3a) Life Processes Flashcards
What type of molecules can’t get through the membrane and what can?
Small molecules can - water
Big molecules can’t - sucrose
What is osmosis?
Net movement of water molecules across a partially permeable membrane from a region of high water concentration to low water concentration
How are exchange surfaces adapted to maximise effectiveness?
Thin - short distance diffuse across
Large surface area - quicker diffusion
Lots of blood vessels - quick exchange for blood
What are stomata?
Holes in the structure of leaves which allow oxygen and water vapour to diffuse out and carbon dioxide to diffuse in
What is the size of the stomata controlled by?
Guard cells
What is the thorax?
Upper part of your body (separated from the abdomen by the diaphragm)
What is the adomen?
Lower part of your body (separated from the thorax by the diaphragm)
What is the trachea?
Windpipe
What is the oesophagus?
Food pipe
What are bronchi?
Two tubes that the trachea splits up into (each one called a bronchus)
What are bronchioles?
Smaller tubes that the bronchi split up into
What are alveoli?
Millions of tiny air sacs in the lungs where gas exchange takes place
What happens when you breathe in?
Intercostal musicales contract Diaphragm contracts Thorax volume increases Pressure is decreased Air is drawn in
What happens when you breathe out?
Intercostal muscles relax Diaphragm relaxes Thorax volume decreases Pressure is increased Air is forced out
How is the leaf adapted for gas diffusion?
Flattened shape - increased surface area
Walls of cells have air spaces
Covered in stomata
How are alveoli adapted to maximise gas diffusion?
Enormous surface area
Moist lining
Very thin walls
Good blood supply
What are villi?
Millions of tiny little projections that cover the small intestine that help absorb digested food
How are villi adapted for diffusion and active transport?
Single layer of cells on surface - thinner
Very good blood supply - quicker absorption
What is active transport?
When substances are absorbed Against a concentration gradient
How are root hairs adapted for active transport?
Root hair cells have long hairs on surface of roots - bigger surface area
Why do humans need active transport?
Allows nutrients to be taken in from the blood against a concentration gradient
Low in gut - high in blood
What 2 types of vessels to plants have for transport?
Phloem tubes
Xylem tubes
Describe Phloem tubes
Transport food substances (dissolved sugars) To storage organs and growing regions In both directions Made of columns of living cells Small holes at ends
Describe Xylem tubes
Take water up - only one direction Made of dead cells joined together No end walls between cells Hole down middle Carry water and minerals from roots To stems and leaves
What is transpiration?
Loss of water from a plant
Caused by evaporation and diffusion from inside leaves
Water lost through stomata
Why is the transpiration system constant?
Water lost through stomata Water shortage More water drawn up from xylem vessels to replace it More water drawn form roots Water lost from stomata again
What does the double circulatory system transport?
Food and oxygen to all cells
Waste materials
Explain how the double circulatory system works?
Deoxygenated blood into right atrium of heart
Pumped out of right ventricle to lungs for oxygen
Becomes oxygenated and travels back into left atrium
Pumped out of left ventricle
Once oxygen used, cycle repeats as blood is deoxygenated again
What is the heart and what does it do?
Pumping organ that keeps the blood flowing around the body
What is the function of valves in the heart?
Push blood in right direction (upwards)
Prevent flowing backwards
Explain how the heart uses it’s four chambers
Blood flows into right and left atrium from vena cava and pulmonary vein
Atria contract pushing blood into the right and left ventricles
Ventricles contact pushing blood into pulmonary artery and aorta
Valves make sure blood flows up
Blood exits heart into arteries
What are the three types of blood vessels?
Arteries - blood away from heart
Capillaries - exchange if materials at tissues
Veins - blood back into heart
Describe how arteries are adapted for their function
Strong, elastic walls - high pressure
Thick walls compared to lumen
Thick layers of muscle - strong
Elastic fibres - stretchy and springy
Describe how capillaries are adapted for their function
Permeable walls - diffusion
Usually walls only one cell thick - short diffusion distance
Carry blood really close to cells - substances can be exchanged
Describe how veins are adapted for their function
Thinner walls - low pressure
Bigger lumen - helps blood flow despite low pressure
Valves - keep blood flowing in right direction
What is blood?
