Chapter 15: Chemical Control Of The Brain And Behavior

Front 1

Homeostasis

Back 1

The maintenance of the body's internal environment by the hypothalamus within a narrow physiological range.

Biochemical reactions in many cells occur at 37C; hypothalamus causes shivering and goosebumps in cold and sweat in heat.

Front 2

Periventricular Zone

Back 2

Hypothalamic functional zone that lies right next to the wall of the third ventricle.

Contains 1) Suprachiasmic nucleus, which controls circadian rhythms with the daily light-dark cycle.
2) Cells that control ANS--sympathetic and parasympathetic responses in visceral organs
3) Neurosecretory neurons that send axons down toward the stalk of the pituitary gland

Front 3

Magnocellular Neurosecretory Cells

Back 3

Extend axons down stalk of pituitary into posterior lobe.
Release two peptide neurohormones into bloodstream: oxytocin and vasopressin.

Front 4

Oxytocin

Back 4

Causes uterine contractions during childbirth, also stimulates ejection of milk from mammary glands.
Sensory stimulus reaches cerebral cortex through thalamus and cortex stimulates hypothalamus to trigger oxytocin release.

Front 5

Vasopressin (Antidiuretic Hormone--ADH)

Back 5

Regulates blood volume and salt concentration:
Adapt us to dehydration (blood volume decrease and salt concentration increase) by acting on the kidneys to lead to water retention and reduced urine output.

Front 6

Kidneys' response to lowered blood volume and pressure

Back 6

1) Secrete enzyme Renin, which 2) converts Angiotensinogen (large protein from liver) into Angiotensin I, which 3) breaks down further to form Angiotensin II. 4) Angiotensin helps increase blood pressure.

Front 7

Subfornical Organ

Back 7

Part of telencephalon that lacks blood-brain barrier; detects angiotensin II and sends signals into the hypothalamus activating vasopressin neurosecretory cells. It also activates cells in the Lateral area of the hypothalamus that produces the sensation of thirst!

Front 8

Hormones of the Anterior Pituitary "Master" gland (which is controlled by secretory hypothalamus)

Back 8

1) Follicle-stimulating hormone (FSH)--gonads--Ovulation, spermatogenesis

2)Luteinixing hormone (LH)--gonads--ovarian, sperm maturationo

3) Thyroid-stimulating hormone (TSH), also called thyrotropin--Thyroid--Thyroxin secretion (increases metabolic rate)

4) Adrenocorticotropic hormone (ACTH)--Adrenal cortex--Cortisol secretion

5) Growth hormone (GH)--all cells--stimulation of protein synthesis

6) Prolactin--mammary glands--growth and milk secretion

Front 9

Parvocellular Neurosecretory Cells

Back 9

Secrete hypophysiotropic hormones into a third ventricle network of blood vessels called the hypothalamo-pituitary portaffl circulation, which facilitates binding to pituitary cell receptors.

Front 10

Differences between somatic motor system and ANS

Back 10

1) ANS commands all tissues and organs besides skeletal muscle that are innervated.
2) ANS cell bodies lie outside CNS within Autonomic Ganglia, with both preganglionic and postganglionic neuron fibers
3) ANS utilizes disynaptic pathway (Sympathetic and Parasympathetic)

Front 11

Enteric Division of the ANS

Back 11

"The Little Brain": embedded in lining of esophagus, stomach, intestines, pancreas and gallbladder. Consists of two networks: Myenteric (Auerbach's) Plexus and Submucous (Meissner's) Plexus. These control transport, digestion and excretion of food.

Front 12

Noradrenergic Locus Coeruleus

Back 12

One on each side of the pons: axons leave in several tracts but innervate just about every part of brain; makes most of the diffuse connections in brain.

Is involved in regulation of attention, arousal, learning and memory, anxiety and pain, mood and brain metabolism.

Best activated by new, nonpainful sensory stimuli in environment; may function generally to increase brain responsiveness.

Front 13

Diffuse Modulatory Systems(their distinguishing principles in common)

Back 13

1) The core of each system has a small set (several thousand) of neurons
2) Neurons arise from the central core of the brain, most of them from the brain stem
3) Each neuron can influence many others owing to axons that may contact more than 100,000 postsynaptic neurons across brain
4) Synapses release neurotransmitters into extracellular fluid rather than synaptic clefts, so they can diffuse to many neurons.

Front 14

Serotonergic Raphe Nuclei

Back 14

Makes up the other half of ther ascending reticular activating system (processing arousal and awakening of forebrain).

Implicated in sleep-wake cycles as well as in mood and certain emotional behaviors.

Front 15

Dopaminergic Substantia Nigra and Ventral Tegmental Area

Back 15

Substantia Nigra dopaminergic cells facilitate initiation of motor responses by environmental stimuli; thus degeneration of them produces Parkinson's disease.

Dopaminergic Ventral Tegmental area (mesocorticolimbic dopamine system) is involved in the "reward" system that reinforces certain adaptive behaviors.

Front 16

Cholinergic Basal Forebrain and Brain Stem complexes

Back 16

The former lies scattered among core of telencephalon, medial and ventral to the basal ganglia. Best known are the medial septal nuclei which innervate the hippocampus, and the basal nucleus of Meynert, which innervates neocortex.

The latter are within pons and midbrain tegmentum, and act on dorsal thalmus to regulate excitabiility of sensory relay nuclei.

Front 17

LSD's effect on diffuse modulatory systems

Back 17

Chemical structure approximates that of serotonin, suggesting that it acts on serotonergic systems.

Perhaps it causes hallucinations by superseding the naturally modulated release of serotonin in perceptual areas.

Front 18

Stimulant drugs (cocaine and amphetamines)

Back 18

Mimic catecholamine structure of dopamine and norepinephrine.
Both target DA reuptake, while amphetamines block NE and DA reuptake AND stimulate the release of DA. This is how they prolong and intensify the effects of released DA or NE.