Introduction to Life Processes

Introduction to Life Processes

• All living organisms share common characteristics, differentiating them from non-living things
• These characteristics include breathing, growing, needing nutrition, producing offspring, and reacting to stimuli
• Life processes are vital for maintaining homeostasis and proper body function
• These processes occur even when not actively performing any action
• Key life processes include nutrition, photosynthesis, transportation, metabolism, respiration, reproduction, and excretion

Life Processes in Plants, Animals, and Humans

• Earth is the only known planet with life
• Living organisms are distinguished from non-living entities based on various parameters of life processes

Nutrition

• Nutrition is the process of acquiring food for nourishment and sustenance
• Two main types of nutrition are autotrophic and heterotrophic
• Autotrophic nutrition occurs in plants, algae, and some bacteria, where organisms produce their own food using light or chemical energy (photosynthesis or chemosynthesis)
• Heterotrophic nutrition occurs in bacteria, fungi, and animals, where organisms derive energy from organic compounds (consuming plants or other animals)
• Heterotrophic nutrition has subtypes such as holozoic, saprophytic, and parasitic nutrition

Autotrophic Nutrition

• Autotrophic organisms make their own food
• Plants use light energy through photosynthesis, and are called photoautotrophs
• Some bacteria use chemical energy, called chemoautotrophs

Photosynthesis

• Photosynthesis is an important process occurring in plants, algae, and some bacteria to produce their food using sunlight
• It involves absorbing light energy to split water into hydrogen and oxygen
• Hydrogen is used to convert carbon dioxide into carbohydrates (usually glucose)
• Chlorophyll is essential for this process; stomata facilitate carbon dioxide intake

Saprophytic Nutrition

• Some organisms feed on dead and decaying matter
• Food is partially broken down outside the body before absorption
• Examples include fungi

Parasitic Nutrition

• Some organisms feed on another organism, causing harm
• Nutrients are directly taken from the host
• Examples include parasites like tapeworms, leeches, and Cuscuta

Nutrition in Amoeba

• Amoeba feeds by holozoic nutrition
• Engulfing food particles using pseudopodia (phagocytosis)
• Enclosed food in a food vacuole, where digestion occurs
• Undigested food eliminated when vacuole opens outside

Nutrition in Paramoecium

• Paramoecium also exhibits holozoic nutrition
• Cilia help engulf food through oral groove
• Food vacuole forms, and digestion takes place through cyclosis
• Undigested food expelled through anal pore or cytopyge

Nutrition in Humans

• Humans are omnivores, consuming both plants and animals
• Complex digestive system including the alimentary canal and digestive glands
• Ingestion, Digestion, Absorption, Assimilation, and Egestion are five main stages in human nutrition
• The alimentary canal consists of the mouth, esophagus, stomach, small intestine, and large intestine

Human Digestive System

• Includes various organs like the mouth, teeth, salivary glands, pharynx, esophagus, stomach, liver, pancreas, small intestine, large intestine, rectum, and anus. These organs work together to ingest, digest, absorb, and eliminate food.

Teeth

• Teeth, also called buccal cavity, are hard structures in the mouth used to cut, shear, and masticate food.
• Four types in humans: incisors, canines, molars, and premolars. Different types have different functions.
• Teeth have layers of enamel, dentine, cement, and dental pulp. Enamel is the outermost hard layer.

Oesophagus and Stomach

• Food passes from the mouth to the stomach via the esophagus.
• The muscular esophagus uses peristalsis to push food down.
• The stomach stores, mixes, and churns food, converting it into chyme

Small Intestine

• Extended portion of the alimentary canal
• Involved in digestion and nutrient absorption
• Duodenum, jejunum, and ileum are the three regions
• Villi are finger-like projections increasing absorption surface area

Large Intestine

• Colon and rectum are two parts of the large intestine
• Water absorption and storing indigestible foods occur, making the stool more solid
• Bacteria living within the large intestine aid in digestion

Peristalsis

• Wave-like muscle contractions in the alimentary canal that push food along
• Important for moving food through the digestive system

Digestive Glands

• Several glands secrete digestive juices, essential for digestion.
• Salivary glands, gastric glands, liver, gallbladder, and pancreas are involved

