Introduction to Anatomy and Physiology

Introduction to Anatomy and Physiology

Relationship between Anatomy and Physiology Anatomy

The study of internal and external structures of the body and the physical relationships among body parts

Physiology The study of how living organisms perform their vital

functions

Someone studying anatomy might examine how and where a particular muscle attaches to the skeleton, whereas someone studying physiology might consider how a muscle contracts or what forces a contracting muscle exerts on the skeleton

Relationship between Anatomy and Physiology Anatomical info provides clues about

functions (physiology), and physiological mechanisms can be explained only in terms of the underlying anatomy

ALL SPECIFIC FUNCTIONS ARE PERFORMED BY SPECIFIC STRUCTURES!!!!!

Relationship between Anatomy and Physiology Anatomy can be divided into gross

(macroscopic) anatomy and microscopic anatomy

Gross AnatomyExamination of relatively large structures

○ Usually visible with unaided eye 5 different forms of gross anatomy

Surface anatomy○ Study of general form and superficial markings

Regional anatomy○ Anatomical organization of specific areas of body

(head, neck, trunk)

Relationship between Anatomy and Physiology 5 different forms of gross anatomy (con’t)

Systemic anatomy○ Study of the structure of organ systems (skeletal

system, muscular system, cardiovascular system, etc.)Developmental anatomy

○ Describes the changes in form that occur between conception and physical maturity

○ Embryology – study of early developmental processesClinical anatomy

○ Subspecialities important in clinical practice Medical anatomy (anatomical features that change during

illness) Radiographic anatomy (anatomical structures seen using

imaging techniques)

Relationship between Anatomy and Physiology Microscopic Anatomy

Study of structures that cannot be seen without magnification

Has 2 major divisionsCytology – analysis of the internal structure

of individual cellsHistology – examination of tissues

Relationship between Anatomy and Physiology Physiology

The study of the function of anatomical strucures

Can be divided into 4 major specialtiesCell physiology – study of the function of cells

○ Chemical processes within cells and chemical interactions between cells

Special physiology – study of the physiology of specific organs

Systemic physiology – study of the functioning of specific organ systems

Pathological physiology – study of the effects of diseases on organ or system fuctions

Introduction to Anatomy and Physiology

Levels of Organization The Chemical (or Molecular) Level

Atoms can combine to form molecules with complex shapes

The functional properties of a particular molecule are determined by its unique 3D shape

The Cellular LevelMolecules interact to form organelles, each of which

has specific functions.Organelles are grouped to form cells

The Tissue LevelGroups of cells working together to perform specific

functions○ Heart muscle cells interact with other types of cells and

extracellular materials to form cardiac muscle tissue

Levels of Organization The Organ Level

Two or more tissues working in combination to perform several functions○ Cardiac muscle tissue, in combination with

connective tissue from the bulk of the heart. The Organ System Level

Two or more organs interacting○ The heart and blood vessels work together to form

the cardiovascular system. The Organism Level

Highest level of organizationAll organ systems working together

Homeostasis

Homeostasis

One of the roles of the organ systems in an organism is to maintain homeostasis.

Homeostasis – maintaining a stable internal environment.Absolutely vital to survival

Homeostatic regulation – adjustment of physiological systems to preserve homeostasis.

Homeostasis

2 mechanisms of homeostasisAutoregulation (intrinsic regulation) – when

a cell, tissue, organ or organ system adjusts its activities automatically in response to an environmental change○ Ex: when blood oxygen levels decrease in a

tissue, the cells release a chemical that dilate local blood vessels. This increases blood flow and, therefore, oxygen.

Homeostasis

2 mechanisms of homeostasis (con’t)Extrinsic regulation – from activities of the

nervous and/or endocrine systems.○ Ex: During exercise, your nervous system

increases heart rate so that blood will circulate faster. Will also decrease blood flow to less active organs.

Homeostasis

The nervous system directs rapid, short-term, and very specific responsesResponse to placing hand on a hot stove

Endocrine system releases hormones that affect tissues and organs throughout the body.Not immediate, not specific, may be long-

term

Homeostasis

Homeostatic regulatory mechanism consists of 3 partsReceptor – sensor that is sensitive to a

particular change in environmentControl center – receives and processes

info from receptor and sends out commandsEffector – cell or organ that responds to the

commands from control center.

Similar to thermostat in your house

Homeostasis Negative feedback

Most regulatory mechanisms involve this opposition to changing conditions

Example is body temperature control (thermoregulation)○ Control center is the hypothalamus region of the brain○ Hypothalamus receives info from two receptors: skin

receptors and one in hypothalamus○ Normal body temp is 98.6o. If temp increases, the

control center targets two effectors: muscles in the walls of the blood vessels supplying the skinsweat glands

Homeostasis Negative feedback (con’t)

The muscles in the skin blood vessels relax, increasing blood flow to skin.

