Question: 1)Why does the cardiovascular system interest you so much?What 2)How do the kidneys regulate in plasma? 3)How much of blood are formed elements? 4)What are 3 characteristics of red blood cells? 5)What does being a complete cell mean? 6)What is the function of neutrophils? 7)What is the function of eosinophils? 8)What happens if there is a prolonged oxygen deficiency in the blood? 9)What is homeostasis? 10)What are the 3 steps in homeostasis? Sorry for asking so many. I'm just so interested by this topic. :)

Laura Haworth answered on 10 Mar 2016:

Wow so many questions I hope I can answer all of these.
1) The CVS has always interested me, without it we wouldn’t be here. It is such a fascinating system which I have always enjoyed learning about throughout school and university. I don’t particularly know why I enjoy it more than any of the other systems in the body- maybe because I am a bit gory and like blood.

2) The kidneys work to ensure an adequate quantity of plasma to keep blood flowing to vital organs. Water balance is achieved in the body by ensuring that the amount of water consumed in what we eat and drink (and generated by metabolism) equals the amount of water we excrete. The consumption side is regulated by behavioral mechanisms, including thirst and salt cravings. While almost a liter of water per day is lost through the skin, lungs, and feces, the kidneys are the major site of regulated excretion of water. One way the kidneys can directly control the volume of bodily fluids is by the amount of water excreted in the urine. Either the kidneys can conserve water by producing urine that is concentrated relative to plasma, or they can rid the body of excess water by producing urine that is dilute relative to plasma. Direct control of water excretion in the kidneys is exercised by a hormone called vasopressin, or anti-diuretic hormone (ADH), a peptide hormone secreted by the hypothalamus. ADH causes the insertion of water channels into the membranes of cells lining the collecting ducts, allowing water reabsorption to occur. Without ADH, little water is reabsorbed in the collecting ducts and dilute urine is excreted.
ADH secretion is influenced by several factors (note that anything that stimulates ADH secretion also stimulates thirst):
1. By special receptors in the hypothalamus that are sensitive to increasing plasma osmolarity (when the plasma gets too concentrated). These stimulate ADH secretion.
2. By stretch receptors in the atria of the heart, which are activated by a larger than normal volume of blood returning to the heart from the veins. These inhibit ADH secretion, because the body wants to rid itself of the excess fluid volume.
3. By stretch receptors in the aorta and carotid arteries, which are stimulated when blood pressure falls. These stimulate ADH secretion, because the body wants to maintain enough volume to generate the blood pressure necessary to deliver blood to the tissues

3) The formed elements of blood include: RBC (millions), white blood cells (7000-25,000) and platelets (150-400,000) so account for about 47% of the blood with the rest being plasma.

4) The three characteristics of a RBC are: it is flexible and a biconcave shape so it can fit through the RBC, they only have a short lifecycle and contain haemoglobin which allows us to carry oxygen around the body.

5) Not sure what you mean with the complete cell question. Maybe a cell which contains all the components to divide and grow.

6) Neutrophils along with eosinophils and basophils, constitute a group of white blood cells known as granulocytes that is filled with microscopic granules, little sacs containing enzymes that digest microorganisms. These are the most abundant WBC and often found in the blood at the early stages of an infection.

7) Eosinophils destroy invading germs like viruses, bacteria, or parasites. Eosinophils also create an inflammatory response, especially if an allergy is involved.

8) A prolonged deficiency can leave a person looking pale, lack of energy and suffering anaemia. It can occur at high altitudes- where hypoxia develops gradually, the symptoms include light-headedness / fatigue, numbness / tingling of extremities, nausea and anoxia.In severe hypoxia, or hypoxia of very rapid onset, ataxia, confusion / disorientation / hallucinations / behavioural change, severe headaches / reduced level of consciousness, papilloedema, breathlessness, pallor, tachycardia and pulmonary hypertension eventually leading to the late signs cyanosis, slow heart rate and low blood pressure followed by death.

9/10) Homeostasis is the maintenance of a constant internal environment. It involves controlling things such as: temperature, water, sugar and carbon dioxide levels. The nervous system and hormones are responsible for this. Homeostatic control is achieved using negative feedback mechanisms:
if the level of something rises, control systems reduce it again
if the level of something falls, control systems raise it again
Conditions in the body change from set point -> the change is detected-> corrective mechanisms are activated ->Conditions then return to set point->corrective mechanisms are switched off.

Hope my answers have helped a little. Let me know if you have any more questions 🙂