Chapter 1: The Human Organism

Anatomy

• investigates body structure

• the term means to dissect

Approaches to the study of anatomy:

Systemic: Studies body organ-systems

Regional: Studies body regions

Surface Anatomy

studies external features, for example,

bone projections

Anatomical imaging

using technologies (x-rays,

ultrasound, MRI)

Physiology

nvestigates processes and functions

Human Physiology

studies the human organism

Systemic Physiology

studies body organ-systems

Cellular Physiology

studies body cells

Levels of Organization

1. Chemical

2. Cellular

3. Tissues

4. Organs

5. Organ-Systems

6. Organism

Chemical

• Smallest level

• atoms, chemical bonds, molecules

Cellular

• cells: basic units of life

• compartments and organelles

• organelles perform particular functions for the cells

Tissues

• group of cells with similar structure and function plus extracellular

substances they release

• Characteristics of the cells and its surrounding materials

determines the function of the tissue

Four types of tissues

Epithelial

Connective

Muscular

Nervous

Organs

• two or more tissue types acting together to perform function(s)

Organ System

Group of organs contributing to some function

Organism

all organ systems working and are mutually dependent on each other

Characteristics of Life

• Organization

• Metabolism

• Responsiveness

• Development

• Reproduction

Organization

functional interrelationships between parts

Metabolism

• sum of all chemical and physical changes sustaining an

organism

• ability to acquire and use energy in support of these

changes

Responsiveness

• ability to sense and respond to environmental changes

• includes both internal and external environments

Growth

• can increase in size or numbers of cells

• size of cells, groups of cells, extracellular materials

Development

• changes an organism undergoes over time

• changes in cell structure and function from generalized to

specialized—differentiation

Reproduction

• formation of new cells or new organisms

• Allows for growth and development

Homeostasis

• maintenance of a relatively constant internal environment

despite fluctuations in the external or internal environment

• To maintain homeostasis, the body must actively monitor

and respond to changes.

• The body’s organ systems work together to maintain _____, while disease can disrupt these processes and disturb it

Homeostasis Variables

• measures of body properties that may change in value,

but must be maintained within a narrow range

• examples: body temp, fluid volume, chemical content, pH

Normal Range

normal extent of increase or decrease

around a set point

Set Point

normal, or average value of a variable

Components of a Feedback Loop

1. Receptor

2. Control Center

3. Effector

Receptor (FL)

detects changes in variable

Control Center (FL)

• receives receptor signal

• establishes set point

• sends signal to effecto

Effector

directly causes change in variable

Negative Feedback

the main mechanism used

homeostatic regulation.

A negative feedback response involves:

• detection of deviation away from set point

• Correction by reversal of deviation toward set point

• return to set point and normal range

• The correction stops once the set point to achieved

Positive Feedback

mechanisms occur when the initial stimulus moves further from the set point

a positive feedback response involves

• system response causes progressive deviation away from

the set point, outside of normal range

• the response continues until the stimulus is removed

• some positive feedback occurs under normal conditions

Example: childbirth, blood clotting

• generally associated with injury, disease

• negative feedback mechanisms unable to maintain

homeostasis

Anatomical Position

person standing erect with face forward, arm hanging to

the sides, and palms forward

Supine

Lying face upward

Prone

lying face downward

Superior

above

Inferior

Below

Anterior (ventral)

front

Posterior (dorsal)

back

Medial

close to midline

lateral

away from midline

proximal

close to point of attachment

distal

far from point of attachment

superficial

structure close to the surface

deep

structure toward the interior of the body

upper limbs

upper arm, forearm, wrist, hand

lower limbs

thigh, lower leg, ankle, foot

central region

head, neck, trunk

trunk divided into…

thorax, abdoomen, pelvis

divisions of the abdomen (quadrants)

right upper, left upper

right lower, left lower

abdomen regions

• Left hypochondriac, epigastric, right hypochondriac

• Left lumbar, umbilical, right lumbar

• Left iliac, hypogastric, right iliac

upper abdomen

right hypochondriac, epigastric, left hypochondriac

middle abdomen

right lumbar, umbilical, left lumbar

lower abdomen

right iliac, hypogastric, left iliac

sagittal plane

separates the body into right and left parts

median (midsaggital) plane

a sagittal plane along the

midline that divides body into equal left and right halves

Transverse (horizontal) Plane

a horizontal plane that

separates the body into superior and inferior parts.

Coronal (frontal) plane

a vertical plane that separates

the body into anterior and posterior parts.

dorsal body cavity

Encloses the organs of the nervous system

cranial cavity

Contains the brain

Vertebral Canal:

Contains the spinal cord

ventral body cavity

Contains the majority of internal organs (viscera)

Divided into:

• Thoracic cavity

• Abdominopelvic cavity

abdominopelvic cavity

• Abdominal cavity

• Pelvic cavity

thoracic cavity

• Space superior to the diaphragm

• Divided into two lateral pleural cavities that contain lungs,

and the mediastinum

mediastinum

• space between lungs

• contains heart and its major blood vessels, thymus gland,

esophagus, trachea

abdominal cavity

• space between diaphragm and pelvis

• contains stomach, intestines, liver, spleen, pancreas,

kidney

pelvic cavity

• space within pelvis

• contains urinary bladder, reproductive organs, part of large

intestine

• No physical boundary between the abdominal and pelvic

cavities

Serous Membranes of the Ventral Body Cavity

Line trunk cavities, cover organs in the ventral body cavity.

visceral serous membrane

covers organs

parietal serous membrane

lines the walls of the cavities

cavity

a fluid-filled space between the membranes

Pericardial Cavity

around the heart

mb name: pericardium

Pleural Cavity

around lungs

mb name: pleura

peritoneal cavity

around abdominopelvic cavity and its organs

mb name: peritoneum

visceral pericardium

covers heart

parietal pericardium

thick, fibrous

pericardial cavity contains__

pericardial fluid that reduces friction

pericarditis

inflamattion of the serous membrane (pericardium)

visceral pleura

covers lungs

parietal pleura

lines inner walls of thorax

pleural cavity with pleural fluid

• reduces friction

• adheres lungs to thoracic wall

pleurisy

inflammation of the serous membrane (pleura)

visceral peritoneum

• covers, anchors organs

• double layers called mesenteries that provide a pathway for nerves

and blood vessels

parietal peritoneum

lines inner wall of abdominopelvic

cavity

peritoneal cavity with peritoneal fluid

reduces friction

retroperitoneal

Some organs or parts of organs behind the

peritoneum

peritonitis

Inflammation of the serous membrane (peritoneum)