Animal responses Flashcards
How is the CNS involved in the spinal reflex
Involves a motor neurone in the spinal cord which is part of the CNS
eg. of how the hypothalamus is involved in the fight or flight response
The hypothalamus releases CRH which causes the pituitary gland to secrete the hormone ACTH from the anterior gland. ACTH causes the adrenal gland to release corticoid hormones such as glucocorticoids which regulates metabolism
How is the medulla oblongata involved in increasing HR
Medulla oblongata receives an ap from sensory receptors that the heart rate needs to increase
-Sends an ap down the sympathetic nerve
-The sympathetic nerve releases noradrenaline
-Binds to receptors on SAN causing it to increase HR
Outline how the myosin and actin filaments interact to shorten the lengths of the sarcomeres
The myosin head binds tot he binding sites on the actin filaments forming cross bridges. The myosin head then bends and pulls the actin filaments along the length of the myosin. Many cross-bridges form and break very rapidly pulling the actin filaments along and breaking the sarcomere.
Why does digestion decrease in the fight/flight response
The sympathetic system prepares the body for activity – oxygen and nutrients must be supplied to the muscles. Therefore blood is diverted towards the muscles and away from the digestive system
Why are there many relay neurons in the CNS
This enables a large number of alternative nervous pathways to be created. One neurone will receive signals from many sources and can contribute to many pathways by sending the impulse to many other regions of the brain or effectors.
Why is a reflex so rapid?
does not involve the brain; the nervous pathway is very short; few synapses involved; most of the length of the neurones involved is myelinated
How is a reflex inhibited
the association areas of the brain send impulses, which inhibit the action of the synapse; this prevents the response to let go
Differences between the blinking reflex and the spinal reflex
Blinking: Cranial reflex / three neurons
Spinal: does not involve the brain/ two neurons
What stretches out the muscle after contraction of the heart
the elastic recoil of the heart walls and the flow of blood into the chambers the elastic recoil of the heart walls and the flow of blood into the chambers
What stretches out the blood vessels after contraction
The recoil of the elastic fibres in the walls of the blood vessels and the pressure of the blood in the vessels.
What stretches out the airways after contraction
The recoil of the elastic fibres in the walls of the airways and the elasticity of the cartilage.
Similarities between a neuromuscular junction and a synapse between new neurons
both transmit signals across a short gap (cleft); both contain vesicles of transmitter in presynaptic swelling; both use acetylcholine as transmitter; both stimulated by action potentials; both release transmitter from vesicles as a result of calcium ions entering the pre-synaptic swelling.
What happens when the thick and thin filament overlap
Cross bridges form and cause the filaments to slide past one another.
What supply of ATP is most important for a) a marathon runner b) a sprinter
a) ATP supplied by aerobic respiration
b) ATP supplied by anaerobic respiration and from creatine phosphate.
