Ch 4 Flashcards
What is meant by “structure reflects evolution”
Primitive brain areas deeper; more central. These older forebrain structures are the most important for animals in terms of motivation.
Hypothalamus influences…
ANS, bodily homeostasis, hormones from the pituitary, basic biological drives (hunger, thirst, sex, maternal behaviour, fear, rage, thermoregulation)
HT signals PG in two ways…
Anterior pituitary receives input from HT through chemical signalling- hormones in the blood picked up by AP which releases more hormones.
Posterior pituitary receives input from HT through electrical signalling- this causes release of hormones from PP.
Autonomic NS made of sympathetic NS and parasympathetic NS. Tell me about it.
SNS: fight or flight; arousal & energy expenditure (catabolic); increases heart rate and respiratory rate; pupils dilate; piloerection; decreases blood flow to digestive tract and skin; increases blood flow to muscles and lungs; fires quickly.
Para-NS: rest and digest; energy storage (anabolic); calming & relaxing; decreases heart rate and respiratory rate; promotes digestion; increases blood flow to digestive tract/skin; promotes secretion from salivary glands; involved in sleep & sexual responses; fires slowly.
Sympathetic and Parasympathetic Systems & the Spinal Cord
Sympathetic system stems from the thoracic and lumbar sections of the spinal cord.
- Outside the spinal cord there is the sympathetic chain ganglia. Nerves leave the spinal cord and synapse in or past this chain before travelling to an organ.
Parasympathetic system stems from the cranial and sacral sections of the spinal cord.
- No chain ganglia. Nerves leave the spinal cord and synapse close to the organ.
A nerve will never travel directly from the spinal cord to an organ!
Acetylcholine…
- Is highly involved in movement and found in neuromuscular junctions
- Is the chief neurotransmitter of the parasympathetic NS (which contracts smooth muscles, dilates blood vessels, facilitates bodily secretions and slows heart rate)
- comes from choline in our diets, synthesized from coA
Catecholamines…
The primary catecholamines are epinephrine, norepinephrine and dopamine. These are released by the adrenal glands (on top of kidneys; made of medulla) in response to SNS which prepares body for stress.
Hormones & Neurotransmitters
Hormones are substances released into the bloodstream to be picked up by receptors at distant sites in the body.
Neurotransmitters are substances released into the synapse between a pre- and post-synpatic neuron. This interaction increases the probability that the PSN will fire, and this can have an excitatory or inhibitory impact.
Neuromodulators & Pheromones
A neuromodulator is a substance in the brain that changes the response of a neuron to some other factor. The ventricles and CSF may be important in these processes.
Pheromones are substances emitted by an individual that influence the physiology or behaviour of another member of the same species.
Steroid hormones & gonads
Steroid hormones are derived from cholesterol, slow-acting, small, lipid-soluble molecules that can travel through the body, act on intracellular receptors and pass the blood-brain barrier.
Gonads are glands that produce gametes. The male gonads are the testes (androgens like testosterone) and the female gonads are the ovaries (estrogens and progesterones).
Anything that ends with “-one” is a steroid.
Peptide Hormones…
Peptide hormones are chains of AAs derived from protein, large, fast-acting molecules that are fragile, water-soluble and do not pass the blood-brain barrier. They act on extracellular receptors.
There are peptide dynamics within the limbic system, hypothalamus, brainstem and elsewhere.
Monoamine Hormones and NTs…
Monoamine hormones are derived from single AAs. They are fast-acting, small, water-soluble, act on extracellular receptors, and do not pass the blood-brain barrier.
Monoamine NTs are derived from single AAs. Tryptophan -> serotonin
Tyrosine -> dopamine and norepinephrine
Dopaminergic Pathways
Ventral Tegmental Area -> Medial Forebrain Bundle -> Nucleus Accumbens
Noradrenergic Pathways…
Locus Coeruleus -> Medial Forebrain Bundle -> Limbic system & neocortex
*LC is the primary brain area for synthesis of noradrenaline
Serotonergic Pathways…
Raphe Nuclei (in the brainstem) -> MFB -> Thalamus, Basal Ganglia, Limbic system, neocortex. We prefer foods rich with tryptophan- wine, chocolate etc. Tryptophan loading in diet increases serotonin levels.
