quizzy poo Flashcards
Know that the hypothalamus controls hormonal secretions by the anterior and posterior pituitary.
-Hypothalamus is link between endocrine system and nervous system
-Understand that the hypothalamus controls hormone secretion by the
anterior and posterior lobes
of the pituitary gland, and that
hormones secreted by the
pituitary gland control growth,
developmental changes,
reproduction, and homeostasis.
TSH
- TSH (thryoid-stimulating hormone): Targets cells of the thyroid to make and secrete thyroxine
HGH
- Growth hormone: Targets cells throughout the body; stimulates mitosis
-acts directly on adipose tissue (reduces adipose cells)
-acts indirectly on muscles/ bones (increases mass/ growth) - does this by activating IGF (insulin growth factor) in liver; IGF increases bone growth and muscle mass
-short half life, small, naturally occuring
Oxytocin
- Oxytocin: Produced in neurosecretory cells in hypothalamus but stored in/ secreted from posterior pituitary; Targets cells of the uterine muscles and mammary glands, causing contractions (for birth) and milk secretion (note that nursing then causes oxytocin to be released to allow milk to be secreted too)
FSH
- FSH (follice-stimulating hormone): Targets cells of the gonads in males and females. In males causes meiotic divisions to produce spermatocytes. In females it causes maturation of an oocyte.
Prolactin
- Prolactin: Targets cells of the mammary glands causing them to grow and produce milk
LH
- LH (luteinizing hormone): Targets cells of the gonads in males and females. In males it causes Leydig cells to make and secrete testosterone (for sperm production). In females, it causes ovulation of an oocyte.
Compare and contrast hormonal and nervous communication (in the body). (CONTRAST)
Hormones
- Chemical (messenger)
Messenger (hormones) transported in blood
Slower
Carried throughout body
Wide range of organs/ tissues affected
Long-term/ persistent response (usually)
Nerves
Electrical (nerve impulse)
Signal transported by neurons
Faster
Carried to single/ specific cell/ muscle fibre
Only muscles/ glands receive signals
Short-term/ short-lived response
Explain the role of melatonin in circadian rhythms.
-Melatonin: produced in pineal gland of brain in response to changes in light.
-Function – Controls/regulates 24-hr circadian rhythm/ biological clock (the body’s physiological responses to the 24-hour day-night cycle of activity).
Melatonin affects sleep-wake cycles and
seasonal reproduction
-Promotes sleep in diurnal animals (like us)
-Promotes activity in nocturnal animals
-As we age, melatonin levels naturally decrease
-Production/ amount of melatonin secreted is controlled by amount of light detected by the retina.
Compare and contrast steroid and peptide hormones (with regard to structure, mode of action, and effect). (compare)
Both
Act on target cells/ organs
Travel through the bloodstream
Effective at very low concentrations
Effects last longer than neurotransmitters
Compare and contrast steroid and peptide hormones (with regard to structure, mode of action, and effect). (pep)
Peptide
- Amino acids (proteins/ water soluble/ polar)
-Do not enter target cells because they cannot pass through plasma membrane, so they bind to receptors on plasma membrane
-Binding of hormones to receptors activates a chain of reactions, carried out by secondary messengers in cytoplasm (such as cAMP), which activates or inhibits enzymes/changes cell’s physiology such as protein kinase in cell.
-ATP is needed
Explain the role of thyroxin and the causes and consequences of thyroxin deficiency.
-thyroxin contains iodine
-prolonged deficiency to iodine causes lack of thyroxin in body
- iodine deficiency causes the thyroid gland to become enlarged (trying to compensate for iodine deficiency), resulting in a disease known as goitre
not enough thyroxin
= hypothyrodism:
Some of the symptoms are weight gain, loss of energy, feeling cold all the time, forgetfulness and depression, stunted growth, stunted mental development
too much thyroxin
= hyperthyrodism:
Some of the symptoms include excessive sweating/ hunger, hyperactivity, mood swings, rapid heart rate, difficulty sleeping, weight loss, muscle weakness/ tremors
ADH
- ADH (Antidiuretic hormone): Targets cells of the kidney, increasing the amount of water that is reabsorbed into the blood
Compare and contrast steroid and peptide hormones (with regard to structure, mode of action, and effect). (STEROID)
Steroid
- Cholesterol (lipid soluble/ nonpolar)
-Pass through plasma membrane of target cells (steroids are small and hydrophobic.
- Hormones bind to receptor proteins and form a receptor-hormone complex - these receptor proteins are often gene regulatory proteins
-Receptor hormone complex moves into nucleus, and regulates gene expression/acts directly on dna/ binds to it which promotes or inhibits transcription of specific genes, drastically altering biochemistry of cell
-Does not require use of ATP
Explain the roles of the hypothalamus thermoregulation.
body temp too low
-hypothermia (<32C)
-Hypothalamus releases chemical signals that trigger:
Vasoconstriction (arterioles get smaller, blood is diverted to deep tissues/ organs, less heat loss)
Shivering of skeletal muscle (generates heat)
“Goosebumps” – raises hair follicles on skin (traps heat/ insulates against heat loss)
body temp too high
-Hyperthermia (>40C)
-Hypothalamus releases chemical signals that trigger:
-Vasodilation (arterioles get bigger, fill with blood, transfer heat to skin and out of body)
Increased sweat gland activity (evaporative cooling)
