1. STAAR Review 8 Interactions between animal systems
Interactions between plant systems
Homeostasis
Response to external stimuli

2. Animal Systems Eleven major organ systems: System Function(s) Skeletal
Structural support
Muscular
Movement
Integumentary (skin)
Barrier from external environment
Circulatory/Cardiovascular
Transport molecules throughout body
Respiratory
Exchange carbon dioxide & oxygen
Digestive
Break down food molecules
Excretory/Urinary
Remove waste products from blood
Immune
Destroy pathogens that enter body
Nervous
Send regulatory messages throughout body
Endocrine
Produce hormones that regulate vital processes
Reproductive
Production of sex cells & offspring
There are eleven major organ systems in an animal. Each system is designed to carry out a specific function necessary for the survival of the animal.
The skeletal system provides support and the muscular system works with the skeletal system to provide movement. The integumentary system, or skin, forms a barrier from the external environment. The circulatory system uses blood to transport needed molecules throughout the body. The respiratory system provides the body with oxygen and removes carbon dioxide. The digestive system breaks down food molecules for the body to use. The excretory system removes waste products from the blood. The immune system kills pathogens, or disease-causing agents, that enter the body. The nervous system sends regulatory messages throughout the body. The endocrine system produces hormones that help regulate vital processes. The reproductive system is responsible for the production of sex cells (egg and sperm) and offspring.

3. Regulation Regulated body conditions include: Body temperature
Heart and respiration rates
Molecule concentrations in blood
Regulated body conditions include body temperature, heart and respiration rates, and molecule concentrations in the blood. Let’s look at how and why each of these conditions are regulated by an animal’s organ systems.

4. Body Temperature
Constant internal temperature required to maintain optimal function of cellular processes
Negative feedback loop:
Receptors in skin and brain monitor temperature
High temperature – brain signals sweat glands to cool body down
Low temperature – brain signals muscles to contract (shiver) to warm body up
A constant internal temperature is required to maintain the optimal function of cellular processes. Body temperature is regulated by a negative feedback loop.
Receptors in the skin and brain monitor external and internal temperatures. If the temperature becomes too high, the brain sends signals to glands in the skin to begin producing sweat. This cools the body down. If the temperature becomes too low, the brain sends signals to muscles to begin contracting, or shivering. This warms the body up.

5. Body Temperature Organ systems involved: System Functions
Integumentary
Skin contains temperature receptors & sweat glands
Muscular
Muscle contractions (shivering)
Nervous
Brain interprets input from temperature receptors and signals effectors to adjust body temperature
Three main organ systems interact to regulate body temperature. In the integumentary system, the skin contains temperature receptors and sweat glands. The muscles in the muscular system contract during shivering. In the nervous system, the brain interprets input from temperature receptors and sends signals to effectors to adjust body temperature.

6. Heart and Respiration Rates
Heart rate – number of times heart contracts per minute
Respiration rate – number of breaths per minute
Example: Exercise
Cells utilize oxygen faster
Blood pressure rises to meet increased oxygen demand
Heart and respiration rates increase
An animal’s heart rate is the number of times the heart contracts per minute. The respiration rate is the number of breaths the animal takes per minute. The body varies these rates based on variation in the oxygen needs of body cells.
An example of an activity that alters the oxygen needs of body cells is exercise. Cells use oxygen faster during exercise. This causes blood pressure to rise in order to speed the delivery of oxygenated blood to cells. Faster delivery of blood to the cells requires an increase in both heart and respiration rates.
Body varies these rates based on oxygen needs of body cells

7. Heart and Respiration Rates
Organ systems involved:
System
Functions
Circulatory
Heart varies heart rate according to signals from brain
Respiratory
Lungs vary respiration rate according to signals from brain
Nervous
Monitors blood pressure and oxygen levels
Sends signals to heart and lungs to adjust heart and respiration rates
Three main organ systems interact to regulate heart and respiration rates. In the circulatory system, the heart varies its heart rate according to signals received from the brain. In the respiratory system, the lungs vary their respiration rate according signals received from the brain. In the nervous system, the brain monitors blood pressure and oxygen levels and sends signals to the heart and lungs to adjust heart and respiration rates.

8. Molecule Concentrations in Blood
Body monitors molecule concentrations in blood to ensure appropriate delivery to and from cells
Utilizes hormones sent through blood
Regulated concentrations include:
Water balance
Blood sugar
An animal’s body monitors the concentration of various molecules in the blood. This is necessary to ensure that needed molecules are delivered to and from the body cell at the appropriate rate.
Two regulated concentrations in the blood are water balance and blood sugar. These concentrations are regulated using hormones sent through the bloodstream.

