Excretory Flashcards
What are two of the major waste products and how are they removed from the body
Carbon dioxide and water; through the respiratory system
Animal cells produce waste while doing what
Carrying out the physiological processes that are necessary for life
What is the third type of waste produced by metabolic processes
The nitrogenous wastes urea and uric acid
When are urea and uric acid created
Amino and nucleic acids are broken down
What have animals done in response to nitrogenous waste
Developed a variety of systems that also play important roles in regulating water and salt balance
How do cnidarians solve the problem of nitrogenous waste
Simple diffusion - most cells of a cnidarian are in contact with the external environment, meaning that nitrogenous wastes can diffuse across the cell membranes and into the surrounding water
Describe the annelid system for excretion
Two small tubes called nephridia exist in each of the annelid’s body segments. The tubes are surrounded by capillaries. Nitrogenous waste in the form of urea is passed from the blood into the nephridia. The waste collected in the nephridia eventually exits the worm through pores in the skin.
What are the Malpighian tubules
A system of structures that are bathed in the fluid of the arthropod’s open circulatory system. It is the annelid’s ways of excreting waste. Nitrogenous waste in the form of uric acid collects in tubules, the waste empties into the digestive tract where water is reabsorbed. Without water, urea converts to solid crystals of uric acid, which are excreted along with the solid waste produced by digestion
What is the answer of the vertebrates to the problem of water balance and nitrogenous waste excretion
The kidneys
What do the kidneys do and how many are there
There are two, and they filter blood, removing urea in the form of urine while also regulating the levels of water and salt present in the blood plasma.
From each kidney, where does urine travel
Through the ureter and then into the urinary bladder
Describe the ureter
A large duct
Describe the bladder
A muscular organ that expands to store urine
What happens when the bladder contracts
Urine is pushed through another duct known as the urethra and out of the body
What is the basic functional unit of the kidney
The nephron (the kidney has millions of nephrons)
What is a nephron
A tiny tubule whose special structure makes it ideal for its blood filtering task
What do nephrons consist of
A cluster of capillaries called the glomerulus
What is the glomerulus surrounded by
A hollow bulb known as Bowman’s capsule
What does the Bowman’s capsule lead into
A long, convoluted tubule with four sections: the proximal tubule, the loop of Henle, the distal tubule, and the collecting duct
Where do the collecting ducts empty into
The central cavity of the kidney, the renal pelvis, which connects to the ureter (that carries urine to the bladder)
How does blood enter the kidney and what happens there
Through renal arteries, which quickly split into smaller vessels and then branch further into the very narrow clusters of capillaries that make up the glomerulus of the nephron
Why is the blood pressure high in the glomerulus’s capillaries
Because the capillaries are very narrow
What does the high pressure do
It squeezes the liquid portion of blood (filtrate) through a sieve structure and into the Bowman’s capsule but leaves the blood cells, platelets, and large protein molecules behind (filtration)
What does the filtrate contain
Large amounts of water, glucose, salts, and amino acids as well as urea
