Introduction to Human Anatomy and Physiology

Defining Anatomy

Human anatomy is the study of the structure of the human body.

LEARNING OBJECTIVES

Define the two major subtypes of anatomy

KEY TAKEAWAYS

Key Points

• Gross anatomy is subdivided into surface anatomy (the external body), regional anatomy (specific regions of the body), and systemic anatomy (specific organ systems).

• Microscopic anatomy is subdivided into cytology (the study of cells) and histology (the study of tissues).

• Anatomy is closely related to physiology (study of function), biochemistry (chemical processes of living things), comparative anatomy (similarities and differences between species), and embryology (development of embryos).

• Knowledge of anatomy is needed to understand human biology and medicine.

Key Terms

• anatomy: The study of the body structure of animals.

• surface Anatomy: The study of anatomical landmarks that can be identified by observing the surface of the body. Sometimes called superficial anatomy.

• microscopic anatomy: The study of minute anatomical structures on a microscopic scale, including cells (cytology) and tissues (histology).

• Gross (or macroscopic) anatomy: The study of anatomical features visible to the naked eye, such as internal organs and external features.

• embryology: The science of the development of an embryo from the fertilization of the ovum to the fetal stage.

• dissection: The process of disassembling an organism to determine its internal structure and understand the functions and relationships of its components.

Defining Anatomy

Anatomy describes the structure and location of the different components of an organism to provide a framework for understanding. Human anatomy studies the way that every part of a human, from molecules to bones, interacts to form a functional whole.

Rembrant’s “The Anatomy Lesson of Dr. Nicolaes Tulp”: Human anatomy is the study of the structure of the human body, from the microscopic to the macroscopic.

There are two major types of anatomy. Gross (macroscopic) anatomy is the study of anatomical structures that can be seen by the naked eye, such as the external and internal bodily organs. Microscopic anatomy is the study of tiny anatomical structures such as tissues and cells.

Gross Anatomy

Gross anatomy can be further subdivided into three different fields:

• Surface anatomy (or superficial anatomy) is the study of external anatomical features without dissection.

• Regional anatomy focuses on specific external and internal regions of the body (such as the head or chest) and how different systems work together in that region.

• Systemic anatomy focuses on the anatomy of different organ systems, such as the respiratory or nervous system.

Regional anatomy is widely used in modern teaching because it is easier to apply to a clinical setting than systemic anatomy. The major anatomy textbook, Gray’s Anatomy, has recently been reorganized from a systems format to a regional format to reflect this preference. Surface anatomy is also widely used to gauge the position and structure of deeper organs, tissues, and systems.

Microscopic Anatomy

Within microscopic anatomy, two topics of study are of great importance:

• Cytology, the study of the structure and function of cells

• Histology, the study of the organization and details of biological tissues

The human body has many layers of organization. Biological systems consist of organs that consist of tissues, and tissue in turn is made up of cells and connective tissue. Microscopic anatomy allows one to focus on these tissues and cells.

History of Anatomy

The history of anatomy has been an evolving understanding of organs and structures in the body. Beginning in Ancient Greece and developing through the Middle Ages and the Renaissance, methods of studying anatomy have advanced dramatically. This field has moved from examination of animals and cadavers through invasive dissection to the technologically complex techniques developed in the 20th century, such as non-invasive imaging and radiology.

Generally, medical and biology students learn about the human body from anatomical models, skeletons, textbooks, diagrams, photographs, lectures, and tutorials. Medical and dental students also learn through the dissection and inspection of cadavers. A thorough working knowledge of anatomy is required for all medical professionals, especially surgeons and doctors working in diagnostic specialties such as radiology.

Anatomy and Physiology

Physiology is the study of how the components of the body function, and biochemistry is the study of the chemistry of living structures. Together with anatomy, these are the three primary disciplines within the field of human biology. Anatomy provides information about structure, location, and organization of different parts of the body that is needed to truly understand physiology.  Together, anatomy and physiology explain the structure and function of the different components of the human body to describe what it is and how it works.

