Biopsychology What is biopsychology All animals have two
Biopsychology
What is biopsychology? All animals have two major systems that allow them to gain information from the environment and respond to this information: the nervous system and the endocrine system. Biopsychologists use their knowledge of these system to explain normal and abnormal behaviour.
Our brain is amazing • • You use more than 10% of your brain (in fact you use all of your brain). Most of your brain is active all of the time, even when you’re asleep. Information can go in between parts of your brain at a speed of 260 mph • You have over 100, 000 miles of axons in your brain. They could wrap around the Earth 4 times. • Your brain doesn’t have pain receptors. It can’t feel anything • Your brain is the fattest organ in your body. It's about 60% fat • Your brain can generate about 25 watts of power at any given time. It could power a light bulb. • Having a bigger brain doesn’t make you smarter. In fact, Albert Einstein had a relatively small brain. • When you were born, your brain was about the size it is now. That’s one reason why babies have such large heads relative to their bodies.
The nervous system is divided into: The central nervous system (CNS) which consists of the brain and the spinal cord. This where all the complex processing of information is done and decisions are made. The peripheral nervous system (PNS) which brings information from the senses to the CNS and transmit information from the CNS to the muscles and glands.
The organisation of the human nervous system Human nervous system Peripheral central nervous system Autonomic nervous system Sympathetic nervous system Somatic nervous system Parasympathetic nervous system Central nervous system Brain Spinal cord
The central nervous system The brain is the centre of awareness. It is divided in two hemispheres. The cortex is more developed in humans than in all other animals. The spinal cord is an extension of the brain. It transports messages to and from the brain to the peripheral nervous system. It is also responsible for reflexes.
The peripheral nervous system Somatic nervous system (SNS): receives information from the senses and transmits it to the CNS. It also transmits information from the CNS to direct movement of muscles. Autonomic nervous system (ANS): responsible for vital functions such as heart beat, breathing, digestion. It transmits information from and to the internal body organs such as the liver and the lungs. It operates automatically, involuntarily. The sympathetic nervous system: It stimulates functions like digestion. It is involved in “the fight or flight response”. The 2 systems interact to create homeostasis. The parasympathetic nervous system: It slows functions like digestion. It is involved in “the fight or flight response”.
Neurones The nerve cells are called neurones. The average human brain has about 100 billion neurons There are three types of neurons • Sensory neurons: carry signals from receptors to the spinal cord and brain. • Relay neurons: carry messages from one part of the CNS to another. • Motor neurons: carry signals from the CNS to effectors (muscles or glands) Stimulus Receptor Sensory neuron Relay neuron Motor neuron Effector Response
The cell body contains the nucleus (chromosomes), from the cell body. The dendrites extend from the cell body. They carry electrical impulses from other neurons towards the cell body. The axon is an extension of the neuron, it carries the impulses away from the cell body. It is covered by a sheath of myelin, a fatty substance. The main purpose of the myelin sheath is to increase the speed at which impulses propagate. There are breaks of between 0. 2 and 2 mm. in the myelin sheath, these are called nodes of Ranvier. Action potentials (nerve impulses) travelling down the axon "jump" from node to node. This speeds up the transmission.
How do neurons transmit signals? Neurons do not make direct contact. There is a very small gap between neurons called a synapse. The signal needs to cross this gap to continue on its journey to, or from, the CNS. This is done using chemicals which diffuse across the gap between the two neurons. These chemicals are called neurotransmitters. Axon Dendrite
The synapse: chemical transmission 1 • An electrical impulse travels along the axon of the transmitting neuron. 2 • This triggers the nerve-ending of the pre-syanptic neuron to release chemical messengers called neurotransmitters. 3 • These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the next neuron. 4 5 • The receptor molecules on the second neuron bind only to the specific chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse. • Reuptake: the neurotransmitter is reabsorbed in the vesicles of the pre-synaptic neuron after it has performed its function of transmitting a neural impulse.
Action potentials When a neuron is not sending a signal, it is "at rest. " When a neuron is at rest, the inside of the neuron is negative relative to the outside. K- Negative charge When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a short time, this is the action potential/ it creates the electrical impulse that travels through the axon to the end of the neuron. Na+ Positive charge
Excitatory and inhibitory effects Some neurotransmitters act by making the neuron more negatively charged so less likely to fire. This is an inhibitory effect. This is the case for serotonin. Other neurotransmitters increase the positive charge so make the neuron more likely to fire. This is the excitatory effect. Adrenalin is which is both a neurotransmitter and a hormone has an excitatory effect.
The endocrine system consists of glands which produce hormones which are released in the blood stream to the target organs which contain receptors for specific hormones. The pituitary gland controls the release of hormones from all the other endocrine glands. Hormones work more slowly than nerve impulses but often together with the nervous system.
The endocrine system and the nervous system work together to produce the acute stress response (SNS) Hypothalamus Sends a signal to the Adrenal Medulla It produces Adrenaline It causes • Increased Heart Rate • Increased Blood Pressure • Mouth Becomes Dry • Digestion Stops • Body becomes ready for FIGHT OR FLIGHT Then the parasympathetic nervous system brings the body back to an optimum state by slowing down the heart rate and bringing the blood pressure back to a normal level
Central nervous system Peripheral nervous system (PNS) Autonomic nervous system Sympathetic nervous system Somatic nervous system Central nervous system (CNS) Brain Parasympathetic nervous system Can you label the diagram? Spinal cord
Can you label the diagram?
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