exam Flashcards
Describe the innervation of skeletal muscle using an example, including the events occurring at the NMJ
- skeletal muscles are stimulated by somatic motor neurons
- Axons of motor neurons travel from the central nervous system via nerves to skeletal muscles
- each axon ending forms a neuromuscular junction with a single muscle fibre
NMJ
- when a nerve impulse reaches the end of a motor neuron, it stimulates the release of the neurotransmitter ACETYLCHOLINE
- ACETYLCHOLINE crosses the nueromuscular junction and binds to receptors on the sarcolemma
- The binding of acetylcholine to the receptor stimulates an action potential in the muscle fibre
how much blood does an average adult have?
5L
males 5-6L
females 4-5L
how much body weight does blood form?
~8% of the body’s weight
what are the two main components of blood?
Plasma 55%
Formed elements 45%
what is in plasma of blood??
water, proteins, electrolytes, gases, nutrients
what’s in the formed elements of blood?
erythrocytes, leukocytes and platelets
Buffy coat = leukocytes and platelets
what are some differences between arteries and veins?
an artery has an external lamina, the vein doesn’t,
tunica media is thicker in artery then vein
vein has a valve, artery doesn’t
vein carries blood to the heart and arteries carry blood away from the heart
how are arteries and veins named?
because of the direction of blood flow
what are the three layers of heart wall?
- Epicardium
- Myocardium = spiral bundles of cardiac muscle
- Endocardium = continuous with endothelial lining of blood vessels
what is the purpose of the endocardium in the heart?
makes the surface of the inside very smooth so no RBC can stick to the heart and cause blood clots
what are the two atria separated by?
interatrial septum
what are the two ventricles separated by?
interventricular septum
what are the two types of valves?
- atrioventricular valves - tricuspid and bicuspid
- semilunar valve - pulmonary valve and aortic valve
how does blood flow through heart?
once the oxygen is used out of the blood it will return to the heart via the superior and inferior vena cava. The blood will fill the right atrium, once full it will pass through the right atrioventricular valve - tricuspid valve and into the right ventricle. from here the the right ventricle will contract and push blood out through the Pulmonary valve (semilunar valve) and into the pulmonary artery. from here the blood will flow towards the lungs where the gaseous exchange will occur and the deoxygenated blood will now become re-oxygenated. the reoxygenated blood will then return to the heart via the left and right pulmonary veins. the returning blood fills the left atrium. once filled the left atrioventricular valve (bicuspid valve) will open allowing blood to go from left atrium to the left ventricle and once filled the valve closes, the ventricle contracts and pushes blood from the left ventricle out through the aortic valve and through the aorta to supply the body with re-oxygenated blood
what opens and closes the valves in the heart?
the papillary muscles that pull on the chord tendinae that attach to the valves