Wk 7: Human Anatomy & Physiology

  1. Sympathetic v Parasympathetic nervous system
    • SNS: fight or flight response, relax lungs, dilate eyes
    • PNS: rest and digestion, vagal nerve & vagal tone often considered, slows heartbeat
  2. ANS neurotransmitters
    • Acetylcholine (ACh)
    • Epinephrine & Norepinephrine: adrenergic receptors (alpha and beta), alpha adrenergic receptors located in vasculature, GI tract.
    • Beta adrenergic receptors located in heat, salivary glands, smooth muscle, and adipose tissues.

    • Not: in addition to release from adrenal glands, SNS also triggers release of norepinephrine from nerve terminal with some spill over.
    • Wide ranging location of receptors allow wide ranging effects of ANS.
  3. Hormones
    • Blood borne chemical messengers
    • Produced by endocrine glands and other organs and cells (eg heart, immune cells)
    • Act on target tissues with specific hormone receptors
  4. 3 broad categories of hormones
    • Steroid hormones: synthesised from cholesterol. Carried by protein. Long lasting effects. Long half life.
    • Adrenal cortex hormones: glucocorticoid (cortisol) and aldosterone
    • Gonadal hormones
    • Protein hormones: chains of amino acids
    • Short= thyrotropin releasing hormone (TRH)
    • Long= growth hormone (GH)
    • Amines: derivatives of amino acids
    • Catecholamines: epinephrine (E), Norepinephrine (NE). High impact but tend to be short lived
    • Thyroid hormone
  5. Hormone production is regulated by
    • Circadian rhythms: 24 hour rhythm guided by internal clock and by external cues
    • Negative feedback: hormone inhibits release of its releasing factor. Stops release of itself at some point
  6. Hypothalamic-pituitary-adrenal (HPA) axis
    • Hypothalamus (brain- pituitary (brain)- adrenal gland (torso)
    • Activated in response to stress and results in the release of glucocorticoids that serve to regulate the physiological stress response.
    • A way of shutting down stress process.
    • Hormonally mediated activity, so slower than neurally mediated stress responses.
  7. HPA: hypothalamus
    H secretes releasing and inhibiting factors:-corticotrophin releasing hormone (CRH): produced by neurons in paraventrivular nucleus of hypathalamus. Acts as neurotransmitter and neuropeptide.Luteinizing hormone releasing hormone (LHRH)Thyrotopin releasing hormone (TRH)Growth hormone releasing hormone (GHRH)Growth hormone inhibiting factor (GHIF)Dopamine
  8. HPA: pituitary gland
    • Separated into anterior and posterior
    • Posterior pituitary:
    • Oxytocin: milk ejection, uterine contractions during labor
    • Role in bonding
    • Vasopressin: antidiuretic hormone

    • Anterior pituitary:
    • Connected to hypothalamus via system of blood vessels known as hypothalamic-hypophyseal portal system.
    • Adrenocorticotrophic hormone (ACTH): secreted by corticotrophs; derived from POMC, cleaved by CRH into ACTH, beta endorphin and other peptides

    CRH turns the other molecules into something else like ACTH
  9. HPA: adrenal glands
    • Adrenal medulla: secretes epinephrine and norepinephrine (catecholamines) (relevant to SNS)
    • Adrenal cortex: secretes glucocorticoids, mineralocorticoids, and sex steroids (relevant to HPA)
  10. Cortisol
    • Up to 95% of secreted cortisol is bound to large proteins including corticosteroid binding globulin (CBG) and albunim, and carried in the body through the blood. (needs to be unbound for it to work)
    • Enters all tissues: passes through parotid gland to saliva; through kidney to urine and through blood-brain barrier.
    • Salivary cortisol is unbound (biologically active)
    • Adrenal steroids have receptors in every nucleated cell:
    • -MR (stronger affinity) compared to GR (low affinity)
    • After binding, receptors moves into  nucleus and regulate gene expression
  11. Cortisol two families of functions
    • 1. Metabolic and diurnal functions (sleep, metabolism). Highest wake up then going down, spikes after food
    • Driven by signal and hypothalamus
    • Highly sensitive to negative  feedback control
    • 2. Stress functions: secretion enhanced by input from amygdala
    • Negative feedback less effective

