Chapter 31: Excretion Flashcards
Describe plant excretion.
Give off little waste
Store some and lose most waste when dead structures fall off
Lose waste gases through stomata and lenticels
What are the three layers of skin?
Epidermis
Dermis
Adipose tissue/subcutaneous tissue
There are 3 layers within the epidermis what are they?
Cornfield layer
Granular layer
Malpighian layer
Describe the cornfield layer.
Keratin build up causes the cell to become hardened
Lack of blood capillaries
This causes the Cells to die and flake off
Describe the granular layer.
Cells push through this layer and make protein called keratin
Describe the malpighian layer.
New cells are made here by mitosis.
Specialized cells make melanin which gives the skin colour and protects against us rays
Describe the dermis.
Made of connective tissue with the protein collagen for strength.
Contains sweat glands, hair follicles, blood vessels, nerve receptors, sebaceous glands
What are sebaceous glands?
They produce oil called sebum
What is adipose tissue?
Fat acts as a food store
What happens to skin in cold conditions?
Erector muscle contracts to form goose bumps
Causes hair to stand up in a reaction called pilorection
A layer of warm air is trapped between the hairs.
Blood vessels contract which reduces heat loss - vasoconstriction
What muscle forms goose bump?
Erector muscle
What process causes hairs to stand up?
Pilorection
What process causes blood vessels to contract?
Vasoconstriction
What happens to skin in warm conditions?
Sweat produced by sweat glands - evaporation of water lowers body temp
Blood vessels dilate - increase heat loss through skin
What are 5 other functions of skin?
Protection Vitamin production Food store Sense organ Excretion
Give 4 examples of how skin protects us.
Epidermis - water loss and entry of pathogens
Dermis - protects internal organs
Melanin - from uv rays
Sebum - prevents skin from drying up
What vitamin is made in skin?
Vitamin d
What is excretion?
Removal of waste products of metabolism from the body
What is egestion?
Removal of undigested unabsorbed material from the digestive system
What are the 4 roles of the excretory system in homeostasis?
- Regulates body temp
- Osmoregulation
- Controls concentration of fluids
- Removes waste
What are the three organs of excretion and the waste products they make?
Lungs - water and carbon dioxide
Skin - water and salt
Kidneys - water salt and urea
What is urea made from and where?
Liver - deamination of amino acids
What is Uric acid made from and where?
Liver - breakdown of nucleic acid
Where does water and co2 come from?
Cellular respiration
What does the renal artery do?
Brings bloods with wastes from all over the body to the kidneys
What are the 3 main processes of the kidneys?
Filtration - filters blood, outer cortex
Reabsorption - useful substances reabsorbed, modulla + cortex
Secretion - substances are secreted from the blood into the cortex of the kidneys, substances such as potassium (k) and hydrogen ions
What is urine made from?
96% water
- 5% nitrogenous wastes
- 5% salts
What does the renal vein do?
Brings purified blood back to the body
What does the renal pelvis do?
Gathers Urine from medulla
Sends urine down ureter
What is the function of the bladder?
Involuntary muscular organ that forces urine out into the urethra
Has two sphincter muscles that contract to allow urine to pass out
What are the 4 functions of the kidneys?
Excretion - remove waste
Osmoregulation - vary water content of urine
Salt concentration - vary amount of salt relished in the urine
Ph control - produces urine that is either basic or acid to maintain body ph at 7.4 (hydrogen ion)
What is the nephron?
The functional unit of the kidney - makes urine
How many nephrons are in a kidney?
1 million +
Describe the blood supply of the nephron.
Aorta - renal artery - renal arterioles - afferent arterioles - glomerulus - efferent arterioles - capillaries (becomes deoxygenated here) - renal venule - renal veins - vena cava
What are the 3 processes involved in the nephron?
Same as kidneys
Filtration
Reabsorption
Secretion
What does filtration mean?
Water and small molecules pass from blood to nephron
What is reabsorption?
Molecules passes from the nephron back into the blood
What is active transport?
Means that energy is used to move molecules from place of low concentration to high concentration
What part of the nephron does filtration occur?
Glomerulus filters molecules out of plasma into the bowmans capsule
What materials are filtered into the bowmans capsule?
Glucose, amino acids, vitamins, hormones, urea, salt, water
What materials cannot be filtered into the bowmans capsule?
Red blood cells, white blood cells, platelets, antibodies, clotting proteins, some hormones
Where does blood enter the nephron?
Afferent arterioles
What is the substance in the bowmans capsule known as?
Glomerular filtrate
What are the 3 ways the glomerulus helps filtration?
- Pressure is greater: efferent arterioles is narrower meaning that blood must be put under more pressure to enter it
- Large surface area in capillaries
- Walls of capillaries are more porous than normal
How much of the glomerular filtrate is reabsorbed?
99%
Explain what happens in the proximal convoluted tubule.
Proximal convoluted tubule is one cell thick, many infoldings (microvilli) and mitochondria
Water is reabsorbed here by osmosis
Salt, glucose, vitamins, amino acid are reabsorbed by diffusion
What structures reabsorb water?
Proximal convoluted tubule
Descending loop of henle
Distal convoluted tubule
Collecting duct
Apart from water what does the distal convoluted tubule controls?
Salt, ph
What does the ascending loop of henle control?
Moves salt into medulla using diffusion, uses active transport at the top of medulla
Where is most water reabsorbed?
Proximal convoluted tubule
What is secretion?
Movement of material from blood to nephron
What is secreted in the distal convoluted tubule?
Potassium and hydrogen ions
What is the difference between glomerular filtrate and urine?
Urine does not have glucose, amino acids but glomerular filtrate does
What happens when there is a lack of water in plasma?
Brian detects it
Pituitary gland releases adh
Adh travels to kidney
Adh causes the distal tubule to become more permeable to water
More water is reabsorbed from nephron into plasma
Lowers the volume of urine produced
What happens when there is too much water in plasma?
Brain detects it
Pituitary gland releases adh
Walls of distal tubule become more impermeable to water
Water not reabsorbed from nephron into plasma
Increases the volume of urine produced
How does blood become too concentrated?
Drink too little water
Consume too much salt
Lose too much water as sweat
How does blood become too dilute?
Consume too much water
Eat too little salt
