B3.3 - Maintaining Internal Environments Flashcards
What is homeostasis?
When a stimulus is detected, the body will be brought back to its normal levels, which is its homeostasis
What happens when you get too hot?
Body hairs lower so the hairs on your skin lie flat, preventing an insulating layer of air being trapped around the body
Sweat glands produce sweat. As the water in sweat is evaporated, energy is transferred by heating from your body to the environment, reducing your temperature
Blood vessels supplying capillaries near the skin’s surface vasodilate to increase blood flow, and therefore heat loss via radiation
What happens when you get too cold?
Body hairs rise, trapping a thin, insulating layer of air close to the body Sweat glands
Sweat glands stop producing sweat.
Blood vessels supplying capillaries near the skin’s surface vasoconstrict to reduce blood flow, and therefore heat loss via radiation
Your body shivers by rapidly contracting and relaxing muscles to increase rate of respiration in your cells, releasing more energy through heat
What happens when blood sugar levels are too high?
This is detected by the pancreas, which releases the hormone insulin
Insulin travels in the blood to the liver, stimulating the liver to turn glucose into glycogen
Glycogen is stored in the liver, so there is less glucose in the blood and levels drop
What happens if blood sugar levels are too low?
The pancreas releases the hormone glucagon
This makes the liver convert glycogen back to glucose.
This is released into the blood, increasing blood sugar levels
What does Type 1 diabetes mean?
The person cannot produce insulin, because the person’s own immune system has destroyed the pancreatic cells that make insulin
Normally begins in childhood
How can Type 1 diabetes be managed?
Regular injections of insulin
Balanced diet and regular exercise
What does Type 2 diabetes mean?
The person cannot effectively use insulin
The person’s cells do not produce enough or they do not respond properly
Occurs later in life and linked to obesity
How can Type 2 diabetes be managed?
Regulating carbohydrate levels through diet
Regular exercise
Overweight people are encouraged to lose weight
In some cases, drugs or insulin injections are used to stimulate insulin production
What is lysis?
If too much water is present, it will move into your blood cells, causing them to swell and burst
What happens if too little water/ too much solute is present in the bloodstream?
Water diffuses out of blood cells, causing them to shrink
Where is urea produced?
Liver
What is the function of the renal artery?
Brings blood containing urea and other substances to the kidney
What is the function of the renal vein?
Carries blood away from the kidney, after urea and other substances have been removed from the blood.
What is the ureter?
Tube through which urine passes from the kidney to the bladder
What is the urethra?
The tube through which urine passes through to the outside of the body
How is urine produced (summary)?
Small molecules (water, glucose, urea and salts) pass into the tubes inside the kidney.
The kidneys put back any useful substances into the blood, including all glucose, any useful salts, and some water, through selective reabsorption.
The urine is the mixture of urea, excess salts and excess water
Alcohol reduces the release of ADH.
What best describes the effect on urine from drinking alcohol?
Diluted urine with a higher volume
What are the three parts of the kidney?
Capsule
Cortex
Medulla
What parts of the kidney produce urine?
1 million nephrons per kidney
Where is the top of the nephron?
Cortex
Where is the loop of Henlé?
Medulla
How does blood enter the nephron?
Blood enters the kidney under high pressure from the renal artery, and goes down one of its many branches to a glomerulus
The glomerulus contains a knot of capillaries
Blood vessels narrow at the exit to the glomerulus, so high pressure forces out small molecules, leaving the large molecules in the bloodstream
Where does selective reabsorption take place and what happens?
Proximal convoluted tubule
All of the glucose is absorbed, as well as water and salts needed by the body
Where does uncontrolled reabsorption of water occur?
Loop of Henlé
What is reabsorbed in the distal convoluted tubule?
Mineral ions
What is the order of a nephron?
Glomerulus
Bowman’s capsule
PCT
Loop of Henlé
DCT
Collecting Duct
What does ADH do and how?
If blood water potential is too low, the hypothalamus produces ADH, which travels to the kidney to make the walls of the collecting ducts more permeable to water, so more is reabsorbed
What does hypertonic mean?
Contains high levels of glucose and salts
Why does hypotonic mean?
Contains low levels of glucose and salts
What does isotonic mean?
Contains ion concentrations equal to those in blood plasma
