Lesson 2: Body Structures & Organ Systems

Epithelial Tissue

• covers external body surfaces & lines internal body cavities, forming barriers & glands & playing roles in absorption & secretion

• can be single, multi layer, or glandular

• epithelial gland types

  • endocrine gland

  • exocrine gland

  • sweet gland

Connective Tissue

• supports, protects, & binds organs to hold organs in place in their body cavities

• includes cartilage, blood, bone, adipose tissue

Muscle Tissue

• contracts to allow body to move

• includes skeletal, cardiac, & smooth muscles

Nervous Tissue

• composes brain, spinal cord, nerves

• carries messages throughout the body to direct its activities

Anatomy

study of body structure

Physiology

study of body function

Pathology

study of disease

Level of Organization

chemicals > molecules > cells > tissues > organs > organ systems > organism

Which body systems are involved in protection, support, & movement?

Integumentary, Skeletal, Muscular

Which body systems are involved in coordination & control?

Nervous, Endocrine

Which body systems are involved in circulation & immunity?

Cardiovascular, Lymphatic

Which body systems are involved in energy supply & fluid balance?

Respiratory, Digestive, Urinary

Which body systems are involved in production of offspring?

Reproductive

Integumentary System

• skin and associated structures (oil glands, sweat glands, hair, nails)

• protection, sensory perception, temperature regulation

Skeletal System

• bones & joints

• support, protection, movement

Muscular System

• skeletal muscles

• movement, support, protection, heat generation

Nervous System

• brain, spinal cord, nerves

• sensory perception, coordination & control of responses, memory, language skills, reasoning

Endocrine System

• endocrine glands

• secretion of hormones that regulate growth, metabolism, behavior, reproduction

Cardiovascular System

• heart & blood vessels

• supply of oxygen & nutrients to tissues, removal of metabolic waste

Lymphatic System

• lymphatic vessels & nodes

• aid in circulation, immunity, & transport of digested fats

Respiratory System

• lungs & breathing passages

• ventilation of lungs & exchanges of oxygen and carbon dioxide between the body & the atmosphere

Digestive System

• digestive organs from mouth to anus, including esophagus, stomach, intestine; accessory organs (salivary glands, liver, gallbladder, pancreas)

• food intake, breakdown of good into usable nutrients, absorption of nutrients into the circulation, & elimination of undigested waste

Urinary System

• kidneys and organs that transport and store urine: ureters, bladder, urethra

• elimination of soluble waste materials and water

Reproductive System

• sex glands (ovaries, testes) and organs associated with transport of germ cells (eggs, sperm) and gestation (uterus)

• production of offspring

Aging Effects

• Gradual changes occur in all body system

• Some changes are harmless (wrinkles & gray hair)

• Some changes may result in injury and disease

  • Decreased kidney function

  • Loss of bone mass

  • Formation of deposits within blood vessels

Homeostasis

• Body’s maintenance of internal balance

• Regulated variables must be kept with a narrow range

  • Body temperature

  • Volume and composition of body fluids

  • Blood levels of oxygen and carbon dioxide

  • Blood pressure

Negative Feedback

• keeps body conditions within a normal range by reversing any upward or downward shift

• components of a negative feedback loop are sensor, control center and effector

  • Sensor measures the level of the variable

  • Control center compares sensor inputs with set point

  • Effector increases or decreases activity to alter the level of the regulated variable.

  • Signals carry information between the components.

Barriers

• Maintain distinct environments.

  • Plasma membrane separates the intracellular and extracellular fluids.

  • Skin/mucous membranes separate the inside of the body from the outside.

Flow

• The movement of a substance from one area to another

• Examples: blood flow, diffusion, air flow

Gradient

• A difference in a specific physical or chemical value between two areas

• Examples: pressure, temperature, concentration

Resistance

• Factors that inhibit flow down a gradient

• Examples: barriers, friction

Standard Anatomical Position

• standardized posture used as a reference point in the medical and anatomical sciences to describe the locations and relationships of body parts to each other. In this position, the body stands upright and faces forward

  • feet: slightly apart & flat on ground, pointing forward

  • arms: positioned at sides w/ palms facing forward, placing thumbs outward

  • head & eyes: facing forward, maintaining level gaze

  • torso: upright & facing forward, aligning w/ head & lower limbs

• ensures clarity and consistency across various medical fields

• eliminates ambiguity in the description of body parts, making it easier for professionals to communicate about physical examinations, surgical procedures, and anatomical analysis

Directional Terms

• used to describe the locations of structures in relation to each other

Superior (Cranal)

• body part located above or toward the head end of the body

• ex: chest is superior to the abdomen

Inferior (Caudal)

• opposite to superior, refers to a body part that is below or toward the feet

• ex: stomach is inferior to the chest

Anterior (Ventral)

• refers to the front or forward part of the organism

• for a human in the standard anatomical position, the chest is on the anterior side

Posterior (Dorsal)

• describes the back or direction toward the back of the body

• ex: spine is posterior to the chest

Medial

• something is closer to the midline or median plane of the body, which divides the body into left and right halves

• ex: heart is medial to the lungs

Lateral

• opposite of medial, away from the midline of the body

• ex: arms are lateral to the chest

Proximal

• used in reference to the limbs and denotes a position in a limb that is nearer to the point of attachment or the trunk of the body

• ex: elbow is proximal to the wrist

Distal

• Opposite of proximal, further from the point of attachment or further from the trunk

• ex: fingers are distal to the elbow

Superficial (External)

