lecture 26

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Questions and Answers

What is the main function of the glomerulus?

To reabsorb electrolytes and nutrients

To regulate blood pressure

To filter blood for water, waste, and solutes (correct)

To secrete waste into the urinary bladder

What is the outer layer of the kidney called?

Nephron

Medulla

Renal pyramid

Cortex (correct)

What brings blood into the kidney?

Renal artery (correct)

Ureter

Renal vein

Collecting duct

What is the renal pelvis responsible for collecting?

Filtrate Signup and view all the answers

What is the term for the tuft of capillaries inside the membranous sac called a Bowman's capsule?

Glomerulus Signup and view all the answers

What is the location where the filtration takes place in the kidney?

Renal pyramids Signup and view all the answers

What is the primary function of aquaporins in a lipid bilayer membrane?

To allow water to move through the membrane Signup and view all the answers

What is the term for a membrane that allows some molecules through it, but not others?

Selectively permeable Signup and view all the answers

What is the process by which essential molecules are transported back into the blood after filtration?

Reabsorption Signup and view all the answers

What is the term for organisms that maintain internal fluids at a stable osmotic pressure that is distinct from that of the environment?

Osmoregulators Signup and view all the answers

What is the byproduct of protein and nucleic acid breakdown that is toxic to living cells?

Ammonia Signup and view all the answers

What are the two mechanisms by which nitrogenous wastes are removed from the blood?

Filtration and secretion Signup and view all the answers

What is the primary function of the pancreas in the midgut?

Releasing bicarbonate to neutralize stomach acid Signup and view all the answers

What is the purpose of the hormone secretin in the midgut?

Regulating the release of bicarbonate from the pancreas Signup and view all the answers

What is the function of the villi and microvilli in the small intestine?

To increase the surface area for absorption of nutrients Signup and view all the answers

How do glucose and other hydrophilic nutrients move into the bloodstream in the small intestine?

Through passive transport facilitated by proteins Signup and view all the answers

What is the primary function of the gallbladder in the midgut?

To release bile into the small intestine Signup and view all the answers

What is the primary function of the large intestine (hindgut)?

To absorb water and eliminate waste products Signup and view all the answers

Study Notes

Mammalian Kidney

Kidneys filter nitrogenous waste and help regulate blood pressure and blood volume.
The renal artery brings blood into the kidney, and the filtered blood is returned via the renal vein.
The ureter leads to the urinary bladder.
Filtration takes place in the renal pyramids, which are filled with nephrons (renal tubules and associated capillaries).

Kidney Anatomy

The outer layer of the kidney is called the cortex, and the inner layer is called the medulla.
The medulla is further subdivided into the inner and outer medulla.
The glomerulus is a tuft of capillaries inside the membranous sac called a Bowman's capsule.
Individual renal tubules in a renal pyramid flow into a collecting duct.

Bowman's Capsule

The Bowman's capsule is the location where blood is first filtered for water, waste, and solutes.
Blood moves from the capillary into the Bowman's space.

Renal Tubules

Renal tubules are divided into:
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
Proximal convoluted tubule: reabsorbs electrolytes, glucose, amino acids, sodium, and chloride into the blood.
Loop of Henle: descending side is water permeable, and ascending side is water impermeable and actively transports electrolytes out.
Distal convoluted tubule: main site of secretion, regulates K+, Na+, and Ca+2, and regulates urine pH with bicarbonate.

Collecting Duct

Permeability is regulated by antidiuretic hormone (ADH), which is secreted by the posterior pituitary to control the amount of water in the body.

Controlling Blood Pressure

The kidney monitors blood pressure due to its high blood flow.
Specialized cells (juxtaglomerular apparatus) in the blood vessels leaving the glomerulus detect low or high blood pressure.
When blood pressure is low, the juxtaglomerular apparatus triggers the hormone angiotensin to be activated, which causes smooth muscles in the blood vessels to contract, raising blood pressure.

Renal System Vocabulary

Selectively permeable: a membrane that allows some molecules through, but not others.
Aquaporins: channels in a lipid bilayer membrane that allow water to move through it.
Osmoconformers: keep internal fluids at the same osmotic pressure as the environment.
Osmoregulators: maintain internal fluids at a stable osmotic pressure that is distinct from that of the environment.

Nitrogenous Waste Removal

Ammonia is produced when proteins and nucleic acids are broken down, and it is toxic to living cells.
Different organisms deal with ammonia production in different ways:
- Ammonia: most toxic, requires high volumes of water
- Urea: less toxic, but requires energy to produce and water to eliminate
- Uric Acid: least toxic, energetically most expensive
Nitrogenous wastes are removed from the blood through two mechanisms: filtration and secretion.
Reabsorption: process by which essential molecules are transported back into blood after filtration.

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Description

Learn about the structure and function of the mammalian kidney, including its role in filtering waste, regulating blood pressure, and more. Explore the anatomy of the kidney and its components.