Autonomic Nervous System, Endocrine, and Circulatory System Overview

Autonomic Nervous System

Helps regulate activity of several major organ systems; Circulatory, respiratory, digestive, urinary, reproductive; Contributes to visceral reflexes; Internal organs; Not under conscious control (Ch. 15 p. 2)

Visceral reflexes

Contributes to visceral reflexes; Internal organs (Ch. 15 p. 3)

Baroreflex

High bp detected by arterial stretch receptors (baroreceptors); Afferent neuron of glossopharyngeal nerve (CN IX) carries signal to CNS; Medulla oblongata integrates info, makes decision; Efferent signals travel along vagus nerve (CN X) to heart; Heart slows, lowering bp; Homeostasis by negative feedback loop (Ch. 15 p. 4)

Baroreceptors

High bp detected by arterial stretch receptors \(Ch. 15 p. 4)

Medulla oblongata

integrates info, makes decision (Ch. 15 p. 4)

Vagus nerve (CN X)

Efferent signals travel along what nerve (CN X) to heart (Ch. 15 p. 4)

Negative feedback loop

Homeostasis by negative feedback loop (Ch. 15 p. 4)

Sympathetic division

(fight or flight); Prepares body for physical activity; Raises heart rate, BP, airflow, blood sugar levels; Reduces blood flow to skin and digestive tract (Ch. 15 p. 5)

Fight or flight

Sympathetic division (fight or flight) (Ch. 15 p. 5)

Parasympathetic division

(rest and digest); Calms many body functions, reducing energy expenditure; Facilitates digestion, waste elimination and other aspects of normal body maintenance (Ch. 15 p. 6)

Rest and digest

Parasympathetic division (rest and digest) (Ch. 15 p. 6)

Autonomic Output Pathways

ANS has components in both the CNS and PNS; Control nuclei in the hypothalamus and other brainstem regions; Motor neurons in the spinal cord and peripheral ganglia; Nerve fibers that travel through the cranial and spinal nerves (Ch. 15 p. 8)

Preganglionic

cell body on brain stem or spinal cord; extends to autonomic ganglion; Synapses with second neuron - ACh (Ch. 15 p. 9)

Postganglionic

cell body in autonomic ganglion; axon extends to target organ - ACh or NE (Ch. 15 p. 9)

Autonomic ganglion

cell body on brain stem or spinal cord; extends to autonomic ganglion (Ch. 15 p. 9)

Sympathetic NS

Diverts blood to skeletal muscles; Away from digestive and urinary systems; Mobilizes glucose; Increases respiration and heart rate; Increases alertness; Inhibits reproductive and immune systems (Ch. 15 p. 11)

Widespread sympathetic effects

Single preganglionic fiber synapses with 10+ postganglionic neurons; Can affect tissues in multiple organs; Effects are widespread ('sympathetic') (Ch. 15 p. 12)

Adrenal gland

Paired gland on top of kidneys with cortex and medulla (Ch. 15 p. 13)

Chromaffin cells

(modified postganglionic neurons) are stimulated by preganglionic neurons (Ch. 15 p. 13)

Epinephrine

Secretes epinephrine (85%) and norepinephrine (15%) in blood (Ch. 15 p. 13)

Norepinephrine

Secretes epinephrine (85%) and norepinephrine (15%) in blood (Ch. 15 p. 13)

Parasympathetic NS

Diverts blood to digestive and urinary systems; Conserves energy; Reduces respiration and heart rates; Allows reproductive and immune systems to function normally (Ch. 15 p. 14)

Parasympathetic preganglionic neurons

Preganglionic neurons terminate in or near target organs; Stimulate only 1 or few organs; More selective effects than sympathetic NS (Ch. 15 p. 15)

Neurotransmitters and Their Receptors

Sympathetic and parasympathetic fibers secrete different NTs (ACh and NE); Target cells respond to the same NT differently depending on the type of receptor; There are two different classes of receptors for ACh and two classes for NE (Ch. 15 p. 16)

Acetylcholine (ACh)

Secreted by all preganglionic neurons in both divisions (Ch. 15 p. 17)

Cholinergic neurons

Neurons that secrete ACh are called (Ch. 15 p. 17)

Cholinergic receptors

Receptors that bind ACh are called (Ch. 15 p. 17)

Muscarinic Receptors

Cardiac muscle, smooth muscle, and glands; Act through 2nd messenger cascade; Receptor subtypes exists, often providing contrasting effects on organs; EX: ACh excites smooth muscle, but inhibits cardiac muscle; Named for toxin muscarine (Ch. 15 p. 18)

Nicotinic Receptors

Postganglionic neuron cell bodies in autonomic ganglia; Cells of adrenal medulla, NMJ; Bind ACh to receptor is always excitatory; Open ligand-gates ion channels, produce EPSP; Named for toxin nicotine (Ch. 15 p. 19)

