Transcript Chapter 1 Notes - Social Circle City Schools

Chapter 44 Notes
Regulating the Internal
Environment
Overview of Homeostasis
Homeostasis: the ability of animals to
regulate their internal environment
- thermoregulation: maintaining
internal temperature
- osmoregulation: regulation of the
gain and loss of water
- excretion: removal of nitrogencontaining waste products
Overview of Homeostasis
Regulating and conforming are the two
extremes in how animals cope with
environmental fluctuations
- regulator: uses mechanisms of
homeostasis to moderate internal
change
- ex. endothermic animals
Overview of Homeostasis
- conformers: allow some internal
conditions to vary with environmental
changes
- ex. animals that live in stable
environments
Overview of Homeostasis
Regulation of Body
Temperature
Q10 effect: the rate of reactions
increases by a factor of 2-3 for every
10oC temperature increase
Each animal has an optimal temperature
range for enzymatic activity
- thermoregulation keeps the body
temp within a range
Regulation of Body
Temperature
Four physical processes account for heat
gain or loss
- conduction: transfer of thermal
motion between molecules in direct
contact
- convection: transfer of heat by the
movement of air or liquid past a surface
Regulation of Body
Temperature
- radiation: the emission of
electromagnetic waves by all objects
warmer than absolute zero
- evaporation: removal of heat from
the surface of a liquid that is losing
some of its molecules as gas
Regulation of Body
Temperature
Regulation of Body
Temperature
Ectotherms have body temperatures close
to environmental temperatures;
endotherms can use metabolic heat to
keep body temperature warmer than
their surroundings
- endotherms have high levels of
aerobic metabolism
Regulation of Body
Temperature
- endotherms can be active in below
freezing weather
- being endothermic is energetically
expensive since animals need to
produce a lot of heat to maintain their
constant body temps. in cold weather
Regulation of Body
Temperature
Water Balance and Waste
Disposal
An animal’s nitrogenous wastes are
correlated with its phylogeny and
habitat
- when proteins and nucleic acids are
broken down for energy and converted
to fats and carbs, enzymes remove the
amino group (NH2) and form ammonia
(NH3)
Water Balance and Waste
Disposal
Some animals will excrete ammonia
directly, but many species will convert it
to urea or uric acid
- less toxic but takes energy to convert
Ammonia
- found in aquatic animals
- diluted with water from the
environment
Water Balance and Waste
Disposal
Urea
- requires a moderate volume of water;
excreted in high concentrations
- sharks, amphibians, and mammals
- produced in the liver and transported
in blood
- requires energy to produce urea
Water Balance and Waste
Disposal
Uric acid
- little water is excreted; water
conserving animals
- insects, reptiles, birds
- precipitated as a solid
Excretory Systems
The urinary system is made-up of the
kidneys, ureters, bladder, and urethra
- the nephron is the functional unit of
the kidneys
- waste is filtered from the blood and
collected as urine in each kidney
Excretory Systems
Excretory Systems
The kidney has two distinct regions, an
outer renal cortex and an inner renal
medulla.
The nephron consists of a single long
tubule and a ball of capillaries called the
glomerulus
- pressure causes water and solutes
from the blood to filter into the capsule
Excretory Systems
The fluid, called filtrate, passes through
three regions of the nephron: the
proximal tubule, the loop of Henle,
and the distal tubule
- fluids and solutes are returned to the
capillaries that surround the nephron
tubule
Excretory Systems
Excretory Systems
The nephron has three functions:
- glomerular filtration of water and
solutes out of the blood
- tubular reabsorption of water and
molecules from the tubules back into
the blood
- tubular secretion of waste products
into the distal tubule
Excretory Systems
The purpose of the kidneys is to
concentrate the filtrate in the kidneys to
produce urine that has a higher
osmolarity than that of blood
Bowman’s capsule  proximal convoluted
tubule  descending loop of Henle 
ascending loop of Henle  distal
convoluted tubule  collecting duct
Excretory Systems
The nervous system and hormones
regulate kidney function
Antidiuretic hormone (ADH): hormone
primarily responsible for producing
urine and regulating water balance
- an antidiuretic is any chemical that
prevents excessive urine production
Excretory Systems
- hypothalamus contains osmoreceptors to
detect the salt/water ratio in the blood and
produces ADH when needed
- if the body is dehydrated, ADH is
produced, and the urine volume decreases
- if the body has a high water
concentration, the hormone secretion stops
Excretory Systems
Coffee, tea, and alcohol are diuretics,
substances that increase urine flow
- alcohol inhibits ADH secretion and
increases urine production
- without ADH, urine flow could be
increased to 25 liters per day 