Lesson #7:

Urinary System / Excretory System

Learning Intention:

Students will be able to investigate the function of the kidneys in humans and compare the function to other organisms.

Success Criteria:

Identify an incorrect response, provide reasoning about why it is incorrect and then construct the correct response.
Engage with a real-world example concerning the importance of filters.
Engage with a scientific phenomenon that relates to our own bodies filtering process.
Explore how the urinary system normally functions through various mediums by actively reading
Explain the function of the excretory system and revise your explanation using feedback from the A.I.
Elaborate by applying your understanding of the endocrine system to a new phenomenon

Standards:

HS-LS1-3: Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.

Reminders

Tutoring today after school from 3-4.

Part 1:

Warm-Up

Review of Nervous System

Question #1

Researchers have determined that silkworm moths have a mechanism that enables them to locate mulberry leaves. Mulberry leaves emit scented chemical molecules that are detected by highly sensitive receptors within the antennae of the silkworm, as shown in the models below

August 2025 Regents Q13:

Which statement best describes how the organization and interactions of two systems present within the silkworm moth enables it to find and use mulberry leaves as their source of nutrients?

(1) Special receptors in the nervous system of the silkworm pick up the scent of the mulberry leaves and send messages to the muscular system to spin a silk cocoon.

(2) Receptors in the nervous system within the antennae pick up scent molecules from mulberry leaves. The silkworm is able to fi nd and eat the leaves, using the digestive system to break down the nutrient molecules into a usable form.

(3) The nervous system of the silkworm sends messages to the digestive system to begin to break down the fats that are taken in to produce new muscle tissue for movement.

(4) The muscular system sends messages to the nervous system to receive scent messages from the mulberry leaves.

Question #2

Survival in the desert also requires that kangaroo rats have the ability to escape predators. Various body systems must work together to enable the kangaroo rat to perform lightning-quick escape maneuvers. Scientists studied the evolution of the kangaroo rat leap. They determined that although 81% of snake strikes were accurate, 78% of the time the kangaroo rats were fast enough to evade a bite that would kill.

August 2025 Regents Q31:

Which statement best describes an interaction that occurs between body systems during the kangaroo rat’s lightning-quick maneuver?

(1) The respiratory and nervous systems interact when sending a signal to the spinal cord to leap.

(2) The circulatory and nervous systems interact when sending a signal to the leg muscles.

(3) The respiratory and muscular systems interact to slow cellular respiration prior to the muscle contraction.

(4) The nervous and muscular systems interact to trigger the leg muscle to contract

Part 2:

Turn n' Talk

Número Uno

Directions: Mr. Pinho took his car for an oil🛢️ change four months ago. They asked if he wanted to replace a doodad called an oil filter.

Mr. Pinho is SUUUPPPPEEERRR cheap so he said no to the new filter. 3 bucks! That's crazy talk!

Today his car engine 🚘 died.

Compare his car engine oil below to brand new oil and discuss why car engines need oil filters.

Mr. Pinho's Car Oil

Normal Car Oil

Part 3

Turn n'Talk

Número Dos

Mechanics call oil the life "blood" of a car. Just like a car needs its oil filtered, we need our blood filtered.

How do you think our body filters out the waste in our blood?

🩸

Drum Roll Please 🥁

Kidneys

Part 4:

Exploring the

Urinary System

Directions: As you read, you will encounter bold words. Write the word down in your medical journal and then make a list of words that are associated with it.

The Urinary System and the Role of the Nephron

The urinary system works closely with the circulatory system to maintain internal balance in the body. Its primary function is to remove nitrogenous wastes from the blood while regulating water levels and blood pH. The major organs of this system include the kidneys, ureters, bladder, and urethra. Among these, the kidneys play the most critical role in filtering the blood and maintaining homeostasis.

Each kidney contains millions of microscopic filtering units called nephrons. Blood enters a nephron through a network of capillaries, where substances such as water, glucose, salts, and wastes move out of the blood. Large molecules and blood cells remain in the bloodstream, while smaller molecules enter the nephron tubule. As fluid moves through the nephron, useful materials are selectively returned to the blood through diffusion, and wastes remain in the forming urine.

A key structure within the nephron is the nephron loop. This loop extends deep into the kidney and plays an essential role in regulating water balance. The nephron loop has a section that allows water to move out of the tubule and a section that allows salts to move out, back into the blood.

The length of the nephron loop varies depending on the needs of the organism. Longer nephron loops, allow more water to be reabsorbed back into the blood. This results in more concentrated urine. Organisms that must conserve water, such as desert mammals, typically have longer nephron loops than organisms that live in environments where water is readily available.

Through the combined actions of filtration, reabsorption, and secretion, the kidneys ensure that the composition of the blood remains stable. The structure of the nephron, especially the length and function of the nephron loop, is directly related to its ability to regulate water and dissolved substances. This close relationship between structure and function is a key principle in understanding how the urinary system maintains homeostasis in the human body.

Part 5:

Stop n' Jot

Urinary System / Excretory System: Removal of metabolic wastes from cells and extra water/salt. NOT FROM FOOD.

Kidneys: In humans, the kidneys filter out waste from the blood, such as urea, salts and extra water. That waste is stored in the bladder and then removed from the body.

Nephron:

A nephron is the basic working unit of the kidney

The nephron is made of tubules surrounded by many capillaries
These capillaries are important because they allow materials to diffuse between the blood and the nephron
Waste materials move out of the blood, while useful materials can move back in

Part 6:

Exit Ticket

How Do Kangaroo Rats Survive in the Desert?

Kangaroo rat species live in the desert and conserve water so efficiently that they can survive without drinking. The body systems of these animals have various adaptations that allow the rats to extract water from the food they eat. Kangaroo rats produce highly concentrated urine containing a minimal amount of water. Urine concentration depends on specialized structures in the kidney called nephrons. The model to the right shows the organization of specific parts of the circulatory and excretory systems that are needed to filter water and waste from the blood.

Describe how specific parts of the circulatory and excretory systems interact within the kangaroo rat to conserve water. [1]

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