Norepinephrine (NE)

Secreted by nearly all sympathetic postganglionic neurons (Ch. 15 p. 21)

Norepinephrine (NE)

Adrenergic fibers and adrenergic receptors r in (Ch. 15 p. 21)

Adrenergic receptors

Adrenergic fibers and adrenergic receptors (Ch. 15 p. 21)

Alpha (α)-adrenergic receptors

Alpha (α)-adrenergic receptors (Ch. 15 p. 21)

Beta (β)-adrenergic receptors

Beta (β)-adrenergic receptors (Ch. 15 p. 21)

α-adrenergic receptors

α-adrenergic receptors; Usually excitatory; Use different 2nd messengers (Ch. 15 p. 22)

β-adrenergic receptors

β-adrenergic receptors; Usually inhibitory; Both act through cAMP as 2nd messenger (Ch. 15 p. 22)

Endocrine System

Glands and tissues that secrete hormones; Stimulate changes in cells of other tissues/organs; Only target cells respond to hormone (Ch. 17 p. 2)

Target cells

Only target cells respond to hormone (Ch. 17 p. 2)

Nervous and Endocrine Systems

Some hormones secreted by neurons •EX: oxytocin of pituitary gland •Some neurotransmitters act as hormones •EX: norepinephrine of adrenal gland

Neurotransmitters act as hormones

Some neurotransmitters act as hormones; EX: norepinephrine of adrenal gland (Ch. 17 p. 3)

Overlapping effects on same tissues

Norepinephrine and glucagon cause glycogen to be converted to glucose (glycogenolysis) (Ch. 17 p. 4)

Glycogenolysis

Norepinephrine and glucagon cause glycogen to be converted to glucose what is it called (Ch. 17 p. 4)

Nervous and endocrine regulation

Both systems can regulate each other; Neurons can trigger hormone secretion; Hormones can stimulate or inhibit neurons (Ch. 17 p. 4)

Pituitary Gland (Hypophysis)

Formed of adenohypophysis and neurohypophysis; Suspended by infundibulum; sits in sella turcica (Ch. 17 p. 6)

Pituitary Gland

Formed of adenohypophysis and neurohypophysis (Ch. 17 p. 6)

Hypothalamo-hypophyseal tract

Bundle of nervous tissue linked to hypothalamus; Hypothalamo-hypophyseal tract (Ch. 17 p. 8)

Oxytocin (OT)

Multiple functions in context of reproduction:; Uterine contractions during labor; Milk ejection during breastfeeding; Pair bonding between mother and child; Feelings of satisfaction and emotional bonding between sex partners (Ch. 17 p. 9)

Antidiuretic Hormone (Vasopressin)

Increases water retention in kidneys; Raises blood pressure; Addition of water to bloodstream from urine; Constriction of blood vessels; Ethanol inhibits secretion of ADH (Ch. 17 p. 10)

Hypophyseal portal system

Hypothalamic hormones arrive via hypophyseal portal system (Ch. 17 p. 11)

Thyroid-stimulating hormone (TSH)

Stimulates release of thyroid hormone (Ch. 17 p. 12)

Luteinizing hormone (LH)

Stimulates release of ovarian and testicular hormones (Ch. 17 p. 12)

Follicle-stimulating hormone (FSH)

Stimulates follicular growth in ovaries and production of sperm in testes (Ch. 17 p. 12)

Adrenocorticotropic hormone (ACTH)

Stimulates release of adrenal glucocorticoids (Ch. 17 p. 12)

Hypothalamus

Secretes 6 releasing/inhibiting hormones; Regulatory; Produces OT and ADH of neurohypophysis (Ch. 17 p. 14)

Endocrine axis

Relationship between hypothalamus, pituitary and third endocrine gland (Ch. 17 p. 15)

Control of Pituitary Secretion

Rates of secretion not constant-regulated by hypothalamus, other brain areas, feedback (Ch. 17 p. 16)

Osmoreceptors

Trigger release of ADH when detect a rise in blood osmolarity (Ch. 17 p. 19)

Negative Feedback

Increase target organ hormone levels inhibit release of hypothalamic and/or pituitary hormones; EX: thyroid gland, cortisol (Ch. 17 p. 20)

Positive Feedback

EX: Oxytocin-stretching of uterus increases OT release → contractions → stretching of uterus, etc. until delivery (Ch. 17 p. 22)

Prolactin

Stimulates milk production in mammary glands; Released following drop in hypothalamic prolactin-inhibiting hormone (PIH); Infant suckling causes further prolactin surge (Ch. 17 p. 23)

Growth Hormone (Somatotropin)

Induces mitosis and cellular differentiation stimulating body growth; Stimulated by hypothalamic growth hormone-releasing hormone(GHRH) and blocked by somatostatin (Ch. 17 p. 24)

Mitosis

Induces mitosis and cellular differentiation stimulating body growth (Ch. 17 p. 24)

