Homeostasis and Body Regulation

Homeostasis

• Homeostasis is the body's process of maintaining a stable internal environment despite external changes.
• It regulates temperature, water, and glucose levels for optimal cellular function.
• Key components:
  • Receptors detect changes (stimuli).
  • Control centers process information & coordinate responses (e.g., brain, hypothalamus).
  • Effectors carry out the response to restore balance (e.g., muscles, glands).
• Example (Thermoregulation):
  • Too hot: Sweating, vasodilation (blood vessel widening).
  • Too cold: Shivering, vasoconstriction (blood vessel narrowing).
• Example (Blood Glucose Regulation):
  • High glucose: Pancreas releases insulin, storing glucose as glycogen in the liver.
  • Low glucose: Pancreas releases glucagon, converting glycogen back to glucose.
• Example (Water Balance/Osmoregulation): Regulated by the kidneys, influenced by ADH (antidiuretic hormone). Excess water intake decreases ADH, leading to dilute urine.
• Example (Ion Balance): Sodium, potassium, and calcium levels maintained by kidneys to ensure proper nerve & muscle function.
• Example (pH Regulation): Blood pH (around 7.4) maintained by buffering systems (like bicarbonate) and adjustments by the respiratory system and kidneys.

Transport in Biology

• Transport in biology involves moving substances (nutrients, gases, waste) within organisms (cells or body).

2.1 Diffusion

• Definition: Passive movement of particles from high to low concentration.
• Examples: Oxygen to blood, carbon dioxide from cells.
• Factors affecting diffusion:
  • Concentration gradient (steeper = faster).
  • Temperature (higher = faster).
  • Surface area (larger = faster).
  • Distance (shorter = faster).

2.2 Osmosis

• Definition: Movement of water across a semipermeable membrane from high to low water potential.
• Examples: Water absorption by root hair cells, water movement into blood cells (hypotonic solutions).
• Importances in plants: Maintains turgor pressure supporting plant structure, facilitates nutrient uptake.

2.3 Active Transport

• Definition: Movement of substances against their concentration gradient, using ATP energy.
• Examples: Mineral uptake by root hair cells, glucose absorption in the small intestine.
• Key features: Needs ATP energy, involves carrier proteins in the membrane.

2.4 Transport in Plants

• Xylem: Transports water and minerals from roots to leaves.
  • Water moves up due to cohesion (water sticking to water) and adhesion (water sticking to xylem walls).
• Phloem: Transports sugars (sucrose) and amino acids from leaves to all parts of the plant, translocation, bidirectional movement.
• Stomata and Transpiration: Pores on leaves for gas exchange and water loss, guard cells regulate opening/closing for balance between water loss and CO2 uptake.
• Factors Affecting Transpiration: Light, temperature, humidity, wind.

2.5 Transport in Animals

• Circulatory system:

  • Open system: Blood flows freely in body cavities (insects).
  • Closed system: Blood confined to vessels (mammals).
  • Mammalian circulatory system components: Heart (pumps), blood vessels (arteries, veins, capillaries), blood (transports).
  • Double circulatory system: Pulmonary (heart to lungs), Systemic (heart to body).

• Lymphatic system: Transports lymph (fluid containing white blood cells) in immune defense and returning excess interstitial fluid.

• Transport of gases: Oxygen (bound to hemoglobin), Carbon dioxide (dissolved, bound to hemoglobin, or as bicarbonate).

• Nutrient Transport:

  • Small intestine: Nutrients absorbed into bloodstream via villi, microvilli increase surface area.
  • Liver: Processes absorbed nutrients, distributes as needed.
  • Lymphatic system: Fatty acids and glycerol absorbed into lacteals.

• Excretion transport: Kidneys filter blood removing urea, salts, water, and producing urine.

• Hormone Transport: Hormones like insulin and adrenaline are secreted, transported via bloodstream to target organs.

• Reproductive Hormones:

  • Oestrogen (ovaries): Growth of uterine lining, secondary sexual characteristics.
  • Progesterone (ovaries): Maintains uterine lining for implantation.
  • Testosterone (testes): Male secondary sexual characteristics, sperm production.
  • FSH (pituitary gland): Ovarian follicle growth & sperm production.
  • LH (pituitary gland): Ovulation & testosterone production.

• Immune System Transport: White blood cells move through bloodstream & lymphatic system to battle infections. Platelets aid blood clotting.

Explore the intricate processes of homeostasis, where the body maintains a stable internal environment amidst external changes. This quiz covers temperature control, glucose regulation, and water balance, highlighting the roles of receptors, control centers, and effectors in these vital functions.