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
what is apart of the upper respiratory system?
nose, pharynx, nasal cavity
what is apart of the lower respiratory system?
Larynx, trachea, bronchi, lungs
how many branches are in the lungs?
23
what are the two different zones in the lungs?
conducting zone (0-20) and respiratory zone (21-23)
what happens in the respiratory zone?
the respiratory zone is where gaseous exchange occurs
what accounts for most of the gaseous exchange in the lungs?
Alveoli, ~300million alveoli = main site of gaseous exchange
what is Boyles law? example
The pressure (P) and the Volume (V) of gas in an enclosed container are inversely proportionate, when the temperature (T) is held constant
eg. if a piston pushed down. the gas is compressed in a smaller V which means the pressure increases
what are the steps in inspiration?
- inspiratory muscles contract and (diaphragm descends, external intercostals contract; rib cage rises)
- thoracic cavity volume increases
- lungs are stretched (intrapulmonary V increases
- Intrapulmonary P drops. Boyles law: Intrapulmonary P becomes lower then the atmospheric P (758 mmHg)
- Air (gases) flows into lungs down its P gradient until intrapulmonary P is equal to atmospheric P
what are the steps in expiration?
- inspiration muscles relax. ( diaphragm rises and external intercostals relax; ribcage descends due to elastic recoil of costal cartilages)
- Thoracic cavity V decreases
- Elastic recoil of lungs; intrapulmonary V decreases
- intrapulmonary P raises (762 mmHg) greater then atmospheric P
- Air (gasses) flows out of the lungs down its P gradient until intrapulmonary P is equal to atmospheric pressure
what muscles are involved in forces expiration?
abdominal and internal intercostal muscles
what are the two different types of alveoli?
type I - squamous epithelial cells
type II - scattered cuboidal cells
what do the type II scattered cuboidal cells do?
secrete alveolar fluid (surfactant) and antimicrobial proteins
what is surfactant?
surfactant is a mixture of phospholipids and lipoproteins (which lower the tension of alveolar fluid reducing the tendency of alveolar wall to collapse)
how thick is the respiratory membrane?
• ~0.5 um thick air-blood barrier to allow rapid diffusion of gasses
what is the respiratory membrane used for?
Exchange of O2 and CO2 between air spaces in the lungs and the blood
what are the 4 layers of the respiratory membrane?
- capillary basement membrane
- alveolar basement membrane
- capillary wall
- alveolar wall
Histology of nervous tissue
- what are the two groups nervous tissue can be divided into?
Neurons = excitable cells that control neurons
Neuroglia (glial cells) = supporting cells
- Astrocytes (CNS)
- Microglia (CNS)
- ependymal cells (CNS)
- Oligodendrocytes (CNS)
- Satellite cells (PNS)
- Schwann cells (PNS)
what are the supporting cells of nervous tissue? (neuroglia)
CNS
- Astrocytes
- Microglia
- Ependymal cells
- Oligodendrocytes
PNS
- satellite cells
- Schwann cells
what are the functions of the supportive cells?
Astrocytes (CNS) - structural support
Microglia (CNS) - immune system
Ependymal (CNS)/ Satellite (PNS) - protection
oligodendrocytes (CNS)/ Schwann (PNS) - insulation
what are the layers of skeletal muscle
epimysium
perimysium
endomysium