9. Molecule Concentrations in Blood
Organ systems involved:
System
Functions
Endocrine
Hormone levels regulate molecule concentrations in blood
Nervous
Receives input from receptors
Signals endocrine glands to alter hormone production
Excretory
Kidneys remove excess water from blood
Integumentary
Skin contributes to water balance (sweating)
Digestive
Liver adjusts glucose level in blood to regulate blood sugar
Circulatory
Blood requires appropriate concentration of molecules
Blood transports hormones
Six main organ systems interact to regulate molecule concentrations in the blood. Regulatory hormones produced by the endocrine system signal effector organs to alter molecule concentrations in the blood. The nervous system receives input from receptors and sends signals to endocrine glands to alter hormone production. In the excretory system, the kidneys remove excess water from the blood. The skin of the integumentary system also helps remove excess water through sweat production. In the digestive system, the liver adjusts glucose levels in the blood. The blood of the circulatory system requires appropriate concentration of molecules and transports hormones to the effector organs.

10. Nutrient Absorption
Nutrient absorption – passage of broken down food molecules through intestinal walls into bloodstream to be delivered to body cells
Nutrient absorption is the passage of broken down food molecules through the walls of the small intestine. The purpose of nutrient absorption is to deposit nutrient molecules into the bloodstream to be delivered to body cells. Body cells require a steady supply of nutrients to maintain cellular functions.
Nutrient absorption is composed of two processes: digestion and absorption.
Two processes:
Digestion
Absorption

11. Nutrient Absorption Organ systems involved: System Functions Digestive
Mouth, stomach, and small intestine digest large food molecules
Small intestine is site of absorption
Muscular
Muscle contractions push food through digestive tract
Muscle contractions in stomach aid mechanical digestion
Circulatory
Blood vessels absorb nutrients through intestinal walls
Blood transports absorbed nutrients to cells throughout body
Three main organ systems interact to carry out nutrient absorption in animals. The mouth, stomach, and small intestine of the digestive system all work to digest food molecules. The small intestine is the major site of nutrient absorption. Muscles of the muscular system contract to push food through the digestive tract. Muscle contractions in the stomach also contribute to mechanical digestion. In the circulatory system, blood vessels absorb nutrients through villi in the intestinal walls. The blood transports absorbed nutrient molecules to cells throughout the body.

12. Defense Against Injury
Organ systems involved:
System
Functions
Integumentary
Skin provides physical barrier to foreign objects
Skeletal
Skeleton protect internal organs
Muscular
Muscle reflexes allow quick reactions
Nervous
Sensory receptors detect changes in environment Brain sends signals to muscles
Three main organ systems interact to carry out injury defense in animals. The skin of the integumentary system provides a physical barrier to foreign objects from the environment. The skeleton protects internal organs. Muscle reflexes allow quick reactions when danger is sensed. In the nervous system, sensory receptors detect environmental changes and signal muscles to react.

13. Defense Against Illness
Organ systems involved:
System
Functions
Integumentary
Skin, hair and mucus provide physical barriers to pathogens
Respiratory
Nasal mucus and hairs, coughing and sneezing provide physical barriers to pathogens
Digestive
Stomach acids kill pathogens in food molecules
Circulatory
Blood transports defensive molecules, white blood cells, and antibodies to site of pathogen
Immune
Phagocytes and lymphocytes attack and destroy pathogens
Adaptive response leads to immune memory
Five main organ systems interact to carry out illness defense in animals. In the integumentary system, skin, hair, and mucus provide physical barriers to pathogens. Nasal mucus and hairs, coughing, and sneezing in the respiratory system also act as physical barriers. Stomach acid in the digestive system is another example of a physical barrier to pathogens.
In the circulatory system, blood transports defensive molecules, white blood cells, and antibodies to the site of a pathogen. Phagocytes and lymphocytes of the immune system attack and destroy pathogens. The adaptive immune response also leads to immune memory.

14. Plant Systems Organ systems: Tissue systems:
Shoot system – above- ground
Root system – below-ground
Dermal
Ground
Vascular
Tissues
Shoot system
Tissue systems:
Dermal – barrier
Ground – metabolic functions
Vascular – transport
Plant systems can be discussed on two levels: organs and tissues. Plants consist of two organ systems. The shoot system includes all above-ground organs, such as leaves, stems, and flowers. The root system includes all below-ground organs, or mainly roots.
These organ systems are composed of three different types of tissue. The dermal tissue is the outer covering of the plant that serves as a protective barrier. Ground tissue is responsible for carrying out most of the plant’s metabolic functions, such as photosynthesis. Vascular tissue transports needed substances throughout the plant, such as food and water. Each plant organ contains of all three types of tissue.
Root system

15. Interactions Among Plant Systems
Organ and tissue systems interact to carry out vital functions
Transport
Reproduction
Response
While each system has its own unique functions, all organ and tissue systems interact to carry out many functions that are vital to the plant’s survival. Three functions that we will discuss in more detail are transport, reproduction, and response.

