T2 animal tissues, organs and systems Flashcards
how does the double circulatory system work
- right pump sends deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart
- left pump sends the newly oxygenated blood around the body, by the time this blood returns to the heart, it has returned to a deoxygenated state
why is the wall of the left ventricle thicker
has to pump blood at a higher pressure around the whole body
how is the heart rate controlled
group of cells in the RA (sinus node) which act as a pacemaker
release waves of electrical activity which cause the heart muscle to contract
how can an abnormal heart rhythm be treated
artificial pacemaker which sends out electrical signals to correct the heart’s rhythm
how are arteries adapted
thick muscle layer - adds strength to resist high pressure at which blood is pumped out by the heart
thick elastic layer - allows arteries to stretch and recoil in order to withstand high pressure
how are veins adapted for their function
wider cross-section (lumen) as unoxygenated blood is carried towards the heart at low pressure. The blood moves slower and against gravity so a larger lumen is needed to ensure it is transported efficiently.
valves - prevent backflow of blood
thinner walls than arteries as blood is at lower pressure
how are capillaries adapted for their function
f: enable transfer of substances between the blood and tissues
walls are 1 cell thick - short diffusion path
permeable walls - substances can diffuse across
narrow lumen - blood moves slowly, more time for diffusion
explain how the lungs are ventilated by the action of intercostal muscles
IM contract
ribcage moves upwards and outwards
diaphragm flattens and volume of chest increases
increased volume results in decreased gradient
air is drawn into lungs down pressure gradient
inverse occurs when air moves out of the lungs
describe how gas exchange occurs at the alveoli
O2 diffuses from the alveoli into the capillary bloodstream down its concentration gradient
CO2 diffuses from the capillary into the alveoli down its concentration gradient
describe how alveoli are adapted for gas exchange
small and arranged in clusters - larger SA
rich blood supply - maintains concentration gradient
thin alveolar wall - short diffusion pathway
equation for breathing rate
number of breaths / number of minutes
substances transported by plasma
red blood cells white blood cells platelets carbon dioxide urea products of digestion
purpose of red blood cells in blood
transport of oxygen around the body
how are red blood cells adapted for their function
biconcave shape - increased SA to vol ratio
no nucleus - more room for haemoglobin to bind to O2
contain haemoglobin - binds to O2
small so can pass through tiny capillaries
purpose of white blood cells in blood
form part of the immune system, which protects the body from invading pathogens
how are white blood cells adapted for their function
have a nucleus - contains DNA which codes for proteins
can produce antibodies and antitoxins
can engulf and digest pathogens (phagocytosis)
can change shape allowing them to squeeze through walls of blood vessels into blood tissues and engulf harmful microorganisms
purpose of platelets in blood
small cell fragments which aid the clotting of blood at the site of a wound
why is the function of platelets important
aid in the process of blood clotting (conversion of fibrinogen to fibrin).
as a result, red blood cells are trapped in the fibrin network, forming a clot which prevents excessive bleeding.
scab formation prevents bacteria from entering
what is coronary heart disease
occurs when the coronary arteries that supply the heart muscle become blocked with a buildup of fatty material
this restricts the supply of oxygen to the heart, possibly leading to a heart attack or death
what is a stent and how does it work
metal mesh tube that is inserted into a blocked artery so that it remains open.
stent is inflated using a balloon, which is later removed to allow blood to flow freely
advantages and disadvantages of stents
A: insertion can be carried out without general anaesthetic
quick recovery time
lower the risk of a HA
D: risk of postop infection
risk of blood clots at site of stent
what are statins
drugs which reduce the level of LDL (bad) cholesterol which contributes to the development of CHD
advantages and disadvantages of statins
A: reduced risk of strokes, CHD and HAs
increased level of HDL (good) cholesterol
D: has to be taken continuously
may have side effects
effect may not be immediate
what is heart bypass surgery
surgery where blocked coronary arteries are replaced with sections of veins taken from other parts of the body
consequences of leaky heart valves
blood flows in wrong direction, causing the heart to become less efficient.
