Humans Flashcards
(24 cards)
What are the substances plasma is important for the transport of
CO2, Digested food, Urea, Heat energy and hormones
Role of plasma in transporting CO2
hTe waste product of respiration, dissolved in the plasma as hydrogencarbonate ions and transported from respiring cells to the lungs
Role of plasma in transporting digested food
dissolved particles absorbed from the small intestine and delivered to requiring cells around the body
Role of plasma transporting urea
the waste substance produced in the breakdown of proteins by the liver. Urea is dissolved in the plasma and transported to the kidneys
Role of plasma transporting hormones
chemical messengers released into the blood from the endocrine organs (glands) and delivered to target tissues/organs of the body
Role of plasma transporting heat energy
created in respiration (an exothermic reaction), heat energy is transferred to cooler parts of the body or to the skin where heat can be lost
Why don’t red blood cells have a nucleus
More space for haemoglobin to be packed
What is haemoglobin
A protein that binds to oxygen to form oxyhaemoglobin
Why does the red blood cell have a biconcave shape
This gives them a large surface area to volume ratio to maximise diffusion
How do phagocytes deal with pathogens
They engulf and digest pathogens.
1) They have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
2) Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
How do lymphocytes deal with pathogens
Lymphocytes produce antibodies
Antibodies are Y-shaped proteins with a shape that is specific to the antigens on the surface of the pathogen
How do antibodies work
Antibodies attach to the antigens and cause agglutination (clumping together). This means the pathogenic cells cannot move very easily
At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed
How do vaccinations work
Lymphocytes recognise the antigens in the bloodstream
The lymphocytes produce antibodies specific to the antigen encountered
Memory cells and antibodies subsequently remain circulating in the blood stream
How do platelets clot blood
Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot
The clot eventually dries and develops into a scab to protect the wound from bacteria entering
Where does blood enter from in the heart
Oxygenated blood from the lungs enters the left side of the heart and is pumped to the rest of the body
Which ventricle has a thicker muscle wall and why
The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body.
Where does deoxygenated blood enter from and where does it go to
Deoxygenated blood from the body enters the right side of the heart and is pumped to the lungs
Which ventricle pumps blood at lower pressures to the lungs
The right ventricle is pumping blood at lower pressure to the lungs
What muscle separates the two sides of the heart
septum
What do valves do
prevent blood flowing backwards
Whats the pathway of blood through the heart
- Deoxygenated blood coming from the body flows through the vena cava and into the right atrium
- The atrium contracts and the blood is forced through the tricuspid (atrioventricular) valve into the right ventricle
- The ventricle contracts and the blood is pushed through the semilunar valve into the pulmonary artery
- The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place
- Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs
- Oxygenated blood returns via the pulmonary vein to the left atrium
- The atrium contracts and forces the blood through the bicuspid (atrioventricular) valve into the left ventricle
- The ventricle contracts and the blood is forced through the semilunar valve and out through the aorta
- Thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body
How does the heart rate change during exercise and why
Heart rate increases to deliver oxygen and glucose and remove waste more frequently
The volume of blood pumped out of the heart also increases to deliver bigger quantities of oxygen and glucose
How is oxygen debt paid off
At the end of a period of exercise, the heart rate may remain high for a period of time as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration
