The Endocrine System

Glands and Secretions
1. EXOCRINE GLANDS
  1. secrete products through a DUCT
    1. e.g sweat glands, salivary glands, pancreas, liver
2. ENDOCRINE GLANDS
  1. products secreted into the BLOOD VESSELS that pass through the gland
    1. e.g. the pituitary gland in the brain
      1. The pituitary gland found at base of brain
        produces many hormones - called controller gland
        contains neurones linking it to the hypothalamus
  2. chemicals secreted are hormones
    1. carried in blood to target organs
    2. e.g. pancreas, ovaries, testes, thyroid gland
Controlling Blood Glucose
1. stored in liver + muscle cells as insoluble carbohydrate GLYCOGEN
  1. when body is short of glucose - glycogen is broken down into glucose
2. concentration of glucose will rise after a meal
  1. as it is absorbed by small intestine
    1. glucose rich blood transported to LIVER by HEPATIC PORTAL VEIN
      1. triggers release of insulin from PANCREAS
        response to high levels of glucose
        stimulates liver cells to absorb glucose and convert to glycogen
        lowers conc. of glucose in blood
        pancreas stops making insulin
        stops liver cells making glycogen
3. How would High blood sugar levels affect cells?
  1. Kidney failure
  2. memory loss
  3. high blood pressure + high cholesterol
  4. higher risk of strokes
  5. bleeding gums
Homeostasis
1. the process where body controls its internal environment
2. 1. Internal body Temp
  1. Warm Blooded animals (endotherms) have:
    1. layer of fat beneath skin
      1. helps to insulate body
    2. fur, hair, feathers
      1. when cold hair stands up + traps a layer of air close to the skin
        poor conductor of heat reduces heat loss
  2. cold blooded animals (exotherms)
    1. varying body temp.
  3. Adaption to cold climates:
    1. shivering
      1. muscles contract and relax rapidly generating heat
    2. layer of fat
    3. fur, hair, feathers
    4. arterioles narrow (VASCONSTRICTION)
      1. reduces flow of blood to skin
        prevents heat loss
    5. erector muscles contract
      1. hairs stand on end - traps an insulating layer of air
  4. Adaptation to warm climates:
    1. lots of skin > more SA > more evaporation
    2. ridges = more SA for evaporation
    3. Sweating
    4. arterioles widen (VASODILATION)
      1. more blood flows to capillaries at surface of skin
        increases heat loss by radiation
    5. sweat glands produce more sweat
      1. energy supplied by body causes sweat to evaporate
        cooling body down
  5. the Skin
    1. protects body from damage
    2. stops germs getting in
    3. controls water loss
    4. Senes temperature,pressure,pain
3. 2. Concentrations of waste products (CO2 + urea)
  1. CO2
    1. produced during respiration
      1. removed via lungs
  2. urea
    1. produced in liver when excess amino acids are broken down
      1. filtered out of blood by kidneys and removed in urine
        The Urinary System
        kidneys filter blood
        removing unwanted substances
        controlling conc. of water + solutes in blood
        supplied with blood through the RENAL ARTERY
        from the AORTA
        blood entering kidney is at HIGH PRESSURE
        In each kidney blood is filtered + leaves vis the RENAL VEIN
        joins the VENA CAVA
        urine produced passes out of kidneys through 2 URETERS
        stored in the bladder
        has tube leading to outside - URETHRA
        contains ring like muscles SPHINCTERS
        can contract to hold back urine
        The Kidney
        dark outer region is called the cortex
        contains many blood vessels that branch to renal artery
        contains microscopic tubes (kidney tubules or nephron)
        run down middle layer of kidney - medulla
        has bulges/pyramids pointing inward
        tubules join up and lead to tips of pyramids
        here contents drain into the pelvis
        connects with ureter carrying urine to bladder for storage
4. 3. Blood water levels
  1. Loop of Henle runs down to medulla of kidney
    1. 2nd / DISTAL CONVOLUTED TUBULE + COLLECTING DUCT help reabsorb water back into blood
      1. area of nephron controlled by ADH
      2. collecting duct attached to many nephrons + carries urine to the pelvis of kidney
5. 4. Blood glucose levels
  1. 1st convoluted tubule useful substances reabsorbed
    1. back into blood - glucose, amino acids + some water + salt
      1. Selective reabsorption - involves active transport
Osmoregulation and ADH
1. KIDNEY regulates amount of water + salts in blood - so a balance maintained between conc. of blood and surrounding tissue
  1. Drank a litre of water - kidneys would excrete a large volume of urine
    1. changes controlled by hormone ADH (anti diuretic hormone) - pituitary gland in brain
      1. If TOO MUCH WATER IN BLOOD
        detected by hypothalamus - causes pituitary to secrete less ADH
        decreasing permeability of collecting ducts - less water reabsorbed back into blood (urine more dilute)
      2. TOO LITTLE WATER
        detected by hypothalamus
        pituitary gland secretes more ADH
        travels in blood to kidneys
        causes collecting ducts in kidney to become more permeable to water - more water re absorbed back into blood
        urine more conc. + blood = dilute
        when water content is normal production of ADH stops (example of negative feedback)
Key Words
1. endocrine
  1. hormones transmitted through the bloodstream
2. hormone
  1. chemical messengers
  2. coordinate systems
  3. travel in blood - secreted by glands
  4. causes changes in how body works
3. gland
  1. secretes hormones
  2. endocrine/exocrine
4. target organ
  1. a tissue or organ effected by a hormone
5. homeostasis
  1. the state of keeping the conditions in the body relatively constant
6. glycogen
  1. made from long chains of glucose sub units
    1. joined together to produce an insoluble molecule
7. diabetes
  1. when pancreas cannot make enough insulin to keep blood glucose level constant
8. excretion
  1. process where products of metabolism are removed from body
9. osmoregulation
  1. keeping salt + water content + internal environment constant
10. nephron
  1. microscopic tubules that branch from renal artery
Hormones
1. ADH
  1. made in pituitary
    1. controls water content of blood - triggers uptake of water in kidneys (osmoregulation)
2. Adrenaline
  1. adrenal
    1. increased awareness, muscle power + heart rate - flight or fight
3. Insulin
  1. pancreas
    1. controls blood sugar levels - removes excess sugar from blood + stores it in water
4. Testosterone
  1. testes
    1. controls development of male secondary sexual characteristics
5. Progesterone
  1. ovaries
    1. regulates menstrual cycle - maintains uterus lining by suppressing (follicle stimulating hormone) production in pituitary gland
6. Oestrogen
  1. ovaries
    1. controls development of female secondary sexual characteristics
Differences between nervous + endocrine system
1. Nervous
  1. electrical impulses transmitted through nerve cells
  2. nerve impulses travel fast + instantly have effect
  3. response is short lived
  4. impulses have a localised effect - impulses act on individual cells
2. Endocrine
  1. hormones transmitted through blood stream
  2. travel more slowly, take longer to act
  3. response long lived
  4. widespread effect on diff. organs - only act on particular tissues
Kidney Failure
1. If both kidneys damages from disease or an accident possible to have transplant / dialysis
  1. machine filters patient's blood - removing wage, urea + excess salt + water
    1. made of visking tubing (partially permeable)
      1. Blood flows on one side on membrane, dialysis solution on the other
        solution of salts + glucose
        as blood flows past membrane urea + unwanted water + salts diffuse through holes into dialysis solution
        dialysis solution constantly replaced

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The Endocrine System

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