patients may become breathless and die
what types of valves can replace leaky valves
mechanical - made of metal or polymers
biological - taken from animals (pigs, humans)
advantages and disadvantages of mechanical valves
A: last for a very long time
D: need to take meds to prevent blood clotting around valve
advantages and disadvantages of biological valves
A: work very well - no meds
D: only last 12-15 years
purpose of an artificial heart
intended to support a patient’s heart while they wait for a suitable donor heart
advantages and disadvantages of artificial hearts
A: less likely to be rejected by immune system
allows damaged heart time to rest to help recovery
D: risk of infection due to surgery
risk of blood clots
have to take blood-thinning drugs
what is a communicable disease
disease caused by a pathogen which can be transmitted from one person to another
how can diet affect health
too little food / lack of nutrition - anaemia, vitamin deficiencies
too much / too much unhealthy - obesity, type 2 diabetes
how can stress affect health
prolonged stress is linked to wide range of health problems including heart disease, cancers and mental health issues
how can life situations affect health
life factors such as location, gender, financial status, ethnic group and healthcare provision can impact a person’s mental and physical health
give examples of how health problems can interact
infection with certain viruses can lead to cancer (hepatitis > liver cancer)
compromised immune system can lead to higher risk of infection with communicable diseases
immune reactions caused by a pathogen can trigger allergic reactions
problems with physical health can lead to mental health issues
what is a risk factor
aspect of a person’s lifestyle or a substance found in the body or the environment which can increase the risk of a disease
what is a casual mechanism
mechanism which demonstrates how one factor biologically influences another
how does obesity affect the development of type 2 diabetes
obesity is linked with the onset of type 2 diabetes - a disease in which the body stops responding to insulin
how does alcohol affect liver and brain function
excessive long-term alcohol use may lead to liver cirrhosis (scarring of liver)
increases risk of liver cancer
damages brain tissue and nerve cells
how does smoking affect the development of lung disease and lung cancer
tar in tobacco can damage the alveoli of the lungs, leading to COPD
tar also damages the cells which line the lungs, leading to lung cancer
how does smoking and alcohol affect unborn babies
carbon monoxide from tobacco smoke reduces the amount of O2 the foetus receives, which can lead to premature birth or stillbirth
alcohol passes across the placenta and damages the developing foetus. Once born, the baby may have a number of deformities and health problems as part of foetal alcohol syndrome.
how do carcinogens affect the development of cancer
ionising radiation is a type of carcinogen which can cause mutations in DNA, potentially leading to cancer
what is cancer
development of a tumour as a result of uncontrolled cell division
what is a benign tumour
tumour contained in 1 location, usually within a membrane
not cancerous and don’t invade other parts of the body
can grow large very quickly - may cause damage to another organ
what is a malignant tumour
tumour that can spread around the body via the blood and lymphatic system
can invade other tissues (metastasis)
cells divide more rapidly and have a longer lifespan
disrupts healthy tissues and may lead to death
give examples of factors which can lead to cancer
genetics smoking obesity ionising radiation - UV light and X-rays viral infections - HPV and cervical cancer
arteries function
transport blood from the heart to the organs
carry oxygenated blood (aside from pulmonary artery)
when/where do veins form
when capillaries join up after passing through the body
veins role
transport deoxygenated blood (aside from pulmonary vein) from the organs back to the heart
what happens when a heart beats
- blood enters via the atria
- once filled with blood, atria contracts, forcing blood down into the ventricles below
- ventricles contract, forcing blood to exit the heart
what type of blood enters through RA
deoxygenated, from the body
what type of blood enters through LA
oxygenated, from the lungs
important veins
vena cava - heart receives deoxygenated blood from the body through it
pulmonary vein - heart receives oxygenated blood from lungs through it
important arteries
aorta - heart pumps out oxygenated blood to the body through it
pulmonary artery - heart pumps out deoxygenated blood to the lungs through it
coronary arteries - supply the heart muscle with oxygenated blood
what does deoxygenated blood enter the heart via
RA
what is air breathed into the lungs through
trachea (windpipe)
what does the trachea divide into
2 tubes - bronchi
what does the bronchi divide into
bronchioles
what do the bronchioles divide into
tiny air sacs - alveoli
what blood arrives at the alveolus
deoxygenated blood
what increases the rate of diffusion in the alveoli
- larger surface area
- concentration gradient
- temperature
what is blood
a tissue made of a fluid called plasma with 3 parts to it
what makes up blood plasma
platelets, white blood cells, red blood cells
how does oxygen and carbon dioxide move between the air and the blood
via diffusion in the alveoli
which chamber of the heart has the thickest wall
left ventricle
where do waste products move out of the cells and into the blood
capillaries
deoxygenated blood arrives at the lungs from the heart via which artery
pulmonary artery
deoxygenated blood arrives at the heart from the body via which vein
vena cava
what do red blood cells contain that bind with oxygen in the lungs
haemoglobin
