Presentation on theme: "Chapter 45 Chemical Signals in Animals"— Presentation transcript:
1 Chapter 45 Chemical Signals in Animals The endocrine system and the nervous system are structurally, chemically, and functionally related.
2 Regulatory systemsHormone~ chemical signal secreted into body fluids (blood) communicating regulatory messagesTarget cells~ body cells that respond to hormonesEndocrine system/glands~ hormone secreting system/glands (ductless); exocrine glands secrete chemicals (sweat, mucus, enzymes) through ductsNeurosecretory cells~ specialized nerve cells that secrete hormonesFeedback mechanisms ~ negative and positive (feature that is also common in the nervous system)
3 Local regulators: cells adjacent to or near point of secretion Growth factors ~ proteins for cell proliferationNitric oxide (NO) ~ (highly reactive& potentially toxic) neurotransmitter; cell destruction (bacteria, cancer cells); vessel dilationProstaglandins ~ modified fatty acids secreted by placenta (induce labor) and immune system (fever, pain); also found in semen (contract smooth muscle in uterus helping convey sperm to egg.
4 Mode of Action: Chemical Signaling 1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones)2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators
5 Vertebrate Endocrine System Page 961 Tropic hormones ~ a hormone that has another endocrine gland as a targetHypothalamus: causes release of hormones produced by posterior pituitary and regulates anterior pit.Pituitary glandPineal glandThyroid glandParathyroid glandsThymusAdrenal glandsPancreasGonads (ovary, testis)
8 The pituitary The posterior pituitary: Oxytocin~ uterine and mammary gland cell contractionAntidiuretic (ADH)~ retention of water by kidneys, increase permiability of epithelium to water, amplifies water reabsorption
12 The adrenal glandsAdrenal medulla (catecholamines-synthesisized from AA tyrosine): •epinephrine & norepinephrine~ increase basal metabolic rate (blood glucose and pressure)Adrenal cortex (corticosteroids): •glucocorticoids (cortisol)~ raise blood glucose •mineralocorticoids (aldosterone)~ reabsorption of Na+ and K+
13 The gonads Steroid hormones: precursor is cholesterol androgens (testosterone)~ sperm formation; male secondary sex characteristics, gonadotropinEstrogens (estradiol)~uterine lining growth; female secondary sex characteristics; gonadotropinProgestins (progesterone)~uterine lining growth
14 Signal Transduction Pathway Signal- transduction pathways allow for small amounts of a hormone to have a large effect.
15 Endocrine SystemHow are chemical signals in the body transmitted from cell to cell?Chemical signals called transmitters include amino acids, polypeptides, and gases that can be received by other cells via a protein receptor on the surface of the receiving cell or by entering the cell directly.
16 What are some of the sources of the body’s chemical signals? Neurotransmitters from nerve cells.Endocrine signals from endocrine glands.How are endocrine signals different from nerve cell signals?Neurotransmitters are usually small, nitrogen-containing compounds that are conveyed from one specialized nerve cell to another along specific nerve highways throughout the body and are designed to elicit immediate responses
17 How are endocrine signals similar to neurotransmitters? Endocrine signals are usually hormones secreted from glands that use blood vessels to disperse their signal molecules, to elicit a slower response.How are endocrine signals similar to neurotransmitters?Some molecules, such as epinephrine, serve as both neurotransmitters and endocrine signals;some specialized nerve cells called neurosecretory cells are located in the endocrine glands and secrete hormones into the bloodstream.
18 HormonesHormones, the most common class of signal molecule used by endocrine glands, affect every cell in the body. How is it possible that very diverse types of cells can respond to these signals?While some hormones require surface receptors, most hormones because they are small and non-polar, can pass through the cell membranes without a channel or receptor and proceed directly to a receptor in the cytoplasm or go into the nucleus to act as a gene activator.
19 Trophic HormonesSome endocrine signals target other glands, stimulating them to secrete their own signals. What is this type of domino effect called?These signals are called trophic hormones.
21 Parathyroid (PTH)-Increase Ca+ Metabolism (throxine)-metabolism, (calcitonin) decrease Ca+Parathyroid (PTH)-Increase Ca+A dramatic drop in calcium would cause convulsive contractions of skeletal musclesAdrenal Glands (top of kidneys)- fight or flightMedullanorepinephrine and epinephrine increase metabolism, increase glucose (breakdown of glycogen)& pressure-Cortex- increase glucose, reabsorption of k+, Na+