9.1 Maintaining Internal Balance

definition of homeostasis

the physiological state of the body in which internal physical and chemical conditions are kept within a range that is suitable for life processes

is homeostasis a static or dynamic process and why?

dynamic process

• adjusts in response to internal and external environment

why is homeostasis important?

it allows cells, tissues, organs, and the entire organism to function and survive properly

what is the internal environment of the body?

the extracellular fluid surrounding the body’s cells

what is the internal environment of the body?

the extracellular fluid surrounding the body’s cells

what are the two components of extracelular fluid?

1. interstitial fluid

2. plasma

what is interstitial fluid?

the fluid that fills the spaces between cells and tissues

what is plasma?

the fluid portion of blood

what does the flow of energy, chemicals, and waste into and out of extracellular fluid allow?

it allows cells to function properly so tissues, organs, and the other organisms can survive.

what is an important macromolecule carried in the fluid portion of blood?

proteins

list 3 things that can cause changes to the internal environment

1. physical activity

2. infection

3. other conditions

how can physical activity affect the internal environment?

it can increase body temperature, oxygen demand, and waste production

how might the body react to an infection in an attempt to kill it?

it may produce a fever to help destroy pathogens

why do we need mechanisms to maintain and regulate internal conditions?

to keep the body in homeostasis and ensure cells function peroperly

what organ systems are involved in homeostasis?

• nervous system

• excretory system

• endocrine system

• circulatory system

• immune system

• digestive system

• integumentary system

how is the nervous system involved in homeostasis?

receives sensory data from the environment and transmits signals through the body to regulate homeostasis

how is the excretory system involved in homeostasis?

rids the body of raste

how is the endocrine system involved in homeostasis?

regulates hormone levels, such as epinephrine

how is the circulatory system involved in homeostasis?

carries these hormones and other chemicals throughout the body

how is the immune system involved in homeostasis?

protects the body from infection

how is the digestive system involved in homeostasis?

organs can detoxify harmful chemicals and manufacture important proteins

how is the integumentary system involved in homeostasis?

maintains constant body temperature

what do body systems work together to carry out?

homeostasis, allowing organisms to survive

list five functions that body systems work together to perform

1. taking in nutrients and disposing of waste

2. synthesizing proteins, fats, and carbohydrates

3. sensing and responding to environmental changes

4. protecting the body from infection

5. reproducing and feeding offspring

what does taking in nutrients and disposing of waste help maintain?

homeostasis by providing cells with needed materials and removing harmful wastes

what does synthesizing proteins, fats, and carbohydrates mean?

producing important molecules needed for growth, repair, and energy storage

why is sensing and responding to environmental changes important?

it helps the body maintain stable internal conditions

how does protecting the body from infection contribute to homeostasis?

it prevents harmful pathogens from disrupting normal body functions

what is a homeostatic mechanism?

a system that monitors internal and external conditions and changes bodily functions to maintain homeostasis

what is the purpose of a homeostatic mechanisim?

to keep the body’s internal environment stable despite changes inside or outside the body

when is it beneficial for the body to go outside normal homeostasis?

during situations like exercise or fighting infection, where temporary imbalance helps the body perform important functions.

why does exercise cause the body to leave homeostasis?

because heart rate, breathing rate, and temperature increase to supply more oxygen and energy to muscles

how does fever show a useful disruption of homeostasis?

the body raises its temperature to help slow or kill pathogens during infection.

why is temporary imbalance in homeostasis sometimes helpful?

it allows the body to respond better to stress, danger, or increased energy demands

what are the body’s homeostatic mechanisms for heat and humidity

• sweating (evaporation cools body)

• vasodilation (blood vessels widen near skin to release heat)

• increased blood flow to skin

• increased breathing rate (minor heat release by distributing heat)

why do you think these mechanisms dont always work?

• high humidity prevents sweat from evaporating

• heat production during exercise may exceed cooling ability

• body can overheat faster than it can lose heat

• prolonged stress can overwhelm homeostasis systems