the body’s own cells safe.
The Reproductive System
The reproductive system is responsible for making and joining gametes (like eggs and sperm) and for carrying a baby during pregnancy.