Defining Physiology

Human physiology is the study of the mechanical, physical, and biochemical processes that support the body’s function.

LEARNING OBJECTIVES

Describe physiology in the context of living systems

KEY TAKEAWAYS

Key Points

• The study of physiology occurs at many levels, including organisms, organ systems, organs, cells, and biomolecules.

• Physiology investigates the processes and mechanisms that allow a living thing to survive, grow, and develop.

• Homeostasis is the maintenance of the overall stability of physiological processes of the body. It is monitored by the brain and nervous system and regulated by the physiology and activity of individual organs.

• While anatomy deals with the structure of the parts of an organism, physiology studies the way that the parts function together.

Key Terms

• homeostasis: The ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium, such as the ability of warm-blooded animals to maintain a constant internal temperature despite changes in outdoor temperature.

• Living Systems: Open, self-organizing living things that interact with their environments. These systems are maintained by flows of information, energy, and matter.

• physiology: A branch of biology that deals with the functions and activities of living matter and the physical and chemical processes and mechanisms involved.

EXAMPLES

The body’s ability to digest and absorb nutrients from food.

Physiology is the science of the normal function of living systems. Physiology studies the processes and mechanisms that allow an organism to survive, grow, and develop. Physiological processes are the ways in which organ systems, organs, tissues, cells, and biomolecules work together to accomplish the complex goal of sustaining life.

Physiological mechanisms are the smaller physical and chemical events that make up a larger physiological process. Human physiology studies the functions of humans, their organs and cells, and how all of these functions combine to make life, growth, and development possible.

Leonardo da Vinci’s “The Vitruvian Man”: Vitruvian Man: A drawing created by Leonardo da Vinci. The drawing is based on the correlations of ideal human proportions with geometry described[4] by the ancient Roman architect Vitruvius in Book III of his treatise De Architectura.

Homeostasis

Homeostatis is the maintenance of the body’s overall inner resistance to change. This resistance stabilizes the body by regulating the internal environment, even as the external environment changes. A stable internal environment is needed for normal physiological function and survival of a living system.

Maintaining a stable internal environment requires constant monitoring, mostly by the brain and nervous system. The brain, more specifically the hypothalamus, receives information from the body and responds appropriately through the release of chemical messengers such as neurotransmitters, catecholamines, and hormones. These chemical messengers signal individual organs to change their functions in order to maintain homeostasis for the whole body.

For instance, if blood oxygen levels are too low, the brain signals the muscles controlling the lungs to breathe faster to increase oxygen intake. The brain also signals the heart to beat faster so other organs and tissues receive the oxygen they need. When oxygen levels return to normal, the brain signals the lungs and heart to return to their normal rates of function, a process called feedback.

Body Systems

Traditionally, the academic discipline of physiology views the body as a collection of interacting systems, each with its own combination of functions and purposes. Each system contributes to the homeostasis of other systems and of the entire organism. No system works in isolation, and the well-being of the person depends upon the well-being of the interactions between body systems. The traditional divisions by system are somewhat arbitrary. Many organs participate in more than one system (such as the heart and kidney), and systems might be organized by function, by embryological origin, or by other categorizations.

For instance, the neuroendocrine system is the complex interactions of the neurological and endocrinological systems. Together, the neuroendocrine system regulates many physiological processes, including those that maintain homeostasis. Furthermore, many aspects of physiology are not easily categorized by traditional definitions of organ systems because they are composed of interactions between organs in multiple organ systems.

The study of how physiology is altered in disease is pathophysiology. Pathophysiology focuses on how physiological processes fail to maintain normal function, resulting in the manifestation of disease symptoms.

Anatomy and Physiology

Human anatomy deals with how all parts of the human body interact to form a functional whole. The study of anatomy is separate from the study of physiology, although the two are often taught together. While anatomy studies the structure of the parts of an organism, physiology is concerned with the way those parts function together. For example, an anatomist may study the types of tissues found in different parts of the heart, while a physiologist may study how the heart regulates blood flow to supply oxygen to other organs in the body. While anatomy and physiology study different aspects of human biology, together they provide a more complete picture of what the human body is and how it works.

