VPHY 3100: Week of 11/30
VPHY 3100: Week of 11/30 VPHY 3100
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This 7 page Class Notes was uploaded by Lorin Crear on Saturday December 5, 2015. The Class Notes belongs to VPHY 3100 at University of Georgia taught by Dr. Li, Dr. Wells, Dr. Brown in Summer 2015. Since its upload, it has received 65 views. For similar materials see Elements of Physiology in Animal Science and Zoology at University of Georgia.
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Date Created: 12/05/15
Chapter 19 Metabolism o Interconversion of Energy Substrates o Absorptive stage anabolic I Excess glucose 9 glycogenesis in liver and skeletal muscles 0 Excess glucose after full glycogenesis 9 lipogenesis I Excess fatty acids 9 lipogenesis I Excess amino acids 9 protein synthesis 0 Postabsorptive stage 4 hours post meal catabolic I Glycogenolysis lipolysis and protein degradation 0 Short term and long term starvation states 18 hours post meal I Gluconeogenesis 0 Formation of glucose from amino acids glycerol lactate etc I Ketogenesis 0 Formation of ketone bodies from lipids 0 Production of energy ATP I Glycolysis I Kreb s cycle aka citric acid cycle 0 Energy Regulation by Islet of Langerhans o Islets of Langerhans I Portions of pancreas I B cells 60 secrete insulin 0 In response to increased blood glucose 0 Glucose binds to GLUT2 receptors in B cells 9 insulin secretion 9 glucose enters cells by facilitated diffusion 0 Normal fasting glucose concentration 65100 mgdL 0 Oral Glucose Tolerance Test I Blood samples taken periodically after drinking glucose solution I Blood glucose should return to normal after 2 hrs I Test measures 0 Insulin resistance 0 Insulin secretion 0 Type 1 Diabetes Mellitus o Aka juvenileonset DM 0 Autoimmunity possible caused by virus 0 Killer T cells begin to target 8 cells 0 Hyperglycemia caused by lack of insulin high glucagoninsulin ratio 0 Type 2 Diabetes Mellitus 0 Cellular resistance to insulin though 8 cells continue secretion 0 95 of diabetes patients mostly midage and overweight 0 Treatment change in lifestyle I Diet hypothesis more unsaturated fats 9 increased cell membrane uidity 9 increased of insulin receptors 0 Reactive hypoglycemia in Oral Glucose Tolerance Test I Tissues respond slowlyinadequately to insulin so 8 cells overcompensate 9 hypoglycemia I Causes shivering sweating restlessness possibly coma I A cells 25 secrete glucagon 0 In response to decreased blood glucose I A cells secrete somatostatin 0 Regulation of Insulin and Glucagon I Autonomic nerves 0 Sympathetic effect 9 increased glucagon stress hyperglycemia 0 Parasympathetic effect 9 increased insulin I Hormones 0 GIP gastric inhibitory peptide 9 increased insulin decreased gastric motility o Activated by contact between chyme and mucosa explains why ingestion produces more insulin secretion than injection of glucose 0 CCK cholecystokinin 9 increased insulin increased pancreatic enzymes 0 Metabolism and Hormones o Adrenal hormones I Medulla 0 Secretes epinephrine and norepinephrine 0 In response to shortterm stress fight or ight when CNS and skeletal muscles need increased glucose I Cortex 0 Secretes corticosteroids 0 Stimulated by ACTH in response to longterm stress 0 Thyroid hormones I T4 0 T3 is active form 0 Calorigenic effects increased metabolic heat and cold adaption 0 Protein synthesis and growth of skeleton I Hypothyroidism 0 Cretinism stunted physical and mental growth is symptom 0 Growth Hormone I Secretion controlled by somatostatin GHIH and GHRH I Anabolic increased protein synthesis I Catabolic increased lipolysis I Diabetogenic decreased glycolysis 9 hyperglycemia I Abnormalities can lead to gigantism dwarfism and acromegaly 0 Calcium and Phosphate 0 Sources of plasma Ca2 and P043quot I Bone formation