Health science 5/6/2026

What is the function of the immune system?

To protect us from bacteria, viruses, and other harmful invaders by using types of white blood cells.

What are the first four lines of defense?

• skin

• tears/saliva

• mucus

• stomach acid

What are the second lines of defense?

• white blood cells

• inflammation

• fever response

What do white blood cells do?

They protect the body from germs by either hunting/eating them, attacking them, and destroying infected cells. They also help coordinate the body’s overall response

Antigens

Markers on germs that act like an ID tag for the immune system

Antibodies

Proteins specifically made to identify and attack those antigens

What is the third line of defense?

Memory Immunity

Purpose of vaccines

Use weakened or inactive parts of germs to trigger a response. This helps your body create more antibodies safely before you encounter the live germ

Allergies

An overreaction to harmless substances like pollen or food

Autoimmune diseases

A condition where the immune system mistakenly attacks the body’s own cells

How to keep your immune system healthy

• eat healthy foods

• exercise regularly

• stay up to date on vaccines

• sleep 8-10 hours

• wash hands often

Lymphatic system

A network of tissues, vessels, and organs that move lymph back to your bloodstream

Lymph

A clear, watery fluid that circulates through the lymphatic system that supports immune function and fluid balance

What is the composition of a lymph?

It contains white blood cells, proteins, and salts. It transports pathogens to “trash centers” for destruction

3 Main functions of lymph

• Fluid balance

• absorption

• immune defense

Lymph Nodes

“The filters”- small, bean shaped structures that filter out germs and waste

Where are lymph nodes clusters found

Neck, armpits, and groin

Spleen

• The largest lymphatic organ

• It filters blood(not lymph)

• destroys old red blood cells

Thymus

• Located in the chest

• It's where “T-cells(immune cells) go to “school" to learn how to fight germs

Tonsils and Adenoids

These are the clusters of lymphatic tissues in the throat area that act as a first line of defense. They trap pathogens(germs) that you breath in or swallow before they can get deeper in your body

Lymphedema

Swelling caused by a blockage in the lymph vessels

Lymphoma

A type of cancer that starts in the lymphatic system

Lymphangitis

Red streaks on the skin that can indicate a lymph vessel infection

What are white blood cells?

(Leukocytes) are part of the immune system and they help the body fight off infections, remove damaged cells, and protect against disease

Neutrophils

• engulf and digestive pathogens(phagocytosis)

• First responders

Lymphocytes

Targeted(adaptive) immune response

B Cells

Produce antibodies to neutralize pathogens

Helper T cells

Coordinate and activate other immune cells

Cytotoxic T Cells

Kill infected or abnormal cells

Natural Killer(NK) cells

Destroy virus-infected and cancer cells

Eosinophils

• Parasite defense and allergies

Basophils

• Inflammation and allergic response

Functions of the Urinary system

• Filtration- oxygen exchange producing metabolic waste and kidney turn it into urine

• Waste & storage excretion- bladder stores urine until its excreted

• Hormone Production-Erythropoietin and Calcitriol produced

• Homeostasis maintenance- monitor/adjust blood volume & pressure, control pH levels in the blood, and regulate fluid & electrolyte balance

Nephron

• Where filtration occurs

• Microscopic functional unit of the kidney where the filtration, reabsorption and secretion occur

Where does the blood enter in a nephron?

It enters a cluster of capillaries called the glomerulus , which is surrounded by Bowman’s capsule

What is the function of the glomerulus?

It allows water, salt, sugar and urea to leave the blood stream and prevent blood cells and vital proteins from filtering out

What is attracted to Bowman’s capsule and what's its function?

A renal tubule is attached and its where the waste or filtrate passes on to and where reabsorption occurs

Reabsorption

The blood reclaims useful substances from filtrate( water, sugar, vitamins, minerals, and salts)

limit rule- if blood levels exceed certain limits, these substances will not be absorbed.

Secretion

Waste products move into tubules for excretion(urine, creatinine, excess water)

Urine composition- 95% water and 5% waste products

Ureters

• Two narrow tubes that transport urine from the renal pelvises of the kidneys to the bladder

• Urine moves through ureters by way of gravity and peristalsis

Urinary bladder

A hollow muscular organ that serves as a reservoir for urine until it’s expelled

Urethra

The tube that transports urine from the bladder to the outside of the body

• before exciting of the body, urine passes through two urethral sphincters composed of muscle tissue and control the flow of urine

Internal sphincter

• Located near bladder neck

• under voluntary control

External Sphincter

• Located closer to the end of the urethra

• under voluntary control

Renal Failure

Caused by accidents, toxic agents, genetic diseases , illnesses

Dialysis

Cleansing of blood; replaces normal kidney function of removing wastes and balancing fluid

Hemodialysis

Patient visits clinic for treatment and the medicine is hooked up by vein shunt

• Mechanical filtration system cleanses blood

• Treatment time: 5 hours, 2-3 times a week

Peritoneal dialysis

Patient is hooked up to bad of osmotic solution via catheter

• catheter is implanted into abdominal cavity

• Osmotic solution flows into peritoneal cavity