The Circulatory System and Blood Flashcards
What does the plasma in blood transport?
-Dissolved nutrients like glucose and amino acids
-Transports blood cells
-Dissolved waste products like urea and carbon dioxide
-Hormones
-Proteins
-Heat energy
What are platelets?
Cell fragments
What do platelets do?
They release chemicals when the blood is exposed to air, which causes soluble fibrinogen to be converted into insoluble fibrin.
What does fibrin do that platelets have created?
It forms a network of fibres across the cut, which trap platelets and red blood cells - this is a clot (scab)
What are the advantage of blood clots when you are cut?
They prevent further blood loss and it also acts a barrier to prevent the entry of pathogens.
Describe what phagocytes are:
White blood cells which are larger cells with a multi-lobed nucleus.
What do phagocytes do?
They engulf and digest pathogens using enzymes, then harmless products leave the phagocyte.
Describe what lymphocytes are:
White blood cells with a very large nucleus.
What part of the brain controls nerve impulses for changes in heart rate?
The medulla.
What detects an increase in carbon dioxide in the body? What does this lead to?
Sensors in the aorta and carotid artery detect the increase in carbon dioxide. They send nerve impulses to the medulla which responds by sending nerve impulses along the accelerator nerve which increases heart rate.
What are nerve impulses from the medulla sent along?
The accelerator nerve.
What sends electrical impulses to decrease heart rate at rest?
The decelerator nerve.
What else other than exercise causes an increase in heart rate?
When we are stressed out heart rate increases, this triggered by the secretion of the hormone adrenaline.
What causes heart attacks?
Clots can also form within blood vessels if plaques cause red blood cells to be broken.
What is the effect of adrenaline on our hearts?
When we feel threatened, the adrenal glands release adrenaline. Adrenaline binds to specific receptors in the heart, this causes the cardiac muscle to contract more frequently and with more force, so the heart rate increases and the heart pumps more blood. This increases oxygen supply to the tissue, getting the body ready for action.
