Homeostasis and Excretion Flashcards
Homeostasis:
Maintaining constant conditions in the body/ internal environment
What is osmoregulation?
This is the regulation of water and salt content in the body
What is the internal environment of your body?
This is the surroundings of the cells, includes blood and tissue fluid
What nitrogenous waste is excreted by humans?
Urea
Explain the deamination process
Amino acid + oxygen ➡ carbohydrates + ammonia
Ammonia + carbondioxide ➡ urea + water
The pathway of urine in the kidney:
Renal artery ⬇ Blood capillaries ⬇ Nephrons (cortex) ⬇ Medulla (bulges called pyramids) ⬇ Pelvis ⬇ Ureters ⬇ Bladder ⬇ Urethra
Process of ultrafiltration in the nephron
Capillaries (glomerulus) ⬇ Bowman's capsule (a hollow cup of cells) ⬇ Capillary networks surrounding the nephron *Resistance to flow caused by the glomerulus ⬇ High blood pressure: the fluid is forced out ⬇ Capillary wall (permeable) ⬇ Basement membrane (not made up of cells-fine molecular filter) ⬇ Capsule wall (coarse filter) ⬇ Capsule (glomerular filtrate)
Name the two coiled tubules:
- Proximal convoluted tubule
- Distal convoluted tubule
Role of the Loop of Henle:
Involved in concentrating the fluid by causing more water to be reabsorbed into the blood
Meaning of diuresis and anti-diuresis
Diuresis: the flow of urine
Anti-diuresis: producing less urine
Describe the negative feedback loop for osmoregulation
Low water levels in the blood ⬇ Receptors in the hypothalamus ⬇ The pituitary gland releases ADH ⬇ It acts on kidney tubules to become more permeable ⬇ More water is reabsorbed into the blood ⬇ Urine becomes more concentrated ⬇ Normal: switch off the release of ADH
*Stimulates the thirst centre ➡ blood becomes more dilute
Mammals are warm-blooded or ____________
Homeotherms (they maintain a constant body temperature despite changes in the surrounding temperature)
OR
Endotherms
Functions of the skin:
- Provides protection against microorganisms
- Prevents water loss (impermeable)
- Controls heat loss
- Sense organ
- A tough outer layer that prevents mechanical damage
What is the outer epidermis layer made of?
Dead cells
Describe hypodermis and dermis layers of the skin
Hypodermis: contains fatty tissue which provides insulation and acts as an energy store
Dermis: sensory receptors, hair follicles, sweat glands, tiny blood vessels (capillary loops)
How does sweat help regulate body temperature?
Sweat secreted onto the skin surface has a cooling effect when it evaporates.
When this liquid evaporates into a gas, it makes use of the body’s heat as the latent heat of vaporization.
How do capillary loops help regulate temperature?
When your body is too hot, arterioles leading to capillary loops dilate (due to the sphincter muscles in the walls of the arterioles), allowing more blood to flow to the skin’s surface, and more heat is lost: VASODILATION
Other methods to regulate body temperature:
- Shivering
- Changes in the metabolism (due to adrenaline, the liver can also produce metabolic heat)
Steps for dialysis:
- An operation is conducted to join a vein to an artery to raise BP. A tube s permanently joined to a vein.
- In the dialysis machine, the patient’s blood is separated from the dialysis solution (of salts and glucose in exact concentrations) by a Visking membrane (large SA: many long narrow tubes/ stack of flat sheets)
- Diffusion of waste products and excess water and salts
. - Dialysis fluid is replaced with a fresh solution all the time. After several hours, the patient is going to have a balance of salts and glucose in their blood, and the waste products removed.
- The purified blood is going to be returned via a second tube attached to the vein.
Features of a dialysis machine (apart from Visking tube):
- Pumps to keep the blood and dialysis fluid flowing
- Traps to prevent air bubbles from getting into the blood
- Oxygenation and the temperature of the blood are controlled
