1 The Cardiovascular System Ellen Black, Ph. D. Department of Neurological Sciences Office phone :

2 We will build on ANPS 19 Material Cells have unique functions An organ’s function is determined by the properties of the cells within it Cells are usually grouped with similar cells into tissues Organs are generally built with tissue layers 4 tissue types in the body: 1.Epithelial tissue 2.Connective tissue 3.Muscle tissue 4.Nervous tissue Review the 4 Tissues by skimming chapter 5

3 We will build on ANPS 19 Material 4 tissue types in the body: 1.Epithelial tissue: glands and epithelial sheets lining organs Glands produce secretions; classified as exocrine or endocrine Epithelial sheets create barriers and regulate exchange between compartments in the organ; cells may be squamous, cuboidal or columnar shaped, and occur in single thickness sheets (simple) or multicellular layers (stratified) Gland Types Sheet classifications

4 We will build on ANPS 19 Material 4 tissue types in the body: 2.Connective tissue: bone, cartilage, blood, and general CT Bone and Cartilage provide support Most CT layers in organs are general CT, rich in collagen fibers, and provide loose space for passage of blood vessels and nerves. These layers are usually sandwiched between epithelial and muscle layers, or surround an organ and connect it to other organs. Loose (aerolar)

5 We will build on ANPS 19 Material 4 tissue types in the body: 3. Muscle tissue: skeletal, smooth, and cardiac muscle makes movement occur – pushing food, blood, urine, etc.

6 We will build on ANPS 19 Material 4 tissue types in the body: 4. Nervous tissue: neurons and glia Nervous tissue allows control of effector target tissues in body (muscle and glands)

7 Organs are built in layers The Esophagus Most organs are either a single hollow structure (ie: digestive tract, heart, bladder) or are built with multiple, small hollow units (lungs, kidneys) In stained tissue sections, the layering of an organ wall is obvious

8 The Autonomic Nervous System The ANS is a branch of the nervous system that closely coordinates with the endocrine system to provide involuntary, or unconscious, control of the internal environment. In the “classical” definition, the ANS is a purely efferent (motor) system. More modern definitions include afferent (sensory) components to describe visceral reflex arcs.

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10 Anatomy of the Autonomic Nervous System The Parasympathetic System The “Craniosacral” system Preganglionic neurons in cranial nerves III, VII, IX, X and from sacral spinal cord levels S2,3,4 The “Rest and Digest” system Functions: Storage of energy reserves Slowing of heart rate Housekeeping functions: emptying of bowel and bladder Protection functions: narrowing pupil, airways

11 Anatomy of the Autonomic Nervous System The Sympathetic System The “Thoracolumbar” system Preganglionic neurons from all thoracic spinal cord levels and lumbar levels L1&2 The “Fight or Flight” system Functions: Release of energy reserves Speeding heart rate, increasing strength of contraction Increasing blood pressure, shunting flow to organs vital to escape Increasing air flow to lungs Dilation of pupil

12 Dual Innervation: Most organs receive both sympathetic and parasympathetic control

13 Chemistry of the Autonomic Nervous System Note that the chemical transmitters used by ANS neurons are acetylcholine and norepinephrine… ONLY Nicotine and Muscarine also stimulate the receptors, but they are not chemicals normally found in the body… they are drugs.

14 Pharmacology of the Autonomic Nervous System Any drug that mimics acetylcholine turns on BOTH systems as well as the activating skeletal muscle. Any drug that blocks the breakdown of acetylcholine prolongs activation of ANS stimulation (ie: nerve gases, pesticides) Note: also causes paralysis by prolonging activation and contraction of all skeletal muscles Nicotine turns on BOTH systems by activating all ganglionic synapses Muscarine turns on ALL parasympathetic systems as well as one sympathetic exception: sweat glands

15 Note: there are TWO ways to activate targets of the sympathetic system 1. Activate individual preganglionic neurons through connections in the CNS. This leads to release of Norepinephrine and allows for fine control of individual organs 2.Activate release of Epinephrine from the adrenal gland; this activates adrenergic receptors everywhere The “fight or flight” response includes activation of all sympathetic neurons as well as release of Epinephrine into the bloodstream Drugs that block, enhance, or mimic actions of the sympathetic system are widely used in clinical medicine

16 So… how does the first neuron in the 2-neuron autonomic chain know when to fire? The preganglionic neuron is controlled by “higher centers” in the CNS often under the control of the hypothalamus includes brainstem and spinal cord cell groups

17 Outside the CNS, sympathetic and parasympathetic axons usually intermingle in weblike networks called autonomic plexuses Axons often travel on blood vessels to enter organs appreciate the difficulty of performing surgery without disrupting these networks of axons