B3.3: Maintaining Internal Environment Flashcards
Define homeostasis?
The maintenance of constant internal conditions no matter what happens in the external environment
What is the optimum conditions for humans and what will happen if they do not stay at these optimum conditions?
Body works best at 37 degrees C
If the trmp is not optimum, enzymes may slow down/denature and reduce their ability to catalyse metabolic reactions
How may exposure to extreme cold affect the human body?
Can reduce core body temperature
Enzyme reactions occur slowly
If temp drops below 35 degrees C, you are at risk of hypothermia
How may exposure to extreme heat affect the human body?
Can cause body to overheat
If core temp increases over 40-42 degrees C, enzymes may denature - body reactions cannot occur
Eextreme cases: death
What is the thermoregulatory centre of the brain?
The hypothalamus which acts as a thermometer. It relies on signals received from receptor cells in your skin (monitors external temp) and internal receptors (monitors bloods temp)
What will the body to when the hypothalams detects a change in body temp?
Brain causes a different parts of the body to respond by sending impulses to effectors, then return back to normal temp
What are examples of conditions that need to be regulated?
Water levels
CO2 levels
Internal body temp
Urea concentration in urine
Blood sugar levels
What may the body do in response to when you’re too hot?
Erecor muscles relax - prevent insulating layer
Sweat glands producing lots of sweat, as sweat evaporates, energy is transferred to the surroundings, cooling the skin
Blood vessels close to the skin vasodilate, allows more blood to flow near the surface
What may the body do in response to when you’re too cold?
Erector muscles contract, hairs rise and create an insulating layer
Blood vessels near the skin undego vasoconstriction - less blood flows to surface, less energy transferred to surroundings
Shivering starts - muscles contract and relax fast, requires respiration, which transfers some energy to warm the body
What is glucose?
An energy store
How can blood glucose levels change?
After eating, glucose from digestion passes into bloodstream, blood sugar levels rise
When you excercise, more glucose is needed as the body needs to transfer more energy, blood sugar levels drop
How does the body respond when blood sugar levels are too high?
Detected by pancreas which releases insulin which travels in the blood to the liver
Liver converts glucose to glycogen
Normal glucose level
How does the body respond when blood sugar levels are too low?
Pancreas releases gluacgon
Liver converts glycogen into glucose
Define glucose
A simple sugar serving as the main energy source for a body cell’s
Define glycogen
A stored form of glucose, usually in the liver and muscles
Define glucagon
Hormone produced by pancreas that stimulates the release and breakdown of glycogen
Features of type 1 diabetes ONLY
Normally begins in childhood
Pancreas doesn’t make insulin
Controlled by insulin injections regularly
Autoimmune condition
Features of type 2 diabetes ONLY
Linked to lack of excercise
Linked to obesity
Begins later in life
Receptors don’t respond to insulin
Might need drugs to increase insulin output
If worsens, might need insulin injections
Features of both type 1 AND type 2 diabetes
Controlled by limiting carb intake
Controlled by increasing excercise
Blood glucose levels are often too high
Define osmoregulation
A process by which the body/an organism regulates the water balance in its body and maintains homeostasis
How can water enter the body?
Salts and water get in through food and drink
Water produced as a result of respiration
How can water exit the body?
Lost through sweating, urine and water vapour when you exhale
What is excretion?
Removal of waste
What is ADH released by?
Pituitary glands
What happens when there is a high concentration of plasma?
Too little waer
ADH release increases from pituitary glands
More water absorbed by nephrons
More concentrated/darker urine
What happens when there is a low concentration of plasma?
Too much water
ADH release decreases from pituitary glands
Less water reabsorbed by nephrons
More dilute/lighter urine
Why is urea harmful?
Too much urea can crystallise the joints
What is urine?
A solution containing urea, excess water, salts and other waste substances. Urine trickles into your bladder where it’s stored until urination
What does the kidney filter out?
Excess water
Salts
Urea
What is lysis?
Too much water present, water goes into the cell due to osmosis, cell bursts
What is crenation?
Too little water present, water goes out of the cell due to osmosis, cell shrinks
What is the ureter?
Tube where the urine passes through from kidney to the bladder
What is the renal artery?
Brings blood containing urea and other substances to the kidney
What is the renal vein?
Carries blood away from the kidney, after urea and other substances have been removed from the blood
What are physical symptoms that you have too less water?
Produces very little urine
Water saved for use
Small amount of concentrated urine
Dark yellow
What are physical symptoms that you have too much water?
Produce lots of urine
Excess water lost
Large amounts of dilute urine
Almost colourless
Function of the liver
Produces urea
Function of bldder
Stores urine
Function of the ring of muscle
Controls opening and closing of the bladder
Describe a typical negative feedback cycle of a human body when salt concentration increases
Receptors in hypothalamus detect change
Pituitary gland releases more ADH
ADH levels of blood increase
Kidney tubules become more permeable to water
More water is reabsorbed back into the blood
Salt concentration of blood alls
CONCENTRATED DARK YELLOW URINE
Describe a typical negative feedback cycle of a human body when salt concentration decreases
Receptors in hypothalamus detects this change
Pituitary gland releases less ADH
ADH levels in blood decrease
Kidney tubules become less permeable to water
Less water reabsorbed back into the blood
Salt concentration of blood increases
DILUTE COLOURLESS URINE
What is the nephron?
Filtering unit of the kidney
What is reabsorbed in selective reabsorption?
Sodium, amino acids and glucose are reabsorbed from filtrate back into the blood
Loop of Henle function
Reabsorbs water for beings that don’t need much water, like camels
What is the function of the distal convoluted tubule?
Controlled loss of water and salts
What is the function of the bowmans capsule?
Membrane has small filtering pores
What is ultra-filtration?
Small things pass, not large
What will the bowmans capsule filter?
Water
Salts
Amino acids
Glucose
Urea
What is the cortex of the kidney?
Where filtering happens
Describe a typical diagram of selective reabsorption and a kidney
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