It comprises several organs whose function is to transport air to and from the lungs, It contains a conducting zone consisting of a series of branching tubes which form the airways

The smallest branches of the respiratory system airways end in alveoli, The smallest branches of the respiratory system conducting zone end in alveoli

It takes place in the alveoli (microscopic air sacs), It takes place in the alveoli which provide a large exchange surface, It takes place in the alveoli consisting of thin membranes, covered with the extensive capillary network of the pulmonary circulation

The blood that exits the lungs via the pulmonary arteries is rich in oxygen

The blood in pulmonary veins – high O2 – low CO2, Alveoli – thin-walled sacs – large exchange surface, The blood in pulmonary arteries – high CO2 – low O2

It belongs to the conducting zone of the respiratory system, It has an external part consisting of cartilage and skin, It has two internal parts called nasal cavities, It represents the normal entry way of air in the respiratory system

The nasal choanae enable the communication between the nasal cavities and the nasopharynx, The nose is responsible for heating, humidifying and filtering air, The external nares (nostrils) are openings of the nasal cavities to the external environment

They represent the internal part of the nose, They communicate with the external environment through the nostrils, They are lined by a mucosa whose inflammation is called rhinitis

The frontal sinus inside the bone bearing the same name, The inferior nasal concha which delimits the inferior meatus, The nasal vestibule, in the ventral part of the nasal cavity

It contains blood vessels which warm cold air, It secretes mucus which humidifies dry air

They open into the nasal cavities, They decrease the weight of the cranium and serve as resonance chambers, They are lined with a mucosa which continues the mucosa of the nasal cavity

The nasal cavity is associated with the olfactory sense, The olfactory region is situated in the upper wall of the nasal cavities, The blood vessels in the nasal mucosa warm up cold air

The oropharynx, situated posterior to the oral cavity, The oropharynx where the digestive and respiratory tracts meet, The laryngopharynx, situated posterior to the larynx, The nasopharynx, situated posterior to the nasal cavities

It belongs to the airways and it has a cartilaginous structure, It is a passageway of air from the pharynx to the trachea, It is involved in the production of sounds

It is involved in the production of sounds, It joins the pharynx and the trachea at the level of the cervical vertebrae, It houses the vocal cords

Larynx – shorter vocal cords – children, Larynx – women – higher-pitched voice, Larynx – thyroid cartilage – more visible in men

It branches in two main bronchi, It continues the larynx, It is lined with ciliary cells which filter air before it enters the bronchi

They belong to the conducting zone of the respiratory system, together with the pharynx, bronchi and bronchioles, The larynx continues with the trachea. A semi-rigid tube, The mucosa lining the trachea contains ciliary cells which filter the air before it enters the bronchi

They are kept open by some cartilaginous rings situated in the posterior part, They belong to the bronchial tree, They result from the branching of the trachea

They are microscopic air sacs, approximately 300 million for each lung, In the alveoli, O2 from the air is exchanged for CO2 from the blood by a passive diffusion process, The respiratory membrane of alveoli forms an extremely thin barrier which allows the passage of respiratory gases

The nasal cavities, the larynx and the trachea belong to the airways and they are lined with mucosa, The branches of the trachea, bronchi and bronchioles form the bronchial tree of the lung, The larynx has true vocal cords and false vocal cords (ventricular folds)

Is based on the principle according to which air travels from a high-pressure area (high density) to a low-pressure area (low density), Is the process by which air flows in and out of the alveoli, Belongs to the breathing process, together with gas exchange

Inhibits the activation of the respiratory control centre, Determines the decrease of the respiratory rate and amplitude

Oxygen passes from the alveoli into the bloodstream, to be transported to the cells, Carbon dioxide passes from the bloodstream to the alveoli, to be expelled by breathing

The pulmonary arteries are the only arteries which carry deoxygenated blood, The capillaries originating in the pulmonary artery form the capillary bed that surrounds the alveoli, After the gas exchange between the bloodstream and the alveolar air, capillaries join together to form the pulmonary veins which exit the lungs

Two kidneys, situated retroperitoneal in the abdominal cavity, Accessory organs (ureters, urinary bladder, urethra), The urethra (a tube that is responsible for eliminating urine from the bladder during micturition)

