Diencephalon & Autonomic Nervous System

Objectives Identify all of the subcortical fasciculi and tracts Define projection, commissural, and association fibers For each fasciculus or tract, identify the type of fibers it consists of and the regions it connects. Compare and contrast the changes that occur to the different regions of the cortex throughout a lifespan. Describe the Anatomy, Blood supply and Functions of Diencephalon structures: Thalamus Hypothalamus & Pituitary Gland Epithalamus & Pineal Gland Subthalamus

Thalamus

Thalamus 3 types of nuclei (by function) Relay nuclei – relays information not involved in a loop Example: sensory information from face  VPM  somatosensory cortex Association nuclei – nuclei involved in executive functioning loops Example: mediodorsal nucleus is involved in the limbic loop (pg 421 LE) Nonspecific nuclei – receive info from several regions, send info to entire cortex, involved with alertness and arousal Example: intralaminar nuclei

Thalamus Blood Supply

Hypothalamus

Hypothalamus 3 zones: Periventricular zone Medial zone (3 regions): oxytocin - intimacy vasopressin - water retention Medial zone (3 regions): Supraoptic region satiety center – body composition Suprachiasmatic n. - circadian rhythm Tuberal region behavioral center – aggression, rage Mammillary region converts short term memory to long term memory (by connections with hippocampus through fornix) Lateral zone involved with satiety

Hypothalamus and Pituitary

It’s Complicated!! Do NOT need to know

Full list of functions of hypothalamus and pituitary Growth Blood pressure Some aspects of pregnancy and childbirth including stimulation of uterine contractions during childbirth Breast milk production Sex organ functions in both males and females Thyroid gland function The conversion of food into energy (metabolism) Water and osmolarity regulation in the body Water balance via the control of reabsorption of water by the kidneys Temperature regulation Pain relief Source: Wikipedia

Hypothalamus Blood Supply Same as Thalamus!

Epithalamus Pineal Gland Blood supply – no BBB! Releases melatonin Collects mineral deposits Calcium, flouride, phosphorous Blood supply – no BBB! Posterior Choroidal A.

Subthalamus Involved in motor control Associated with the Basal Ganglia (striatum, lentiform, PPN, substantia nigra)

Objectives Compare and contrast the sympathetic and parasympathetic nervous systems (neurotransmitters, receptors and effects) Describe how afferent information enters the CNS Describe the difference between pre-ganglionic and post-ganglionic Describe or draw the structure of the sympathetic trunk Identify and locate the centers that control respiration, cardiac regulation, and vasomotor regulation

Organization Efferents Neurotransmitters Receptors Effects Afferents Symp. Para. Symp. Para. Symp. Para. Afferents Anatomy Symp. Para. Control Centers

Neurotransmitters Cholinergic – all preganglionic, & postganglionic parasympathetic Adrenergic – postganglionic sympathetic only Adrenal glands have no postganglionic neuron – they receive acetylcholine and release adrenaline to bloodstream to stimulate sympathetic activity of all organs Receptor types vary Acetylcholine = cholinergic Adrenaline & noradrenaline = Adrenergic Brilliant system: adrenal glands stimulate all sympathetic activity hormonally for longer lasting effects (to escape predators!) SC Ganglia Target Organ

Discuss With a partner, 2 minutes What is the significance of pre-ganglionic vs. post-ganglionic? How is this different from the somatic NS? What systems are adrenaline and noradrenaline used in? What systems are acetylcholine used in?

Answers Pre-ganglionic is the neuron from the CNS that ends in a peripheral ganglia Post-ganglionic is the neuron from the peripheral ganglia that ends in a target organ The somatic NS has no synapses outside the CNS Adrenaline & Noradrenaline are only in the Sympathetic NS Acetylcholine is used in parasympathetic, sympathetic, and somatic systems

Receptors (sympathetic) Adrenergic receptors (sympathetic on target organs) α1, a2, b1, b2, b3 a1 & a2 receptors constrict blood vessels to skin, viscera, brain, reproductive system, constrict bronchioles B1 controls pacemaker potential B2 dilates coronary arteries, arteries to skeletal muscles, dilates bronchioles Adrenaline is most effective in b2 receptors, noradrenaline more effective in a1, the rest are equal A blockers produce vasodilation – decreases blood pressure B1 blockers decrease sympathetic activity on heart – decreases blood pressure

Functions (sympathetic) Dilates pupil, increases pacemaker potential & force of contraction Blood vessels – depends on what organs they are supplying (see previous slide)

Receptors (parasympathetic) Muscarinic & Nicotinic receptors (parasympathetic) No parasympathetic receptors in uterus a1 cause contraction & b2 cause relaxation No parasympathetic receptors in sweat glands, liver, most blood vessels, ventricular muscle Many functions are controlled only by the sympathetic system – more activity vs less activity

Functions (parasympathetic) Dilate blood vessels to reproductive system & salivary glands Decreases cardiac output Contracts bronchioles Constricts pupils

Organization Efferents Neurotransmitters Receptors Effects Afferents Symp. Para. Symp. Para. Symp. Para. Afferents Anatomy Symp. Para. Control Centers

Visceral Afferents Organ  splanchnic nerves  dorsal root ganglion  spinal cord  solitary nucleus Collaterals synapse in laminae 5-6 of the spinal cord Autonomic reflexes

Parasympathetic Anatomy “Craniosacral outflow” Preganglionic somas located in solitary n., ambiguus, dorsal motor n. of X (medulla), and sacral spinal cord Vagus nerve and splanchnic nerves contain preganglionic axons Ganglia are located near target organs

Sympathetic Anatomy “Thoracolumbar outflow” Preganglionic somas located in the lateral horn Postganglionic somas located in either the sympathetic trunk/chain or near the target organs Cervical cardiac and thoracic visceral nerves contain postganglionic axons Thoracic, lumbar and sacral splanchnic nerves contain preganglionic axons

Sympathetic trunk

Overview

Respiratory centers: ventral = intercostal muscles, dorsal = diaphragm Pneumotaxic and apneustic areas coordinate the two (somewhat unknown) Cardiovascular center: info from blood pressure, joint movements, blood composition to effect heart rate Vasomotor center: part of CV center All communicate and coordinate to balance systems

Venn Diagram

Conclusion Hypothalamus & Pituitary ANS – parasympathetic vs sympathetic Sensory info from special regulatory centers directly to Solitary nuc. Receptor types and neurotransmitter types Presentations If time – meet with groups