Homeostasis of blood sugar and gas concentrations Flashcards
where is insulin released from?
beta cells in the pancreas (Islets of Langerhans)
where is glucagon released from?
alpha cells in the pancreas (Islets of Langerhans)
what is glycogen?
glucose that is stored in mainly muscle and liver cells
what are the roles of insulin and glucagon?
insulin lowers BGL and glucagon raises BGL
what is glycogenesis?
conversion of glucose to glycogen
what is glycogenolysis?
conversion of glycogen back into glucose
what is the general role of the liver in BGL?
the liver is able to convert glucose into glycogen for storage or glycogen into glcose for release into blood. it also has the ability to store some glucose as glycogen.
what are the four main effects that insulin has on the body to reduce BGL?
- enables entry of glucose into cells
- promotes conversion of glucose into glycogen in the liver and muscles
- promotes fat storage
- promotes protein synthesis
what are the two main effects that glucagon has on the body to increae BGL?
- convert liver glycogen into glucose
- promote gluconeogenesis
which hormone is secreted from the adrenal cortex?
glucocorticoids (cortisol)
which hormones are secreted from the adrenal medulla?
adrenaline and noradrenaline
what are the two roles of cortisol in maintaining BGL?
- stimulate conversion of glycogen into glucose in the liver
- stimulate protein breakdown in muscles and conversion of amino acids into glucose in the liver
what is the role of adrenaline and noradrenaline in maintaining BGL?
- stimulates the breakdown of glycogen in the liver and rlease of glucose into the blood
what is the diaphragm stimulated by?
impulses from the phrenic nerve
what are the intercostal muscles stimulated by?
intercostal nerves
where do the impulses from the intercostal muscles and diaphragm come from?
respiratory centre in the medulla oblongata
what effect does oxygen have on breathing rate?
oxygen concentration has a very small effect on breathing rate
what are aortic and carotid bodies and where are they located?
chemoreceptors located in the heart that are sensitive to oxygen concentration in blood plasma
what effect does carbon dioxide have on breathing rate>
a small increase in the concentration of carbon dioxide will result in a large increase in breathing eate
where are the chemoreceptors that are sensitive to carbon dioxide concentration located?
in the medulla oblongata
why is voluntary control of breathing important?
it is important in speech and for activities such as swimming
why is it impossible to stop breathing forever?
the build-up of carbon dioxide sends impulses to the inspiratory muscles which force a person to take a breath
what is hyperventilation?
rapid, deep breathing that can provide more oxygen than required and can remove more carbon dioxide than necessary. it is brought about by physical stress (severe pain) or emotional stress such as anxiety)
how is cardiac output determined?
heart rate X stroke volume
what are some factors that blood pressure depends on?
- cardiac output
- diameter of blood vessles
what is the sinoatrial node and atrioventricular node (SA node and AV node)?
bundles of specialised cells that control the heart’s activity.
what is the role of the SA node? where is it located?
the SA node is located in the wall of the right atrium below the opening of the superior vena cava. It is responsible for the rhythmical contractions of the heart (aka pacemaker)
what is the role of the AV node? Where is it located?
the AV node is located at the bottom of the right atrium and has conducting fibres that extend throughout the septum of the heart.
what happens when the heart beats?
- SA node sends out a nerve impulse that spreads throughout the atria
- stimulus reaches the AV node and the contraction of the atria begins
- stimulation of the AV node causes it to send impuses down the septum (between the ventricles)
- the impulses then spread through the muscles of the ventricles. Atrial contraction ends and ventricular contraction begins.
