Question

Now that you have almost completed the course, as a new expert in Anatomy and Physiology, you have been shrunk and placed into a miniature submarine tasked with traveling through the human body.

For this discussion, describe three organ systems that you would visit and tell us which physiological processes you would like to witness first hand. In your description, please use new terms that you learned in the class (for example, you might want to describe a chemical process that breaks down fat in the intestines).

Answer 1

Three organ systems that I would visit and their physiology

1) KIDNEY

The functions of the kidney are the regulation of water balance; regulation of the concentration of the salts in the blood and of the reactin(acid base balance) of the blood and the excretion of waste products and any excess of salts.

The secretion of the urine and the mechanism of renal function. The glomerulus is a filter. Even minute about 1 litre of blood, containing 500ml of plasma, flows through all these glomeruli and about 100 ml ( 10 percent) of it is filtered off. the plasma containing all the salts, glucose and other small substances is filtered. The cells and plasma proteins are too big to pass through the pores of the filter and stay behing in the blood stream. The fluid that is filtered,the glomerular filterate, then passes along the renal tubules and the cells absorb those substances which the body wants and leave behind those that are not wanted. By varying the amount that they absorb or leave behind the tubule cells can adjust the composition of the urine on one side of them and the blood on the other side. Normally, glucose is all reabsorbed; water is largely reabsorbed. Most of the waste products are excreted. In some special cases the tubules add substances to the urine. Thus the secretion of urine consists of three factors; glomerular filtration, tubular reabsorption, tubular secretion. By comparing the amount filtered by the glomeruli each day with the amount usually excreted in the urine we can how selective the tubule cells are:

FILTERED EXCRETED

Water 150 litres 1 litres

Salt 700 grams 15 grams

Glucose 170 grams 0

Urea 50 grams 30 grams

The filterate has by now reached the pelvis of the kidney and the ureter as urine.   

2) RESPIRATORY SYSTEM

Pathway of air: Nasal cavity>pharynx>larynx>trachea>primary bonchi (right and left) > secondary bronchi > tertiary bronchi > terminal bronchioles > respiratory brochioles > alveoli ( site of gas exchange)

The inhaled air is:

a) filtered ( coarser impurities like dust particles are removed by hairs in the nose and the unidirectional whip like motions of cilia that line the tracheobroncial tree)

b) warmed by the rich capilleries that lined the respiratory tract.

c) humidified with moisture that prevent alveoli from drying.

Alveoli are microscopic thin-walled air sacs that provide an enormous surface area for gas diffusion.

a) the region of the lungs ( respiratory bronchioles and alveoli) where gas exchange with the blood occurs is known as the respiratory zone.

b) the trachea , bronchi, and bronchioles that deliver air to the respiratory zone comprise the conducting zone.

The thoracic cavity is limited by the chest wall and diaphgram.

a) the stuctures of the thoracic cavity are covered by thin,wet pleural membranes.

b) the lungs are covered by visceral pleura that are normally flush against the parietal pleura that line the chest wall.

c) the potential space between the visceral and parietal pleura is called the intrapleural space. This enables the lung to expand whenever thoracic cage expands.

LIVER

The liver is the largest gland in the body,weighing between 1 and 2.3 kg. It is situated in the upper part of the abdominal cavity occupying the greater part of the right hypochondriac region, part of the epigastric region and extending into the left hypochondiac region. its upper and anterior surfaces are smooth arid curved to fit the under surface of the diaphgram,its posterior surface is irregular in outline.

Organs associated with the liver

superiorly and anteriorly - diaphgram and anterior abdominal wall

inferiorly - stomach,bile ducts, duodenum, hepatic flexure of the colon, right kidney and adrenal galnd

posteriorly - oesophagus, inferior vena cava, aorta gall bladder, vertebral coloumn and diaphgram

laterally - lower ribs and diaphgram

The liver is an extremely active organ. some of its functions have already been described

Carbohydrate metabolism

conversion of glucose to glycogen in the presence of insulin, and changing liver glycogen back to glucose in the presence of glucagon. these changes are important regulators of the blood glucose level content and insulin converts some to glycogen. Glucagon converts to glycogen back to glucose

Fat metabolism

Desaturation of fat i.e, converts stored fat to a form in which it can be used by the tissues to provide energy.

Protein metabolism

Deamination of amino acids

removes the nitrogenous portion from the amino acids not required for the formation of new protein. Forms urea from this nitrogenous portion which is excreted in urine.

breaks down nucleoprotein of worn out cells if the body to form uric acid which excreted in the urine.

Transamination - removes the nitrogenous portion of amino acids and add it to other carbohydrate molecules forming new non essential amino acids.

Synthesis of plasma proteins and most of the blood clotting factors from the available amino acids.

Breakdown of erythrocytes and defence against microbes is carried out by phagocytic kupffer cells in the sinusoids.

Detoxification of drugs and noxius substances, such as toxins produced by microbes.

Metabolism of ethanol in alcoholic acids

Inactivation of hormones, including insulin, glucagon, cortisol, aldostrenol thyroid and sex hormones.

Synthesis of vitamin A from carotene, the provitamin found in some plants, eg. carrots and green leaves of vegetables.

Production of heat - The liver uses a considerable amount of energy, has a high metabolic, rate and produses a great deal of heat. Its is the main heat producing organ of the body.

Secretion of bile - The hepatocytes synthesis the constituents of bile from the mixed arterial and venous blood in the sunisoids. These include bile salts, bile pigments and cholestrol.

Storage of :

fat soluble vitamin A, D, E, K

iron,copper and some water soluble vitamins eg riboflavin, niacin 7 pyridoxine, folic acid and vitamin B12.