Week 8 Day 1 Animal Bodies and Homeostasis

The process whereby living organisms regulate their cells and bodies to maintain relatively stable internal conditions

homeostasis

some examples of homeostasis in humans (3)

1. minerals (sodium, potassium, calcium

2. energy sources (glucose and fat)

3. oxygen and carbon dioxide

this part of the control system is the normal value of the variable

set point

this part of the control system monitors the level/activity of the variable

sensor

this part of the control system compares the signal from the senor with the set point

integrator

this part of the control system compensates for any deviation between actual value and set point

effector

body temperature example of homeostasis

Body Temperature

Body gets cold

Sensor neurons in skin are activated

Integrator in the brain compares sensor input and set point

Skeletal muscle effectors are activated

Person starts to shiver

Shivering produces heat

Temperature comes up

A homeostatic mechanism in animals in which a change in the variable being regulated brings about a response or responses that move the variable in the opposite direction

neg. feedback loop

In animals, a mechanism that accelerates or amplifies a process, leading to what is sometimes called an explosive system.

pos. feedback loop

The process by which an animal’s body begins preparing for a change in some variable before it even occur

feedforward regulation

Allows body to adjust to changes slowly, what is it

feed forward regulation

example of feed forward regulation (just understand)

Salivating when you see/smell food

Body temp increases just before you wake up

Increased heart rate and respiration when anticipating fear

Cellular communication in which molecules are released into extracellular fluid

and act on nearby cells

paracrine signalling

Example: damage to skin causes cells to release molecules to promote tissue repair

Molecules (hormones) are released into the circulatory system and communicate with tissues at a distance

endocrine signalling

Example - BP decreases

Approximately 2/3 of body weight is __

fluid

of the 2/3 body weight that is fluid, __ is intracellular

Fluid contained inside cells

2/3

of the 2/3 body weight that is fluid, ___ extracellular Fluids outside of cells Plasma, interstitial fluids

1/3

true or false -Solute composition is very different between intra- and extra- cellular

true

Movement of a solute down its concentration gradient

No energy required

passive transport

Molecules that can cross the phospholipid bilayer can move in/out of cells

Lipids, gasses - Non-polar molecules

what process

simple diffusion

• channels in plasma membrane

• Polar molecules (Sodium, potassium)

• Protein shuttles

• Solutes bind to a protein in the membrane & get moved across

facilitated diffusion

 Movement of a solute against its concentration gradient

 Requires energy – ATP

active transport

 Muscle cells

 Neurons

these use ___ transport

active

the movement of water depends on… (2)

pressure gradients and solute concentration

Movement of water from a region of low solute concentration to high solute

concentration

osmosis

(water moves from a region of high water concentration to a region of low

water concentration)

osmosis

 Major portion of animals body mass

 Solvent that helps solutes in chemical reactions

 Transport vehicle for oxygen and nutrient

water

Also known as electrolytes

ions

levels of ions are maintained by (2 organs)

kidneys and liver primarily

Sodium, potassium, calcium, chloride & bicarbonate are examples of

ions aka electrolytes

The solute concentration of an aqueous solution, expressed as milliosmoles/liter

(mOsm/L).

the number of dissolved solute particles in a solution

osmolarity

Osmolarity > 300 is

hyperosmotic

Osmolarity < 300 is

hypotonic

Iso-osmotic is =

300

• eliminating nitrogenous wastes

• obtaining oxygen

• eliminating carbon dioxide

• consuming and metabolizing food

• regulating body temperature

these are examples of

obligatory exchanges

Nitrogenous waste is generated when ___ and __ ___ are broken down

proteins, nucleic acids

eliminating nitrogenous wastes requires

body water

nitrogenous wastes are excreted by

kidneys

• Water vapor from mouth, nasal cavity &

airways lost when exhaling

• Increased breathing rate increases

water vapor loss

what is this called

respiration

Digested food is excreted as waste and __ and __ are lost in the process

ions and water

 animals that generate body heat

 Use body water to cool off

 Sweat, panting

Endotherms