Biopsychology Flashcards
Nervous System
Consists of the central nervous system and the peripheral nervous system.
Central Nervous System (CNS)
Consists of the brain and the spinal cord and is the origin of all complex commands and decisions.
Brain and Spinal Cord
Brain is the centre of all conscious awareness. The spinal cord is an extension of the brain and is responsible for reflex actions. Passes messages to and from the brain and connects nerves to the PNS.
Peripheral Nervous System (PNS)
Sends information to the CNS from the outside world, and transmits messages from the CNS to muscles and glands in the body. Consists of the somatic and autonomic nervous systems.
Somatic Nervous System
Transmits information from receptor cells in the sense organs to the CNS. It also receives information from the CNS that directs muscles to act.
Autonomic Nervous System
Transmits information to and from internal body organs. It is ‘autonomic’ as the system operates involuntarily. It has two main divisions: the sympathetic and parasympathetic nervous systems.
Sympathetic Nervous System
Activates internal organs for vigorous activities and emergencies (fight or flight). Works in opposition to the parasympathetic branch.
Parasympathetic Nervous System
Controls the relaxed state. Slow acting and brigs the body back to an optimum state. Works in opposition to the sympathetic branch of ANS. One or the other is active at any time.
Afferent and Efferent Neurons
Afferent = sensory information travelling to the brain/CNS. Efferent = Brain communicates with PNS to signal physical changes in body.
Endocrine System
One of the body’s major information systems that instructs glands to release hormones directly into the bloodstream. These hormones are carried towards target organs in the body.
Gland
An organ in the body that synthesises substances such as hormones.
Hormones
Chemical substances that circulate in the bloodstream and only affect target organs which have the right receptor hormones. They are produced in large quantities but disappear quickly. Have a powerful effect.
Fight or Flight Response
The way an animal responds when stressed. The body becomes physiologically aroused in readiness to fight an aggressor or flee. This response is created through the endocrine and autonomic nervous systems working together.
Pituitary Gland
Main gland. Controls release of all other endocrine glands in the body.
Hypothalamus
Controls the pituitary gland.
Thyroid
Produces thyroxine which controls the metabolism.
Adrenocorticotrophic Hormone (ACTH)
What is released to activate the adrenal gland to produce adrenaline.
Adrenaline
A hormone produced by the adrenal glands which is part of the human body’s immediate stress response system (fight/flight). Adrenaline has a strong effect on the cells of the cardiovascular system.
Neuron
The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals.
Sensory Neurons
These carry messages from the PNS to the CNS. They have long dendrites and short axons.
Relay Neurons
These connect the sensory to the motor or other relay neurons. They have short dendrites and short axons.
Motor Neurons
These connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons.
Structure of a Neuron
Neurons vary in size from less than a mm to up to a metre long, but all share the same basic structure. The cell body includes a nucleus (contains the genetic material of the cell). Branch-like structures called dendrites protrude from the cell body. The axon carries the impulses away from the cell body down the length of the neuron. The axon is covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical transmission of the impulse. If the myelin sheath was continuous this would have the reverse effect and slow down the electrical impulse. Thus, the myelin sheath is segmented by gaps called nodes of Ranvier. These speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon. Finally, at the end of the axon are terminal buttons that communicate with the next neuron in the chain across a gap known as the synapse.
Action Potential
When a neuron isn’t sending a signal, it’s ‘at rest’. When at rest, the inside of the neuron is negatively charged compared to the outside. When a neuron is activated by a stimulus, the inside of the cell becomes temporarily positively charged, this is the action potential. It creates the electrical impulse that travels through the axon to the end of the neuron.