Animal Systems: DEFENSEIntegumentary, Immune and

Lymphatic Systems

DEFENSE

These systems work to protect the body from pathogens. The integumentary system (skin) is the first barrier against infection, and any invading pathogens are destroyed and removed via the immune and lymphatic systems.

How do the integumentary, immune and lymphatic systems work together to defend the body?

• Integument – Latin “to cover”

Integumentary System

Functions of the Integumentary SystemPurpose: • Protection :• Protects deeper tissues (organs)• Blocks UV radiation• Prevents infectious agents from entering the body

• Aids in temperature regulation (sweat or shiver)

• Prevents dehydration • Produces Vitamin D – from

sunlight• Vitamin D increases

absorption of calcium for healthy bones

• Aids in excretion of wastes (salts)

• Sensory organ (heat, cold, pressure and pain receptors)

Functions of the Integumentary System cont.

Parts of the System: • Skin is composed of three layers: – Epidermis – outer layer, site of rapid cell division (mitosis),

production of keratin and melanin. • Melanocytes – give skin pigmentation and protect from UV rays

– Dermis – inner layer, contains major structures of skin– Collagen, blood vessels, nerve endings, glands, sensory receptors, hair follicles

– Subcutaneous fat – adipose tissue, provides insulation for body

Evolutionary Trends of Integumentary SystemAnimalTaxon Simple Invertebrates Vertebrates

Adaptations

Simple integumentary system used predominantly for diffusion. Diffusion allows movement of gases, nutrients, fluids, and wastes products in and out of the organism to maintain homeostasis.

More complex integumentary system. Used to maintain internal body temperature, fluid and salt levels. Contains nerve receptors, glands, subcutaneous fat, hair follicles to interpret environmental stimuli.

Picture of Adaptation

Some organisms contain structures such as feathers, scales,

and mucous glands for additional protection and support

Examples Jellyfish, Flat worms, Earthworms, Sponges Mammals, Reptiles, Amphibians, Fish, Birds

Simple Complex

Integumentary SystemLevels of Organization

Epidermis, Dermis

Skin

Integumentary

Epithelial Cells (skin cells)

Fun Fact: Believe it or not, the integumentary system is the largest organ system and your skin is the largest organ in your body.

Interaction with Other Body SystemsSkin is the first line of defense in the

immune system response.The circulatory system and skin

regulate body temperature.Skin and the excretory system

excrete water, urea, salts, and other wastes through sweat.

Receptors of the nervous system are located in skin.

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Dear 16-Year-Old Mehttp://www.youtube.com/watch?v=_4jgUcxMezM

Lymphatic SystemPurpose:1. Collects fluid lost by the blood during movement of nutrients into

body tissues and returns it back to the circulatory system.

2. Plays a role in the immune system by producing, storing and circulating white blood cells.

Network of vessels and associated organs:

1. lymph – fluid in lymph vessels

2. lymph vessels – move the lymph throughout the body

3. lymph nodes - densely packed areas of tissue that filter the lymph; white blood cells are stored in them

4. Tonsils, thymus and spleen are all composed of lymphoid tissue

tonsils – filter and destroy bacteria

thymus – produces hormones that aid in maturation of T-cells; T-cells

recognize foreign pathogens

spleen – removes worn-out red blood cells from circulatory system;

contains white blood cells that engulf and destroy bacteria.

The lymphatic system removes fluid from around cells and returns it to the blood.

When this fluid passes through the lymph nodes white blood cells attack and kill any pathogens.

To review:

Interactions with other Body SystemsLymphatic system works with the

circulatory system to maintain homeostasis of body fluids.

Lymphatic system plays a role in the immune system by producing white blood cells and destroying pathogens within lymph nodes and spleen.

The excretory system excretes excess fluids.

Immune System

Purpose: The immune system protects the body from disease by producing specialized cells that inactivate or destroy pathogens.

Parts of the System - consists of specialized cells and organs that respond to the presence of a pathogen

• skin – body’s first line of defense (also part of integumentary system)

• white blood cells – recognize disease agents (antigens) and create antibodies to tag and remove these antigens. Macrophages are the white blood cell type that

actually eat and destroy these antigens.

Macrophage of a mouse stretching its “arms” (pseudopodia) to engulf 2 pathogens

How the Immune System works:

1. First line of defense (pathogen does not enter body)

o Skin & other non-specific defenses such as mucous, saliva, and tears trap and destroy pathogens.

2. Second line of defense (pathogen enters body)

o If pathogen does enter the body, this triggers the inflammatory response – Tissue becomes swollen and painful due to white blood cell accumulation.

o Chemicals are released by immune system to cause fever (increased body temperature); increased temperature can kill some bacteria and viruses.

o White blood cells called macrophages engulf and destroy pathogens.

3. Third line of defense (pathogen gets past first and second line of defense)• Immune response

1. Triggered by an antigen; virus, bacteria or other pathogen.

2. T cells and B cells recognize the specific pathogen and produce antibodies that will help destroy

the invader and protect us the next time it enters the body. This process

is called immunity.

3. The reaction to a second infection by the same pathogen is much faster.

Antigen

Antibody

Antigen binding sites

Lymph nodes, bone marrow

Spleen, Liver

Lymph and Immune

White Blood Cells, B-cells, T-cells, macrophages

Lymph & Immune SystemLevels of Organization

**H.I.V. is the virus that causes AIDS, or acquired immune deficiency syndrome. It attacks a special T cell known as a helper T cell.

**Penicillin and other antibiotics can also be used to help the immune system, but it is important to remember that antibiotics only kill bacteria!

**Vaccines work by mimicking the body’s natural immune response. A small amount of the specially treated virus, bacterium or toxin (vaccine) is injected into the body. The body then makes antibodies. If a vaccinated person is exposed to the actual virus, bacterium or toxin, they won’t get sick.

Interactions with other Body SystemsSkin of the integumentary system is

the first line of defense of the immune system.

The circulatory system transports immune cells around the body.

Bones of the skeletal system produce lymphocytes and macrophages.