Fluid Balance
Balance:

Fluid Balance:


Electrolyte Balance:


When the water coming into the body precisely
equals the water being lost by the body each day.
Gains and losses of electrolytes are equal.
Acid-base balance:

When the production of H+ is precisely offset by
H+ loss and/ or HCO3- production.
Overall body composition:
Ionic composition of body fluids:
Electrolyte balance:
Acid-base balance
Respiratory acid-base
regulation
Metabolic acid-base
regulation
The Integumentary System: An
Overview
Integumentary system functions:






Protection
Excretion
Temperature maintenance
Nutrient storage
Vitamin D3 synthesis
Sensory detection
The integumentary system consists
of

Cutaneous membrane
Epidermis
 Dermis



Accessory structures
Subcutaneous layer
The Components of the
Integumentary System
Thin Skin and Thick Skin

The epidermis is composed of layers of
keratinocytes
Thin skin = four layers (strata)
 Thick skin = five layers

The epidermis



Provides mechanical protection
Prevents fluid loss
Keeps microorganisms from invading the body
Layers of the epidermis:





Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum (found in thick skin only)
Stratum corneum
The Epidermal Ridges of Thick
Skin
Figure 5.3
Epidermal characteristics:


Cells accumulate keratin and eventually are shed
Epidermal ridges are interlocked with dermal
papillae
Fingerprints
 Improve gripping ability



Langerhans cells (immunity) in s. spinosum
Merkel cells (sensitivity) in s. germinativum
The Structure of the Epidermis
Skin color depends on


Blood supply
Carotene and melanin


Melanocytes produce melanin and protect from UV
radiation
Epidermal pigmentation

Interrupted blood supply leads to cyanosis
Melanocytes
Epidermal cells


Synthesize vitamin D3 (cholecalciferol) when
exposed to UV
Respond to epidermal growth factor
Growth
 Division
 Repair
 Secretion

Dermal Organization

Papillary layer


Contains blood vessels, lymphatics, sensory nerves of
epidermis
Reticular layer

Contains network of collagen and elastic fibers to resist
tension
Dermal Circulation and
innervation


Cutaneous plexus arteries found in
subcutaneous layer/ papillary dermis
Cutaneous sensory receptors (light touch,
pressure)
Stretch marks


Caused by excessive stretching of the dermis
Patterns of collagen and elastic fibers form lines
of cleavage
Lines of Cleavage of the Skin
Hypodermis

Stabilizes skins position against underlying
organs and tissues
Hairs





Originate in hair follicle
Composed of root and shaft
Root base (hair papilla) surrounded by hair bulb
and root hair plexus
Hairs have soft medulla and hard cortex
Cuticle = superficial dead protective layer
Hair types



Vellus hairs (peach fuzz)
Terminal hairs ( heavy)
Club hair (cessation of growth)

Shed and grow according to hair growth cycle
Arrector pili muscle attaches to hair
The Anatomy of a Single Hair
Hair Follicles
Glands in the skin




Sebaceous (oil)
Suderiferous (sweat)
Mammary
Ceruminous
Sebaceous glands


Discharge waxy sebum onto hair shaft when
associated with hairs
Sebaceous follicles discharge onto epidermal
surface
Sebaceous Glands and Follicles
Suderiferous glands

Apocrine sweat glands


Produce odorous secretion
Merocrine (eccrine) sweat gland

Sensible perspiration
Figure 5.12 Sweat Glands
Figure 5.12a, b
Other glands

Mammary glands


Structurally similar to apocrine sweat glands
Ceruminous glands

In ear, produce waxy cerumen
Nails




Nail body covers the nail bed
Nail production occurs at the nail root
Eponychium (cuticle) overlies root
Free edge of nail extends over hyponychium
The Structure of a Nail
Injury and repair


Regenerates easily
Regeneration process includes formation of
Scab
 Granulation tissue
 Scar tissue

Integumentary Repair
Integumentary Repair
With age




Integument thins
Blood flow decreases
Cellular activity decreases
Repairs occur more slowly