pathogens and immune response

What is a pathogen?

A pathogen is a disease causing organism.

List some ways diseases can be transmitted.

Contaminated Food, another Animal, dirty Water, Air, and direct physical Contact.

What does it mean if we are classed as unhealthy?

It suggests the presence of a disease.

What is a communicable disease?

A disease that can be transmitted from one person to another.

What is a non-communicable disease?

A disease that cannot be transmitted from one person to another.

Give examples of communicable diseases.

measles, mumps, rubella, malaria.

Give examples of non-communicable diseases.

cancer, heart attack, diabetes, asthma.

How is an immune response triggered?

Pathogens have unique antigens that the immune system recognises as harmful invaders.

What are antigens?

Unique components found on the surface of pathogens.

What types of white blood cells respond to pathogens?

lymphocytes or phagocytes.

What are the three ways the immune system responds?

Antibody production, Antitoxin production, Engulfing the pathogen (Phagocytosis).

How does antibody production work?

Antigens trigger lymphocytes to produce specific antibodies which destroy the pathogens.

What happens to lymphocytes after antibody production?

They duplicate and are stored as memory lymphocytes.

What is the benefit of memory lymphocytes?

They allow faster antibody production upon reinfection – the Secondary Response.

How does antitoxin production work?

Lymphocytes produce antitoxins that counteract toxins released by pathogens.

What is engulfing the pathogen also known as?

Non-specific immune response or Phagocytosis.

Describe the process of phagocytosis.

Pathogen is engulfed, forms a food vacuole, fuses with lysosomes, and is digested by phagocytes.

What is the definition of Homeostasis?

The self-regulating process by which organisms maintain internal stability despite external changes.

How do we achieve homeostasis?

Receptors detect stimuli, CNS processes it, Effectors respond.

What percentage of the human body is water?

60-70%.

How is water balance controlled?

By the endocrine system via negative feedback using the hypothalamus.

What is ADH?

Anti Diuretic Hormone.

Where is ADH released from?

The pituitary gland.

What does ADH do?

Controls kidney water reabsorption; more ADH means more water reabsorbed into blood.

How does the body respond to too little water in blood?

Hypothalamus signals pituitary to release more ADH; kidneys retain water; urine is concentrated.

How does the body respond to too much water in blood?

Hypothalamus signals less ADH; kidneys release more water; urine is dilute.

Where is blood plasma concentration monitored?

In the brain.

What happens if blood is too dilute?

More water is excreted in urine.

What happens if blood is too concentrated?

Less water is excreted in urine.

What affects the amount of water in the blood?

External temperature, exercise, intake of fluids and salts.

What are the kidneys’ main jobs?

Remove urea and maintain chemical balance including water.

How do kidneys filter blood and produce urine?

Nephrons filter blood; reabsorb useful substances; excrete waste as urine.

What is the optimum human body temperature?

37°C.

What monitors and controls body temperature?

The thermoregulatory centre in the hypothalamus.

How does the body respond when cold?

Shivering, raised body hairs, vasoconstriction, reduced sweating.

How does the body respond when hot?

Vasodilation, increased sweating, evaporation cools the body.

What are hormones?

Chemical messengers made by endocrine glands that act on target organs.

Example of a hormone and its target?

Adrenaline targets the heart to increase heart rate.

What happens to hormones after use?

They are destroyed by the liver.

How do hormones compare to nerves?

Slower acting but longer lasting effects.

What is the sequence of a nervous response?

Stimulus → Receptor → Sensory Neurone → CNS → Motor Neurone → Effector → Response.

What is the Central Nervous System (CNS)?

The brain and spinal cord.

Main brain parts and their functions?

Cerebral cortex (thinking), Medulla (automatic functions), Cerebellum (movement/balance).

What is a reflex arc?

A neurone pathway used by reflexes.

What are characteristics of reflexes?

Automatic, fast, brain-bypassing responses for protection.

What is a synapse?

A gap between neurones where impulses pass chemically.

How is an impulse passed across a synapse?

Neurotransmitters cross the gap, bind to receptors, triggering the next impulse.

Why do synapses exist?

To keep impulses flowing in one direction using chemical signaling.