Bio and Neuropsychology Summary (ENG) (Biological Psychology; ISBN13:9781337408202/ ISBN10:1337408204)
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Course
Bio- En Neuropsychologie
Institution
Universiteit Leiden (UL)
Book
Biological Psychology
In this document you will find a summary of the book: Kalat, J.W. (2019). Biological Psychology (13th edition, Cengage technology edition). Wadsworth/Cengage Learning. ISBN13: 9781337408202/ ISBN10: 1337408204
This is the book used in the course bio- and neuropsychology (first year, Psychology).
...
Chapter 1: Nerve Cells and Nerve Impulses
1.1 The cells of the nervous system
The nervous system consists of two types of cells:
- neurons: receive information and transfer it to other cells. (86 billion)
- glia: serve many functions.
o glia : neurons = 1:1 → more glia in cerebral cortex + more neurons in other areas
o astrocytes:
▪ wrap around synaptic terminals and shield it from chemicals.
▪ It takes up ions and transmitters released by axons and releases them back,
which helps synchronize related neurons; sending messages in waves.
▪ dilate blood vessels to bring more nutrition to the brain areas with
heightened activity.
▪ tripartite synapse hypothesis: tip of axon releases chemicals → astrocyte
does as well → message to neuron is magnified
o microglia: immune system; removes viruses and fungi from brain, remove dead or
damaged neurons + weak synapses (apoptose)
o oligendrocytes: (in brain, spinal cord and Schwann cells) build myelin sheaths
o radial glia: guide migration of neurons and their axons and dendrites during
embryonic development. After they often differentiate into neurons.
Santiago Ramón y Cajal → founders of neuroscience
Camillo Golgi → stain nerve cells with silver salts; examine cells individually
A cell consists of:
- membrane: protein channels permit flow of water and chemicals
- nucleus: contains chromosomes
- mitochondrion: provides energy
- ribosomes: make new protein molecules
- endoplasmic reticulum: network of thin tubes that transport new proteins to other locations
Neuron:
- soma (cell body): nucleus + ribosomes + mitochondria
- dendrites: surface has synaptic receptors that receive info from other neurons. They become
smaller toward the end.
- axon: thin fiber, constant diameter. Conveys impulse to other neurons, organs or muscles.
o covered with myelin sheath (not invertebrate neurons) with interruptions known as
nodes of Ranvier.
o a neuron only has 1 axon
o Afferent axon: brings info into structure
o Efferent axon: carries info away from structure (exit)
o Interneuron/ Intrinsic neuron: when a cell’s dendrites and axon are entirely
contained within a single structure (one part of the brain); relatively short
, - presynaptic terminals (motor neuron): Connect to muscle. Sensory endings (sensory
neuron): connect to skin fe
- dendritic spines: short outgrowths that increase the surface area of the dendrites
Types of neurons:
- motor neuron: spinal cord → muscle
- sensory neuron: specialized to be highly sensitive to a particular type of stimulation; fe skin
→ spinal cord
o purkinje cell: found only in cerebellum
o pyramidal cell: of the motor area of cerebral cortex
o bipolar cell of retina of the eye
o Kenyon cell from a honeybee to distinguish different smells
Blood-brain barrier: the mechanism that excludes most chemicals from the vertebrate brain (helpful
nutrients and harmful virusses).
→ because the vertebrate brain does not replace neurons damaged by a virus
→ viruses that enter the blood-brain barrier: syphilis + chicken pox/shingles + herpes
--Passive transport: Water crosses through endothelial cells, oxygen, carbon dioxide
--Active transport: pump chemicals from the blood into the brain. (glucose>brain main fuel, amino
acids>building blocks of proteins, purines, choline and a few vitamins and iron).
→ to use glucose the body need B1, thiamine: deficiency (alcoholism) leads to death of neurons
→ Korsakoff’s syndrome; severe memory impairments.
1.2 The nerve impulse
The membrane: 8 nanometers; composed of two layers of phospholipid molecules through which
certain chemicals can pass.
- at rest the membrane maintains an electrical gradient, polarization: difference in electrical
charge between the inside and outside of the cell.
- selective permeability: some chemicals pass more freely through membrane than others.
- resting potential: the difference in charge between the outside and the inside of the
membrane. The inside of the membranes is slightly negatively charged.
o sodium-potassium pump: transports three sodium ions (+) out of the cell while
drawing two potassium ions(+) in due to electrical gradient. → There’s more sodium
ions outside membrane, inside is more -
▪ sodium stays out, but potassium slowly leaks out due to concentration
gradient taking their positive charge with them, increasing the membranal
charge
o resting potential stays stable until it’s stimulated
- action potential: messages sent by axons.
o hyperpolarization: increase negative charge inside the neuron
o threshold of excitation is reached → sodium and potassium channels open →
depolarization: reduce polarization toward zero; sodium ions move into neuron
o positive charge flow down the axon and opens voltage-gated sodium channels at the
next point
▪ Propagation of the action potential: the transmission of an action potential
down an axon. One causes another closeby.
o at the peak of an action potential, the sodium gates snap shut
, o potassium gates stay open → potassium flows out axon → return to depolarization
o potassium channels close
o any subthreshold stimulation produces a small response that quickly decays. → no
action potential
all-or-none law: the amplitude and velocity of an action potential are independent of the intensity of
the stimulus that initiated it, provided that the stimulus reaches the threshold.
