Biopsychology Revision What do you need to know

Biopsychology Revision What do you need to know? . . . • Biopsychology • The divisions of the nervous system: central and peripheral (somatic and autonomic). • The structure and function of sensory, relay and motor neurons. The process of synaptic transmission, including reference to neurotransmitters, excitation and inhibition. • The function of the endocrine system: glands and hormones. • The fight or flight response including the role of adrenaline.

Key assumptions of biopsychologists • Biopsychologists assume that behaviour and experiences are caused by activity in the nervous system • The nervous system transmits signals for communication via the billions of nerve cells (neurons) it houses • These nerve cells communicate with each other, through electrical and chemical messages, within the body and the brain.

The divisions of the nervous system… On your whiteboard… see if you can remember the divisions of the nervous system.

Your diagram should look like this

Our nervous system has 2 parts – the CNS and the PNS CNS = Central nervous system = The brain and spinal cord PNS = Peripheral nervous system = all other nerve cells around the body

Central Nervous system • Brain and spinal chord • some parts of the brain are involved in vital functioning, others are involved with problem solving and planning • Spinal chord transmits messages to and from the brain to the peripheral nervous system (PNS). It is also involved in reflex actions such as the startle response.

Our peripheral nervous system has 2 parts – the SNS and the ANS SNS = somatic nervous system Transmits info to and from senses and to and from CNS = voluntary movements = skeletal muscles and bones ANS = AUTONOMIC NERVOUS SYSTEM Transmits info to and from internal organs to sustain life processes = involuntary movements = heartbeat & breathing

Our autonomic nervous system has 2 parts – the sympathetic and the parasympathetic branch SYMPATHETIC PARASYMPATHETIC BRANCH = activates arousal = conserves and stores and energy resources The 2 branches work antagonistically – in opposition to each other These two systems are involved in the fight or flight response.

Glands & hormones • Most hormones affect cells in several organs or throughout the entire body, leading to powerful responses • E. g thyroid gland produces the hormone thyroxine (increases heartrate) • Also affects chemical processes taking place in cells – affects growth rates

What do you need to know? . . . • Biopsychology • The fight or flight response including the role of adrenaline.

Fight or Flight Response Increase oxygen intake Release stored glucose Divert resources away from digestion Ready to expend energy, either by fighting or by running away

Fight or flight? • This leads to physiological changes in the body which are summarised in the table below… Sympathetic state Parasympathetic state Increases heart rate Decreases heart rate Increases breathing rate Decreases breathing Dilates pupils Constricts pupils Inhibits digestion Stimulates digestion Inhibits saliva production Stimulates saliva production

Fight or flight • Parasympathetic nervous system calms you down after a state of stress • You are all in a parasympathetic state now • Blood pressures decreases, pulse rate slows down, digestion can start.

“The fight or flight response is a physiological reaction to a stressful or threatening situation. The ANS (autonomic nervous system) changes from a parasympathetic state to the physiologically aroused (sympathetic state). This produces changes in the body such as dilated pupils and increases heart rate to prepare us for either fight or flight. ”

For each of the scenarios decide: • Parasympath etic or sympathetic nervous system is responsible • What the branch of the nervous system is doing (e. g. dilates pupils)

Answers • • • Sue: S, inhibits digestion Les: S, causes increased breathing rate Lenny: S, dilates pupils Amadeep: S, inhibits saliva production Mary: P, returns heart rate to normal Jerry: P, stimulates digestion

Exam question

Mark scheme

Biopsychology Revision What do you need to know? . . . • Biopsychology • The structure and function of sensory, relay and motor neurons. The process of synaptic transmission, including reference to neurotransmitters, excitation and inhibition.

Neurons and synaptic transmission Biopsychology Specification details The structure and function of sensory, relay and motor neurons. The process of synaptic transmission, including reference to neurotransmitters, excitation and inhibition.

Biopsychology Revision What do you need to know? . . . • Biopsychology • The function of the endocrine system: glands and hormones.

