BIOL 203 · L1: An Introduction to the Human Body

What is anatomy?

​​The study of body structures and their relationships; for example, the arrangement of bones and muscles.

What is physiology?,

The study of how body parts function; for example, how muscle contraction produces movement.

Besides identifying body structures, what relationships does anatomy examine?

How structures are organized and connected; for example, how muscles are arranged around bones.

What is gross anatomy?

The study of structures visible to the naked eye, such as organs, bones, and muscles.

What does gross mean in the term gross anatomy?

visible to the naked eye.

What kinds of body structures are studied in microscopic anatomy?

Cellular, subcellular, and microscopic tissue structures.

How can gross anatomy be studied using dissection or imaging techniques?

Dissection exposes structures by separating tissues; imaging allows internal structures to be viewed without dissection.

What is developmental anatomy?

The study of structural changes as an organism grows and develops.

is examining the structure and location of a body organ primarily anatomy or physiology?

Anatomy.

Is examining how a body organ performs its function primarily anatomy or physiology?

Physiology.

If we examine individual skeletal muscle cells under a microscope, which subdivision of anatomy are we using?

microscopic anatomy

If we examine an entire muscle without a microscope, which subdivision of anatomy are we using?

Gross anatomy.

Which subdivision of anatomy examines how a body structure changes during growth and development?

Developmental anatomy.

If we study where the heart is located and how it is connected to nearby structures, are we studying anatomy or physiology?

Anatomy.

If we study how the heart pumps blood, are we studying anatomy or physiology?

Physiology.

What principle describes the relationship between anatomy and physiology?

Form (anatomy) influences function (physiology).

In the principle ‘form determines function,’ what do form and function represent?

Form = anatomy; function = physiology.

Using red blood cells (RBCs) as an example, how does anatomy support physiology?

RBCs are biconcave, flexible discs with no nucleus. Their shape increases surface area for gas exchange, and flexibility allows passage through tiny capillaries, supporting efficient oxygen transport.

What does RBC mean, what is an RBC’s shape, and what function does that form support?

RBC = red blood cell. It is a biconcave, flexible disc; this form supports efficient oxygen transport.

Why does the biconcave shape of an RBC support efficient oxygen transport?

It provides a large surface area for gas exchange.

Why is RBC flexibility important for oxygen transport?

It allows RBCs to squeeze through tiny capillaries.

What would become more difficult if RBCs were much less flexible?

Passing through tiny capillaries.

What would likely happen to gas exchange if an RBC had less surface area?

Gas exchange would be less efficient.

Using alveoli in the lungs as an example, how does anatomy support physiology?

Alveoli are tiny, thin-walled, balloon-like sacs surrounded by capillaries. Their large surface area and thin walls allow rapid gas exchange between air and blood.

What are alveoli, and what structural features make them effective for gas exchange?

Tiny, thin-walled lung sacs surrounded by capillaries; their large surface area and thin walls support rapid gas exchange.

In alveolar gas exchange, what do O₂ and CO₂ mean, and how does alveolar structure support their exchange?

O₂ = oxygen; CO₂ = carbon dioxide. Thin walls and large surface area allow rapid diffusion between air and blood.

Why are the walls of the lung alveoli very thin?

To allow rapid O₂–CO₂ diffusion.

What would happen to gas exchange if alveolar walls became thicker?

Gas diffusion would become slower.

Why are capillaries located around the alveoli?

They place blood close to alveolar air for gas exchange.

How do RBCs and alveoli together demonstrate the relationship between anatomy and physiology?

Their specialized structures support efficient gas exchange and oxygen transport.

What are the major levels of organization in the human body from simplest to most complex?

Chemical → cellular → tissue → organ → organ system → organismal.

What occurs at the chemical level of organization?

Atoms combine into molecules; molecules contribute to cell fluid and organelles.

What defines the cellular level of organization?

Individual cells, the basic structural and functional units of living organisms.

Why is the cell important at the cellular level of organization?

Cells are the basic structural and functional units of living organisms.

What defines the tissue level of organization?

Groups of similar cells working together for a specific function.

What defines the organ level of organization?

Multiple tissues organized into a structure that performs a specific function.

What defines the organ system level of organization?

Multiple organs working together for a common, coordinated function.

What defines the organismal level of organization?

All organ systems functioning together as one living organism.

Atoms and molecules belong to which level of organization?

Chemical level.

A group of similar cells working together belongs to which level of organization?

Tissue level.

A structure composed of multiple tissues belongs to which level of organization?

organ level

Multiple organs working together belong to which level of organization?

Organ system level.

Why is the stomach considered an organ rather than a tissue?

It is composed of multiple tissues organized into one functional structure.

What level of organization comes immediately after the chemical level?

Cellular level.

What level of organization comes immediately after the cellular level?

Tissue level.

What level of organization comes immediately after the tissue level?

Organ level.

What level of organization comes immediately after the organ level?

Organ system level.

What level of organization comes immediately before the organismal level?

Organ system level.

If several tissues work together to perform one function, have they formed a tissue or an organ?

An organ.

If several organs coordinate their functions, what level of organization has been reached?

Organ system level.

What structures and functions characterize the integumentary system?