• position closer to or on the surface of the body

• ex: skin is superficial to the muscles

Deep (Internal)

• something that is more internal or closer to the core of the body than another structure

• ex: lungs are deep to the rib cage

Central

• denote the center of the body or a body part

• ex: central nervous system refers to the brain and spinal cord which are central to the body’s functions

Peripheral

• occurring or located away from the center

• often refers to the nerves and blood vessels that are not central

Ipsilateral

• structures occurring on the same side of the body

• ex: right arm injury and a right leg injury are ipsilateral

Body Planes & Sections

• imaginary lines drawn through the human body to specify the spatial relationships of structures and to guide dissection and medical imaging

• allows healthcare professionals to describe the location of injuries or diseases accurately, conduct precise medical interventions, and interpret medical images correctly

Frontal (Cronal Plane) [front & back]

• runs vertically but divides the body into anterior (front) and posterior (back) sections

• runs perpendicular to the sagittal plane and parallel to the face

• used to view the front and back parts of the body and is often used in both clinical and diagnostic settings, such as in X-rays or CT scans to examine the chest or abdominal cavities

Sagittal Plane [left & right]

• runs vertically through the body, dividing it into right and left sections

• if it divides the body into two symmetrical halves, it is called the median or midsagittal plane

• any sagittal plane that does not pass through the midline and divides the body into unequal right and left sides is called a parasagittal plane

• used in imaging techniques to view lateral sections of the body, such as in MRIs or during neurological examinations to assess the left and right hemispheres of the brain

Transverse (Horizontal) Plane [Up & Down]

• runs horizontally from right to left, dividing the body into superior (upper) and inferior (lower) parts

• perpendicular to both the sagittal and frontal planes

• essential in cross-sectional imaging, frequently utilized in CT scans and MRI to provide a cross-section view of the body, particularly useful for examining structures in the abdomen and chest

Body Cavities

• body is organized into major compartments that help protect internal organs and allow them to function properly. These are primarily divided into the dorsal (posterior) and ventral (anterior) cavities

Dorsal Cavity

• Located along the body's back, houses the brain and spinal cord within the cranial and vertebral canals, respectively, forming the central nervous system's protective enclosure

Ventral Cavity

• situated at the front, the ventral cavity includes the thoracic cavity and the abdominopelvic cavity

• provides a flexible space that accommodates the expansion and contraction of organs

• crucial for organ protection and function, enabling organs like the heart, lungs, and stomach to operate without impacting each other or surrounding tissues

• structural organization is fundamental for understanding how the body functions in health and in medical treatments

Thoracic Cavity

• Contains the heart and lungs, protected by the ribcage yet flexible enough to allow for breathing and heartbeats

Abdominopelvic Cavity

• encompasses the abdominal and pelvic areas, housing organs like the stomach, intestines, liver, bladder, and some reproductive organs

• supports digestive, excretory, & reproductive functions by allowing organs to change size and shape during their activities

9 Abdominal Cavity Regions

• subdividing the abdominopelvic cavity using two horizontal and two vertical lines

  • horizontal lines: upper horizontal line (subcostal line) is drawn just below the ribs, and the lower horizontal line (transtubercular line) is drawn just above the pelvis

  • vertical lines: lines drop vertically from the midpoint of each clavicle (collarbone), typically aligning with the nipples in a forward-facing individual

4 Abdominal Cavity Quadrants

• useful in emergency settings or initial evaluations, where a quick determination of the location of pain, discomfort, or other symptoms is necessary

• single vertical line and a single horizontal line intersect at the umbilicus (navel), dividing the abdomen into four quadrants

  • left upper quadrant (LUQ)

  • right upper quadrant (RUQ)

  • left lower quadrant (LLQ)

  • right lower quadrant (RLQ)

Oblique Plane

• planes pass through the body at an angle

• not parallel to the standard sagittal, coronal, or transverse planes

• particularly useful in surgical procedures or imaging techniques that require a more specific angle to better view or treat a particular area

• each plane offers a unique perspective and is chosen based on the specific diagnostic or therapeutic needs of the medical situation

Anatomical Body Movements

Flexion

• Bending a body part or decreasing the angle of a joint

• Straightening a body part or increasing the angle of a joint

Hyperextension

• Extending a body part past the normal anatomical position

Dorsiflexion

• Pointing the toes up

Plantar Flexion

• Pointing the toes down

Abduction

• Moving a body part away from the midline of the body

Adduction

• Moving a body part toward the midline of the body

Rotation

• Twisting a body part—for example, turning your head from side to side

Circumduction

• Moving a body part in a circle—for example, moving your arm in a circular motion

Pronation

• Turning the palm of the hand down or lying face down

Supination

• Turning the palm of the hand up or lying face-up

Inversion

• Turning the sole of the foot medially

Eversion

• Turning the sole of the foot laterally

Retraction

• Moving a body part posteriorly

Protraction

• Moving a body part anteriorly

oste/o

bone

myo

muscle

neur

nerve

derm

skin

cardi/o

heart

vasc/o

veins & arteries

hem/o or sangu

blood

angi/o

blood vessels

ven/o or phleb/o

veins

aort

aorta

cardi/o

arteri/o

arteries

enceph

brain

rhino

nose

myringo or tymphan

eardrum

odont or dento

tooth

crani

skull

opthalm or oculo

eye

oto

ear

lingu

tongue

hepat/o

liver

cholecyst

gallbladder

esoph/a

esophagus

colo

large intestine

gastr/o

stomach

ileo

small intestine