The heart and circulatory system Flashcards
What is a singular circulatory system?
In singular circulatory systems, the blood is pumped from the heart to the gas exchange organ and then directly to the rest of the body
What are double circulatory systems?
In double circulatory systems, the blood is pumped back from the heart to the gas exchange organ, back to the heart and then to the rest of the body
Advantages of a double circulatory system?
Higher blood pressure and greater flow of blood to the tissues
Blood flow through the heart (order)
Left atrium, left ventricle, aorta, vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein
Cardiac cycle
Blood enters the atria, valves open, blood passes through ventricles, ventricles comtract, (because of increased pressure in ventricles valves close), semi-lunar valves open, blood rushed through pulmonary artery and cycke repeats
Deoxygenated blood passes through these blood vessels, valves and parts of the heart:
Vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve and pulmonary artery. It then moves onto the lungs
How many times does the heart beat per minute?
About 70 times per minute but it can vary due to circumstances. The accelerator and decelerator nerve increases and decreases heart rate respectively (with the force of contractors?..)
What effect does exercise have on heart rate?
Muscles need to release more energy and need more oxygen so the heart pumps more blood and more often to increase the amount of oxygen the muscles get
What effect does stress have on heart rate?
When stressed, you are tense and being pumped with adrenaline and therefore need more blood (ie. Oxygen) in your muscles, due to flight or flight responses
What effect does sleep have on heart rate?
Heart rate decreases as our organs are working slower. They then need to release less oxygen, because they need to release less energy
What other things can effect heart rate?
Other things such as geographical position and age can also effect the heart rate
Control of the heart rate
Osmoreceptors in aorta sense CO2 levels; Cardiac centre in medulla receives information via sensory nerve; cardiac centre sends nerve impulses via accelerator/decelerator nerves; pacemaker increases (/decreases) heart rate; blood pressure increases(/decreases)
What are the effects of adrenalin on heart rate?
Adrenaline stimulates pacemaker to increase heartrate
What is coronary heart disease?
It is the blockage of the coronary artery, which results in the blood supply to area of heart muscle cut off, less oxygen and glucose reaches heart muscle, the area of heart muscle cannot respire which results in a HEART ATTACK
Risk factors for coronary heart disease?
No exercise, fatty foods, smoking, genetics, stress, age, being male
Blood is pumped around a closed circuit made up of the heart and blood vessels. As it travels around it collects materials from some places and unloads them in others. In mammals, blood transports:
Oxygen from the lungs to all other parts of the body// carbon dioxide from all parts of the body to the lungs// nutrients from the gut to all parts of the body// urea from the liver to the kidneys
Pulmonary circulation:
Transports blood to and from the lungs to exchange O2 and CO2 with air
Systemic circulation:
Transports blood to and from the body to exchange O2 and CO2 with body cells
What is the function of the placenta?
To supply the baby with nutrition and oxygen as well as to remove carbon dioxide and urea
Arteries: (key info)
Arteries carry blood from the heart to organs in the body. Blood pressure high, blood oxygenated except in PULMONARY ARTERY, no valves except in AORTA and PULMONARY ARTERY
Artery structure
Thick wall with muscle fibres and elastic tissue, small lumen, endothelium
Vein : (key info)
The vein carries blood from organs back to heart, low blood pressure, deoxygenated (therefore dark red colour) except in PULMONARY VEIN, no valves
Vein structure
Thin wall with little muscle and elastic tissue, large lumen, endothelium
Capillary: (key info)
Capillaries carry blood through organs exchanging oxygen, glucose and carbon dioxide, low blood pressure, blood deoxygenated (starting oxygenated ending up deoxygenated after exchange), no valves
Capillary structure
One cell thin endothelium
Why do veins have valves?
To prevent the back-flow of blood
Why are capillary walls only 1 cell layer thick?
To allow materials to pass through their walls easily
High levels of blood cholesterol can lead to the narrowing of arteries. Suggest how this might affect the ability of the heart to function
When an artery is blocked, less blood and therefore glucose and oxygen reach heart cells. (This means that there is less aerobic respiration and more anaerobic respiration. Lactic acid builds up.) The heart has to contract harder to move blood past the blockage, which increases blood pressure in the coronary artery. If the plaque ruptures, a blood clot may form. This could lead to a heart attack if the coronary artery os blocked.
Composition of blood
Cells, solute, liquid
What is blood plasma?
Liquid part of the blood (mainly water) //carries the blood cells around the body, carries dissolved nutrients, nutrients, carbon dioxide and urea //distributes heat around the body
Phagocytes
Much larger cells with a large spherical or lobed nucleus, phagocytes engulf bacteria and other microorganisms have infected our bodies
Lymphocytes
Produce antibodies to destroy microorganisms, some lymphocytes persist in our blood after infection and give us immunity to specific diseases
Platelets
The smallest cells (platelets are really fragments of other cells), platelets release chemicals to make a blood clot when we cut ourselves
Explain how oxygen passes through from the mother to the baby
Oxygen diffuses out of maternal capillaries into intervillous space from high concentration to low and travels towards the foetus’ heart in the foetal veins
What (other) functions does the placenta have?
Prevents/reduces the number of large molecules or microbes from passing from the mother to the foetus, so protects foetus from microbial infections, stops mothers immune system (antibodies)attacking the foetus, makes progesterone
Why Is it important that the mother’s and foetus’ blood supply don’t mix?
So that harmful substances/microbes are prevented from reaching the foetal blood (they have to cross the wall of the villus to get to the foetal blood, few substances can do this)
Why can it be harmful for the developing baby if the mother smokes?
If the mother smokes, there is less oxygen supplied to the baby, because pf carbon monoxide. This is harmful as it leads to babies habing a potentially low birth mads
Why do we need a circulatory system, but amoeba don’t?
Amoeba are small enough to absorb nutrients and oxygen via diffusion, but we have a circulatory system to transport substances to and from their cells as diffusion is not possible (we are much larger than amoeba)
