Hoja de repaso: Life Processes and Human Physiology

📋 Course Outline

1. Food and Energy Needs
2. Modes of Nutrition
3. Photosynthesis in Plants
4. Human Nutrients and Balanced Diet
5. Human Digestion
6. Deficiency and Food Adulteration
7. Transport in Plants
8. Human Circulatory System
9. Blood, Lymph, and Disorders
10. Respiration and Gas Exchange
11. Mechanism of Human Breathing
12. Human Excretion and Kidneys

📖 1. Food and Energy Needs

🔑 Key Concepts & Definitions

• Life processes : The activities by which living organisms take in food, derive energy, remove waste, and respond to environmental changes.
• Nutrition : The process by which living beings obtain food, convert it into simple absorbable forms, and use it to make substances needed by the body.

📝 Essential Points

• Food provides energy for life processes, raw materials for growth and tissue repair, and materials for producing enzymes and hormones.

📖 2. Modes of Nutrition

🔑 Key Concepts & Definitions

• Holozoic nutrition : Involves ingestion, digestion, and absorption of food, as in Amoeba, frogs, and human beings.
• Parasitic nutrition : Occurs when organisms live on or inside another living organism and derive their food from it; examples include Cuscuta, leeches, and head lice.
• Saprotrophic nutrition : Occurs when organisms such as mushrooms, yeast, and bread mould obtain food from dead and decaying organic matter.

📝 Essential Points

📌 Autotrophic organisms manufacture their own food, whereas heterotrophic organisms depend on other organisms for food.

• Green plants, algae, and certain bacteria are autotrophs and are called producers because other organisms depend on them for food.

💡 Memory Hook

Autotrophs make food; heterotrophs obtain it.

📖 3. Photosynthesis in Plants

🔑 Key Concepts & Definitions

• Photosynthesis : The biochemical process by which green plants manufacture food from carbon dioxide and water in the presence of sunlight and chlorophyll, releasing oxygen as a by-product.

★ Must-know

• The overall equation of photosynthesis is $6CO_2 + 12H_2O \xrightarrow{\text{light, chlorophyll}} C_6H_{12}O_6 + 6H_2O + 6O_2.$

• Photosynthesis occurs in two simultaneous steps: the light reaction captures light energy in chloroplasts, and the dark reaction forms glucose in chloroplasts.

Further detail

• Glucose produced by photosynthesis is used by cells or converted and stored as starch, while oxygen diffuses into the atmosphere through stomata.

• Photosynthesis uses carbon dioxide released by respiration and supplies oxygen for respiration, helping maintain atmospheric gas balance.

📖 4. Human Nutrients and Balanced Diet

🔑 Key Concepts & Definitions

• Balanced diet : Contains adequate amounts of carbohydrates, fats, proteins, vitamins, minerals, and water in proper proportions, which vary with age, sex, and pregnancy.

★ Must-know

• Carbohydrates and fats are energy-yielding nutrients, proteins are body-building nutrients, and vitamins and minerals are growth-regulating nutrients.

• Proteins mainly support the growth of body tissues and are found in:

  • foods such as milk
  • pulses
  • eggs
  • meat
  • groundnuts
  • and soyabeans

Further detail

• One gram of fat releases about 37 kilojoules, or 9 kilocalories, of energy on oxidation.

• Vitamins B-complex and C are water-soluble, whereas vitamins A, D, E, and K are fat-soluble.

• Water forms 65–70% of body weight, regulates body temperature, and provides a medium for biochemical reactions.

📖 5. Human Digestion

🔑 Key Concepts & Definitions

• Digestion : The conversion of complex food materials into smaller substances that can be absorbed by body cells.

★ Must-know

• Human nutrition includes ingestion, digestion, absorption, assimilation, and egestion.

• Salivary amylase in the mouth breaks starch into sugar, while the oesophagus moves food to the stomach by peristalsis without digesting it.

• Hydrochloric acid in the stomach activates pepsinogen to pepsin and kills bacteria, while pepsin breaks proteins into peptones.

• In the small intestine, bile emulsifies fats and creates an alkaline medium, while pancreatic trypsin, amylase, and lipase digest proteins, starch, and fats respectively.

• Villi in the small intestine increase the surface area for absorption of digested food into blood capillaries.

Further detail

• The large intestine absorbs water from undigested food, forms faeces, and passes them through the rectum and anus during egestion.

💡 Memory Hook

Ingestion → digestion → absorption → assimilation → egestion.

📖 6. Deficiency and Food Adulteration

🔑 Key Concepts & Definitions

• Malnutrition : The intake of an improper or inadequate diet and can retard the mental and physical growth of children.
• Food adulteration : The deliberate mixing of food with cheaper, substandard, edible, or inedible substances.

📝 Essential Points

• Protein-energy malnutrition causes marasmus in children up to one year and kwashiorkor in children aged one to five years.

• Iodine deficiency causes goitre, iron deficiency reduces haemoglobin production and causes anaemia, and vitamin A deficiency causes night blindness.

📖 7. Transport in Plants

🔑 Key Concepts & Definitions

• Transpiration pull : The upward force produced when evaporation of water vapour from stomata creates a vacuum that draws water through xylem.
• Translocation : The transport of sugars and other food molecules from leaves to other parts of a plant through living phloem sieve tubes.

