Keeping Balance
The body’s ability to keep a stable internal environment
Homeostasis (Ch 1)
Smallest to largest: organ, cell, atom, tissue, organ system
Atom → cell → tissue → organ → organ system (Ch 1)
I make ATP using oxygen; I’m the “powerhouse of the cell”
Mitochondria (Ch 3)
The pH of a neutral solution like pure water
7 (Ch 2)
After 6 weeks in a cast, a patient’s calf muscle has shrunk. What’s this called?
(Disuse) atrophy; it’s reversible once he uses the muscle again (Ch 6)
You shiver when you’re cold. Which tissue makes the heat, and is this positive or negative feedback?
Skeletal muscle (makes ~75% of body heat); negative feedback (Ch 1, 6)
Starting from the heart, put in order: veins, capillaries, arteries, venules, arterioles
Arteries → arterioles → capillaries → venules → veins (Ch 11)
I connect bone to bone
Ligament (Ch 5)
A resting heart rate above this is tachycardia; below this is bradycardia
Above 100 bpm; below 60 bpm (Ch 11)
A hiker on a 14er is short of breath even though the air is still about 21% oxygen. Which survival need is the problem?
Atmospheric pressure (Ch 1)
Chemicals that resist big pH swings by grabbing or releasing H⁺
Buffers (e.g., bicarbonate) (Ch 2)
Most to least numerous in blood: WBCs, RBCs, platelets
RBCs → platelets → WBCs (Ch 10)
I’m a cell junction that lets ions flow straight from one cell to the next, so heart cells contract as one unit
Gap junction (Ch 3, 11)
How long a red blood cell lives
About 120 days (Ch 10)
A baby born at 28 weeks has alveoli that collapse after every breath. What substance is missing, and which cells make it?
Surfactant; alveolar cells (Ch 13)
A construction worker collapses in July with a core temperature of 41°C (106°F). Which survival need is off, and what happens to his enzymes?
Normal body temperature; enzymes (proteins) denature and reactions stop (Ch 1, 2)
Outside to inside: endomysium, epimysium, perimysium
Epimysium → perimysium → endomysium (Ch 6)
I’m a giant cell in red bone marrow, and I break apart into platelets
Megakaryocyte (Ch 10)
Blood leaving resting tissues is still about this % saturated with O₂
About 75% (Ch 13)
Pregnant patients are told to take folate (vitamin B9) to help prevent this birth defect. Name it and what fails to close
Spina bifida; the neural tube (Ch 7)
Blood calcium is too HIGH. Name the gland, the hormone, and what it does to osteoclasts and osteoblasts
Thyroid; calcitonin; it inhibits osteoclasts and stimulates osteoblasts, so blood Ca²⁺ falls (Ch 5)
Bone remodeling: put in order (formation, activation, reversal, resorption)
Activation → resorption → reversal → formation (Ch 5)
I’m a CNS glial cell that anchors neurons to capillaries and helps form the blood–brain barrier
Astrocyte (Ch 7)
Classify each blood pressure: 116/74, 126/78, 142/92
Normal; elevated; stage 2 hypertension (Ch 11)
An asthma attack can nearly shut the bronchioles but not the trachea. Why?
Bronchioles have no cartilage rings, so smooth muscle spasms can squeeze them shut; the trachea is held open by C-shaped hyaline cartilage (Ch 13)