Respiration

RESPIRATION

DEFINITION • External respiration: mechanical process that maintains a continuous exchange of gases between respiratory surfaces of an organism and its environment. • Internal respiration: also known as cellular respiration is the biochemical process in which energy is made available to all living

ENERGY REQUIREMENT • • • • • •

Muscle contractions Active transport Transmission of nerve impulses Synthesis of proteins Formation of new protoplasm Cell division

AEROBIC RESPIRATION • Requires continuous supply of oxygen • Involve the complete breakdown of glucose in the presence of oxygen. • Occurs in the mitochondrion • Equation: C6H12O6+6O2 CO2+6H2O+2898kJ

ANAEROBIC RESPIRATION • Anaerobes: Organisms that respire anaerobically. • Examples: bacteria and certain type of yeast • Occurs in the cytoplasm • Limited supply or no supply of oxygen • Glucose breakdown is incomplete

ANAEROBIC RESPIRATION • Product: Lactic acid (in muscle), ethanol (in yeast cells) • Energy released: 2ATP (150kJ) • High level of lactic acid in the muscle can cause muscular cramps and fatique • Equation: C6H12O6 2C3H6O3 + 150kJ (2ATP)

ANAEROBIC RESPIRATION • Equation (anaerobic respiration in yeast) • C6H12O6

zymase

C2H5OH + 2CO2 + 210kJ

The Respiratory Structures and Breathing Mechanisms in Humans and Animals • Adaptations of respiratory surfaces: - the respiratory surface is moist - cells lining the respiratory surface are thin - the respiratory structure has a large surface area

• Unicellular organisms do not need specialised respiratory structure as the outer surface of these organisms provides an adequate surface area for the diffusion of gas. • The larger the size of an organism, the smaller the surface area per unit volume of organism. • For larger and complex organisms, the volume of body requires oxygen increases more rapidly than the surface area • Complex organism need specialised respiratory structures for efficient gaseous exchange.

Respiratory Structure and Breathing Mechanism of Insects • Known as tracheal system : composed of air tubes (trachea) • Air enters the tracheae through a series of openings called spiracles • Tracheae branch into finer tubed called tracheoles • Larger number of trachaeols provides a large surface area

• The tips of the tracheoles are closed and contain fluid. Air enters the tracheae through the spiracles and travels through the tracheoles to the fluid-filled tips, where oxygen diffuses directly from the tracheoles into the cells, and CO2 diffuses from the cells into the tracheoles.

Breathing Mechanism of A Fish

• Gills have an interesting structure. The gill filaments (which absorb the oxygen) are very numerous and are attached to bony gill arches. On the opposite side of the gill arches are the gill rakers which face forward towards the mouth to filter clean water as it passes over the fills. • During respiration, water enters the buccal cavity and flows over the gills. Oxygen is absorbed into the gill filaments and then into the bloodstream. Water that has oxygenated the gills leaves the fishes body through the operculum on the side of the head.

Breathing Mechanism (fish) • Mouth opens, floor of buccal cavity lowered, operculum closed, pressure inside the mouth is lowered, water is drawn into the mouth. • Mouth closes, floor of buccal cavity is raised. Water flows through lamellae and gaseous exchange takes place. The increased of water pressure forces the operculum to open and water flows out.

Respiratory Structure of Amphibians • Gaseous exchange in frogs occurs through skin and lungs • Skin: thin, highly permeable to respiratory gasses, moist by the secretion of mucus by glands on the surface of body, network of blood capillaries underneath of skin.

Respiratory Structure of Amphibians • Lungs: a pair of thin walled sacs connected to the mouth through glottis. Membranes of the lungs are thin, moist and covered by network of blood capillaries.

Amphibian (inhale) • Frog breathes through nostrils • Bucco-pharyngeal floor lowered, glottis closed • Air drawn into the bucco-pharyngeal cavity • Nostrils close, glottis open, buccopharyngeal floor raised, air is pushed into lungs • Lungs expand

Amphibian (exhale) • Lung muscles contract • Air expelled from the lungs • Some air escapes through the nostrils, the rest mixes with the air in the bucco-pharyngeal cavity

The Respiratory Structure And Breathing Mechanism Of Humans • Gaseous exchange in humans occurs in the lungs. • Lungs: located in the thoracic cavity, protected by rib cage. • Air enters lungs through a special tube called trachea, supported by Cshaped ring of cartilage. The cartilages keep the trachea open and prevent it from collapsing.

The Respiratory Structure And Breathing Mechanism Of Humans • Bronchi: the lower end of the trachea divides into two primary tubes called bronchi • Bronchus branches repeatedly to form bronchioles. Each bronchiole ends in a cluster of microscopic air sacs called alveoli

The Respiratory Structure And Breathing Mechanism Of Humans • Alveoli: numerous, provide huge surface area for gaseous change. • Inner surface of each alveolus is lined with a layer of moist epithelial cells • The outer surface of each alveolus is covered by a dense network of blood capillaries. • Both alveolus and nearby capillary walls are one cell thick.

ALVEOLUS

INTERCOSTAL MUSCLE

DIAPHRAGM

INHALATION • External intercostal muscles contract • Internal intercostal muscles relax • Diaphragm contract (becomes flat) and cause the volume of the thoracic cavity to increase. • Air pressure in lungs decreases, so air from the environment is drawn into the lungs. • Rib cage move outward and upward

EXHALATION • The processes involved are vice versa of inhalation • Can you figure them out?