Zoology 101: Animal Biology Last Lecture Outline Lecture 28 1. Endocrine system and hormones2. Anterior pituitary and other hormonesCurrent lecture 1. Stress and the body's response1. hormones 2. Immune systemStress and the body's response • Adrenal glands are adjacent to the kidney• 2 types (atop the kidney)◦ Adrenal Medulla (inner)◦ Adrenal cortex (outer) • Adrenal cortex: ◦ slower, long-term response ◦ steroid hormones: glucocorticoids and mineralcorticoids◦ Hypothalamus: corticotropin releasing hormone (CRH) → Anterior pituitary produces ACTH (adrenocorticoid) → adrenal cortex secretes mineralcorticoid or glucorticoid◦ Mineralcorticoid: increases blood volume and pressures, retention of sodium and water by kidneys ◦ Glucocorticoids: cortisol, increase blood glucose levels, breaks down fat and protein ,suppresses immune system • Factors of Long term stress: health, relationships, workplace pressures, finances ◦ Perpetual stress is the stress that wears on people continuously ◦ Animals limited to food and water availability • Why is long term stress harmful?◦ Damage to brain cells (hippocampus have many glucocorticoid receptors)◦ Increased risk of cardiovascular disease (Increased blood pressure and heart beat)◦ Problems with reproduction (decreased sex drive and sperm productions)◦ Immune system suppression • Short term stress:◦ reaction to immediate stress◦ reaction to real or perceived threats ◦ in animals, avoid predators• Adrenal Medulla: mediates fight or flight ◦ immediate signal from hypothalamus to adrenal medulla ◦ Epinephrine and norepinephrine: increase blood glucose, blood pressure, breathing rate, metabolic rate, blood for to the brain, heart and muscles. Decreases blood flow to the digestive tract, skin and kidneys◦ Enhances sympathetic nervous system • Steroid hormones regulate reproduction ◦ primarily produced by gonads (ovaries and testes)◦ 3 categories▪ androgens (testosterone), Estrogens (estradiol), progestins ▪ All found in females and males; SIGNIFIANTLY DIFFERENT PROPORTIONS ▪ Synthesism controlled by FSH and LH • Neurosecretory cell of hypothalamus receives signal → gonadotropin releasing hormone (GnRH) → leutinizing hormone (LH), follicle stimulating hormone (FSH) → steroid production release ◦ estradiol/progeterone from ovaries ◦ testosterone from testes ◦ Controlled by negative feedback • Hormones play important role in sex characteristics in birds ◦ Rooster experiment • Estrogens: Estradiol, maintain female reproduction system and development of secondary sex characteristics • Progestins: progesterone: prepare/maintain uterus in mammals • Androgens: testosterone, male reproductive system, increases muscle and bone mass; take as a supplement◦ health risks: Increased aggression and facial hair, decreased sex drive, levels of TSH, development of sleep apnea, baldness • Growth hormones (GH): normal bone development ◦ abnormal: dwarfism (too little levels of anterior pituitary hormones)◦ Normal: gigantism (high levels of anterior pituitary hormones)Immune system• defense against invaders • Pathogens are agents of disease ◦ bacteria: single celled organism ◦ virus: pathogen requires a host to produce cell◦ parasites: hosts needed for growth • Immune system responds with immune cells and proteins • All animals have innate immunity (defense active immediately upon infection)• Vertebrates have adaptive immunity • Innate ◦ rapid response to broad pathogens ◦ present at birth◦ all animals have it◦ nonspecific response to pathogens◦ external barriers, internal cellular and chemical defense ◦ 1st and 2nd line of defense • Adaptive◦ slower◦ specific microbes develop after exposure to foreign substances ◦ vertebrate only ◦ specific response to pathogens ◦ internal cellular and chemical defense ◦ 3rd line of defense• First line of defense is skin, mucus, secretions (acid/enzymes)• Second line of defense: phagocytic cells, antimicrobial proteins, inflammatory response • third line of defense: antibodies defend in body fluids, cell mediated
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