B3.1 Control Systems Flashcards
What does the biological clock do?
It is a part of the brain that regulates many reactions taking place in the body over a 24 hour period, including the release of hormones.
What are hormones?
Hormones are chemical messengers that are made in the body and cause different reactions to take place in different parts of the body.
What is melatonin?
Melatonin is a hormone which is released around 10pm, which makes us feel sleepy. In the morning the levels of melatonin secreted drop, making us wake up. This is why feel alert during the day and sleepy at night.
What to rhythms do plants have?
Photoperiodism and circadian rhythms.
What are the circadian rhythms of plants?
Flowers are open during the day and closed during the night, so at night the pollen is protected from the wind but at day the plant is open and ready for pollination.
What is photoperiodism?
Plants using change in the day length to flower at the right time of year.
How does photoperiodicity help with germination?
Plant species die during the harsh winter, but their seeds survive. In the spring the days get longer, so the seeds germinate so that the flowers can survive in the summer.
How photoperiodicity effect growth?
Some plant species grow all through winter but respond to lengthening days by growing quicker. In Autumn other plant species stop growing in preparation for winter.
What is a circadian rhythm?
Biological rhythms which happen over a 24 hour period.
What are the three main roles of the kidneys?
-Remove urea from the blood. Urea is produced in the liver from the breakdown of excess amino acid.
-Adjustment of ion levels in the blood.
-Adjustment of water content in the blood.
They do this by filtering stuff out of the blood under high pressure and then tea sorting useful stuff. End product is urine.
What are nephrons?
Nephrons are the filtering units in the kidneys.
Describe ultrafiltration (step one in the nephrons)
1- a high pressure is built up which squeezes water, urea, ions and glucose out of the blood and in to the Bowman’s capsule, from the glomerus.
2- the glomerus an the Bowman’s capsule act like filters, so big molecules like proteins and blood cells are not squeezed out of the blood.
Describe reabsorption (step 2 in the nephrons)
As the liquid flows through the nephrons useful substances are reabsorbed.
1- all the glucose is selectively reabsorbed back into the blood over a concentration gradient.
2- sufficient water is absorbed depending on the level of ADH. The process of maintaining the water level constant is called osmoregulation.
This happens between the first convoluted tubule, the loop of Henlé and the second convoluted tubule.
Describe the release of wastes (third step in the nephrons)
Urea and excess water aren’t reabsorbed. They continue out of the nephron, whilst the blood continues to the renal vein, through the collecting duct, Into the ureter, down to the bladder and out through the urethra.
Describe how water content is controlled by negative feedback.
- The water content is controlled by ADH.
- The brain monitors the water content of the blood an instructs the pituitary gland to release ADH into the blood depending on how much is needed.
- Water content is controlled by negative feedback, so changes in the environment trigger a response that counteracts the changes. This means that the internal environment stays at a constant.
How do lupins protect themselves?
They produce poisonous alkaloids which are released following a circadian rhythm. These chemicals make the leaves poisonous to pests or larger herbivores that might want to eat them.
How do potato plants protect themselves from pathogens?
Potato plants protect themselves from potato blight by producing chemicals which kill it, but only few produce it.
How can foxgloves be used medically?
Digoxin is chemical found in foxgloves which can kill in high doses because it affects the heart beat. However in low doses it can be used to treat heart disorders.
How can cinchona trees be used medically?
Quinine, the position cinch one produces has been used to treat malaria.
How can willow trees be used medically?
Aspirin is produced by willow trees and it is used to treat symptoms of disease such as pain or fever.
What did Louis Pasteur do?
Pasteur demonstrated that microorganisms were responsible for some foods going of. So he proposed the idea of keeping microorganisms away from people and food to stop some diseases and preserve food. Today we refer to the methods we use to keep things free from living organisms as aseptic techniques. This includes pasteurisation.
What did Edward Jenner do?
He noticed that milkmaids didn’t get smallpox because of the cowpox they had in their hands. So he spread cowpox blister pus on a young boy, and then smallpox blister pus on him, and because of the cowpox, he was immune to the smallpox.
Explain the process of immunisation.
All viruses and pathogens have antigens, which our bodies recognise as foreign and so destroy with antibodies.
A vaccine contains harmless versions of a pathogen or parts of it, which the white blood cells (lymphocytes) respond to. The immune response is the way the body responds to infection.
As well as producing antibodies the antigens trigger the creation of memory lymphocytes which then can create more antibodies on the future.
What is kidney dialysis?
Patients who have kidney failure can’t filter their blood properly, so they a re connected to a dialysis machine which filters their blood for them.
How does dialysis work?
Dialysis fluid has the same concentration of salts and glucose as blood plasma, so that these aren’t removed from the blood.
The dialysis barrier is permeable so that things like ions and waste substances can be removed but not big molecules like proteins.