📝 Essential Points

• Root hairs absorb water and minerals from soil, and xylem tracheids and vessels transport them upward to the leaves.

📖 8. Human Circulatory System

🔑 Key Concepts & Definitions

• Circulatory system : Consists of a muscular heart, blood vessels, and circulating fluids that distribute nutrients and oxygen, remove wastes, and transport hormones.

★ Must-know

• Arteries carry blood away from the heart, veins bring blood toward the heart, and capillaries allow exchange between blood and tissues.

• The human heart has four chambers: right and left atria and right and left ventricles.

Further detail

• A normal healthy young person's blood pressure is about 120/80 mm Hg, measured with a sphygmomanometer, and the normal heart rate is about 72 beats per minute.

• The pulmonary artery carries carbon-dioxide-laden blood, whereas the pulmonary vein carries oxygen-laden blood.

💡 Memory Hook

Heart → arteries → capillaries → veins → heart.

📖 9. Blood, Lymph, and Disorders

★ Must-know

• Red blood cells contain haemoglobin and transport oxygen to tissues and carbon dioxide back from tissues; they lack a nucleus.

• White blood cells are colourless, irregularly shaped cells that fight infection by engulfing germs or producing antibodies.

📌 Lymph is a light-yellow fluid flowing one way from tissues to the heart that returns proteins and fluid to circulation, whereas blood circulates through the heart and blood vessels.

📌 In the ABO system, group O can donate blood to all four groups and group AB can receive blood from all four groups, but transfusion is safe only when donor and recipient blood are compatible.

Further detail

• Blood platelets are small cell fragments without nuclei that participate in blood clotting.

• Hypertension is high blood pressure, anaemia results from reduced haemoglobin, and leukemia involves excessive white blood cells and few red blood cells produced by bone marrow.

📖 10. Respiration and Gas Exchange

★ Must-know

📌 Breathing is the physical exchange of respiratory gases between an organism and its environment, whereas cellular respiration oxidizes food in cells to release energy and form ATP.

• Human respiratory passages are the nostrils, nasal cavities, internal nostrils, pharynx, trachea, bronchi, bronchioles, and alveoli within the lungs.

• Alveoli have thin walls and many surrounding capillaries, providing a large surface for diffusion of oxygen and carbon dioxide.

Further detail

• Plants exchange gases through root hairs, stomata, and lenticels; guard cells open stomata when turgid and close them when flaccid.

• Cartilage rings support the trachea and prevent it from collapsing during breathing.

📖 11. Mechanism of Human Breathing

★ Must-know

• During inhalation, the diaphragm contracts and flattens, the ribs move upward and outward, thoracic volume increases, pressure decreases, and air enters the alveoli.

• During exhalation, the diaphragm relaxes into a dome shape, the ribs move downward and inward, thoracic volume decreases, pressure rises, and carbon-dioxide-rich air leaves the lungs.

• Oxygen diffuses from alveoli into blood capillaries, while carbon dioxide diffuses from tissue blood into the alveoli for exhalation.

• Cellular respiration occurs in mitochondria when oxygen acts on glucose, releasing energy and carbon dioxide.

Further detail

• An adult human at rest breathes about 16–18 times per minute, and the breathing rate increases during exercise, disease, fever, pain, or stress.

📖 12. Human Excretion and Kidneys

🔑 Key Concepts & Definitions

• Excretion : The removal from the body of products of chemical reactions that are unnecessary or harmful if they accumulate.
• Nephron : The structural and functional unit of the kidney and consists of Bowman’s capsule, the glomerulus, the renal tubule, the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule.
• Osmoregulation : The maintenance of the correct amounts of water and mineral ions in the blood and internal environment.

★ Must-know

• The human urinary system consists of two kidneys, two ureters, a urinary bladder, and a urethra.

• Blood is filtered in the glomerulus and Bowman’s capsule; useful substances, excess water, and salts are reabsorbed from the renal tubule into surrounding capillaries, leaving mainly urea to form urine.

Further detail

• Urine passes from the kidneys through the ureters to the urinary bladder for temporary storage and then leaves through the urethra.

• The lungs remove carbon dioxide, the skin removes excess salts in sweat, and the liver also contributes to waste removal in addition to the kidneys.

• Dialysis removes wastes from a patient's blood across a membrane into dialysis fluid when both kidneys fail, while a kidney transplant replaces a non-functioning kidney with a donated kidney.

💡 Memory Hook

Filtration → reabsorption → urine → ureter → bladder → urethra.

📊 Synthesis Tables

Nutrition Modes

Mode	Food source	Examples
Autotrophic	Self-manufactured by photosynthesis	Green plants, algae, certain bacteria
Holozoic	Ingested food	Amoeba, frogs, humans
Parasitic	Living host	Cuscuta, leech, head louse
Saprotrophic	Dead and decaying matter	Mushroom, yeast, bread mould

ABO Blood Compatibility

Blood group	Can donate to	Can receive from
A	A, AB	A, O
B	B, AB	B, O
AB	AB	A, B, AB, O
O	A, B, AB, O	O