Explain how the autonomic nervous system is responsible for the control of many functions?
The autonomic nervous system (ANS) is a regulatory branch of the central nervous system that helps people adapt to changes in their environment. It adjusts or modifies some functions in response to stress. The ANS helps regulate blood vessels' size and blood pressure, the heart's electrical activity and ability to contract (regulation of heart beats), the bronchial diameter (and thus air flow) in the lungs and the rate of respiration, the lacrimal glands (tear glands), the ANS also regulates the movement and work of the stomach, intestine and salivary glands, the secretion of insulin and glucagon (hormones), the urinary and sexual functions.
The ANS acts through a balance of its two components, the sympathetic nervous system and parasympathetic nervous system. The sympathetic nervous system at the nerve endings secrete adrenaline and nor adrenaline while the parasympathetic system at the nerve endings, secrete acetylcholine.
Explain that there are many internal receptors that are picking up information about blood pressure, oxygen levels and carbon dioxide concentration?
The numerous receptors checks and sense changes on the carbon dioxide, blood pressure and oxygen levels, also, they send off information to the cardiac towards that brain which regulates the heart rate. However, the barorecptor sense changes on blood pressure which is located in the walls of the aorta and also helps carry blood towards the head and neck its also an element of the carotid arteries.
Explain that these receptors send information to the cardiac centre in the brain that controls heart activity?
These receptors that send information to the cardiac centre in the brain that controls heart activity is that the message pass down the cardiac nerve the heart rate increases and message pass down the vagus nerve the heart rate decrease. In contrast, barorecptor can also importantly sense the changes that are been made and depend on the information that has been provided by the impulses nerve to the cardiac centre. In the vagus, the activity makes the nerves to slow the heart rate down and reduce BP to normal temperature.
Cardiac output is the volume of blood pumped by the heart per minute (mL blood/min). Cardiac output is a function of heart rate and stroke volume. The heart rate is simply the number of heart beats per minute. The stroke volume is the volume of blood, in milliliters (mL), pumped out of the heart with each beat. Increasing either heart rate or stroke volume increases cardiac output.
When a person exercise the heart rate increases this means more blood is pumped out per minute known as cardiac output, the heart beats 125 cm3 of blood (stroke volume) is pumped out. 125cm2 x 120 =
Explain the roles of sympathetic and parasympathetic nerve supply to the heart and also the role of the sinoatrial node (SAN- the pacemaker)?
The roles of sympathetic and parasympathetic
Sympathetic and parasympathetic have their cell bodies outside of the brain and spinal cord. But, only nerves of the parasympathetic have direct link to both brain and spinal cord. While Sympathetic nerves are linked directly only to the spinal cord. Neurons are not interchangeable. They have specific functions but the end-organs have dual nerve supply and for example, the iris muscles of the eye. It has dual nerve supply the ophthalmic nerve which serves as Sympathetic control to promote pupil dilation and at the same time, the oculomotor nerve which handles the Parasympathetic control which constricts the pupils. SNS and PNS works in opposition. SNS handles the body's stress response (fight or flight) while PNS handles brings the body to its resting state (rest and relaxation). Not only is the built-in impulse a huge part in the heart beating, the heart is influenced by autonomic nerves. These originate in the cardiovascular centre in the medulla oblongate. This is reached through the autonomic nervous system. There are two types of nerves present here, the parasympathetic (P.N) and sympathetic (S.N) nerves. These actions are antagonistic to one another. The P.N main supply is to the A.V and S.S nodes, and the atria muscle.
The stimulation from P.N reduces the rate of impulses, and lessens the rate and force of a heart beat. The S.N works opposite to this. These work with the S.A and A.V nodes and the myocardium of atria and ventricles. It increases the rate and force of a heart beat. Chemicals can give the same effect as a S.N by increasing the heart beat. These chemicals include; hormone adrenaline, and noradrenaline. Other hormones including thyroxine increase the heart beat by their metabolic effect. Drugs, dissolved gases and electrolytes in the blood can have either effect. The Sympathetic nerve increases the rate and force of the heart beat, increases heart rate, force of contraction, and blood pressure. It supplies the SA node and AV nodes, myocardium of atria and ventricles. In contrast, parasympathetic decreases heart rate, force of contraction, and blood pressure. The Parasympathetic nerve supply mainly to the SA node, AV node and atrial muscle. It tends to reduce the rate at which impulses are produced decreasing the rate and force of the heart.
The role of the sinoatrial node
The role of the sinoatrial is the upper part of the right atrium of the heart is a specialized bundle of neurons known as the sinoatrial node (SA node). It act as the heart's natural pacemaker, the SA node "fires" at regular intervals to cause the heart of beat with a rhythm of about 60 to 70 beats per minute for a healthy, resting heart. The electrical impulse from the SA node triggers a sequence of electrical events in the heart to control the orderly sequence of muscle contractions that pump the blood out of the heart. The heart's natural pacemaker the SA node sends out regular electrical impulses from the top chamber (the atrium) causing it to contract and pump blood into the bottom chamber (the ventricle).
The heart pumping as we know it is controlled by the cycle of contractions and relaxation of the atria’s ventricles, (systole & diastole). This sequence of events however is initiated rhythmically within the heart at the sinoatrial node (S.A NODE). This is situated close to where the vena cava enters the right atrium. The stimulation for each heart beat comes from within the heart itself, this is known as an intrinsic rhythm. The SAN works with the AVN / Atrio-Ventricular Node, which does the same thing, only with the ventricles, forcing blood out of the heart into the lungs or body, depending on the side of the heart.
To clarify what was said by the other poster, the atrioventricular (AV) node is not responsible for contracting the ventricles in a normal heart. The electrical impulses that contract the atria and the ventricles come from the SA node. The AV node's job is to slow down the electrical impulses from the SA node so that there is a delay between contraction of the atria and contraction of the ventricles. The delay is important because the ventricles need time to fill up with blood before they contract
Finally explain that an increase in body temperature and also the release of adrenaline (a hormone) will also increase heart rate?
An increase shown in body temperature on heart rate is by thermoreceptor towards the brain which allow the hypothalamus to turn on the sympathetic system this significantly effect the heart rate to increase and fasten. On the other hand, the release of adrenaline on the heart rate by flowing and passing adrenaline which comes from the adrenal gland that is normally discharged at some point of being frighten, pressure and physical exertion. This however, motivates and arouses the sino-atrical node to strike speedy and swiftly which creates an improvement in the sympathetic system.
