Biology - Chapter 9 Homeostasis

Homeostasis

(Homeostasis 1)

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

tolerable range can be narrow for

(Homeostasis 1)

blood pH and internal temperature

range of human blood pH

7.35-7.45

what happens when blood pH falls below 7.35?

(Homeostasis 1)

leads to a serious medical condition called acidosis

what happens when blood pH is over 7.45?

(Homeostasis 1)

leads to a serious medical condition called alkalosis

tolerable range is more broad for…

(Homeostasis 1)

blood flow, glucose levels, and hormone levels

what is intracellular fluid

(Homeostasis 1)

fluid inside our bodies

what is homeostasis more focused on?

(Homeostasis 1)

extracellular fluid

what is extracellular fluid comprised of?

(Homeostasis 1)

blood plasma and interstitial fluid

what is blood plasma?

(Homeostasis 1)

the fluid portion of blood

what is interstitial fluid?

(Homeostasis 1)

the fluid that fills the spaces between cells and tissues

how much extracellular fluid does a typical adult human have?

(Homeostasis 1)

around 15L (approx. 20% of body mass)

Homoestatic mechanisms may incorporate

(Homeostasis 1)

multiple organ systems

What do homeostatic mechanisms do?

(Homeostasis 1)

monitor internal and external conditions and change bodily functions to maintain homeostasis

Why is a thermostat a good analogy for homeostasis?

(Homeostasis 1)

A thermostat works much like a biological system maintaining homeostasis. It monitors temperature, detects changes, and triggers corrective actions to keep the environment stable and within the desired range, similar to how living organisms regulate their internal conditions.

Thermoregulation:

(Homeostasis 1)

the regulation of internal temperature using a negative feedback system

What are homeotherms?

(Homeostasis 1)

animals that maintain a stable body temperature regardless of the temperature of the external environment

What are homeotherms also known as?

(Homeostasis 1)

endotherms

examples of homeotherms

(Homeostasis 1)

birds and mammals

Poikilotherms:

(Homeostasis 1)

animals that have a varying body temperature, and who often match the temperature of the external environment

What are poikilotherms also known as?

(Homeostasis 1)

ectotherms

How do endotherms maintain their body temperature?

(Homeostasis 1)

by internal/physiological mechanisms

How do ectotherms maintain their body temperature?

(Homeostasis 1)

by absorbing thermal energy from the environment

examples of ectotherms

(Homeostasis 1)

fish, amphibians, reptiles, and invertebraes

What controls thermoregulation in humans?

(Homeostasis 1)

the hypothalamus

What happens when the blood is warmer than they hypthalamic set point?

(Homeostasis 1)

it activates the heat-loss centre in the hypothalamus, which sends a signal to the skin blood vessels to dilate. making the capillaries flushed with warm blood, radiating heat from the skin surface. the sweat glands are also activated, secreting perspiration, which is vaporized by body heat, helping to cool the body. the body temperature decreases as the blood temperature declines, and the hypothalamus heat-loss centre shuts off. the body temperature returns to 35.6°C—37.8°C

What happens when the blood is cooler than the hypothalamic set point?

(Homeostasis 1)

it activates the heat-promoting centre in the hypothalamus, which sends a signal to the skin blood vessels to constrict, sending blood to deeper tissus instead of the skin capillaries, minimizing the overall heat loss from the skin surface. the skeletal muscles are also activated when more heat is needed, causing shivering to occur. The body temperature increases as the blood temperature rises, and the hypothalamus heat-promoting centre shuts off. The body temperature returns to 35.6°C—37.8°C

Hypothermia

(Homeostasis 1)

a medical emergency caused by the body losing heat faster than it can produce heat, causing a dangerously low temperature

At what temperature does hypothermia occur?

(Homeostasis 1)

below 35° C

What happens to the body when the temperature drops?

(Homeostasis 1)

the heart, nervous system, and other organs cannot work normally

What happens if hypothermia is left untreated?

(Homeostasis 1)

it can lead to a complete failure of the heart an respiratory system and eventually death

What is hypothermia caused by?

(Homeostasis 1)

exposure to cold weather or immersion in cold water

Primary treatments for hypothermia

(Homeostasis 1)

any methods to warm the body back to a normal temperature

Hyperthermia:

(Homeostasis 1)

a condition when an individual’s body temperature is elevated beyond normal due to failed thermoregulation. the person’s body produces or absorbs more heat than it dissipates.