16. Transport Movement of needed materials throughout plant
Major function of vascular tissue
Xylem – transports water and minerals
Phloem – transports glucose
Both transport hormones
Transport is the movement of needed materials throughout the plant. Needed materials, such as food and water, are produced or absorbed by a specific organ and must be transported to the rest of the organs to be used.
Transport is carried out by two types of vascular tissue. Xylem transports water and minerals. Phloem transports food in the form of sucrose. Both types of vascular tissue transport hormones throughout the plant.

17. Interactions Among Plant Systems
Interactions during transport
Root system
Absorbs water and minerals
Shoot system
Ground tissue produces glucose through photosynthesis
Both organ systems
Produce hormones
Vascular tissue transports all materials throughout the plant
Successful transport depends on interactions among several systems. The root system absorbs water and minerals. Ground tissue in the shoot system carries out photosynthesis to produce glucose. Both organ systems produce hormones. All of these needed substances are then transported throughout both organ systems by vascular tissue. These interactions ensure that all substances are delivered to the organs that need them.

18. Image by Roberto MM [GFDL]
Reproduction
Vegetative propagation – offspring produced from part of a plant organ
Asexual
Pollination – offspring produced via pollinated seeds
Sexual
In general, plants utilize two methods of reproduction. Plants can reproduce asexually by the process called vegetative propagation. In this type of reproduction, the offspring plant grows directly from an organ of the parent plant, such as a root or stem. The offspring plant is genetically identical to the parent plant.
Plants can reproduce sexually by the process of pollination. In this type of reproduction, the offspring plant is produced by the combination of a male and female gamete into a pollinated seed. This process produces a completely independent offspring plant whose genetic makeup is a result of the gametes that were combined. A common example of this occurs in flowering plants.
Image by Roberto MM [GFDL]

19. Reproduction by Pollination
Flower – organ that produces seeds
Seed – fertilized ovule (embryo) and stored food (cotyledon) surrounded by a protective seed coat
The flower is the plant’s reproductive organ. Flower structure differs slightly, but in general a flower contains several male stamen and a single, larger female pistil. When pollen from a stamen is transferred to the ovule of the pistil, pollination has occurred. A fertilized seed is produced, and a fruit develops around it. The entire process is regulated by hormones.
A seed consists of three major structures. The embryo is the fertilized ovule produced during pollination. The cotyledon stores food for the developing plant. Both structures are surrounded by a protective seed coat that allows the seed to retain moisture.
Fruit – develops around fertilized ovule(s)

20. Interactions Among Plant Systems
Interactions during reproduction
Vegetative propagation
Shoot and root systems: part of an organ produces a new plant
Pollination
Shoot system: flowers are the site of seed pollination and fruit development
Shoot and root systems: produce hormones, transported by the vascular tissue, that regulate flower budding, fruit ripening and seed growth
Successful reproduction depends on interactions among several systems. In vegetative propagation, an entirely new shoot and root system grows from part of an organ from a parent plant.
In pollination, the flowers of the parent plant’s shoot system are the site of seed pollination and fruit development. Important steps in the reproductive process, such as flower budding, fruit ripening, and seed growth are regulated by hormones. Remember that the shoot and root systems both produce hormones. These hormones are transported to flowers by the vascular tissue. These interactions ensure the best chances of producing viable offspring.

21. Response
Tropisms – plant’s hormonal growth response toward or away from an external stimulus
Examples:
Phototropism – stem and leaves grow toward a light source
Positive gravitropism – roots grow toward gravity (downward)
Negative gravitropism – stem and leaves grow away from gravity (upward)
Response is a plant’s ability to react to changes in its environment. Tropisms are a type of response in which hormones signal a plant to grow toward or away from a stimulus in the environment. Examples of common plant tropisms include phototropism and gravitropism.
In phototropism, a plant’s stem and leaves grow toward a light source. This allows the plant to gain the greatest possible exposure to the light energy needed for photosynthesis. In positive gravitropism, a plant’s roots grow toward gravity. This increases the plant’s likelihood of finding water. In negative gravitropism, a plant’s stem and leaves grow away from gravity. This increases the plant’s chances of finding light.