Skin, hair, and nails; protection and temperature regulation.

Which organ system contains the skin, hair, and nails and helps protect the body and regulate temperature?

Integumentary system.

What structures and functions characterize the skeletal system?

Bones, cartilage, and ligaments; support, protection, and mineral storage.

Which organ system provides support, protection, and mineral storage?

Skeletal system.

What structures and functions characterize the nervous system?

Brain, spinal cord, and nerves; rapid communication, coordination, and control.

Which organ system provides rapid communication, coordination, and control?

Nervous system.

What structures and functions characterize the cardiovascular system?

Heart, blood, and blood vessels; transport of nutrients, gases, hormones, and wastes.

Which organ system transports nutrients, gases, hormones, and wastes throughout the body?

Cardiovascular system.

What structures and function characterize the respiratory system?

Lungs, trachea, and bronchi; gas exchange.

Which organ system primarily performs gas exchange?

Respiratory system.

What structures and functions characterize the digestive system?

Mouth, esophagus, stomach, intestines, liver, and pancreas; food breakdown and nutrient absorption.

Which organ system breaks down food and absorbs nutrients?

Digestive system.

What structures and function characterize the reproductive system?

Male and female reproductive organs, such as testes, ovaries, and uterus; gamete production and reproduction.

Which organ system produces gametes and supports reproduction?

Reproductive system.

What structures and functions characterize the muscular system?

Skeletal, smooth, and cardiac muscle; movement and heat production.

What three types of muscle are included in the muscular system?

Skeletal, smooth, and cardiac muscle.

Which organ system enables movement and contributes to heat production?

Muscular system.

What structures and function characterize the endocrine system?

Hormone-producing glands such as the thyroid, pancreas, and adrenal glands; regulation of long-term processes.

Which organ system uses hormone-producing glands to regulate long-term processes?

Endocrine system.

What structures and functions characterize the lymphatic/immune system?

Lymph nodes, lymph vessels, spleen, and thymus; pathogen defense and return of fluid to blood.

Which organ system both defends against pathogens and returns fluid to the blood?

Lymphatic/immune system.

What structures and functions characterize the urinary system?

Kidneys, ureters, bladder, and urethra; waste elimination and water/electrolyte regulation.

Which organ system eliminates wastes and regulates water and electrolytes?

Urinary system.

Which system produces hormones, and which system transports hormones?

Endocrine produces them; cardiovascular transports them.

Which system provides rapid control, and which system regulates long-term processes?

Nervous = rapid; endocrine = long-term.

Which two organ systems in this lecture directly contribute to body-temperature regulation through protection/temperature regulation and heat production?

Integumentary and muscular systems.

What is homeostasis?

Maintenance of relatively constant conditions in the internal environment.

Does homeostasis mean that internal conditions remain perfectly constant?

No. They fluctuate within a narrow range suitable for normal function.

What is a homeostatically regulated variable?

An essential internal variable maintained within a narrow range.

What five criteria must a variable meet to be considered homeostatically regulated in this lecture?

Blood association, essential for life, dedicated sensors, defined set point, and negative-feedback control.

What is the first criterion for a homeostatically regulated variable regarding where it is measured?

It is measured in or associated with the blood.

What biological importance must a homeostatically regulated variable have?

It must be essential for sustaining life.

Why must a homeostatically regulated variable have a dedicated sensor?

The sensor must detect changes in the variable.

In homeostasis, what is a sensor?

A specialized cell or receptor that detects changes in a regulated variable.

What is a set point in homeostatic regulation?

The target value used by the integrator as a reference.

Where is the set point used during homeostatic regulation?

In the integrator, or control center.

What type of feedback regulates the homeostatic variables listed in this lecture?

Negative feedback.

What does negative feedback do to a change in a regulated variable?

It counteracts the change and moves the variable toward its set point.

If an important body variable has no dedicated sensor, does it meet all five lecture criteria for a homeostatically regulated variable?

no

If a body variable has no defined set point, does it meet all five lecture criteria for homeostatic regulation?

no

If a response amplifies rather than counteracts a change, does it meet the negative-feedback criterion for these homeostatically regulated variables?

no

Why is ‘relatively constant’ more accurate than ‘unchanging’ when describing homeostasis?

Regulated variables can fluctuate within a narrow normal range.

What does arterial PO₂ mean, and why is it homeostatically regulated?

Partial pressure of oxygen; it supports tissue oxygen delivery for aerobic metabolism.

What can happen to ATP production if arterial PO₂ becomes insufficient?

ATP production can be impaired.

Which homeostatically regulated variable helps ensure adequate oxygen delivery for aerobic metabolism?

Arterial PO₂.

What does arterial PCO₂ mean, and why is it homeostatically regulated?

Partial pressure of carbon dioxide; it helps regulate acid–base balance.

Which homeostatically regulated respiratory variable is closely associated with acid–base balance?

Arterial PCO₂.

What does K⁺ represent, and why is blood K⁺ homeostatically regulated?

Potassium ion; it is critical for resting membrane potential and action potentials.

Blood K⁺ is especially important for electrical activity in which cells?

Neurons and muscle cells.

Which regulated ion is critical for resting membrane potential and action potentials?

K⁺.