Quiz 3 true or false

Question 1

Concerning the autonomic nervous system: Parasympathetic preganglionic neurones are located in thoracic and lumbar segments of the spinal cord.

Answer 1

FALSE

-This is the location of the sympathetic outflow. Parasympathetic outflow exits at cranial and sacral levels.

Question 2

With regard to receptor subtypes: Blocking β2- receptors would relieve asthma.

Answer 2

FALSE
-Activation of β2- receptors by the sympathetic system causes relaxation of smooth muscle in the airways, allowing more efficient gas exchange (makes sense in terms of the fight or flight system). To relieve asthma you therefore want to activate these receptors, not block them.

Question 3

Across a secondary cartilaginous joint, the sequence of tissue types runs
bone - fibrocartilage - hyalin cartilage - fibrocartilage - bone

Answer 3

FALSE
- Across a secondary cartilaginous joint, the sequence of tissue types runs bone - hyalin cartilage - fibrocartilage - hyalin cartilage - bone.

Question 4

Concerning skeletal muscle: Actin and myosin filaments shorten during contraction.

Answer 4

FALSE
-This is the crux of the sliding filament theory – the actin and filaments do not shorten, but slide past each other, hence shortening the muscle as a whole.

Question 5

Concerning skeletal muscle: Mature skeletal muscle cells are mononucleate.

Answer 5

FALSE
-A single mature skeletal muscle fibre is formed during development from the fusion of many single myoblasts. This creates a multinucleate mature cell.

Question 6

When glycogen is synthesised (or degraded), monomers are added (or removed) from the reducing ends.

Answer 6

FALSE
-Glycogen is a polymer having only one reducing end, but many non-reducing ends. It is to(or from) these non-reducing ends that monomers are added (or removed).

Question 7

Concerning reflexes: Activation of cutaneous pain fibres causes extension of the affected part of the body.

Answer 7

FALSE

-Activation of cutaneous nociceptive fibres causes reflex withdrawal of the affected limb.

Question 8

Concerning the autonomic nervous system: Adrenergic receptors are stimulated by the natural agonist acetylcholine.

Answer 8

FALSE
-The natural endogenous agonists at adrenergic receptors are epinephrine and norepinephrine. Acetylcholine stimulates cholinergic receptors.

Question 9

With regard to receptor subtypes: Blocking Beta 2 receptors would relieve asthma.

Answer 9

FALSE
-Activation of β2- receptors by the sympathetic system causes relaxation of smooth muscle in the airways, allowing more efficient gas exchange (makes sense in terms of the fight or flight system). To relieve asthma you therefore want to activate these receptors, not block them.

Question 10

Concerning skeletal muscle: Isometric contraction involves both development of tension AND muscle shortening.

Answer 10

FALSE
-The clue is in the question. Iso-metric means same-length, so this indicates a contraction in which tension is produced, but the length of the muscle stays the same. An example would be when you carry a pile of books in your arms. Muscles in your arms would be contracting to produce sufficient tension to support the load of the books, but the muscle would not be shortening.

Question 11

Concerning the complement system: The alternate pathway is upregulated by bacterial endotoxin.

Answer 11

TRUE

-Endotoxin provides a surface on which the alternate pathway C3 convertase is

Question 12

Concerning blood: Haemorrhage, hypoxia, heart and lung disease are all factors which inhibit erythropoietin secretion from the kidney

Answer 12

FALSE
-These conditions all increase erythropoietin (EPO) secretion. EPO is the hormone which stimulates the maturation of red blood cells from immature precursors. Conditions such as those named all result in a decrease in the oxygen carrying capacity or the oxygen delivery capacity of the blood. By increasing EPO, red blood cell number is increased and the ability of blood to carry oxygen also increases and compensates, to some extent, for the condition.

Question 13

When glycogen is synthesised (or degraded), monomers are added (or removed) from the reducing ends.

Answer 13

FALSE
-Glycogen is a polymer having only one reducing end, but many non-reducing ends. It is to (or from) these non-reducing ends that monomers are added (or removed).

Question 14

An analogue of ATP called GTP participates in glycogen synthesis.

Answer 14

FALSE
-The ATP structural analogue is not GTP (guanosine 5-triphosphate) but UTP (uridine 5’-triphosphate). It reacts with glucose 1-phosphate to form UDPglucose, which then donates the glucose to the growing glycogen chain. The first monomer is laid down in a process catalysed by glycogenin. Subsequent monomers are added from UDPglucose in reactions catalysed by glycogen synthase. Notice that the energy input for this otherwise endergonic biosynthetic pathway comes not from ATP, but from an energetically equivalent structural analogue.

Question 15

Concerning reflexes: Information from muscle spindles in a reflex activation does not pass to the brain.

Answer 15

FALSE
-In addition to activating the motor neurones that mediate the stretch reflex, information is also sent up the dorsal columns to the postcentral gyrus of the cortex where it enables conscious perception of the position of the limb.

Question 16

Concerning the neuromuscular junction: Acetylcholine binds to muscarinic cholinergic receptors on the postsynaptic membrane to evoke the end-plate potential

Answer 16

FALSE
-Acetylcholine binds to the other type of cholinergic receptor – the nicotinic ones. These are ionotropic (ie have an integral ion channel) and are well suited to producing a very fast response at the neuromuscular junction.

Question 17

Concerning the neuromuscular junction: The endplate potential is curtailed by an inhibitory postsynaptic potential.

Answer 17

FALSE
-Unlike most central nervous system synapses, no IPSP is generated at the neuromuscular junction. In many ways it can be considered to be a very simple synapse.

Question 18

Concerning blood: Platelets are subcellular components of megakaryocytes which are critical for blood clotting to place.

Answer 18

TRUE
-Small parts of megakaryocyte cytoplasm bud off to form platelets. These are essential for clotting as they form an initial plug in the vessel wall around which a blood clot forms.

Question 19

Electrons passing along the electron transport chain of the terminal respiratory system finally associate with electropositive molecular oxygen.

Answer 19

FALSE
-The statement is correct except for the word ‘electropositive’. Electrons are attracted to electronegative molecules. Oxygen is an extremely electronegative element.

Question 20

During flow through the citric acid cycle, oxidation of cycle intermediates occurs in four separate reactions.

Answer 20

TRUE
-There are four reactions in the cycle in which a co-substrate of the reaction is reduced. These are the reactions that generate 3 NADH and 1 FADH2.

Question 21

Liver lacks glucose-6-phosphate dehydrogenase

Answer 21

FALSE
-Glucose 6-phosphate dehydrogenase is an enzyme of the pentose phosphate pathway, and this occurs in many tissues, including the liver. In liver in particular, pentoses generated by the pathway are used in production of RNA molecules associated with protein synthesis, and the NADPH generated by the pathway is used in fatty acid synthesis, steroid synthesis, and the metabolism of various drugs.

Question 22

Concerning reflexes: The primary sensory ending of a muscle spindle in a voluntary muscle is stimulated when gamma efferent fibres to the spindle are activated.

Answer 22

TRUE
-gamma efferent fibres innervate the intrafusal fibres, which lie in series with the muscle spindles. Contraction of just the intrafusal fibres will therefore stretch, and stimulate, the sensory ending of the muscle spindle. This will in turn trigger reflex contraction of extrafusal muscle fibres.