They are located on the posterior abdominal wall, They lie retroperitoneally (behind the peritoneum)

There are two kidneys, situated retroperitoneally, They lie laterally to the spinal column, Superiorly, they are in contact with the adrenal glands, They are supported by fatty and connective tissue

Inferior to the diaphragm, in the abdominal cavity, The upper extremity is higher (close to the diaphragm), in the left kidney

The upper extremity of the left kidney is higher than the upper extremity of the right kidney, Their medial surface has a concave area called renal hilum

Two distinct areas, cortical and medullary, A deep area, the renal medulla, represented by the renal pyramids, An external area, called cortex, containing renal glomeruli, parts of the nephron tubules and blood vessels

It contains the renal glomeruli and Bowman’s capsule, the afferent and the efferent arteriole and parts of the nephron tubules, It does not contain the loop of Henle, It is situated at the periphery of the kidney and sends projections to the renal medulla

It contains several triangular masses, the renal pyramids, It contains renal pyramids delimited by renal columns, It contains certain parts from the nephron structure (the loop of Henle) and the peritubular capillaries

The glomerulus, a capillary network resulting from the branching of the afferent arteriole, The glomerulus, capillary network which join together forming the efferent arteriole, The proximal convoluted tubule and the distal convoluted tubule

The afferent arteriole takes blood from the renal artery to the glomerulus, The afferent, microscopic, arterioles form the glomerular capillary network, The efferent arterioles form the peritubular capillary network, The peritubular capillaries drain into small veins which join together to form eventually the renal vein

The proximal convoluted tubule is situated in the renal cortex, The loop of Henle continues the proximal convoluted tubule and is U-shaped, The distal convoluted tubule continues the ascending branch of the loop of Henle

Filtration (the passage of small-molecule dissolved substances from the glomerular capillaries to the glomerular capsule), Reabsorption (the passage of water, salts and other substances from the tubule lumen into the peritubular capillaries), Tubular secretion (the passage of certain substances from the blood of peritubular capillaries into the distal convoluted tubule)

Is represented by the passage of fluid from blood plasma into the glomerular capsule through submicroscopic apertures, It pushes water and small plasma molecules out of the glomerular capillaries and into Bowman’s capsule

Its wall contains millions of microvilli which considerably enlarge the contact surface with the contents of the lumen, Glomerular filtrate arrives here and then leaves the glomerular capsule, Hosts the reabsorption process of certain ions

In the proximal convoluted tubule, By active transport (with ATP uptake)

Glomerular filtrate from the proximal convoluted tubule enters the descending branch of the loop (after the selective reabsorption in the proximal tubule), Na+ and Cl- pass into the medullary interstitium in the ascending branch, where the fluid in the tubule flows

No water reabsorption takes place in it (or only very small amounts), It enables sodium and chloride ion reabsorption, It ascends from the medulla back to the cortex

The selective reabsorption of ions by active transport, The reabsorption of water under the influence of ADH, Secretion of certain medicines and certain hormones

Takes place in the nephron tubules (especially in the distal convoluted tubule) and in the collecting ducts, Is an active process which transports chemical compounds from the bloodstream into the tubular fluid, Transports certain chemical compounds from the peritubular capillaries into the tubular fluid

The glomerulus and the glomerular capsule are responsible with filtering blood plasma, Glucose and amino acid reabsorption takes place in the proximal tubules, The secretion of certain medicines takes place in the distal tubules, Sodium is reabsorbed by active transport in the ascending branch of the loop of Henle

It is secreted by the cortex of the adrenal glands and mainly influences the nephron’s distal convoluted tubule, It stimulates sodium ion reabsorption from the distal convoluted tubule, It stimulates the secretion of blood potassium in the distal convoluted tubule fluid

Pigments, the most important being urobilinogen, produced by bilirubin in the bowel, Hormones and various medicines, Urea, synthesized in the liver by amino acid metabolism and the use of their amino (-NH2) groups

Potassium and sodium are monovalent cations, Calcium (Ca2+) and magnesium (Mg2+) belong to cations and are bivalent, Sulphate ion and chloride ion are anions

Its inferior part opens in the urinary bladder, Its superior part continues the renal pelvis, It is a long tube which carry urine to the urinary bladder