Higher Human Biology - Neurobiology and Immunology

Presynaptic neuron

Neuron before the synaptic cleft

Describe how nervous system is organised

The nervous system has 2 parts; central nervous system (CNS) and peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord. The PNS consists of the somatic nervous system and autonomic nervous system. The autonomic nerve system consists of the sympathetic and parasympathetic systems.

Central Nervous System

Branch of the nervous system composed of the brain and spinal cord.

Peripheral Nervous System

Branch of the nervous system containing other nerves

Autonomic Nervous System

Branch of the peripheral nervous system that is associated with subconscious actions. Contains the sympathetic and parasympathetic systems.

Somatic Nervous System

Branch of peripheral nervous system that is associated with voluntary actions

Sympathetic Nervous System

Branch of autonomic nervous system that prepares the body for fight or flight responses

Parasympathetic Nervous System

Branch of autonomic system that prepares the body to rest and digest

Neurons

Cells of nervous system

Sense Organs

Structures that detect sensory stimuli

Sensory Neurons

Neurons that carry information/ impulses from sense organs to the CNS

Motor Neurons

Neurons that carry information/ impulses from sense organs to the muscles and glands

Antagonistic

Term used to describe the opposite actions of the parasympathetic and sympathetic nervous systems.

Describe the flow of information in the somatic nervous system

Sensory neurons take impulses from sense organs to the CNS. Motor neurons take impulses from CNS to muscles and glands.

Describe the impact of the sympathetic and parasympathetic responses

The sympathetic system speeds up the heart rate and breathing rate while slowing down peristalsis and production of intestinal secretions. The parasympathetic system changes these in the opposite way.

State the 3 types of neural pathways

Converging, Diverging, Reverberating

Describe the converging neural pathway

Impulses from several neurons travel to one neuron

Describe the diverging neural pathway

Impulses from one neuron travel to several neurons

Describe the reverberating neural pathway

Neurons later in the pathway link with earlier neurons

Describe the function of converging pathway

Converging pathway increases sensitivity to excitatory or inhibitory signals

Describe the function of diverging pathway

Diverging pathway allows more than one destination to be affected at the same time

Describe the function of reverberating pathway

Reverberating pathway allows repeated stimulation of the pathway from a single impulse

Hemisphere

Term used to describe each half of the cerebrum

Cerebral cortex

The outer layer of the cerebrum

Sensory areas

Sensory areas are areas within the cerebral cortex that deal with incoming information from sense organs

Motor areas

Motor areas are areas within the cerebral cortex that send information to muscle and glands

Association areas

Association areas are areas within the cerebral cortex that deal with complex functions such as language processing, personality, imagination and intelligence.

Corpus Callosum

Structure that allows information to be transferred between the left and right hemisphere

Name the 3 different types of area found in the cerebral cortex

Motor area, sensory area, association area

Describe the information process in the cerebrum

Information from one side of body is processed in the opposite side of cerebrum

State what side left hemisphere of the brain processes information from and what it controls

Left hemisphere of the brain processes information from the right visual field and right side of body. Left hemisphere controls language production.

State what side right hemisphere of the brain processes information from and what it controls

Right hemisphere of the brain processes information from the left visual fiels and left side of the body. Right hemisphere controls movement of the left side.

Encoding

Conversion of nerve impulses into a form that can be held by the brain and retrieved later

Retrieval

The process that must me utilised if information stored in memory needs to be recalled

What does memories include

Past experiences, knowledge and thoughts

State the 3 different types of memory

Sensory, short-term and long-term memory

Describe sensory memory

First 'stage' of memory that all incoming information passes through. It retains all the visual and auditory input received for a few seconds.

Auditory

Term used to describe information coming from the ears

What is memory span

The amount of information that can be held

Describe the short-term memory

Temporarily stores information received from the sensory memory.

It contains information currently being thought about. It has a limited capacity and can hold 7 items for around 30 seconds

Describe the 2 ways that the information in STM can be lost by

Displacement, where old information is pushed out by new as STM has limited capacity.

Decay, where old memory breaks down

Describe a way to improve capacity of short-term memory

Chunking, where you group information into bits.

Describe a way to maintain items in the short term memory for longer

Rehersal can be used to help retain information in short term memory for longer. It involves repeating information over and over.

Describe what is a working memory

Working memory is an extension of the short term memory because it can process and manipulate data to a limited extent, as well as storing. This explains why STM can perform simple cognitive tasks like remembering steps in a recipe.

State a way to demonstrate memory storage

One way to demonstrate memory storage is to investigate the serial position effect.

Describe the serial position effect

Shows that when given a list of items to remember we are more likely to recall items at the start of the list , which is called primary effect, and the items at the end of the list, which is called recency effect, but struggle to remember with those in the middle

Describe how serial position effect can be distrupted

Serial position effect can be distrupted by asking participants to complete a distraction task before recall. Recall of items at the end would be lost due to decay and displacement.

Describe the long-term memory

It is the final 'stage' of memory that information passes into if it is not discarded from short term memory. It has an unlimited capacity and holds information for a long time.

Describe 3 ways that information STM memory can be transferred to LTM

• Rehersal is regarded as shallow form of encoding information into the LTM

• Organisation is grouping items together in logical categories, which increases their change of being successfully transferred into LTM

-Elaboration invloves adding additional/ meaningful information to a piece of information. It is regarded as a deeper form of encoding which leads to improved information retention.

