Chapter 15 - Homeostasis Flashcards
- 4
- what is metabolic waste and what is the definition of excretion and egestion
- waste substances that are toxic to or produced in excess
- removal of metabolic waste from the body
- removal of undigested material from an organism
- 4
- What are the 3 main metabolic waste products and where do they come from
- Carbon dioxide = cellular respiration
- Bile pigments = breakdown of haemoglobin
- nitrogenous waste products (urea) = breakdown of amino acids
- 4
- How does oxygenated blood enter and leave the liver and why does the liver this need oxygenated blood
- enters = hepatic artery
- leaves = hepatic vein
- liver needs oxygenated blood because it needs this for aerobic respiration and produce ATP - metabolic processes require this
- 4
- What is the name of the other vessel that carries blood to the liver and what is the blood loaded with, how much of the total blood into the liver comes from this vessel
- Hepatic portal vein
- blood filled with products from of digestion straight from the intestine to the liver
- 75%
- 4
- What are liver cells called and what two things do they have in abundance, what’s the reason for this ?
- hepatocytes
- Golgi apparatus and mitochondria as the cells are very metabolically active
- 4
- What are sinusoids, what are they surrounded by and why do they exist ?
- Spaces where blood from the hepatic artery and hepatic portal vein mix
- hepatocytes
- the mixing increases the oxygen content of the blood which supplies the hepatocytes with enough oxygen for their metabolic needs.
- 4
- What are the Kupffer cells and where are they located
- act as resident macrophages of the liver, ingesting foreign particles , helping protect against disease.
- sinusoids
- 4
- what are the 3 steps of hepatocytes secreting bile
1) secrete bile from the breakdown of haemoglobin into spaces called conaliculi
2) the bile then drains from these into the bile ductules
3) they then take it to the gall bladder
- 4
- What are two ways the liver helps with carbohydrate metabolism
- when insulin causes blood glucose concentration levels to fall the hepatocytes help this by converting glucose into glycogen
- vica versa - converts glycogen into glucose in order to help blood glucose concentration levels to rise
- 4
- hepatocytes carry out transamination - what is the definition of this and why is it important
- conversion of one amino acid into an another
- this is important as the diet does not always contain the required balance of amino acids
- 1
- what is the definition of homeostasis
- mechanisms to maintain a dynamic equilibrium, with small fluctuations over narrow range of conditions
- 1
- what is the definition of negative feedback and how does it do it
- mechanism by which the body maintains conditions within particular limits - it does this by opposing a change that deviates from the norm e.g. insulin decreasing blood glucose levels
- 1
- what is the definition of positive feedback and what is a way to remember the difference between
- a change in the internal environment is increased in response
- positive = emphasises change
- negative = stops the change/ returns change to normal
15.2
why is it important that we have thermoregulation/maintain our core temperature (37 degrees) and what could it cause
- enzymes optimum temperature is 37 degrees and if it goes too low or too high they will not work as efficiently or they will become denatured - enzymes control most reactions
- death, hyperthermia, hypothermia, heat stroke
15.2
How does hyperthermia and hypothermia occur and what happens at both
hyperthermia = temperature is above 40 degrees
hypothermia = temperature is below 35 degrees
thermoregulatory mechanisms break down when either occur
15.3
What is the definition of an endotherm and what organisms are this
- organisms tat can control the production and loss of heat to maintain body temperature (use internal sources)
- mammals and birds
15.3
What part of the brain controls thermoregulation and what two sections is it subdivided into
- hypothalamus
- heat gain centre and heat loss centre
15.3
How do endotherms detect temperature changes (2) and how is the combination of the to beneficial
- thermorecpetors in the skin that detect changes in the surface temperature
- thermoreceptors in the hypothalamus detect the temperature changes in the blood in the body
- the combination gives the body great sensitivity and can respond to changes in temperature if the blood as well pre-empt changes in the external environment
15.3
Two additional human behavioural adaptations
- wear clothes
- build homes
15.3
How does vasodilation and the arteriovenous shunt vessels help the body to cool down
- arterioles near the skin vasodilate to increase the amount of blood flowing towards the skin as well as meaning the vessels are nearer to the skin as they dilated
- the arterio-venous shunt vessels constrict forcing blood through the capillary networks close to the surface of the skin
- when the blood is close to the skin it radiates which cools down the skin
