Breathing, circulation and blood Flashcards
(37 cards)
What is spontaneous respiration controlled by?
Medulla, however can be overridden for periods of time, eg holding breath
What leads to a higher breathing rate?
And what are chemoreceptors?
The central and peripheral chemoreceptors are effected by blood pH, level of acid and amount of co2 (known as partial pressure or PaCO2) , When there is more CO2, this leads to a higher breathing rate.
Chemoreceptors are specialized cell groups responsible for acquiring information about the chemical environment and subsequently conveying the information to neurons.
What do we need to ensure that respiration occurs?
we need adequate ventilation, air coming in and adequate perfusion, air coming out. we also need haemoglobin in red blood cells and adaquate uptake of oxygen at the lungs and the body’s cells.
What conditions help haemoglobin to release oxygen?
An increace in CO2, temperature and 2,3 DGP
2,3-diphosphoglyceric acid’s function is to bind to haemoglobin and facilitate oxygen transport.
How is CO2 transported around the body?
Carbon dioxide is transported in the blood from the tissue to the lungs in three ways:1 (i) dissolved in solution; (ii) buffered with water as carbonic acid; (iii) bound to proteins, particularly haemoglobin.
Approximately 75% of carbon dioxide is transport in the red blood cells (bound to haemoglobin) and 25% in the plasma.
How can oxygen levels be measured?
- Haemoglobin saturation assumes you have normal Hb levels, but is very easy to do. Uses adsorption spectroscopy to work out the concentration of Hb by placing a device on a finger
- Arterial blood gas analysis is more complicated and invasive. It measures the level of oxygen and CO2, which is helpful as it is dissolved and so cannot use a colour spectroscopy to measure it. Blood needs to be taken from patient.
What are some medical conditions that effect the rate of respiration?
Asthma= the airway membrane thickens
Cystic fibrosis= genetic disease that causes mucus build up and inflammation of airways.
Pneumonia= an infection which causes inflammation and damage in the small airways and alveoli
Pulmonary embolism= clots move into the lungs and stop blood from getting to the lungs. Can be seen in a CT scan, or a tracer
What are the main functions of the circulation system?
Transporting oxygen, CO2, hormones, nutrients, waste products, regulating temperature and the clotting system.
How much blood does a 60kg human have on average?
In a 60kg human they have 36L of fluid, so 24L of that is intra, 12 is extra and 3L is plasma and 2.4 is red blood cells, so blood makes up around 5.4L.
What is Poiseuille’s law?
Liquid in the middle of a tube moves faster than liquid on the edge of a tube- not perfect for predicting blood flow but useful.
How does blood speed and pressure vary in arteries, veins and capillaries?
How does vessel diameter and cross sectional area of the vessels change?
- The pressure decreases as the blood moves from the heart
- The blood is fastest in the arteries, then slows down in capillaries then speeds up again slightly in the veins.
- The vessel diameter is large in arteries, drops and then rises again
- The cross sectional area of the vessels is greatest in capillaries.
How do walls of smaller arteries regulate blood flow?
They have more smooth muscle and less elastin than the aorta, helps to regulate blood flow.
What do veins have that arteries don’t and why?
Due to their low pressure system veins have valves. veins do not need a large increace in pressure to increace their volume, whilst arteries do.
What do some/ all capillaries have? (2 answers)
ALL have an endothelial layer (a thin layer of single flat (squamous) cells that line the interior surface), which is relatively permeable
SOME have specialisations such as fenestrations (small openings or pores) or larger holes such as sinusoids in the liver, which allow much freer exchange.
How does exit/entrance work in capillaries?
At the start of the bed there is favourable conditions for materials to enter the cells, and towards the end for materials to exit into the blood.
Hydrostatic pressure and osmotic pressure helps to make these favourable conditions. At start there is a larger hydrostatic pressure and smaller osmotic pressure, and vice versa at the end of the bed.
What happens when there is a build up of fluid in the capalliries?
Oedema, a build up fluids caused by a greater hydrostatic pressure which can happen in heart failure, or when vein valves are not working great or when someone stands still for a long time
Detected by listening to the lungs, pressing on the tissue or collection of fluid around ankles.
What is the yellow dot on the heart diagram?
The pacemaker of the heart- called cardiac conduction system. Gives off electric signals.
What are the steps of the cardiac cycle?
In what vessels does the blood enter and exit the heart?
Blood returns from the inferior and superior vena cava, then travels through the right atrium and then ventricle. The pulmonary artery takes the blood to the lung, then through the pulmonary vein and through the left atrium and ventricle, and out into the aorta.
What are the two formulae for cardiac output?
- Cardiac output = heart rate x stroke volume*
- Cardiac output = arterial blood pressure/ total peripheral resistance*
(TPR= It is the resistance offered by vessel wall for flow of blood.)
What does the venous return determine?
Preload and cardiac output
What can cause heart failure?
when the pre load rises and if the heart isn’t working properly there might be venous back pressure
What is peripheral resistance?
It is the resistance offered by vessel wall for flow of blood.
Is largely due to damage in resistance arterioles and determines afterload.
What is P02?
PO2 (partial pressure of oxygen) reflects the amount of oxygen gas dissolved in the blood.