Liver

• The largest digestive gland in humans
• Located in the upper right abdomen
• Filters blood coming from the digestive tract
• Produces bile, important for fat digestion
• Plays roles in detoxification, protein production, and blood clotting

Pancreas

• Mixed gland (endocrine and exocrine functions)
• Releases hormones like insulin and glucagon (regulation of blood sugar)
• Produces pancreatic juice containing enzymes for digestion of proteins, fats, and carbohydrates

Gallbladder

• Small sac-like organ
• Stores bile produced by the liver
• Releases bile into the small intestine when needed

Holozoic Nutrition

• Animals consume food in whole pieces
• This type of heterotrophic nutrition

Respiration

• Respiration involves the exchange of gases
• Animals and plants differ in how they respire
• Cellular respiration involves burning food to create chemical energy (ATP) needed for the organism's functions; this can occur in the presence (aerobic respiration) or absence (anaerobic respiration) of oxygen.

Respiration in Humans

• Includes breathing, which involves inhaling and exhaling gases (oxygen and carbon dioxide)
• Respiratory system consists of the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli. These all are in the lungs
• Complex internal system used to transport gases

Respiration in Lower Animals

• Various organisms utilize simple exchange mechanisms
• Ex: Earthworms use their skin; fishes use gills; insects have a tracheal system; frogs use skin and lungs

Respiration in Muscles

• Muscles can respire anaerobically (without oxygen)
• Leading to the production of lactic acid, potentially causing muscle soreness. This is called lactic acid fermentation.

Respiration in Plants

• Plants have stomata (on leaves) and lenticels (on stems) for gas exchange
• Respiration rate generally lower than in animals

Transportation

• Plants and animals both require a way to move materials around their bodies for survival.
• Vascular system in plants: xylem transports water and minerals, while phloem transports food.
• Circulatory system in animals: the heart pumps blood through blood vessels to carry nutrients, oxygen, and remove waste.

Transportation in Humans

• Blood, blood vessels, and the heart make up the circulatory system
• Heart pumps blood through the body
• Blood carries oxygen and nutrients to the tissues.
• It also removes carbon dioxide and other waste products.

Blood Vessels (Arteries, Veins, Capillaries)

• Arteries carry blood away from the heart; these carry oxygenated blood and are thick-walled
• Veins carry blood back to the heart; these carry deoxygenated blood and have thinner walls
• Capillaries are tiny vessels for exchange of substances between the blood and tissues

Blood Pressure

• The pressure exerted by blood on the walls of blood vessels.
• Systolic pressure (heart's pumping) and diastolic pressure (heart is refilling)
• Blood flow through veins is generally at lower pressures than in arteries

Double Circulation

• Blood passes through the heart twice in a complete cycle
• This helps to efficiently deliver oxygen to the body

Excretion in Humans (and Organisms)

• The process of removing metabolic waste products from the body
• Excretion processes in humans include kidneys, ureters, urinary bladder, and urethra
• Kidneys are the main excretory organs in humans, filtering waste materials from blood.
• They regulate water balance, electrolytes, and pH, and produce urine.

Excretion in Plants

• Plants also excrete some products like gums, oils, resins, etc., which are stored in various plant parts and eventually excreted.
• Carbon dioxide is a waste product of respiration. Excess water is transpired, released through openings in leaves called stomata

Dialysis

• A technique used when kidneys fail
• A machine, called a dialyzer, filters the blood to remove waste and excess fluids

Circulatory System

• The circulatory system is a network of vessels and the heart involved in transporting nutrients, oxygen, waste products, and other vital substances throughout an organism
• The system's complexity varies amongst organisms – from simple diffusion in some unicellular organisms to a complex network of vessels and a heart for efficient transport in more complex ones.

Transportation in Plants

• Xylem: transports water and minerals from roots to the rest of the plant
• Phloem: transports food (sugars) from leaves to other parts of the plant (both in one direction and the other)

Additional Notes about Transport in Humans

• Heart: Four-chambered organ that pumps blood; upper chambers (atria) receive blood; lower chambers (ventricles) pump blood; the heart valves ensure one-way blood flow.