Components of the central and peripheral nervous systems.
The central nervous system (CNS) consists of mainly brain and the spinal cord. The peripheral nervous system are nervous cells that sends signals to the CNS and allows us to respond to the stimuli detected by the surroundings. Peripheral nervous system divides into somatic nervous system and autonomic nervous system. The somatic nervous system contains nerves that carry sensory signals from the body to the CNS also nerves that carry motor signals from the CNS to the skeleton muscles. The somatic nervous system is also associated as the voluntary movements. Whereas the autonomic nervous system is known as the involuntary movements and it regulates the internal of the body, carries signals from the internal organs to the CNS and from the CNS to the internal organs, for examples heartbeat, digestion mostly outside the conscious control.
- Neuron and glial cells, to include a comparison of myelinated and unmyelinated neurons.
- Transmission of action potentials and saltatory conduction, including interpretation of graphs.
- Transmission at synapses, neuromuscular junctions and neuroglandular junctions.
- Stimuli detection by receptor cells and sense organs.
How changes in concentrations of oxygen and carbon dioxide come about
The concentration of oxygen changes due to the from the capillaries in the alveoli and capillaries present in the respiring tissues. The concentration of the air inside the alveoli is high is oxygen whereas oxygen concentration in the capillary from the respiring tissues is low, this creates a concentration gradient, which causes the oxygen to diffuse across the alveoli wall into the blood through the capillary wall, down the concentration gradient, from an area where the concentration of oxygen is high to an area where is it low. In contrast to this, with carbon dioxide the concentration changes as it is low
- Gaseous exchange at tissues and alveoli.
- Autonomic nervous system; sympathetic and parasympathetic pathways.
- Role of medulla oblongata in coordination.
- Elasticity of blood vessels related to function.
Arteries: carry blood away from the heart to the rest of the body, very thick, always under high pressure, aorta carries oxygenated blood.
Capillaries: they are one cell thic0k, they can go very in deep in the muscles, carry blood in every single cells and organs, they can reach all the tissues and cells, they have holes in their vessels and that is where gas exchange and dissolve substances go inside.
Veins: thicker than capillaries but smaller than arteries, they carry deoxygenated blood back to the heart, the blood is under lower pressure, there I no pulse, have valves to prevent backflow, against gravity, superior vena cava and inferior vena cava are the main veins.
Role of chemoreceptors and baroreceptors
Control of heart rate – role and action of: sinoatrial and atrioventricular nodes, Bundle of His, Purkinje fibres.
Cardiac muscle long fibres formed by the individual cells branches to form cross bridges between the fibres. Electrical impulses in the heart walls are able to spread evenly over the walls of the chambers because of the cross bridges. Heart muscle is said to be myogenic which means it initiates its own beats, own contraction without getting fatigue easily.
A closed double circulatory system, it has blood enclosed in vessels, substances diffuse through the vessel. One pump with lungs blood gets oxygenated and second pump with the body.
The cardiac cycle begins with atrial systole then ventricular systole and last diastole.
Deoxygenated blood comes from the body, through the vena cava vein into the right atrium. The tricuspid valve closes only to not let the blood run backwards as it travels against the gravity. Blood fills the atrium and ventricle until the atrium is full, the it releases all the blood by contracting. At this moment the ventricle is under a very high pressure which causes the blood to raise into the pulmonary artery by the valve. There is a delay between the contraction of the atrium and ventricles. Atria contracts because of the SAN (sino atrial node) and the ventricles contracts because of the AVN (atrial ventricular node).
Control of inspiration, expiration and rate of ventilation
- changes in contraction and relaxation of diaphragm and intercostal muscles
During inhalation the diaphragm contracts and flattens, intercostal muscles contracts external, moving the ribs upwards and outwards, more volume of the thorax increases and the pressure of the thorax decreases so air moves in. Air moves from the higher pressure to a lower,
During Exhalation diaphragm relaxes returning to its doomed shape, external intercostal muscles relaxes so the ribs moves down and inwards, volume of the thorax decreases the pressure of the air is higher inside than outside so air moves out.