    • During stress, numerous effects:
    • Permissive: GCs present before stressor, prime response
    • Stimulating: Increases in GCs enhance effects of first wave hormone response
    • Suppressive: increase in GCs rein in stress-induced defense reactions
    • Preparative: modulate response to subsequent stressor.
    • Enhance SNS effects on cardiovascular stress response
    • Increase circulating glucose
    • Overall suppress immune response, but permissive on initial activation

    Acts as a break
  12. Cortisol negative feedback loop
    • Hippocampus activates hypothalamus which releases CRF, goes to anterior pituitary to release ACTH, goes to adrenal cortex and releases cortisol. 
    • Cortisol in addition to effects on tissues, also has negative impact on anterior pituitary and hypothalamus.
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  13. HPA axis is measured via
    • Wake level and before sleep. (If slope flat, due to constant stress)
    • Average 24 sample
    • Urine: accumulation of cortisol in urine

    • Total daily cortisol
    • Overnight/24 hour cortisol
    • Diurnal cortisol rhythm
    • Morning rise
    • Response to acute stress
    • Sensitivity tests
    • -> dexamethane (synthetic glucocorticoid) give it to them, see what happens when give cortisol
    • -> how much less cytokines blood releases when GC is added.
  14. Immune system
    • The immune system generally serves to:
    • Discriminate self from non-self
    • Destroy and clear foreign substances
    • Ignore self, possibly destroy altered self (tumor cells)

    • Antigen= any substance that can be identified by the immune system
    • Pathogen: microorganisms that can cause disease when they enter the host
    • Phagocytosis: ingestion of matter by cells
  15. Innate vs adaptive immune response
    • Innate: Fast, non specific. Phagocytosis, inflammation
    • Adaptive: slow, specific. Recognised by B and T cells
  16. White blood cells (WBCs)
    • Also known as leukocytes
    • 3 types
    • 1. Granulocytes:
    • Neutrophils: 50-70% of circulating WBC. Phagocytosis and activation of bacterial mechanisms.
    • Eosinophils: 1-3% killing antibody-coated parasites.
    • Basophils = <1%% of circulating WBC
    • 2. Monocytes 1-6% of circulating WBC
    • Early immune response including phagocytosis and antigen presentation.
    • Macrophages are mature monocytes in tissue
    • Dendritic cell: antigen uptake in peripheral sites. Antigen presentation in lymph nodes
    • 3. Lymphocytes:
    • 1. Natural killer (NK) cells= 5-10% of lymphocytes: plays role in innate immunity against virally infected cells
    • B cells= 10-15% of lymphocytes
    • T cells= 75-80% lymphocytes
    • Helper T cells (CD4)
    • Cytotoxic T cells (CD8) kills the bacteria
    • Called t cells because produced in thymus
  17. Inflammation: Cytokines
    • Immune cells communicate with each other and with other cells by releasing soluble proteins called cytokines.
    • Many different types of cytokines, produced by many different types of cells, with wide variety of biological effects, target cells, receptors, and molecular structures.
    • Produced during innate and adaptive immune responses, serve to mediate and regulate immune and inflammatory responses
    • Generally, cytokines are produced briefly and locally, in a self limiting manner.
  18. Cytokines conitued
    • Cytokines are extremely potent, activity needs to be carefully regulated
    • Typically produced rapidly and have short half life, inherently limiting effects
    • Activity is modulated by:
    • Receptor antagonists
    • Cytokine binding serum proteins and/or soluble receptors
    • Other cytokines with antagonistic effecrs
    • Cytokine receptor expression.
Card Set
Wk 7: Human Anatomy & Physiology
Wk 7: Human Anatomy & Physiology