Tissue
Acts as a huge transport system
What 4 main things does the blood have?
Red blood cells - carry oxygen
White blood cells - defends against diseases
Platelets - help blood clot at wound
Plasma - carries substances
How are red blood cells adapted for their function?
Concave doughnut shape - large surface area - absorb oxygen
No nucleus - more rooms for oxygen
Red pigment called haemoglobin
How are white blood cells adapted for their function?
Can change shape - engulf unwanted microorganisms
Produce antibodies - fight pathogens
Produce antitoxins - neutralise or counteract toxins
Nucleus
What are platelets designed to do?
Small fragments of dead cells Help blood clot at wound Stops microorganisms getting in Stops blood pouring out Have a nucleus
What is coronary heart disease?
When arteries get blocked by fatty deposits
arteries become narrow and blood flow is restricted
What are stents and what do they do?
Tubes inserted inside arteries
Ensure arteries stay open by squashing the fatty deposit and blood can pass through
What are the advantages and disadvantages of an artificial heart?
Not rejected - not living tissue so body doesn't respond same way Parts can be replaced Bleeding, blood clots and infection Don't work as well as natural ones Parts of the heart could wear out Electric motor could fail Needs drugs to thin blood
What is homeostasis?
Maintenance of a constant internal environment or unchanging balance
What things does homeostasis need to control?
At right level: - Temperature - Water content - Ion content - Blood sugar level To be removed: - Carbon dioxide - Urea
Why does body temperature need to be maintained?
Enzymes work best at the optimum temperature - 37 degrees Celsius in humans
How does your body respond when your too hot?
Hair erector muscle relaxes - hairs lie flat on skin
Sweat gland produce sweat - evaporates removing heat
Vasodilation - blood flow close to skin surface increases - easier for heat to transfer to environment
How does your body respond when your too cold?
Hairs erect - hairs stand up and trap insulating layer of heat on skin
No sweat produced
Vasoconstriction - blood flow constricts to close off skins blood supply - harder for heat to transfer
Shiver - muscles contract which needs respiration, releasing energy to warm up body
What 3 things do the kidneys do?
Remove urea - filtered out of blood
Adjust ion content - excess ions removed from blood
Adjust water content - excreted by kidneys in urine
What is urea?
Waste product produced from the reaction to convert any excess amino acids into fats and carbohydrates
What can sports drinks replace?
Water and ions lost in sweat
Sugar used up by muscles during exercise
What are nephrons?
Filtration units in the kidneys
Explain the process of ultrafiltration
High pressure squeezes out water, urea, ions and sugar out of blood
Membranes between Normans capsule and blood vessels act like filters so big molecules like proteins remain in the blood
Explain the process of reabsorption
Useful substances re absorbed back into blood along nephron
All sugar re absorbed through active transport
Sufficient ions reabsorbed trough active transport, excess ions aren’t
Sufficient water reabsorbed
What happens as remaining substances continue our of the nephron?
Continue to ureter as urine
Stored in bladder temporarily
Excreted out of the body
What are the two main treatments of kidney failure?
Dialysis - machine filters blood to maintain concentration of substances
Transplant
What are the advantages and disadvantages of dialysis?
Only waste substances and excess ions can diffuse across barrier
Session 3 times a week, 3-4 hours
May cause blood clots or infections
What are the advantages and disadvantages of Kidney transplant?
Could be rejected by immune system
Only cure for kidney failure
Need donor with similar tissue type
Drug treatment to suppress immune system
What two hormones does the pancreas use to control blood sugar level?
Insulin - when level is too high
Glucagon - when level is too low
What does insulin do to reduce blood sugar levels?
Converts glucose into glycogen stored in liver
Reduces amount of glucose in blood
What does glucagon do to reduce blood sugar levels?
Converts glycogen stored in liver back into glucose
Increased amount of glucose in blood
What is type 1 diabetes?
Condition where pancreas produced little or no insulin
No control when blood sugar level too high
How can type 1 diabetes be avoided?
Avoiding foods rich in carbohydrates
Exercising
Injecting insulin at mealtimes
Pancreas transplant
