Chapter 41: Animal Hormones Flashcards
Endocrinology
study of hormones and their actions
Hormone
intercellular chemical messenger that travels within body tissue
What do hormones travel between?
endocrine cells and target cells
Endocrine cell function
produces and/or stores hormones
Target cell
contains receptor molecules that bind to hormone molecules–>activates cellular mechanisms–>hormone = “message” and the target cell responds by either activating or inhibiting enzyme-catalyzed reactions–>results in activation of gene expression or protein synthesis
What does the receptor-hormone activate?
secondary messenger systems (hormone = first messenger)
Circulating hormones
transported by the blood and bind to receptors on distant cells
Paracrine hormones
bind to receptors on nearby cells
Autocrine systems
hormones bind on cells that secrete them
Cells with no receptors
don’t respond to hormones
What do neurons secrete?
chemical neurotransmitters that bind to receptors on other cells
Local hormones
chemical message released into ECF, localized effects (paracrine, autocrine)
Histamine
hormone released by mast cells, diffuses into damaged tissue to dilate local blood vessels as part of inflammation response
Circulating hormone
a chemical message released into circulatory system with goal of reaching more distant cells
How many actions can a single hormone have?
many
Glands
organs composed of clusters of secretory cells
Exocrine glands
release secretions to outside of the body through ducts (salivary, sweat)
Endocrine glands
“ductless” glands that store and release hormones into ECF from which it may enter the body’s circulatory systems
What kind of environment does homeostasis maintain?
stable internal environment (within cells and systems)
What mediates homeostasis?
nervous and endocrine systems
what kind of regulation does homeostasis involve?
feedback regulation
what is the goal of homeostasis?
to prevent harmful fluctuations
how many endocrine glands?
9
What kinds of cells secrete hormones?
nerve cells, digestive tract cells, mast cells in tissue
Histamine
hormone released by mast cells, diffuses into damaged tissue to dilate local blood vessels as part of the inflammation response
Hypothalamus HORMONE = Release and Release-inhibiting 1. chemical nature 2. target(s) 3. Important properties or actions
- peptides
- anterior pituitary
- control secretion of hormones of anterior pituitary
Hypothalamus HORMONE = Oxytocin, antidiuretic 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptides
- Anterior pituitary
- Stored and released by posterior pituitary
Anterior pituitary: Tropic hormones HORMONE=Thyrotropin 1. chemical nature 2. target(s) 3. Important properties or actions
- Glycoprotein
- Thyroid gland
- Stimulates synthesis and secretion of thyroxine
Anterior pituitary HORMONE=Adrenocorticotropin 1. chemical nature 2. target(s) 3. Important properties or actions
- Polypeptide
- Adrenal cortex
- Stimulates release of hormones from adrenal cortex
Anterior pituitary HORMONE=Luteinizing 1. chemical nature 2. target(s) 3. Important properties or actions
- Glycoprotein
- Gonads
- Stimulates secretion of sex hormones from ovaries and testes
Anterior Pituitary HORMONE=Follicle-stimulating 1. chemical nature 2. target(s) 3. Important properties or actions
- Glycoprotein
- Gonads
- Stimulates growth and maturation of eggs in females; stimulates sperm production in males
Anterior Pituitary HORMONE=Growth 1. chemical nature 2. target(s) 3. Important properties or actions
- Protein
- Bones, liver, muscles
- stimulates protein synthesis and growth
Anterior pituitary HORMONE=Prolactin 1. chemical nature 2. target(s) 3. Important properties or actions
- Protein
- Mammary glands
- Stimulates milk production
Hormone= melanocyte-stimulating
- chemical nature
- target(s)
- Important properties or actions
- Peptide
- Melanocytes
- controls skin pigmentation
Hormone=endorphins and enkephalins
- chemical nature
- target(s)
- Important properties or actions
- Peptides
- Spinal cord neurons
- decrease painful sensations
Posterior Pituitary HORMONE=Oxytocin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Uterus, breasts
- induces birth by stimulating labor contractions; causes milk flow
Posterior Pituitary HORMONE=Antidiuretic 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Kidneys
- Stimulates water reabsorption and raises blood pressure
Thyroid HORMONE=Thyroxine 1. chemical nature 2. target(s) 3. Important properties or actions
- Iodinated amino acid derivative
- Many tissues
- stimulates and maintains metabolism necessary for normal development and growth
Thyroid HORMONE=Calcitonin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Bones
- Stimulates bone formation; lowers blood calcium
Parathyroids Thymus HORMONE=Parathormone 1. chemical nature 2. target(s) 3. Important properties or actions
- Protein
- Bones
- Stimulates bone formation; lowers blood calcium
Parathyroids Thymus HORMONE=Thymosins 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptides
- Immune system
- Activate immune responses of T cells in the lymphatic system
Pancreas HORMONE=Insulin 1. chemical nature 2. target(s) 3. Important properties or actions
- protein
- muscles, liver, fat, other tissues
- stimulates uptake and metabolism of glucose; increases conversion of glucose to glycogen and fat
Pancreas HORMONE=Glucagon 1. chemical nature 2. target(s) 3. Important properties or actions
- Protein
- Liver
- Stimulates breakdown of glycogen and raises blood sugar
Pancreas HORMONE=Somatostatin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Digestive tract; other cells of the pancreas
- Inhibits insulin and glucagon release; decreases secretion, motility, and absorption in the digestive tract
Adrenal medulla HORMONE=Epinephrine, norepinephrine 1. chemical nature 2. target(s) 3. Important properties or actions
- modified amino acids
- heart, blood vessels, liver, fat cells
- Stimulate fight-or-flight reactions; increase heart rate, redistribute blood to muscles, raise blood sugar
Adrenal cortex HORMONE=Glucocorticoids (Cortisol) 1. chemical nature 2. target(s) 3. Important properties or actions
- Steriods
- Muscles, immune system, other tissues
- Mediate response to stress; reduce metabolism of glucose; increase metabolism of proteins and fats; reduce inflammation and immune responses
Adrenal cortex HORMONE=mineralocorticoids 1. chemical nature 2. target(s) 3. Important properties or actions
- Steriods
- Kidneys
- Stimulate excretion of potassium ions and reabsorption of sodium ions
Stomach Lining HORMONE=Gastrin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Stomach
- Promotes digestion of food by stimulating release of digestive juices; stimulates stomach movements that mix food and digestive juices
Lining of small intestine secretes: HORMONE=secretin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Pancreas
- Stimulate secretion of bicarbonate solution by ducts of pancreas
Lining of small intestine HORMONE=Cholecystokinin 1. chemical nature 2. target(s) 3. Important properties or actions
- Peptide
- Pancreas, liver, gallbladder
- Stimulates secretion of digestive enzymes by pancreas and other digestive juices from liver; stimulates contractions of gallbladder and ducts
Lining of small intestine HORMONE=Enterogastrone 1. chemical nature 2. target(s) 3. Important properties or actions
- Polypeptide
- Stomach
- Inhibits digestive activities in the stomach
What feedback loops control hormone secretion?
negative feedback usually
- level of hormone in blood can exert feedback on glands responsible for its production
- internal conditions can exert feedback regulation on glands responsible for hormone production. hormone regulates particular internal condition and helps maintain homeostasis
Releasing Factors from Hypothalamus (4)?
- TRF
- GnRF
- CRF
- GRF
TRF
Thyrotropin-releasing factor
GnRF
Gonadotropin-releasing factor