22. Interactions Among Plant Systems
Interactions during response
Root system
Grows toward gravity
Shoot system
Grows toward light and/or away from gravity
Both systems
Produce hormones
Transported hormones
Successful response depends on interactions among several systems. The root system grows toward gravity to seek water. The shoot system grows toward light and away from gravity to seek light energy for photosynthesis. These growth responses are all stimulated by hormones produced in both organ systems. You will recall that hormones are transported to the sites of cell growth by the vascular tissue. These interactions ensure that the plant is able to obtain needed materials from the environment.

23. Homeostasis Homeostasis – maintaining a stable, internal environment
Essential for life
Involves body systems working together
Involves monitoring levels of variables and correcting changes
Body temperature
Blood glucose
Water potential
O2 and CO2 concentrations
Blood pH
Homeostasis is defined as maintaining a stable, internal environment. This process is essential for life and involves various body organs and systems working together.
Homeostasis involves monitoring levels of variables and correcting changes in these variables. If a particular level deviates too far from a set point, changes will be made to correct the deviations. Examples of levels that are kept in check by homeostasis are body temperature, blood glucose, water potential, oxygen and carbon dioxide concentrations, and blood pH.

24. Negative Feedback Mechanisms
Negative Feedback Mechanism – control system (loop) that monitors and corrects changes to maintain homeostasis
Regulation is in a negative, or reverse, direction
Ex: body temperature rises, body acts to cause body temperature to drop
Negative feedback mechanisms, referred to as negative feedback loops, are control systems that monitor and correct changes to maintain homeostasis. This regulation takes place in a negative, or reverse, direction. For example, as body temperature rises, the body works to cause body temperature to drop.

25. Body Temperature Regulation
A negative feedback loop keeps body temperature within a normal range. The perturbing factor which initiates a change is the sun shining on a body. The sun directly causes the stimulus of a rise in body temperature. This rise in body temperature is a deviation from normal body temperature.
Skin receptors detect this change and send a nerve signal to the integrating center. In this case, the integrating center is the hypothalamus of the brain. The hypothalamus signals the effectors to initiate a response. Blood vessels dilate which cools the skin surface. Sweat glands release sweat which also acts a body coolant.
These effectors have successfully initiated the response of a drop in body temperature, and this negative feedback loop is complete. If the original stimulus returns, the feedback mechanism may begin again.

26. Blood Glucose Regulation
Regulation of blood glucose (sugar)
Involves negative feedback loop
Rise in glucose stimulates secretion of insulin
Insulin – hormone that lowers blood glucose levels
Regulation of blood glucose, or sugar, levels involves negative feedback loops. A rise in glucose stimulates secretion of the hormone, insulin. Insulin lowers blood glucose levels.

27. Blood Glucose Regulation
A negative feedback loop keeps blood glucose levels within a normal range. The perturbing factor which initiates a change is the act of eating. Most food contains some form of sugar. Ingesting food directly affects the stimulus of a rise in blood glucose levels. This rise in blood sugar is a deviation from normal blood sugar levels.
Specialized receptors located in cells of the pancreas, called the Islets of Langerhans, detect this change and send a signal to the integrating center. In this case, the integrating center includes the cells of the pancreas. The cells of the pancreas signal the effector to initiate a response. These same cells act as the effector by releasing the hormone, insulin.
Insulin successfully initiates the response of a drop in blood glucose levels. This response is accomplished by the uptake of glucose into the skeletal muscles and other tissues. This negative feedback loop is complete. If the original stimulus returns, the feedback mechanism may begin again.

28. Comparison of Feedback Mechanisms
Negative Feedback:
Maintains homeostasis
Corrects change
Regulation is in reverse direction
Examples:
Body temperature regulation
Blood glucose regulation
Positive Feedback:
Leaves homeostasis
Increases change
Regulation is in forward direction
Examples:
Blood clotting
Contractions during childbirth
This summarizes a comparison of negative and positive feedback mechanisms. Negative feedback maintains homeostasis. Positive feedback systems act to move the system outside of the normal range.
Negative feedback corrects a change, while positive feedback increases a change.
Negative feedback regulates in a reverse, or negative, direction. The response is the opposite reaction from the initial stimulus. In contrast, positive feedback regulates in the forward direction, accentuating the change. The response amplifies the initial stimulus.
Examples of negative feedback are body temperature and blood glucose regulation. Examples of positive feedback are blood clotting and contractions during childbirth.