Sweat glands increase their secretionThe skin acts like a radiator by losing heat to the

environment○ Evaporation of sweat speed the process

As temp returns to normal, temp at hypothalamus declines, and the control center becomes less active

Blood flow and sweat production return to normal.

Homeostasis

There are variations in normal homeostatic levels between individuals95% of population has body temp between

36.7oC and 37.2oCPhysicians must keep this in mind when

treating patients.

Homeostasis Positive feedback

Produces a response that enhances the change in the original conditions.

Usually produces extreme responsesWhat if your thermostat was connected to your

heater instead of your air conditioner?○ What would occur if the temp in your house increased?

When temp exceeds set point, thermostat would turn on the heater, and it would continue to run until someone turned off the thermostat, heater, or intervened in some other way.

This escalating cycle is called a positive feedback loop

Homeostasis Positive feedback (con’t)

In your body, these loops are found when a potentially dangerous process must be completed quickly before homeostasis can be restored.○ Ex: immediate danger from a severe cut will

decrease blood pressure and reduce efficiency of the heart

○ The response is to clot the blood.○ Each step in the process accelerates the process

until a clot is formed Labor and delivery of a baby is another

example

Frames of Reference for Anatomical Studies

Frames of Reference for Anatomical Studies Early anatomists faced communication

problems.A “bump on the back” doesn’t give very

precise info about its location

Prominent anatomical structures serve as landmarks, distances are measured in centimeters, and specialized directional terms are used

Frames of Reference for Anatomical Studies Superficial Anatomy

Anatomical landmarks are used in reference to the anatomical position○ Anatomical position – hands at side, palms

facing forward, and feet together○ Descriptions given are in reference to the

anatomical position, unless otherwise notedProne – lying face down in the anatomical

positionSupine – lying face up in the anatomical

position

Frames of Reference for Anatomical Studies Anatomical Regions

Abdominopelvic quadrants○ Formed by a pair of lines that intersect at the

umbilicus (naval)○ Used by physicians to help determine possible

cause of aches, pains, injuries.○ Internal organs can be found in different

quadrantsAbdomiopelvic regions

○ More specific than quadrants○ Preferred by anatomists

Frames of Reference for Anatomical Studies Anatomical Directions

The terms left and light always refer to the left and right sides of the subject, NOT of the observer

Frames of Reference for Anatomical Studies Sectional Anatomy

Sometimes the best way to understand anatomy is to slice through it and look at the internal organization

Useful with imaging techniquesRadiologists use these when looking at films

Frames of Reference for Anatomical Studies Planes and Sections

Transverse plane – right angle to long axis of object, dividing it into superior and inferior○ A cut in this plane is called a transverse section

Frontal plane – parallel to long axis; extends from side to side, dividing the body into anterior and posterior○ A cut in this plane is called a frontal section

Sagittal plane – parallel to long axis; extends from front to back, dividing the body in to left and right○ A cut down the midline is called a midsagittal section○ Parallel cuts are called parasagittal sections

Frames of Reference for Anatomical Studies Body cavities

Internal chambers where many vital organs can be found

2 functions○ Protect organs○ Permit change of size and shape of the organs

Your diaphragm divides your torso into two cavities○ Thoracic cavity○ Abdominopelvic cavity

Viscera – organs enclosed (fully or partially) by these cavities

Frames of Reference for Anatomical Studies Body cavities (con’t)

Thoracic cavity○ Contains lungs and heart, associated organs

of respiratory, cardiovascular, and lymphatic system; lower esophagus; thymus

○ Boundaries are the ribs and diaphragm○ Subdivided into left and right pleural cavities,

which each contain a lung.○ Contains pericardial cavity, which surrounds

the heart

Frames of Reference for Anatomical Studies Body cavities (con’t)

Abdomiopelvic cavity○ Extends from diaphragm to pelvis○ Divided into a superior abdominal cavity and

an inferior pelvic cavity○ The peritoneal cavity surrounds the abdominal

and pelvic cavities

Frames of Reference for Anatomical Studies Body cavities (con’t)

Abdominal cavity contains the liver, stomach, spleen, small intestine, and most of the large intestine○ The kidneys and pancreas lie posteriorly

between the peritoneal cavity and the muscles of the abdominal cavity

The pelvic cavity contains distal large intestine, urinary bladder, and various reproductive organs