→ it does not apply to dendrites, because they don’t have action potentials
local anesthetic drugs attach to the sodium channels of the membrane, preventing sodium ions from
entering. The axons cannot transmit the message to your brain.
An action potential travels faster if the axon is thicker and if it’s myelinated.
Saltatory conduction: the jumping of action potentials from node to node.
A myelinated axon only admits sodium at its nodes. The closer the nodes are to each other the
slower the action potential travels. But if they are too far the potential cannot jump from one node
to another.
Multiple sclerosis: the immune system attacks myelin sheaths. The places where myelin sheaths are
lost are no sodium channels, so the action potential dies out.
refractory period: the cell resists the production of further action potentials. The more action-
potentials that can be fired in a second, the shorter the refractory period.
→absolute refractory period: membrane cannot produce another action potential, regardless of
stimulation (sodium channels are closed)
→ relative refractory period: a stronger-than usual stimulus is necessary to initiate an action-
potential. (potassium needs to flow out at a faster-than-usual rate).
Local neurons: are very small, don’t have an axon and don’t follow the all-or-none law. When it
receives info from other neurons it has a graded potential: a membrane potential that varies in
magnitude in proportion to the intensity of the stimulus. Change in membrane potential is conducted
to adjacent areas of the cell gradually decaying as it travels.
Chapter 2: Synapses
2.1: The concept of the synapse
Reflexes: automatic muscular response.
Reflex arc: circuit from sensory neuron to muscle response. There’s a delay.
Sherrington’s observations:
- reflexes are slower than conduction along an axon
- several weak stimuli presented at nearby places or times produce a stronger reflex than one
stimulus alone does.
o Temporal summation: repeated stimuli within a brief time have a cumulative effect.
▪ cannot result in AP
▪ Presynaptic neuron: neuron that delivers transmission. Postsynaptic
neuron: the one that receives it
▪ Excitatory postsynaptic potential (EPSP): it’s a graded depolarization in the
postsynaptic neuron. It results from a flow of sodium ions into the neuron.
, → graded potential can be either depolarization (excitatory) or
hyperpolarization (inhibitory). but EPSP is excitatory
o Spatial summation: synaptic input from separate locations combine their effects on
a neuron. Both individually below the threshold, but combined able to elicit an action
potential.
- when one set of muscles becomes excited, a different set becomes relaxed
o inhibitory postsynaptic potential (IPSP): temporal hyperpolarization of a membrane
that occurs when synaptic input selectively opens the gates for potassium ions (+) to
leave the cell or for chloride ions (-) to enter. The negative charge within the cell is
increased, decreasing the probability of an action potential thus inhibiting response.
Spontaneous firing rate: a periodic production of action potentials even without synaptic input.
2.2: Chemical events at the synapse
Loewi found that neurotransmission depends on the release of chemicals, because he transferred
the blood of a frog with a decreased heart rate into another frog, whose heart rate decreased as
well.
Neurotransmitters: chemicals that affect another neuron.
→ the oddest one is nitric oxide: a gas released by many small local neurons when neurons are
stimulated and it dilates the nearby blood vessels, increasing blood flow to that brain area.
1. synthesis of transmitters
a. L-dopa helps increase the supply of dopamine which can be helpful for Parkinson’s
b. AMPT temporarily blocks the production of dopamine; used to study dopamine
c. see fig. 2.13 for synthesis steps
2. storage of transmitters
a. vesicles: packets where the presynaptic terminal store neurotransmitter (except for
nitric oxide, which is released right when it’s formed)
b. the enzyme MAO (monoamine oxidase) breaks down serotonin, dopamine or
norepinephrine; preventing it from accumulating to harmful levels. (antidepressant:
MAO blockers, increase listed neurotransmitters)
3. release and diffusion of transmitters
a. depolarization opens voltage-dependent calcium gates in the presynaptic terminal
b. this causes exocytosis: bursts of release of neurotransmitter form the presynaptic
neuron, it then diffuses across the synaptic cleft
c. some neurons release one, some release two neurotransmitters at a time
d. sometimes neurons change their transmitters (summer vs winter)
4. activating receptors of the postsynaptic cell
a. when the transmitter attaches to its receptor, the receptor may open a channel:
i. ionotropic effect: the receptor is twisted just enough to open its central
channel, which has a shape that lets a particular type of ion pass through.
1. channels controlled by a neurotransmitter are transmitter-gated or
ligand-gated.
2. neurotransmitters used: glutamate, GABA (inhibitory, opens
chloride- gates), glycine (also inhibitory, spine), acetylcholine
(excitatory)
3. vision, hearing
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