Section VIII. Section VIII. Tissue metabolism Many tissues carry out specialized functions: Ch. 43 – look at different hormones affect metabolism of fuels, especially counter-insulin Ch. 44 – Proteins and cells of the blood Ch. 45 – Hemostasis and the clotting cascade
Section VIII. Section VIII. Tissue metabolism Many tissues carry out specialized functions: Ch. 43 – look at different hormones affect metabolism of fuels, especially counter-insulin Ch. 44 – Proteins and cells of the blood Ch. 45 – Hemostasis and the clotting cascade. Chapt. 43. - PowerPoint PPT Presentation
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Section VIII.
Section VIII. Tissue metabolism
Many tissues carry out specialized functions:
Ch. 43 – look at different hormones affect metabolism of fuels, especially counter-insulin
Ch. 44 – Proteins and cells of the blood
Ch. 45 – Hemostasis and the clotting cascade
Chapt. 43
Ch. 43 hormone regulationStudent Learning Outcomes:• Describe the role of hormones in regulating fuel
metabolism – appetite, absorption, transport, oxidation• Explain the main functions of insulin• Explain the role of glucagon• Describe the role of epinephrine, cortisol,
somatostatin, growth hormone and thyroid hormone
• Describe how these hormones exert control quickly by changes in phosphorylation state of enzyme, and more slowly by changes of gene expression
• Stimulates storage of glycogen in liver, muscle• Stimulates synthesis of fatty acids and triagcylglyerols and
storage in adipose tissue• Stimulates synthesis in various tissues of >50 proteins• There are insulinlike growth factors I and II (IGF-1, IGF-II)• Paracrine action: release of insulin from -cells suppresses
secretion of glucagon from -cells.
II. GlucagonGlucagon• Major insulin counterregulatory hormone• Produced as preglucagon in cells of pancreas• 4 peptides in tandem:
Glucocorticoids (GC) have diverse effects:• bind intracellular receptors, bind DNA, induce
transcription of target genes• Fuel metabolism effects
often stimulate degradation• Also nonmetabolic effects
(Table 3)
Signal transduction by cortisol, intracellular receptors
Cortisol and thyroid hormone bind intracellular receptors:
• Binding of hormone causes hormone-receptor complex to bind specific DNA sequences, increase transcription from target genes.
Figs. 11.7,8
Thyroid hormone (TH)
E. Thyroid hormone (TH) is derived from tyrosine:
• T3 and T4 made in thyroid acinar cells• signal by binding intracellular nuclear receptors
Fig. 9
Formation of thyroid hormone
Fig. 10
Formation of thyroid hormone (TH):• Protein thyroglobulin secreted into colloid space• Iodination, coupling• Pinocytosis • Digestion by lysosomes
• ~ 10:1 T4:T3
• Synthesis stimulated byTSH in anterior pituitary
• TSH stimulates release T1/2 days in plasma
Regulation of TH levels
Fig. 11
Regulation of TH levels:• TRH = thyrotropin-releasing hormone• TSH = thyroid-stimulating hormone
• TSH binds membrane receptor, ↑cAMP• Also through IP3 + DAG, Ca2+
• T3 & T4 secreted from thyroid
• T3 inhibits release of TSH, TRH
Physiological effects thyroid hormone
Normal TH affects fuel metabolism:Liver: carbohydrate, lipid metabolism
• Increase glycolysis, cholesterol synthesis• Increase sensitivity of hepatocyte to gluconeogenic &
glycogenolyticactions of epinephrine
Adipocytes: • sensitizes adipocyte to lipolytic action of epinephrine • also increase availability of glucose to fat cells
Muscle: increase glucose uptake, stimulate protein synthesis
TH can increase heat production by stimulating ATP utilization in futile cycles (increase heat production by uncoupling)
F. GI hormones affect fuel metabolism
Fig. 12
Many GI hormones affect fuel metabolism:• Direct and indirect effects: produced by many tissues (Table 4,5)• GLP-1, glucagonlike peptide; GIP, Gastic inhibitory peptide • CCK, cholecystokinin has indirect effects
Key concepts
Key concepts:• Insulin is major anabolic hormone• Counterregulatory (counterinsulin) hormones include:
• Glucagon• Somatostatin• Growth hormone has diverse roles
• Catecholamine hormones• Cortisol (glucacorticoid) promtoes survival• Thyroid hormones secretion is highly regulated• Intestines and stomach secrete hormones (incretins)
Review question
Review question.3. A dietary deficiency of iodine will lead to which of the
following?a.A direct effect on the synthesis of thyroglobulin on
ribosomesb.An increased secretion of thyroid-stimulatory hormone
(TSH)c.Decreased production of thyrotropin-releasing hormone