Homeostasis Flashcards
(31 cards)
What is homeostasis?
The maintenance of a stable internal environment within set limits.
What are the key components of a homeostatic system?
Receptors, a control centre, and effectors.
What is negative feedback?
A response that counteracts a change to return conditions to normal.
What is positive feedback?
A response that amplifies a change in conditions (e.g., childbirth).
Why is temperature regulation important?
Because enzyme activity is temperature-dependent and extreme changes can denature enzymes.
What is the role of the hypothalamus in temperature control?
It acts as the body’s thermostat, detecting and responding to blood temperature changes.
What is the importance of maintaining blood glucose levels?
To ensure a constant supply of glucose for respiration, especially in the brain.
What is osmoregulation?
The control of water potential in the body to maintain homeostasis.
What organ is primarily responsible for osmoregulation?
The kidney.
What are the main parts of the kidney?
Cortex, medulla, renal pelvis, ureter, and nephrons.
What is a nephron?
The functional unit of the kidney responsible for filtering blood and forming urine.
What is ultrafiltration?
The filtration of blood at the glomerulus due to high hydrostatic pressure.
What substances are filtered out during ultrafiltration?
Water, glucose, salts, urea, and other small molecules.
What remains in the blood after ultrafiltration?
Proteins and blood cells (too large to pass through the filter).
Where does selective reabsorption occur?
In the proximal convoluted tubule (PCT).
What substances are reabsorbed in the PCT?
Glucose, amino acids, water, and some ions.
What adaptations does the PCT have?
Microvilli, many mitochondria, and tight junctions for efficient reabsorption.
What is the loop of Henle responsible for?
Creating a concentration gradient in the medulla to enable water reabsorption.
How does the loop of Henle work?
Descending limb is permeable to water, ascending limb is impermeable to water but actively transports Na⁺ and Cl⁻ out.
What is the role of the distal convoluted tubule (DCT)?
Fine-tunes ion and pH balance under hormonal control.
What is the role of the collecting duct?
Reabsorbs water under the influence of ADH to produce concentrated urine.
What is ADH?
Antidiuretic hormone that increases the permeability of the collecting duct to water.
Where is ADH produced and released?
Produced in the hypothalamus, released from the posterior pituitary gland.
