The nervous and endocrine systems help to protect the human body. Use suitable examples to describe how this is achieved through a reflex action and by the hormone adrenalin. Mechanism of Reflex Action Example: withdrawal of hand after being pricked by a pin/from hot surface/ (any other suitable example) (1) - Receptors in the skin receive the stimulus - The stimulus is converted into a nerve impulse - The impulse travels along the sensory neuron towards the spinal cord along the dorsal root of the spinal nerve - In the spinal cord, the sensory neuron makes synaptic contact with the connector/ interneuron - and then the impulses are transmitted along the motor neuron along the ventral root of the spinal nerve - to the effector organ/muscle which contracts and pulls the hand away - The reflex action provides a quick response to the stimulus so injury is minimised max (10) Action of Adrenalin Example: chased by a ferocious dog/(any other suitable example) (1) Adrenalin prepares the body to cope with the emergency, danger and stress in the following ways: - The brain becomes aware of danger/emergency situation through impulses from the sense organs - The adrenal gland is stimulated to secrete adrenalin - Messages are then sent to various parts of the body (blood vessels, heart) - Blood vessels of the skin/digestive system constrict, but the blood vessels to the heart muscles and brain (important vital organs during an emergency) dilate - The heart rate also increases - The rate and depth of breathing increases - The conversion of glycogen to glucose is promoted in the liver - The vital organs receive more blood/oxygen/glucose to raise metabolic activities of cells to release more energy - Muscle tone increases pupils dilate to allow a rapid response to ensure safety (5) Content (17) Synthesis (3) ASSESSING THE PRESENTATION OF THE ESSAY Marks Description 3 Well structured – demonstrate insight and understanding of question 2 Minor gaps or irrelevant information in the logic and flow of the answers 1 Attempted but with significant gaps and irrelevant information in the logic and flow of the answers 0 Not attempted/nothing written other than question number/no correct information
Posted on: Sun, 21 Jul 2013 18:50:36 +0000