AS Biopsychology - Fight/Flight Response, Synaptic Transmission, Nervous System and Endocrine System Flashcards
Describe the fight or flight response
1) Sensory organs detect a stressor.
2) Message is sent to the hypothalamus.
3) Sympathetic nervous system and endocrine system are activated by the hypothalamus.
4) Adrenal gland releases adrenaline as a result.
5) Fight/flight now ready (causing various behavioural responses e.g. increased breathing and heart rate, slowed digestion, pupil dilation etc.
What happens if the stressor continues vs when the stressor subsides?
If the stressor continues, the pituitary gland releases cortisol which aids our metabolism, but too much over a long period of time can weaken our immune system, which is why people get sick when they are stressed.
If the stressor subsides, the parasympathetic nervous system kicks in and returns everything to the resting state.
Evaluate the fight or flight response.
(-) Can negatively impact health over time as blood pressure is raised which damages blood vessels and increases risk of heart disease. Also, cortisol weakens the immune system.
(-) May have been useful to our ancestors for escaping predators but is rarely needed today.
(-) Gray (1988) says there’s also a “freeze” response so therefore the fight or flight response is an incomplete explanation
(-) Taylor et al (2002) says that the model is gender biased and that instead of fight/flight, females use tend and befriend response instead; protect and tend to their young and collaborate and form alliances with other women (befriend) i.e. problems generalising to all humans.
Outline the central and peripheral nervous systems.
The CNS is comprised of the brain (which has various functions) and the spinal cord (which brings messages to and from the brain and is also involved in reflex actions).
The PNS is comprised of the somatic nervous system (brings info from sensory organs to CNS and receives info from CNS for voluntary movement) and the autonomic nervous system (responsible for involuntary movement and takes info to and from organs).
The autonomic system is split into the sympathetic and parasympathetic divisions (see fight/flight response).
Describe the general structure of a neuron.
The cell body contains the nucleus, which contains all the genetic information of the cell.
Branch-like structures called dendrites protrude from the cell body and carry nerve impulses from the adjacent neurons towards the cell body.
Axons carry information away from the cell body and down the length of the neuron. Axons are covered in fatty layers of myelin sheath which protect the axons and speed up transmission.
Between segments of myelin sheath are gaps called nodes of Ranvier; the transmission is forced to “jump” these gaps which speeds up the transmission of the impulse.
At the end of each axon is an axon terminal button which communicates with the next neuron via synaptic transmission.
Describe a sensory neuron.
Sensory neurons take information from sensory organs to the brain.
They have long dendrites and short axons.
Describe a motor neuron .
Motor neurons take information from the brain to the effectors.
They have short dendrites and long axons.
Describe a relay neuron.
Relay neurons link motor and sensory neurons and are only found in the central nervous system.
They have short dendrites and short axons.
Describe electrical transmission.
At a resting state, the inside of a neuron is negatively charged in comparison to the outside.
When a neuron is activated by a stimulus, the inside becomes positively charged for a split second, causing an action potential to occur.
This causes an electrical impulse to travel down the axon and towards the end of the neuron, i.e. the axon terminal button.
Describe synaptic transmission.
Once the electrical impulse has reached the axon terminal button, the vesicles containing the neurotransmitter (NT) move to the pre-synaptic membrane. The NT is released into the synaptic cleft and diffuses across the synapse, and then binds to receptor sites on the post-synaptic neuron. Receptor sites are specific; only a certain NT will fit a given receptor site; think of it as a lock and key mechanism.
When the right NT meets the right receptor site, a specific ion channel is opened up which causes a flooding of ions which flow along the specific pathway into the neuron.
This flooding of ions causes a potential in the dendrites. If there are more exitatory than inhibitory NTs received, the post synaptic neuron is more likely to fire and consequently carry on the impulse. This process of exitatory vs inhibitory is called summation. Exitatory NTs e.g. adrenaline make the post-synaptic neuron more positively charged and therefore more likely to fire, and inhibitory NTs e.g. serotonin have the opposite effect.
Describe the endocrine system.
A system of glands (organs which synthesise and produce hormones) and hormones (chemicals that travel through the bloodstream and target specific cells. Hormones have powerful, physical effects on the body.
The pituitary gland is known as the “master gland because it controls the synthesis and release of hormones from all other glands in the body.
The pancreas produces insulin which helps to control blood sugar levels, and the thyroid gland produces thyroxine, which controls metabolic rate.
