Brain Anatomy and Function

• The brain processes sensory information, controls motor functions, and manages higher cognitive functions like thinking, memory, and emotion.

Brain Parts and Functions

• The cerebrum is the largest part of the brain and controls thinking, decision-making, movement, and emotions.
• The cerebellum coordinates voluntary muscle movements and helps with balance and motor control.
• The medulla (brainstem) controls vital, involuntary functions like breathing, heart rate, and blood pressure.

Brain Lobes and Functions

• The frontal lobe, located at the front of the brain, is responsible for reasoning, planning, movement, and problem-solving.
• The parietal lobe, located at the top of the brain, processes sensory information related to touch, temperature, and spatial awareness.
• The occipital lobe, at the back of the brain, is primarily responsible for processing visual information.
• The temporal lobe, located on the sides of the brain, is involved in auditory processing, memory, and emotional responses.

Hormones

• Hormones are chemical messengers produced by endocrine glands.
• Hormones are released into the bloodstream and travel to specific target cells, where they bind to receptors.
• This binding triggers changes in the target cells, such as altering metabolism, growth, or mood.
• Hormones regulate body functions, from growth and development to immune response and energy balance.

Homeostasis

• Homeostasis is the process by which the body maintains a stable internal environment despite external changes.
• An example of homeostasis is temperature regulation, where the body keeps its temperature around 37°C (98.6°F) through sweating or shivering.
• Maintaining a constant internal environment ensures optimal cell function and overall health.

Blood Glucose Regulation

• The pancreas regulates blood glucose levels.
• High glucose levels trigger the pancreas to release insulin, which helps cells absorb glucose and lowers blood sugar.
• Low glucose levels trigger the pancreas to release glucagon, which signals the liver to release stored glucose into the bloodstream to restore balance.

Disease

• Disease is a condition that disrupts the normal functioning of the body, caused by pathogens (infectious) or other factors like genetics and lifestyle (non-infectious).
• Symptoms are physical or physiological signs that indicate illness, such as fever, fatigue, pain, or swelling.
• Transmission is the way a disease spreads from one organism to another, including direct contact, airborne particles, bodily fluids, or contaminated food and water.

Infectious vs. Non-Infectious Diseases

• Infectious diseases are caused by pathogens such as bacteria, viruses, fungi, or parasites, and can be transmitted between people (e.g., flu, COVID-19, tuberculosis).
• Non-infectious diseases are not caused by pathogens and cannot be transmitted between people, resulting from genetic factors, lifestyle choices, or environmental conditions (e.g., diabetes, cancer, heart disease).

Pathogens and Disease

• Bacteria are single-celled organisms that can reproduce on their own and release toxins that damage tissues (e.g., tetanus, strep throat).
• Viruses are non-living particles that invade host cells and take over their machinery to replicate, destroying cells (e.g., flu, HIV, COVID-19).
• Fungi are organisms like molds and yeasts that can infect the skin, nails, or internal organs, thriving in warm, moist environments (e.g., athlete’s foot, ringworm).

Lines of Defence

• The body has three levels of defence against pathogens.
• The first line of defence involves physical and chemical barriers that prevent pathogens from entering.
• The second line of defence involves non-specific immune responses, such as inflammation and white blood cells, that fight off invaders.
• The third line of defence involves specific immune responses using B cells and T cells to target and eliminate pathogens.

Specific vs. Non-Specific Immunity

• Non-specific immunity (innate immunity) provides general protection against all pathogens, including barriers like skin and immune responses like inflammation and phagocytosis.
• Specific immunity (adaptive immunity) targets particular pathogens using specialized cells (B cells and T cells) and memory cells that remember past infections for faster future responses.

Components of the First Line of Defence

• Physical barriers include skin, mucus, and cilia, preventing pathogens from entering.
• Chemical barriers include stomach acid, saliva, and tears, which contain enzymes that destroy microbes.
• Biological barriers include beneficial bacteria on the skin and gut, which outcompete harmful microbes.

Fever and Inflammation

• Fever raises body temperature to slow down pathogen reproduction and boost immune cell activity.
• Inflammation increases blood flow to infected areas, bringing white blood cells to fight infections and remove damaged cells.

Phagocytes

• Phagocytes (like macrophages and neutrophils) engulf and digest pathogens through phagocytosis.
• They recognize foreign invaders, break them down, and alert other immune cells to mount a response.

Disease Control

• Disease can be controlled through hygiene (washing hands, clean drinking water).
• Vaccination stimulates immunity against specific diseases.
• Antibiotics & Antivirals treat bacterial and viral infections.
• Quarantine & Social Distancing reduces the spread of contagious diseases.
• Insect Control reduces mosquito populations to prevent malaria.

B Cells and T Cells

• B cells produce antibodies that bind to and neutralize pathogens; some become memory cells for long-term immunity.
• T cells directly attack infected cells (killer T cells) or help activate other immune cells (helper T cells).

Vaccines

• A vaccine contains a weakened or inactive form of a pathogen, stimulating the immune system to produce memory B and T cells.
• If the real pathogen enters the body later, the immune system can respond quickly and effectively, preventing illness.