State the use of what aids the retrieval of information

Contextual cues

Describe what contextual cues are

Contextual cues are reminders, they trigger memories of the time and place when the information was originally transferred to LTM

State what nervous system consists of in terms of cells

The nervous system contists of nerve cells called neurons and glial cells.

Whats the function of neurons

Neurons receive and transmit electrical signals (nerve impulses)

Whats the function of glial cells

They support neurons and maintain neurons

State whats each neuron is made up of

Each neuron is made up of:

• Cell body

• Several dendrites

• One axon

Whats are dendrites

Dendrites are part of a neuron that allows it to make connections with other cells

What are axons

Axons are part of a neuron that allows an electrical impulse to be carried over a distance

What is a myelin sheath

A myelin sheath is a layer of fatty material that surrounds most axons which insulates the axons and increases the speed of conduction.

What are the small gaps in the myelin sheath called

The small gaps in the myelin sheath are called nodes.

What does myelinated mean

Myelinated is a term used to neurons that have myelin sheath around their axons

What is myelation

It the process of myelin sheath being laid down around axons that occurs from birth to adolescence

Describe the conduction in a myelinated neurons

In a myelinated neuron, impulses 'jump' between sections of myelin sheaths , which makes conduction faster

Explain why stimuli in the first two years of life are not rapid or coordinated as those of an older child or adult

This is because myelination occurs from birth to adolescene

Decsribe what would happen if a disease destroyed the myelin sheath

This would lead to loss of coordination, beacuse impulses cannot be conducted along these neurons as quickly.

State what glial cells produce

They produce myelin sheath

What are synapses

Synapses are connections between neurons or between a neuron and its target cell

Whats a synaptic cleft

A synaptic cleft is the small gap between the plasma membranes of two neurons at a synapse, where they are in very close contact but not touching.

Postsynaptic neuron

Neuron after the snapse

Where are neurotransmitters stored before being released

Neurotransmitters are stored in vesicles at the axon endings of the presynaptic neuron.

What triggers the release of neurotransmitters from the presynaptic neuron

The arrival of a nerve impulse at the presynaptic neuron triggers the release of neurotransmitters from vesicles into the synaptic cleft.

How do neurotransmitters cross the synaptic cleft

Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic neuron

Describe how signals are transmitted at a synapse

Neurotransmitters are stored in vesicles inside the presynaptic neuron. The arrival of a nerve impulse at the presynaptic neuron triggers the release of neurotransmitters from vesicles into the synaptic cleft. Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron. If enough neurotransmitter is released, it reaches the threshold, triggering a new impulse in the postsynaptic neuron.

What must happen for the postsynaptic neuron to generate a new impulse

For the postsynaptic neuron to generate a new impulse, enough neurotransmitter must bind to reach the threshold. If the threshold is reached, a new nerve impulse is triggered

State the reason why neurotransmitter molecules must be removed from the synaptic cleft after each impulse

To prevent continuous stimulation of the postsynaptic neuron

Describe the two mechanisms to remove neurotransmitter molecules from the synaptic cleft

Re-uptake : proteins in the presynaptic neuron reabsorb the neurotransmitter molecules back into the neuron to be restored inside a vesicle to be used again.

Degradation by enzymes: Enzymes in the synaptic cleft break down the neurotransmitter molecules

Why does the brain need a lot of energy for synaptic transmission

Because continual synthesis and removal of neurotransmitters requires a very large amount of energy

Describe what does receptors on the postsynaptic membrane determines

Receptors on the postsynaptic membrane determine whenther the signal received is excitatory or inhibitory

What is an excitatory signal at a synapse and what does it cause

An excitatory signal makes the postsynaptic neuron more likely to send a nerve impulse by bringing it closer to the threshold. This leads to increase in action such as muscles to contract

What is an inhibitory signal at a synapse, and what does it cause

Inhibitory signal makes the postsynaptic neuron less likely to send a nerve impulse by moving it further from the threshold. This causes a decrease in action (prevents a response basically) such as slowing the heart rate.

What causes a stimulus to be ignored at a synapse

If the stimulus is too weak, it may not cause the presynaptic neuron to release enough neurotransmitter.This means the threshold is not reached on the postsynaptic neuron, so no impulse is transmitted and the stimulus is ignored.

State what must happen for the postsyanptic neuron to transmit an impulse

A minimum number of neurotransmitter molecules must bind to receptors on the postsyanptic membrane. If this reaches the threshold, the neuron sends an impulse

What is summation

Process by which a series of weak stimuli can be added together to produce a response in the postsynaptic cell when normally a single weak stimulus would not be enough

Describe what type of neural pathways can go throught the process summation

Convergent neural patways can release enough neurotransmitter molecules to reach threshold and trigger an impulse

Suggest how converging arrangement of rod cells increases sensitivity to allow vision in dim light.

-Each rod cell releases a small number of neurotransmitters when stimulated.

-The combined neurotransmitter input released from several rod cells and then the threshold is reached to trigger an impulse.

State 2 neurotransmitters that are involved in controlling mood and behaviour

Endorphins and dopamine

What are endorphins

Endorphins are neurotransmitters that stimulate neurons involved in reducing intensity of pain and acts as a natural pain relief

Whats the function of endorphins

They promote feelings of pleasure and wellbeing, and help the body cope with pain and stress.

When are endorphins released

Severe injury

Prolonged exercise

Stress