Topic 8: Endocrine System (HL) Flashcards
8.1.1. Label the location of the major endocrine organs in the human body (brain)
- Hypothalamus
- Pineal Gland
- Pituitary Gland (anterior & posterior)
8.1.1. Label the location of the major endocrine organs in the human body (neck)
Thyroid
8.1.1. Label the location of the major endocrine organs in the human body (stomach)
Pancreas
Gonads (ovaries = women, testes = men)
8.1.1. Label the location of the major endocrine organs in the human body (above kidney)
Adrenal Glands
8.1.2. Describe the role of circulating (blood) and local hormones
Local hormones - Become active without entering bloodstream. Act locally on the same cell that secreted them or on neighboring cells
Circulating hormones - enter the bloodstream to be transported to their target cell
8.1.3. Explain how circulating hormone levels are regulated
Negative Feedback Loop:
- A regulatory mechanism in which a ‘stimulus’ causes an opposite ‘output’ in order to maintain an ideal level of whatever is being regulated.
8.1.4. Explain the relationship between the hypothalamus and the pituitary gland
- The hypothalamus and pituitary gland maintain homeostasis.
- The hypothalamus controls the pituitary gland, located below it in the brain.
- Neurohormones (e.g., GHRH, somatostatin) and nerve impulses from the hypothalamus stimulate the pituitary.
- The pituitary secretes hormones like ADH and GH, regulating growth, water balance, and temperature
What are hormones?
- Chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ
- They coordinate and regulate a range of bodily functions
- Target specific cells must have specific membrane or intracellular receptors that hormones can bind
Hypothalamus
- vital link between the endocrine and nervous system
- controlling hormone release from the pituitary gland to maintain bodily functions and homeostasis
- produces releasing and inhibiting hormones that regulate the production of other hormones
- secretes ADH and oxytocin, stored in the pituitary gland
Pituitary gland
Anterior pituitary:
- receives signalling molecules from hypothalamus –> synthesizes and secretes seven hormones.
Posterior pituitary:
- doesn’t produce any hormones on its own
- stores and secretes ADH and oxytocin
Anti-diuretic hormone (ADH)
increases water absorption into the blood by the kidneys
Oxytocin
Involved in a variety of processes, such as body temperature, sleep cycles, and the release of breast milk
Pineal gland
- Produces melatonin, which modulates sleep patterns.
- Melatonin production is stimulated by darkness and inhibited by light.
Thyroid gland
- Regulates metabolism, protein production, and hormone sensitivity by producing thyroid hormone, the principal ones are T3, T4, and calcitonin.
- Its hormone output is controlled by the anterior pituitary and hypothalamus.
Parathyroid gland
- Located on the back of the thyroid gland
- Maintain calcium levels for proper nervous and muscular function by producing parathyroid hormone (PTH), which raises blood calcium levels.
Adrenal Glands
- Located on top of the kidneys
- Regulate kidney function, metabolism, stress response, and sex hormone levels
- Release epinephrine and norepinephrine for short-term stress (fight-or-flight) and cortisol for long-term stress.
Pancreas
The pancreas has endocrine cells:
- beta cells secrete insulin to lower blood glucose
- alpha cells secrete glucagon to raise it
- Insufficient insulin production or response leads to diabetes.
The male and female gonads (ovaries and testes)
- Testes produce testosterone for spermatogenesis and male secondary sex characteristics.
- Ovaries secrete estrogen for female secondary sex characteristics and reproductive organ maintenance, and progesterone for menstrual cycle changes.
- Ovaries also produce testosterone, albeit in smaller amounts than males.
Example of a negative feedback loop in the body
Pancrease maintaining blood sugar level:
- beta cells release insulin
- adipose cell takes up glucose, exercising = decrease blood sugar
- alpha cells release glucagon
- liver breaks down glycogen to glucose, eating = increase blood sugar
Example of Positive Feedback Loop
less common, during childbirth:
- baby push against cervix
- nerve impulse from cervix sent to brain
- brain stimulates pituary gland to secrete oxytocin
- oxytocin carried via bloodstream to uterus
- oxytocin stimulates uterine contraction, pushes baby to cervix
Which of these hormones are stored and secreted by the posterior pituitary?
A. GHIH and GHRH
B. Oxytocin and ADH
C. Adrenaline and testosterone
D. Prolactin and GH
B.
Oxytocin and ADH
The posterior pituitary doesn’t produce any hormones on its own, rather, it stores and secretes two hormones made in the hypothalamus (oxytocin and ADH)
Sustained and intense exercise has the following effect…
A. Increases adrenaline and cortisol production.
B. Decreases adrenaline and cortisol production.
C. Neutral effect on adrenaline and cortisol production
D. Adrenaline goes down but cortisol production increases.
A.
Increases adrenaline and cortisol production.
Complete this sentence
Hormones affect only specific ____ ____ by (chemically) binding to specific receptors.
Hormones affect only specific target cells by (chemically) binding to specific receptors.
What is homeostasis?
the body’s attempt to adjust to a fluctuating environment
