Adrenaline, Insulin, Hormones, Tropism, and Reproduction
Hormones: Adrenaline and Insulin
A hormone is a chemical substance secreted by an endocrine gland. It is carried by the blood, which alters the activity of one or more specific target organs and is then destroyed by the liver.
Chemical Control of Metabolic Activity by Adrenaline
Adrenaline is a hormone secreted by the adrenal glands. When you are frightened or excited, your brain sends impulses along a nerve to your adrenal glands. This makes them secrete adrenaline into the blood.
Adrenaline helps
Read MoreNephrons and Urinary Health: Function, Conditions, and Care
Nephrons: The Functional Units of the Kidney
Each kidney contains about one million nephrons. Nephrons are microscopic tubular structures, approximately 2-3 cm in length and about 5 mm in diameter, capable of forming urine. In their initial part, they have a widened capsule called Bowman’s capsule, which surrounds a ball of blood capillaries known as the glomerulus. The Bowman’s capsule is continuous with a long tubule that is responsible for carrying urine. The tubules forming the collecting ducts
Read MoreDigestive System: Food Digestion and Nutrient Absorption
The digestive system performs the processes of food digestion and absorption of nutrients. These processes require two types of actions:
- Mechanical: This involves the fragmentation of food and the movement of the bolus through the digestive tract via muscle contractions called peristaltic contractions.
- Chemical: This involves the hydrolysis of food by enzymes found in digestive juices and bile. These processes break down food into smaller molecules that can cross the gastrointestinal wall and enter
Cellular Respiration: Krebs Cycle and Oxidative Phosphorylation
Krebs Cycle
Adolf Krebs discovered a series of oxidation-reduction reactions known as the Krebs Cycle. The cycle occurs in the mitochondrial matrix in eukaryotic cells, comprising a set of reactions that oxidize acetyl-coenzyme A to CO2. The molecules NAD+ and FAD collect the electrons and are reduced to NADH and FADH2. These electrons will be transferred to an electron transport chain, regenerating NAD+ and FAD to continue the Krebs Cycle.
Stages of the Krebs Cycle
- Acetyl-coenzyme A binds to oxaloacetate
Mendelian Inheritance and Genetic Processes
Mendelian Inheritance
Inheritance is transmitted by hereditary factors stored in gametes. These factors are of maternal and paternal origin and join in the new individual without mixing, separating again when these individuals form reproductive cells.
Mendel’s Laws are the primary rules that govern the inheritance of characteristics from one generation to another.
Mendel’s First Law: The Law of Uniformity
Based on pure breeds, all individuals of the first generation are equal. All hybrids for the character
Read MoreHuman Nutrition, Diet, Food Safety, and Digestion
Human Nutrition
Understanding Nutrients
Nutrition is the set of processes by which the body receives, transforms, and incorporates the necessary nutrients for its cells. Nutrients are chemical compounds in foods that cells need to live.
Features of Nutrients:
- Energy Efficiency: Supplying energy for the functioning of cells.
- Plastic or Repair: Providing components for growth and renewal of cells that are destroyed.
- Regulatory: Supplying chemical substances that control the reactions of the cells.