Cellular differentiation

Induces mitosis and cellular differentiation stimulating body growth (Ch. 17 p. 24)

Growth hormone-releasing hormone (GHRH)

Stimulated by hypothalamic growth hormone-releasing hormone(GHRH) and blocked by somatostatin (Ch. 17 p. 24)

Somatostatin

Blocked by somatostatin (Ch. 17 p. 24)

IGF-I

Liver produces growth stimulates IGF-I; Prolongs action of GH; GH half-life 6-20 mins; IGF-I half life ~20 hrs (Ch. 17 p. 25)

Protein synthesis

Boosts transcription and translation; Increases amino acid uptake into cells; Suppresses protein catabolism (Ch. 17 p. 26)

Carbohydrate metabolism

Mobilizing fatty acids reduces dependence of cells on glucose (Ch. 17 p. 27)

Electrolyte balance

Promotes Na+, K+, and Cl- retention in kidneys, enhances Ca2+ absorption in intestine; Make electrolytes available to growing tissues (Ch. 17 p. 28)

Thyroid Gland

Largest endocrine gland; Secretes thyroid hormone (TH) and calcitonin; Two lobes connected by isthmus; Rich blood supply (Ch. 17 p. 29)

Thyroid hormone (TH)

Secretes thyroid hormone (TH) and calcitonin (Ch. 17 p. 29)

Calcitonin

Secretes thyroid hormone (TH) and calcitonin (Ch. 17 p. 29)

Isthmus

Two lobes connected by isthmus (Ch. 17 p. 29)

Follicular cells

Produced by follicular cells and deposited into colloid of thyroid follicles (Ch. 17 p. 30)

Colloid

Produced by follicular cells and deposited into colloid of thyroid follicles (Ch. 17 p. 30)

Thyroid follicles

Produced by follicular cells and deposited into colloid of thyroid follicles (Ch. 17 p. 30)

Thyroxine (T4)

Thyroxine or tetraiodothyronine (T4) (Ch. 17 p. 30)

Triiodothyronine (T3)

Triiodothyronine (T3) (Ch. 17 p. 30)

Functions of Thyroid Hormone

Increases metabolic rate and heat production; Raises O2 consumption, heart rate, and breathing rate; Secretion increases when cold; Promotes alertness and fast reflexes (Ch. 17 p. 31)

Thyrotropin-releasing hormone (TRH)

Thyrotropin-releasing hormone (TRH; hypothalamus) (Ch. 17 p. 32)

Endemic Goiter

Thyroid swells due to excess TSH; Results from iodine deficiency; Anterior pituitary receives no feedback to stop TSH secretion, causing hypertrophy of thyroid gland (Ch. 17 p. 33)

Iodine deficiency

Results from iodine deficiency (Ch. 17 p. 33)

Parafollicular (C) cells

Produced by parafollicular (C) cells of thyroid gland (Ch. 17 p. 35)

Osteoclast inhibition

Osteoclast inhibition (Ch. 17 p. 35)

Osteoblast stimulation

Osteoblast stimulation (Ch. 17 p. 35)

Parathyroid Gland

Four small, ovoid glands on posterior side of thyroid gland; Vary in number (5% of people have more) (Ch. 17 p. 36)

Parathyroid Hormone

Binds to osteoblast, which then stimulate them to produce RANKL; Raises osteoclasts levels and promotes bone resorption (Ch. 17 p. 37)

Pancreas

Both exocrine and endocrine functions; Hormones produced from cells in pancreatic islets (islets of Langerhans); 1-2 million; 2% of tissue; Important in glycemia--blood glucose concentration; α, β, δ, PP cells (Ch. 17 p. 39)

Pancreatic islets (islets of Langerhans)

Hormones produced from cells in pancreatic islets (islets of Langerhans) (Ch. 17 p. 39)

Glycemia

Important in glycemia--blood glucose concentration (Ch. 17 p. 39)

Glucagon

α cells secrete glucagon between meals when blood glucose falls; Stimulates gluconeogenesis, glycogenolysis, and the release of glucose; Stimulates release of fatty acids from adipocytes (Ch. 17 p. 40)

α cells

α cells secrete glucagon between meals when blood glucose falls (Ch. 17 p. 40)

Gluconeogenesis

Stimulates gluconeogenesis, glycogenolysis, and the release of glucose (Ch. 17 p. 40)

Insulin

Secreted by β cells during/after meals when blood glucose rises; Stimulates cells to store or metabolize blood glucose and blood fats; Prevents breakdown of fat or protein (Ch. 17 p. 41)

β cells

Secreted by β cells during/after meals when blood glucose rises (Ch. 17 p. 41)

δ cells

δ cells secrete somatostatin in response to glucose, amino acids (Ch. 17 p. 42)

Paracrine regulator

Paracrine regulator of glucagon and insulin (Ch. 17 p. 42)