blood and circulation Flashcards
components of the blood
plasma 55%, white blood cells <1%, platelets <1%, red blood cells 44%
how many litres of blood in the body
5
what is plasma
a yellow watery fluid with substances dissolved in it
plasma components
water, nutrients: glucose, amino acids, lipids, mineral ions, proteins: antibodies, hormones, dissolved oxygen, waste substances: CO2, urea
mnemonic (WNMPDW)
role of plasma
distributes heat around the body
red blood cells
erythrocytes, biconcave shape= large SA:V ratio= faster diffusion, no nucleus= more space for haemoglobin, contains lots of haemoglobin which transports oxygen (haemoglobin + oxygen=oxyhaemoglobin), small size= can pass through narrow capillaries
white blood cells
part of the immune system, 1. phagocytes: large, lobed nucleus, engulf and destroy pathogens by phagocytosis 2. lymphocytes: small, round nucleus, make antibodies and provide immunity
pathogens
microorganisms that cause disease, have ‘markers’ on their surface called antigens, antigens are a specific shape for each pathogen, e.g viruses and bacteria
phagocytosis
pathogen is engulfed by phagocytosis 1. recognition of antigen 2. surround pathogen and engulf into a vacuole 3. enzymes break down and destroy pathogen
lymphocyte activation
when a lymphocyte meets a pathogen with an antigen it recognizes, it becomes activated (primary response), lymphocyte will start to produce lots of antibodies that are specific to the pathogen, antibodies are ‘y’ shaped proteins
antibody action
antibodies kill pathogens by: causing bacteria to stick together so that phagocytes can ingest them easier, acting as a ‘label’ on the pathogen so it’s more recognizable to phagocytes, causing bacteria cells to burst open, neutralizing toxins produced by pathogens
memory cells and immunity
after becoming activated some lymphocytes turn into memory cells, memory cells remember the shape of the antigen, if a memory cell meets the same type of pathogen it will make antibodies very quickly (secondary response), pathogen will be destroyed quickly and you will not feel sick, this is called immunity it can last months, years or even a lifetime
vaccination
a harmless pathogen is injected into your body which has antigens but does not make you feel sick: weakened strain of actual microorganism, dead microorganism, modified toxins of the bacteria, just the antigens themselves, harmless bacteria, viral mRNA. antigens trigger an immune response by lymphocytes which produce antibodies, memory cells are produced that give long-term immunity
how vaccines control disease
vaccines provide individuals with protection against diseases but: they don’t always work the same way in every person (some may have less protection). Pathogens can mutate their antigens= less or no recognition by memory cells. some people can’t get vaccinates, weak immune systems or have other diseases e.g cancer. vaccines provide a population with herd immunity
herd immunity
when a high percentage of a population is vaccinated meaning an infectious disease cannot spread easily
platelets
platelets are fragments of cells, no nucleus, help blood clotting
blood clotting
if your skin is cut or damaged, pathogens can enter your body and cause infection, you can lose a lot of blood, blood clotting can prevent: entry of pathogens, blood loss
single celled organisms circulatory system
single celled organisms do not need a circulatory system, how they transport substances: diffusion, they have a large SA:V ratio
small vs large organisms circulation
small cells have a large SA:V ratio, they have more SA to carry out diffusion, they can get necessary gases and nutrients by diffusion. Larger organisms don’t have enough ‘surface’ to get gases and nutrients by diffusion, they need a transport system/ gas exchange system/ circulatory system/ digestive system to get gases and nutrients to all cells
