Excretion Flashcards
What is excretion
Elimination of metabolic waste from the body
Why do plants not need excretion
They make their own food and waste products of reactions are usually reused
Where are many waste products of plants stored
Vacuoles in living plants within dead cells
What is homeostasis
Maintenance of a constant internal environment in an organism
What are 3 example of what remain a constant internal environment
Temperature, fluid balance, chemical composition
Why is there a need to regulate temperature
Temperature regulates the rate of chemical reactions
What are the two different methods animals use to control their temperature
Ectothermy and endothermy
What are ectotherms
Gain or loose heat from or to their external environment
What are endotherms
Generate their own heat from metabolic reactions
What are the two layers of skin
Outer epidermis and inner dermis
What is beneath the dermis
Adipose tissue
Where do cells constantly divide by mitosis to produce new epidermis cells
Malpighian
What happens to cells produces in the malpighian
They are pushed out through the granular layer and they produce a waterproof protein called keratin
What happens to cells after the granular layer
They die due to excess keratin and lack of blood cappillaries
What is the name of the pigment that gives colour to skin in the malpighian layer
And what does it do
Melanin
Protects skin from harmful rays
What does the dermis consist of
Connective tissue and strengthening protein called collagen
Sweat glands, hair follicles, sebaceous glands, blood vessels and nerve receptors
What are the functions of skin
Epidermis protects the skin from loss of water and entry of pathogens
Dermis protects internal organs from damage
Melanin protects skin from ultraviolet rays
Sebum keeps hair moist and flexible and prevents skin from drying up
What vitamin is produced in skin and how
D
Following exposure to ultraviolet radiation and it helps calcium absorption in the intestines
Where is food stored in skin
Adipose tissue
What allows skin to be a sense organ
Variety of receptors
Eg touch pain and temperature
What allows skin to excrete
Sweat glands
How does skin regulate temperature in cold conditions
Erector muscle contracts forming goosebumps causing hair to stand up
A layer of warm air is trapped close to the skin by these hairs
Blood vessels contracts to reduce heat lost through the skin
Brain causes muscles to contract and relax causing shivering to raise temps
What is the term for
1) causes hair to stand up
2) causes blood vessels to contract
1) piloerection
2) vasoconstriction
How does the body react to warm conditions
Sweat as water evaporation lowers our body temp
Blood vessels increasing the heat loss through the skim
What is the role of excretion and homeostasis
Regulates body temp
Controls osmosis
Controls concentration of body fluids
Removes waste of metabolism
What are the organs of excretion
Lungs - co2 and water
Skin - water and salts
Kidneys - water salts urea
What is the urinary system consisted of
2 kidneys
2 ureters
Bladder
Urethra
What are the 3 processes in the kidneys
Filtration
Reabsorption
Secretion
What happens in filtration
Incoming blood is filtered in the outer cortex
Results in small substances being forced out of the bloodstream into the kidneys
What happens in reabsorption
Where does it take place
Useful materials are taken back into the blood
Occurs in cortex and medulla
What happens during excretion
Substances are excreted out of the cortex eg potassium
Purified blood leaves the kidneys through renal veins
Where does the renal vein take purified blood
Vena cava
What happens after filtration reabsorption and secretion
Unwanted waste and toxic products are left in the kidneys to form urine
What is urine composed of
96% water
- 5% nitrogenous waste
- 5% salt
Where is urea produced and how
In the liver and from excess proteins
Where does urine flow from and to
From medulla to renal pelvis
What is the bladder
Muscular organ that stores urine
Is the bladder under voluntary control
No
What muscles control urination
Sphincter
What are the functions of the kidneys
Excretion
Osmoregulation
Ph control
How do the kidneys control water content
Varying water content of urine eg on hot days produce low volumes of urine
How do the kidneys control salt content
Vary amount released in urine eg if we consume too much it will release more
Whwt do the kidneys do
Remove waste products of the blood
How does the kidneys control ph of body fluids
Producing urine that is either more or less acidic to allow ph of blood to remain at 7.4
What is a nephron
Functional unit of kidneys they make urine
What happens to the arteries when blood enters the kidneys
Blood enters kidney through renal artery
Once inside kidneys this vessel divides to form renal artioles
These then split to form smaller afferent arterioles
These divide to form a cluster of capillaries - glomerulus
Blood leaves glomerulus
This then divides to form capplilaries surrounding nephron
Eventually rejoin renal venules and combine and emerge from the kidneys as the renal vein
Where is the glomerulus found
Bowmans capsule - cup shaped structure
Where is urine produced
Nephron
What happens during filtration
Blood enters nephron in the afferent arterioles which contains waste products
In the glomerulus particlas such as glucose amino acids and vitamins are forced out of the plasma and into bowmans capsule here they dialute to a solution called glomerular filtrate
What structure of the glomerulus helps filter
Pressure here is greater than normal blood pressure
Surface area of cappilaries are large - increase area for filtration
Walls of glomerular cappilaries are more porous
Cells in wall of bowmans capaule are one cell thick
Why is pressure in the glomerulus greater
Already high pressure of the afferent arteriole is increased as efferent arterioles are narrower
How mucn of glomerular filtrate is reabsorbed
99%
Where is majority of water absorbed by osmosis
Proximal convoluted tubule
Where are useful molecules eg glucose reabsorbed and how
Proximal convoluted tubule
Diffusion and active transport
How is the proximal convoluted tubules adapted to help reabsorption
One cell thick
Long
Numerous infoldings
High concentration of miochondria - eneegy for active transport
After the roximal convoluted tubule where does reabsorption tales place
Descending limb of the loop of henle
What is reabsorbed in the loop of henle
Small amount of water and minerals
Permeabled to water
What happens in the ascending limb of the loop of henle
Salts are reabsorbed as it is permeable to salts
Salts move out of nephron into fluid of the medulla
How is water removed out of ascending
At the top,soium is pumped out making the medulla more concentrated
Water then moves out by osmosis
What can be reabsorbed in the distal convoluted tubules
Some water and salts
It is involved in the prcise control of water salt and ph of blood
What can be re absorbed in the collecting duct
Water - it is permeable to water
Also medulla is more concentrated
What liquid flows from collecting duct to pelvis of kidneys to bladder
Urine
Why does potassium need to be secreted
Too much prevents nerve impulses travelling correctly and reduced strength of muscular contractions
How does glomerular filtrate differ to urine
Has more water
Has more useful molecules
What controls the volume of urine produced
Antidiuretic hormone
What is ADH
Produced by hypothalamus and stored in pituitary gland
Released by pituitary to blood tream
Affects distal convoluted tubule and collecting ducts
Causes more water to be reabsorbed in the nephron
Controls osmoregulation
When does blood plasma become too concentrated
Drink tok much water
Sweat too much or faces
Consue too much salt
What happens when blood plasm is too concentrated
ADH released
Travels to kidneys
Walls of distal and collecting tubes becomes from permeable to water
What happens if blood plasm is too dilted
Consume too mch water
Eat low salt
Adh not released
Distals and collecting tubes become impermeable
