Chapter 1 – Introduction to anatomy and physiology

A new language

Anatomical Position

Body erect feet slightly apart palms facing forward thumbs point away from

body

The new language – anatomical position The anatomical position is

extremely important in studying anatomy since it is universal.

This allows professionals to easily communicate with each other, even if they are from different countries or backgrounds

Regardless of the patient body position – you ALWAYS refer to anatomical position

Other concepts you need to know if you want to speak the language

(you’ll do most of it in the lab)

Body planes Dorsal and ventral cavities Abdominopelvic quadrants and 9 regions Organ systems Membranes

Overview of Anatomy and Physiology Anatomy – the study of the structure of body parts and their

relationships to one another Gross or macroscopic – large visible body structures (heart,

lungs, kidney etc.) Different ways to approach gross anatomy:

Regional – study of all the structure in a particular region of the body (leg, abdomen etc.)

Systemic – study a particular system at a time. Microscopic – deals with structures that are too small to be seen

with the naked eye Cytology – relates to the cells Histology – study of the tissues

Physiology – the study of the function of the body

Specialized Branches of Anatomy

Pathological anatomy – study of structural changes caused by disease

Radiographic anatomy – study of internal structures visualized by specialized scanning procedures such as X-ray, MRI, and CT scans

Molecular biology – study of anatomical structures at a subcellular level

Keep in mind......... Anatomy explains physiology

Form and function are interrelated

The function and process

Those are 2 related topics of physiology The function of a physiological system is the “why” of a

system event Why does the system exist and why does the event

happen? Why red blood cells transport oxygen? They do so because the cells need oxygen to

survive The process is “how”

How do the RBC transport the oxygen? The oxygen binds to hemoglobin

The levels of organization in the body, with the four primary tissue types

EXTRACELLULARMATERIAL

AND FLUIDS

CELLS

combineto form

TISSUEScombineto form ORGANS

interactin ORGAN SYSTEMS

EPITHELIAL TISSUE CONNECTIVE TISSUE MUSCLE TISSUE NEURAL TISSUE

2401

2402

Necessary Life Functions Maintaining boundaries – the internal environment

remains distinct from the external environment Cellular level – accomplished by plasma

membranes Organismal level – accomplished by the skin

Survival Needs

Nutrients – needed for energy and cell building Oxygen – necessary for metabolic reactions Water – provides the necessary environment for

chemical reactions (60-8% of body weight) Normal body temperature – necessary for chemical

reactions to occur at life-sustaining rates (why is it important to maintain core body temperature?)

Atmospheric pressure – required for proper breathing and gas exchange in the lungs

Some environments in our body – fluid compartments Fluids in the body are compose of water and solutes There are 2 distinct fluid compartments

Intracellular fluid (ICF) The cytosol of cells Makes up about two-thirds of the total body water

Extracellular fluid (ECF) Major components include the plasma and lymph Minor components include all other extracellular

fluids (water in dense CT, bone, fluid between visceral and parietal membranes.)

Cations and Anions in Body Fluids

Homeostasis Homeo – unchanging + stasis – standing The ability to maintain a relatively stable internal

environment in an ever-changing outside world The internal environment of the body is in a

dynamic state of equilibrium – it is not a precise value

Homeostatic regulation is the adjustment of physiological systems to preserve homeostasis

It happens in an environment that is inconsistent, unpredictable and at times – dangerous

Important components of homeostasis in the ECF*Normal range Approximate

short-term nonlethal limit

units

Oxygen 35-40 10-1000 mmHgCarbon dioxide 35-45 5-80 mmHgSodium ions 138-146 115-175 mmol/LPotassium ions 3.8-5.0 1.5-9.0 mmol/LCalcium ions 1.0-1.4 0.5-2.0 mmol/LChloride ions 103-112 70-130 mmol/LBicarbonate ions 24-32 8-45 mmol/LGlucose 75-95 20-1500 Mg/dlBody temperature 98-98.8 (37.0) 65-110 (18.3-

43.3)0F (0C)

Acid-base 7.3-7.5 6.9-8.0 pHMedical Physiology – Guyton and Hall, 11th ed.

Maintaining homeostasis involves cooperation between systems

Homeostatic imbalances If the body fails to maintain homeostasis it may result in a

disease or pathological condition Diseases divide into 2 groups according to their origin:

Internal failure of normal physiological process Abnormal cell growth, Production of antibodies

against the body’s own tissues, Premature cell death, Inherited disorders

External sources Toxic chemicals, Trauma, Foreign invaders

Local and long-distance control pathways Local / autoregulation/ intrinsic control – in the cell or

tissue – autocrine or paracrine mechanisms (CO2 levels in the tissue influence diameter of local capillaries)

Long distance control/extrinsic involves the nervous and endocrine systems.

The long distance neural control involves 3 components – sensor, integration center and effector

The endocrine cells receive the stimulus directly and respond by releasing hormones (will be discussed in APII).

Homeostatic control Some aspects of control systems:

Tonic control – maintaining “moderate activity” –

example – blood vessel diameter. Tonic control is not

stopping or starting activity (similar to turning radio

volume louder or softer)

Antagonistic control – for systems that are not under

tonic control either by hormones or the nervous system

(insulin and glucagon, sympathetic and parasympathetic)

Tonic control

Homeostatic Control Mechanisms components

The three components of control mechanisms: Sensory receptor (NOT a membrane receptor) –

monitors the environments and responds to changes (stimuli)

Control center – determines the set point at which the variable is maintained

Effector – provides the means to respond to stimuli

Pathways – afferent (sensory) and efferent (motor)

Homeostatic Control Mechanisms

Change detected by receptor

Stimulus: Produces changein variable

Input:Informationsent along afferentpathway to

Receptor (sensor) Effector

Controlcenter

Variable (in homeostasis)

Response ofeffector feedsback toinfluencemagnitude ofstimulus andreturns variableto homeostasis

Output:Information sentalong efferentpathway to

2

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1

Figure 1.5

Signalwire turnsheater on

Signalwire turnsheater off

Response;temperaturerises

Response;temperaturedrops

Stimulus: rising roomtemperature

Stimulus: dropping roomtemperature

Balance

Effector(heater)

Effector(heater)

Setpoint

Control center(thermostat)

Heateroff

Setpoint

Receptor-sensor(thermometer inThermostat)

Control center(thermostat)

Heateron

Imbalance

Imbalance

Receptor-sensor(thermometer inThermostat)

Positive Feedback

In positive feedback systems, the output enhances or exaggerates the original stimulus

Body is moved away from homeostasis

Normal range is lost

Used to speed up processes Positive feedback is also known as a “vicious cycle” – if

not stopped can lead to death

Figure 1.6

Positive feedback is NOT homeostatic process