Physiology of Homeostasis and Feedback Mechanisms

Thermoregulation

• Some animals can elevate their upper lethal temperature to survive in extreme temperatures between 30-45°C.
• Endotherms (animals that regulate their body temperature internally) maintain a relatively constant body temperature, despite external environment changes.
• Examples of endotherms include birds, mammals, and some fish (e.g., tuna) and reptiles (e.g., female python).

Adaptations to Extreme Temperatures

• Endotherms adapt to extreme cold by tolerating it, using positive feedback mechanisms, or controlling temperature through homeostasis.
• In hot environments, endotherms can:
  • Increase water loss through evaporation (e.g., sweating in humans, panting in dogs and birds).
  • Use gular fluttering (rapid movement of the throat region) to increase evaporation (in birds).
  • Become hyperthermic by retaining metabolic heat (e.g., desert camels).

Gametogenesis

• Gametogenesis is the production of gametes (sperm or eggs).
• Spermatogenesis (sperm production) is continuous and prolific, with millions of sperm produced daily.
• Oogenesis (egg production) is a prolonged process, with immature eggs forming in the female embryo and completing development years or decades later.
• Spermatogenesis differs from oogenesis in three ways:
  • All four products of meiosis develop into sperm, while only one becomes an egg.
  • Spermatogenesis occurs throughout adolescence and adulthood.
  • Sperm are produced continuously without interruptions.

Fertilization

• Fertilization depends on mechanisms that bring together sperm and eggs of the same species.
• External fertilization occurs when eggs shed by the female are fertilized by sperm in the external environment.

Animal Nutrition

• All animals eat other organisms, either dead or alive, whole or by the piece (including parasites).
• Animals fit into three dietary categories:
  • Herbivores (eat mainly autotrophs, such as plants and algae).
  • Carnivores (eat other animals).
  • Omnivores (consume animal and plant or algal matter).
• A nutritionally adequate diet must satisfy three nutritional needs:
  • Provide fuel for cellular work.
  • Supply organic raw materials for constructing organic molecules.
  • Provide essential nutrients that the animal cannot make from raw materials.

ATP Generation

• ATP generation is based on the oxidation of organic fuel molecules (carbohydrates, proteins, and fats) in cellular respiration.
• The monomers of these substances can be used as fuel.
• Excess energy can be used for biosynthesis, growth, reproduction, or stored in energy depots.

Understand the concepts of homeostasis, non-homeostatic mechanisms, and positive feedback in the context of physiological processes, such as temperature control and childbirth.