Unit 7 Part 7 and 8 - Screencasts Flashcards
What hormone defends against hypocalcemia and through which mechanisms does it act?
a) Calcitonin; increases calcium excretion
b) Parathyroid hormone (PTH); increases gut absorption, renal reabsorption, and bone resorption
c) Vitamin D3; reduces calcium absorption
d) Estradiol; suppresses calcium uptake
b) Parathyroid hormone (PTH); increases gut absorption, renal reabsorption, and bone resorption
Explanation: PTH is secreted in response to low calcium and acts on intestines, kidneys, and bone to restore calcium levels.
Where is the majority of the body’s calcium stored?
a) Cytosol of cells
b) Mitochondria
c) Extracellular fluid
d) Bone and teeth
d) Bone and teeth
Explanation: 99% of the body’s calcium is stored in bones and teeth, acting as a long-term reservoir.
What condition results from excessive growth hormone after growth plate closure?
a) Acromegaly
b) Dwarfism
c) Gigantism
d) Hypothyroidism
a) Acromegaly
Explanation: Acromegaly occurs when GH is overproduced in adulthood, leading to growth of hands, jaw, and other soft tissues.
Which hormone enhances calcium absorption in the gut and works collaboratively with PTH?
a) Vitamin D3 (calcitriol)
b) Insulin
c) Calcitonin
d) Growth hormone
a) Vitamin D3 (calcitriol)
Explanation: Vitamin D3 increases calcium absorption in the gut and reabsorption in the kidney, and helps mobilize bone calcium.
Which cell type is responsible for bone resorption?
a) Osteoblasts
b) Osteocytes
c) Osteoclasts
d) Chondrocytes
c) Osteoclasts
Explanation: Osteoclasts are large multinucleate cells that break down bone matrix, releasing calcium into the bloodstream.
What does T3, the active thyroid hormone, do at the cellular level?
a) Binds to membrane receptors to trigger second messenger cascades
b) Acts at the nuclear receptor to regulate gene transcription
c) Stimulates G protein-coupled receptor signaling
d) Inhibits calcium reabsorption in the kidneys
b) Acts at the nuclear receptor to regulate gene transcription
Explanation: T3 binds to nuclear receptors and modulates gene expression, similar to steroid hormones.
How does growth hormone (GH) influence blood glucose levels?
a) Decreases blood glucose by promoting uptake into muscle
b) Has no effect on blood glucose
c) Increases blood glucose indirectly through gluconeogenesis
d) Blocks cortisol to reduce glucose
c) Increases blood glucose indirectly through gluconeogenesis
Explanation: GH increases blood glucose and promotes fat breakdown, making it anti-insulin with respect to glucose and fat.
What hormone stimulates the production of IGFs in the liver?
a) Cortisol
b) Parathyroid hormone (PTH)
c) TSH
d) Growth hormone (GH)
d) Growth hormone (GH)
Explanation: GH stimulates liver to produce insulin-like growth factors (IGFs), which mediate many of GH’s growth-promoting effects.