and resorption Bone stores Ca2 and PO4339 Osteoblasts participate in bone formation Ca2 from blood to bone Osteoclasts participate in bone resorption Ca2 from bone to blood I Intestinal absorption and urinary excretion 0 Regulation of Ca2 and PO4339 Balance I Parathyroid hormone PTH Increases blood Ca2 Most important for blood Ca2 regulation Stimulates bone resorption and renal reabsorption Oversecretion 9 osteoporosis lower bone density I 125dihydroxyvitamin D3 aka OH2 Vit D3 Formed in liver and kidney Sunlight stimulates formation Increases intestinal absorption bone resorption and renal reabsorption I Calcitonin Secreted by parafollicular cells of thyroid Lowers plasma Ca2 Reduces bone resorption Reduces renal reabsorption Used as nasal spray to treat osteoporosis I Estrogen Chapter 20 Reproduction 0 Reproduction Causes epiphyseal disc cartilaginous growth plates to seal stopping bone growth Necessary for proper bone mineralization and prevention of osteoporosis 0 Not secreted by postmenopausal women explains higher prevalence of osteoporosis Stimulates osteoblast Suppresses formation of osteoclasts 0 Means of transmitting genetic code to next generation 0 Sexual reproduction I Genes from two individuals combined randomly to produce new individual I Fertilization germ cells gametes combine 9 zygote I Zygote 9 embryo 9 fetus 0 Sex 0 Genetic chromosomal sex I Determined by sperm cell 0 XY male 0 XX female I X and Y chromosomes 0 Y much smaller than X 0 Y has testisspecific genes 0 Barr body 0 One X chromosome of female is randomly inactivated in each cell and remains inactive throughout lifetime 0 Gonadal sex I Gonads remain indifferent until day 40 of conception in human fetus I Sexdetermining region in Y chromosome SRY 0 Encodes testisdetermining factor TDF o TDF is transcription factor 0 Determines gonadal sex of individual 0 Induces formation of testes in males 0 Formation of testis 0 Development of testis I Seminiferous tubules form day 4350 0 Made of o Germinal cells sperm 0 Sertoli cells I Leydig cells 0 Secrete testosterone o Masculinizes embryonic structures 0 Testosterone secretion decreases again until puberty 0 Absence of SRY absence of TDF gonads develop into ovaries o Phenotypic sex I Mullerian inhibition factor MIF MIH or AMH 0 Secreted in males by Sertoli cells 0 Causes regression of Mullerian ducts 0 Absent in females 0 Mullerian ducts develop into uterus and uterine tubes I Testosterone o In males 0 Causes growth and development of Wolffian ducts into male accessory sex organs epididymis vas deferens seminal vesicles and ejaculatory duct 0 Dihydrotestosterone DHT I Produced from testosterone I Controls development of penis scrotum and prostate o In females 0 Wolffian ducts degenerate due to absence of testosterone o Accessory sex organs develop as result of absence of testes I External genitalia 0 Same in males and females during first 6 weeks 0 Develop in male due to testicular secretions 0 Develop in females in absence of testicular secretions o Disorders of Embryonic Sexual Development I True hermaphroditism 0 Very rare 0 Presence of both ovary and testes in body 0 Due to defective SRY 9 TDF production in only some cells I Female pseudohermaphroditism 0 Congenital adrenal hyperplasia 9 increased androgen production 9 male genitalia 0 No MIF so female internal genitalia remains I Male pseudohermaphroditism 0 Testicular feminization syndrome 0 No androgen receptor 9 female external genitalia but vagina not fully developed internally 0 Lack of 51reductase to convert testosterone into DHT 0 male internal genitalia o Ambiguous external genitalia 0 Endocrine Regulation of Reproduction o Hypothalamicpituitarygonadal axis I Hypothalamus releases GnRH into portal vessels I Anterior pituitary secretes gonadotropins o Luteinizing