Endocrine System

The endocrine system • The endocrine system works alongside the nervous system to control vital functions in the body. The endocrine system acts more slowly that the nervous system but has very widespread and powerful effects.

Glands & hormones • Most hormones affect cells in several organs or throughout the entire body, leading to powerful responses • E. g thyroid gland produces the hormone thyroxine (increases heartrate) • Also affects chemical processes taking place in cells – affects growth rates

The endocrine system • Various glands produce hormones • Thyroid gland produces hormones • Hormones are secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone • Hormones have powerful responses throughout the body. • Major endocrine gland = pituitary gland (located in the brain) • Controls release of hormones from all other endocrine glands in the body.

Neurons • Cells that conduct nerve impulses are called neurons • The things that people think and feel, say and do are caused, one way or another, by electrochemical events occurring within and between the neurons that make up the nervous system, particularly those in the brain (80%)

Three types of neurons Relay Neuron Myelin sheath… Terminal Buttons Nodes of ranvier

Different types of neurons The cellular structure of all neurons is the same. There anatomical differences in size, depending on their function 1. Motor neuron 2. Relay 3. Sensory (Interconnecting) neuron Function Carries messages from the CNS to effectors such as muscles and glands Transfers messages from sensory neurons to other interconnecting neurons or motor neurons Carries messages from the PNS to the brain and spinal cord Length of fibres Short dendrites and long axons Short dendrites and short or long axons Long dendrites and short axons Structural and functional differences

MOTOR RELAY SENSORY

The knee-jerk reflex In a reflex arc, like the knee-jerk reflex, a stimulus, such as a hammer hitting the knee, is detected by sense organs in the peripheral nervous system, which conveys a message along a sensory neuron. The message reaches the central nervous system where it connects with a relay neuron. This then transfers the message to a motor neuron. This then carries the message to an effector such as a muscle, which causes the muscle to contract and, hence, the knee to move or jerk.

Relay neuron

Synapse between two neurons. Synaptic tramsmission

Neurotransmitters… • …are chemicals that are released from a synaptic vesicle into the synapse by neurons. • They affect the transfer of an impulse to another nerve or muscle • These neurotransmitters are “taken back up” into the terminal buttons of neurons through the process of reuptake • Or they are broken down by an enzyme

Synaptic transmission • • nerve impulse travels down an axon nerve impulse reaches synaptic terminal this triggers the release of neurotransmitters the neurotransmitters are fired into the synaptic gap • neurotransmitter binds with receptors on the dendrite of the adjacent neuron • if successfully transmitted the neurotransmitter is taken up by the post-synaptic neuron • the message will continue to be passed in this way via electrical impulses

How a synapse works • A synapse

Answers 2. = C

Action Potential An action potential occurs when a neuron sends information down an axon, away from the cell body. The action potential is an explosion of electrical activity - this means that some event (a stimulus) causes the resting potential to move forward

Excitation and inhibition • Synaptic connections can be excitatory or inhibitory – the difference lies in the action of the neurotransmitter at the postsynaptic receptor • Excitatory - they make it more likely the next neuron will fire (such as acetylcholine) • Inhibitory - they make it less likely the next neuron will fire (such as GABA) • Normal brain function depends upon a regulated balance between excitatory and inhibitory influences

Synapse: The gap between the end of one neuron and the dendrites of the next neuron. What you need to label: 1. Direction of impulse. 2. Axon terminal 3. Synaptic vesicles containing neurotransmitter 4. Synaptic gap 5. Dendrite 6. Receptor site

Can you? 1. Explain what is meant by sensory, relay and motor neurons (2 marks each) 2. With reference to neurotransmitters, explain what is meant by both excitation and inhibition (4 marks) 3. With reference to sensory, relay and motor neurons, explain the knee-jerk reflex (4 marks) 4. Explain the difference between excitatory or inhibitory synaptic connections (4 marks) • Answer the ‘Check it’ questions on page 117