Endocrine System and Hormonal Regulation

The endocrine system coordinates body functions through hormones released by various glands. The pituitary gland acts as the master gland, controlling other endocrine glands. Key hormones include insulin from the pancreas, adrenaline from adrenal glands, and reproductive hormones from the testes and ovaries.

Definition: Negative feedback occurs when high hormone levels suppress further hormone production to maintain balance.

Highlight: Type 1 and Type 2 diabetes differ in their mechanisms - Type 1 involves no insulin production, while Type 2 involves insulin resistance.

Example: BMI ranges indicate health status: under 18.5 kg/m² is underweight, 18.5-25 kg/m² is normal, and over 30 kg/m² is obese.

Growth and Development

Cell growth involves increases in size and mass, affecting the organism's overall development. This process is regulated by various hormones and environmental factors.

Definition: Growth refers to the increase in cell size and mass over time.

Highlight: Growth patterns are influenced by hormones, nutrition, and genetic factors.

Cellular Growth and Differentiation

Cell growth occurs through division (mitosis) and differentiation. Stem cells play a crucial role in development and repair, with different types having varying potential for specialization.

Definition: Cell differentiation is the process by which cells become specialized for specific functions.

Highlight: Plant cells can differentiate throughout their life, while animal cell differentiation is mostly restricted to growth and repair.

Example: Red blood cells are highly specialized cells that have lost their nucleus to maximize oxygen-carrying capacity.

Blood Vessels and Circulation

The circulatory system consists of specialized blood vessels that facilitate transport throughout the body. Arteries have thick muscular walls and small lumens to carry blood away from the heart under high pressure. Veins feature thinner walls, larger lumens, and valves to prevent backflow as they return blood to the heart.

Definition: Surface area to volume ratio (SA:Vol) refers to the relationship between an organism's surface area and its volume, which affects its ability to exchange materials with the environment.

Example: A mouse has a higher surface area to volume ratio than an elephant, making it more efficient at heat and material exchange.

Highlight: Blood cells play distinct roles - red blood cells transport oxygen using hemoglobin, white blood cells produce antibodies and fight pathogens, and platelets help form blood clots.

Vocabulary: Cardiac output = Heart rate × Stroke volume, measuring blood pumped per minute.