What happens when extreme temperature elevation occurs?

(Homeostasis 1)

it becomes a medical emergyency requiring immediate treatment to prevent disability or death

hyperthermia causes ___ more deaths than hypothermia

(Homeostasis 1)

10x

common causes for hyperthermia

(Homeostasis 1)

heatstroke and an adverse reaction to drugs

what is heatstroke?

(Homeostasis 1)

an acute temperature elevation caused by exposure to excessive heat, or a combination of heat and humidity, that overwhelms the heat-regulating mechanisms of the body

Hormones:

(Homeostasis 2)

chemicals released by specialized cells that affect cells in other parts of the body

Endocrine hormones:

(Homeostasis 2)

chemicals secreted by endocrine glands directly into the blood

the majority of the body’s glands are

(Homeostasis 2)

endocrine glands

examples of endocrine glands

(Homeostasis 2)

digestive, mucous, and sweat glands

difference between endocrine and exocrine glands

(Homeostasis 2)

endocrine: release chemicals directly into the blood

exocrine: secrete substances onto body surfaces and/or cavities via ducts or tubes

non-target hormones

(Homeostasis 2)

growth hormones, insulin, adrenaline

targeted-gastrin hormones

(Homeostasis 2)

specifically stimulate cells in the stomach to produce digestive enzymes

along with the nervous system, the endocrine system provides

(Homeostasis 2)

integration and control of organs and tissues

Difference between the nervous system and endocrine system (in regards to integration and control of organs and tissues)

(Homeostasis 2)

nervous system: enables a more immediate response to changes

endocrine system: designed to maintain control over long periods of time (eg. growth and sex hormones regulate development over years)

why do hormones not affect all cells?

(Homeostasis 2)

because cells may have receptors for one hormone bu not for another, and the number of receptors found on individual cells may vary.

2 types of hormones

(Homeostasis 2)

steroid and protein hormones

how do steroid and protein hormones differ?

(Homeostasis 2)

in chemical structure and action

what are steroid hormones made from?

(Homeostasis 2)

cholesterol (a lipid)

What do steroid hormones include?

(Homeostasis 2)

male and female sex hormones, and cortisol

What is cortisol?

(Homeostasis 2)

a hormone that stimulates the conversion of amino acids to glucose by the liver

What do protein hormones contain?

(Homeostasis 2)

contain water-soluble chains of amino acids of varying lengths

examples of protein hormones

(Homeostasis 2)

insulin and growth hormones

what are pituitary hormones produced by?

(Homeostasis 2)

the pituitary gland

what is the pituitary gland?

(Homeostasis 2)

a two lobed gland within the cranial cavity

why is the pituitary gland also called the master gland?

(Homeostasis 2)

because it produces hormones that control most of the other endocrine glands

(eg. the anterior pituitary gland produces thyroid-stimulating hormones which target the thyroid glad and stimulate the release of thyroid hormones)

(eg. the posterior pituitary gland produces antidiuretic hormones which target the kidneys, leading to an increase in volume and pressure by increasing water absorption in the kidneys)

give examples of hormones that the pituitary gland controls

(Homeostasis 2)

(eg. the anterior pituitary gland produces thyroid-stimulating hormones which target the thyroid glad and stimulate the release of thyroid hormones)

(eg. the posterior pituitary gland produces antidiuretic hormones which target the kidneys, leading to an increase in volume and pressure by increasing water absorption in the kidneys)

Thyroid gland

(Homeostasis 2)

a two lobed gland at the base of the neck that regulates metabolic processes

Parathyroid glands:

(Homeostasis 2)

4 pea-sized glads in the thyroid gland that produce parathyroid hormones to regulate blood calcium and phosphate levels

Islets of Langerhans:

(Homeostasis 2)

clusters formed by specialized endocrine cells in the pancreas

where are the islets of langerhans found?

(Homeostasis 2)

in all vertebrates

what do the islets of langerhans produce?

(Homeostasis 2)

insulin and glucagon (protein hormones that control blood sugar

who discovered insulin and glucagon?

(Homeostasis 2)

Canadian scientist Frederick Banting and his colleague Charles Best

What does insulin do?

(Homeostasis 2)

lowers blood sugar by stimulating cells to uptake sugar for cellular respiration

What does glucagon do?

(Homeostasis 2)

increases blood sugar by stimulating the liver to convert stored carbohydrates (glycogen) into glucose