Osmoregulation
Marine bony fishes live in a ______ environment and must ______.
Hyperosmotic; excrete excess electrolytes
Aldosterone promotes:
Na⁺ reabsorption through stimulation of Na⁺/K⁺ pumps
In mammalian lungs, gas exchange occurs in the:
Alveoli
Albumin's primary function in plasma is to:
Thicken blood and help regulate osmotic pressure
Blood returning from systemic circulation enters the heart through the:
Right atrium
Which structure in insects is primarily responsible for forming the initial filtrate?
Malpighian tubules
ADH increases water reabsorption by acting on:
A. podocytes
B. PCT cells
C. DCT and collecting duct
D. the glomerulus
DCT and collecting duct
During inhalation in humans:
A. diaphragm relaxes
B. thoracic cavity pressure increases
C. external intercostals contract
D. lungs recoil inward
External intercostals contract
Compared to veins, arteries:
A. have thinner walls
B. contain valves to prevent backflow
C. have higher elasticity and thicker smooth muscle layers
D. carry only deoxygenated blood
Have higher elasticity and thicker smooth muscle layers
The "lub" sound of the heartbeat is caused by the closing of the:
Atrioventricular valves
Freshwater fishes tend to ______ because their environment is ______ relative to their tissues.
Gain water; Hypo-osmotic
In the thick ascending limb of the loop of Henle:
A. water is freely permeable
B. Na⁺ and Cl⁻ are actively transported out
C. filtrate becomes more concentrated
D. ADH directly controls water movement
Na⁺ and Cl⁻ are actively transported out
Birds achieve highly efficient respiration because:
Air sacs allow unidirectional flow through parabronchi
In an open circulatory system:
Pressure is low and tissues are bathed directly in hemolymph
Cardiac output increases when:
A. stroke volume decreases
B. heart rate decreases
C. preload and contractility both rise
D. afterload increases dramatically
Preload and contractility both rise
During dehydration, insects increase water retention by:
Actively removing electrolytes from the filtrate
The renal corpuscle consists of:
Glomerulus and Bowman’s capsule
Which statement best describes insect respiration?
A. Hemolymph carries oxygen to tissues
B. Ventilation depends on positive pressure breathing
C. Air diffuses directly to tissues through tracheal tubes
D. Gas exchange occurs only at the spiracles
Air diffuses directly to tissues through tracheal tubes
Capillary exchange efficiency is due to their:
Single-cell-thick endothelium
The QRS complex of an ECG corresponds to:
Ventricular depolarization
Osmoconformers differ from osmoregulators in that they:
Directly match internal osmolarity to the environment
Filtration occurs because:
A. podocytes actively pump solutes out of blood
B. the glomerulus has fenestrated capillaries
C. the collecting duct uses osmotic gradients
D. the vasa recta absorbs water by diffusion
the glomerulus has fenestrated capillaries
Countercurrent flow in fish gills is effective because it:
maintains a gradient for oxygen diffusion along the entire filament
Which of the following correctly describes erythropoiesis regulation?
A. Triggered by high oxygen levels
B. Regulated by the liver in response to dehydration
C. Stimulated by EPO released from kidneys during hypoxia
D. Occurs only in lymph nodes
Stimulated by EPO released from kidneys during hypoxia
The SA node is able to spontaneously depolarize because it is:
Permeable to sodium ions at rest