Chapter 10- Removal Of Waste Flashcards
Excretion
Removal of the wastes of metabolism from the body
What organs are involved in excretion for either processing wastes or the excretion of the wastes
Lungs Liver Sweat glands Kidneys Alimentary canal.
Liver
. Located in upper abdominal cavity
. Prepares materials for secretion
. Proteins are primarily body builders that make up the structural materials of cells
. As long as the body has sufficient supply of fats and carbohydrates then little protein is used in energy releasing reactions
. Excess proteins from the diet cannot be stored in the cells so processes are required to remove it from the body
. Most protein is broken down in the body but the breakdown is mostly incomplete
. Liver detoxifies alcohol and many drugs
. Deactivates many hormones and converts them into a dorm that can be excreted by the kidneys
. Haemoglobin from red blood cells is is broken down in the liver to produce bile which are then passed out through the body with the faeces
Amino acids breakdown in the liver
. Red blood cells are a source of protein and they are broken down into the constituent amino acid, some of these proteins are then made to make new proteins
. A small amount of amino acid is lost from the body through the urine, skin, hair and fingernails
. Proteins which have been built up from amino acids become the primary constituents of cell structures, enzymes, antibodies, and many glandular secretions
. If other energy sources have been used up, the body is able to metabolise large amounts of proteins.
Deamination in liver
. To make use of proteins for an energy source the amino group (NH2) must be removed from amino acids
. Occurs in the liver with the aid of enzymes
. Once the amino group has been removed its is converted by the liver cells to ammonia (NH3) and then finally to urea
. Urea is eliminated in the body through the urine
. The remaining part of the amino acid which is mainly made up of carbon and hydrogen is converted into a carbohydrate this carbohydrate is readily broken down by the cells to release energy, carbon dioxide and water
Ammonia in liver
. Extremely soluble in water and highly toxic to cells
. Cells of the liver rapidly convert ammonia to urea
. Moderate amounts of urea are harmful to the body
. Urea is easily excreted by the kidneys and is eliminated through the body as urine
. Small amounts of urea are lost as sweat from sweat glands
The skin functions
. Provides a protective layer covering the surface of the body
. Regulates body temperature
. Has an important role in excretion
Excretion from the skin
. Sweat glands secrete about 500mL of water each day
. Dissolved in the water is sodium chloride, lactic acid and urea
. Some drugs are also secreted by the skin
Where are the sweat glands in the skin located
. Lower layers of the skin
. Sweat gland is a duct that carries the sweat to a hair follicle or to the skin surface where it opens into a pore
. Cells surrounding the sweat gland are able to contract and squeeze the sweat to the skin surface
The kidneys
. Reddish brownish
. Located in the abdomen
. Kidney, bladder and their associated ducts are often referred to as the urinary system
Microscopic structure of a kidney
. When seen under a microscope the kidney is seen to be composed of a large number of nephrons and collecting ducts
What is a nephron
. The functional unit of the kidney where the urine is formed
. Each nephron is surrounded by a network of blood capillaries
The way in which substances travel through a nephron
. Each nephron consists of a renal corpuscle and a renal tubule
. Nephron begins with an expanded end called the glomerular capsule and it looks like a double walled cup that surrounds and almost completely encloses a knot of arterial capillaries called the glomerulus
. Leading away from the glomerular capsule is the renal tubule and it begins withs winded section called the proximal convoluted tubule
. After eh proximal convoluted tubule there is a descending limb which then leads to the loop of henle
. After the loop of henle there is an ascending limb and the then tube coils and winds again and that is the distal convoluted tubule
What happens after the distal convoluted tubule
The distal convoluted tubule of many nephrons join up into a collecting duct which opens into a chamber in the kidney called the renel pelvis
The renel pelvis is shaped like a funnel and it channels fluid from the collecting ducts and into the ureter
What are nephrons of the kidney responsible for
. Removing wastes from the blood
. Regulating blood composition
How are the kidneys able to carry out their function
. Well supplied with blood vessels
How does blood flow through the kidneys
. The nephrons are well supplied with blood vessels
. Blood enters the kidneys through the renal arteries ams these arteries a quite large so the kidneys receive a lot of blood
. The renal artery divides into small arteries and arterioles
. Each renal corpuscle is supplied by an arteriole which is the afferent arteriole which then forms a knot of capillaries called the glomerulus which is located within the glomerular capsule
. The capillaries then unite to form another arteriole called the efferent arteriole which then passes out the renal corpuscle
. Efferent arteriole breaks up into a second capillary network that surround the proximal and distal convoluted tubules, the ascending snd descending limbs and the loop of henle which is called the peritubular capillaries
. Venous blood eventually drains away from this newtwork and leaves through the renal vein
What three major processes does urine formation involve
. Glomerular filtration
. Selective reabsorption
. Secretion by the tubules
Glomerular filtation
. Takes place in the renal corpuscle where fluid is forced out of the blood and is collected by the glomerular capsule
. Achieved by high blood pressure in the capillaries
. The afferent arterioles leading into the glomerulus has a wider diameter than the efferent arteriole leaving it and this narrowing increases resistance of flow of blood and produces a higher pressure in the glomerulus
. The pressure outside the capillaries in the glomerular capsule is negligible and the blood in the capillaries is separated from the capsule by only two layers of thin flat cells—— one which makes up the capillary wall and one that makes up the wall of the capsule
. When blood enters the glomerulus, the high pressure forces water and dissolved blood components through the membrane and into the capsule, the resultant fluid is called the filtrate
Filtrate from glomerular filtration
. The resultant material from water and dissolved blood components from the blood in the capillary moving to the glomerulus capsule
What does the filtrate consist of from glomerular filtration
. In a healthy person it consists of materials in the blood except for red and white blood cells and plasma proteins these are not in the filtrate because they are too large to pass through the differentially permeable membrane
. Water, salts, amino acids, fatty acids, glucose, urea, uric acid, creatinine, hormones, toxins and various ions
Selective reabsorption
. Many of the things filtered from the capillaries to the glomerular capsule can be of use to the body so excretion of these things would be undesirable
. Therefore some selective reabsorption of filtrate must take place
. Process is carried put by cells that line the renal tube
. Materials that are reabsorbed include water, glucose, amino acids, ions (such as sodium, potassium, calcium, chloride and bicarbonate) some wastes like urea are partially absorbed as well and they are all returned to the blood
What is needed for appropriate selective reabsorption
. Large surface area that is achieved by the long length of the renal tubule, two sets of convolutions and the loop of henle, and a huge number of nephrons in each kidney
Reabsorption of water in selective reabsorption (facultative reabsorption)
. Absorption of water can be regulated depending on the body’s water requirements,
. The regulation of water can be controlled by the permeability of the plasma membranes of the cells making up parts of the tubules can be changed
. This is an active process under hormone control and is referred to as facultative reabsorption