hormone LH amp folliclestimulating hormone FSH o Stimulation of spermatogenesis and oogenesis o Stimulation of gonadal hormone secretion 0 Maintenance of gonadal structure 0 Pulsatile secretion I Gonads 0 Male sex steroids androgens mainly testosterone 0 Female sex steroids estrogen mainly estradiol E2 amp progestogens mainly progesterone P4 0 Peptides including inhibin I Negative feedback loop 0 Sex steroids decrease LH amp FSH secretion 0 Inhibin decreases FSH o Onset of Puberty I In humans and primates 0 Brain maturational changes of GnRH neurons in hypothalamus I In rats and sheep 0 Decreases sensitivity of gonadotropins to negative feedback of sex steroids I Increased GnRH increased LH amp FSH increased sex steroid production of secondary sexual characteristics I Age of onset related to body fat in females 0 Leptin secretion by adipocytes required for onset 0 Too much exercise or stress may inhibit GnRH secretion I Secondary sexual characteristics 0 Females growth spurt breast development menarche first menstrual ow 0 Males occurs later than females growth of penis testis body amp muscle 0 Both body hair growth stimulated by androgens secreted from adrenal gland 0 Male Reproductive System 0 Structure of testis I Seminiferous tubules 0 Germinal epithelium for spermatogenesis 0 Sertoli cells secrete inhibin contain FSH receptors 0 Forms bloodtestes barrier I Tightly joined by gap junctions I Prevents autoimmune destruction of sperm 0 Phagocytosis in spermiogenesis o Secretes androgenbinding protein ABP I Binds and concentrates testosterone in tubules I Leydig cells 0 Secrete testosterone contain LH receptors 0 Function of testes I Production of testosterone o Anabolic effects 0 Initiation amp maintenance of puberty changes 0 Stimulates growth of bone muscle and larynx 0 Promotion of erythropoiesis hemoglobin synthesis 0 Behavior 0 Arousal amp aggression excessive testosterone 0 Spermatogenesis 0 Production of spermatozoa 0 Process I Spermatogonia replicate by mitosis to form primary spermatocytes I Primary spermatocytes undergo meiosis 0 1st division 9 2 secondary spermatocytes diploid 0 2nd division 9 4 spermatids haploid I Spermiogenesis O 0 Maturation of spermatid to spermatozoa o Phagocytosis of cytoplasm by Sertoli cells cytoplasm of spermatid eliminated Regulated by testosterone during meiosis amp early stage of sperm maturation Regulated by FSH for later stage of spermatid maturation FSH binds to receptors on Sertoli cells 9 increased LH receptors on Leydig cells 9 increased responsiveness to LH 9 increased testosterone production Sperm moves closer to center of seminiferous tubule as it matures 0 Male Accessory Sex Organs Epididymis 0 Site of maturation and storage of sperm 0 Sperm gains motility as well as resistance to pH and temperature changes Ductus deferens aka Vas deferens 0 Carry sperm from epididymis to pelvic cavity Seminal vesicles 0 Secrete uid containing fructose composes 4580 of semen 0 Secrete prostaglandins Prostate gland 0 Secretes alkaline uid composes 1530 of semen Semen spermatozoa uid from prostate and seminal vesicles 0 Erection Emission Ejaculation Erection 0 Controlled by cerebellum hypothalamus sacral region of spinal cord 0 Parasympathetic stimulation of erectile tissues Emission O O 0 Increased blood ow to erectile tissues amp partial constriction of out ow Nitric oxide neurotransmitter activates guanylate cyclase enzyme 9 production of cGMP 9 closure of Ca2 channels 9 smooth muscle relaxation 9 vasodilation 9 erection Viagra inhibits phosphodiesterase Which breaks down cGMP 0 Movement of semen into urethra 0 Controlled by sympathetic stimulation Ejaculation o Expulsion of semen from urethra out of penis 0 Sympathetic stimulation 9 contraction of testes seminal vesicles prostate and tubular smooth muscle