Atoms --> Molecules --> Macromolecules --> Organelles --> Cells --> Tissues --> Organs --> Organ Systems --> Organism

*A group (mass) of cells working together to carry out certain common functions form a tissue

*A group of tissues working together to carry out certain common functions form an organ

*A group of organs working together to carry out certain common functions is an organ system

*A group of organ systems working together to carry out certain common functions is an organism 

General Organization of the Body:

Axial Portion - head, neck, trunk

Appendicular Portion - arms & legs

1. Several body cavities

2. Layers of membranes within cavities

3. Variety of organs and organ systems within cavities (VISCERA = internal organs. "Visceral organs")

Body Cavities (see p.9)

A. Dorsal Cavity ---Cranial Cavity - Brain, Spinal Cavity - Spinal Cord

B. Ventral Cavity

1. Thoracic Cavity - right and left compartment separated by mediastinum. Heart , lungs, esophagus, trachea

2. Abdominopelvic Cavity

---Abdominal cavity - stomach, spleen, liver, gall bladder, small intestine

---Pelvic cavity - part of the large intestine, urinary bladder, reproductive organs

*Thoracic and abdominopelvic cavity separated by DIAPHRAGM

*The organs within the cavities are surrounded by a type of two layered membrane called the SEROUS MEMBRANE

*The outer lyer of each membrane is called the PARIETAL layer and forms a "lining" against the inner wall of each cavity

*The inner layer of each membrane covers the surface of each organ and is called the VISCERAL layer

Membranes:

1. Pleura (or pleural membrane) - surrounds the lungs

--outer layer = parietal pleura

--inner layer = visceral pleura

2. Pericardium (or pericardial membrane) - surrounds the heart

--outer layer = parietal pericardium

--inner layer = visceral pericardium

3. Peritoneum (or peritoneal membrane) - surrounds all the organs within the abdominopelvic cavity

--outer layer = parietal peritoneum

--inner layer = visceral peritoneum

*Between the layers of each membrane is a lubricating fluid which is called SEROUS FLUID

ORGAN SYSTEMS

1. Integumentary Body covering. Skin, hair, nails, sweat glands.

Function: protect underlying tissues and regulate body temperature

2. Skeletal Bones, ligaments, cartilage

Function: Support, movement, protection, and production of blood cells

3. Muscular Muscles of the body

Function: Movement, maintenance of posture, production of body heat

4. Nervous Brain, spinal cord, nerves through the body

Function: Communication throughout body, mental activities, maintaining homeostasis

5. Endocrine Ductless glands = pituitary, adrenal, thyroid, parathyroid, pancreas, ovaries, testes, thymus, pineal glands

Function: Secretion of hormones, communication between body parts

6. Digestive

Mouth, teeth, pharynx, esophagus, stomach, small intestine, large intestine, liver, gall bladder, and many glands including the pancreas

Function: Breakdown of food substances into simpler forms that can be absorbed (digestion).

7. Circulatory Heart, blood vessels, blood.

Function: Transports materials throughout the body.

*Lymphatic system usually included with the circulatory system

8. Urinary Kidneys, ureters, urinary bladder, urethra

Function: Removes ("filters") wastes from the blood and helps maintain the body's water and electrolyte balance

9. Reproductive Reproductive organs, primarily the ovaries (females) and testes (males)

Function: Produce special reproductive cells for reproduction

Anatomical Terminology

Anatomical Position = standing erect, face forward, arms at side, palms facing forward

*Study and learn the following terms which are used to describe relative positions -- location of one body part with respect to another (p.13 -14)

1. Superior                                  5. Medial                                   9. Superficial

2. Inferior                                     6. Lateral                                     10. Deep

3. Anterior                                  7. Proximal

4. Posterior                                 8. Distal

*Learn and understand the following body sections ("slices") through th body for observing internal structures

1. Sagittal

2. Transverse

3. Frontal (or coronal)

concept map

*Learn to Identify and Describe the Body Regions body cavity lableing 

review unit 1