Download APDC Unit VIII-Homeostas

Unit VIII- Homeostasis
Chapter 32*, 33*, 34*
Chapter 32 Homeostasis
What you must know:
 Three categories of nitrogenous waste, which animal groups
produce each, and why.
 The components of a nephron, and what occurs in each
region.
 How hormones affect water balance by acting on the
nephron.
Control of the Internal Environment
 Feedback control maintains the internal environment in
many animals
 Multicellularity allows for cellular specialization with
particular cells devoted to specific activities
 Specialization requires organization and results in an internal
environment that differs from the external environment
Organ Systems
Homeostasis
 Organisms use homeostasis to maintain a “steady state” or internal
balance regardless of external environment
 In humans, body temperature, blood pH, and glucose concentration
are each maintained at a constant level
 Regulation of room temperature by a thermostat is analogous to
homeostasis
Figure 32.4
Response:
Heating stops.
Room
temperature
decreases.
Sensor/
control center:
Thermostat
turns heater off.
Stimulus:
Room
temperature
increases.
Set point:
Room temperature
at 20C
Stimulus:
Room
temperature
decreases.
Room
temperature
increases.
Response:
Heating starts.
Sensor/
control center:
Thermostat
turns heater on.
 Animals achieve homeostasis by maintaining a variable at or near a
particular value, or set point
 Fluctuations above or below the set point serve as
a stimulus; these are detected by a sensor and trigger a response
 The response returns the variable to the set point
 Homeostasis in animals relies largely on negative feedback, a
control mechanism that reduces the stimulus
 Homeostasis moderates, but does not eliminate, changes in the
internal environment
 Set points and normal ranges for homeostasis are usually stable, but
certain regulated changes in the internal environment are essential
 Osmoregulation: control solute concentrations and
balance water gain/loss
 Excretion: removal of nitrogenous wastes from body
Types of Nitrogenous Wastes:
1. Ammonia – water soluble, very toxic; aquatic animals
2. Urea – produced by liver; less toxic, conserves water;
most vertebrates
3. Uric acid – excreted as paste or crystals; birds & reptiles
Types of Nitrogenous Wastes
Various forms of excretory systems
Protonephridia - Platyhelminthes (Planaria)
Metanephridia - Annelida
Malpighian tubules – Insects, arthropods
Kidneys - Vertebrates
Least  Most Complex:
Protonephridium: closed tubes lacking an internal
opening capped by a cellular unit called flame bulb. Urine
passes out of small pores.
2. Metanephridia: internal openings collect body fluids
into a long tube surrounded by capillaries. Urine exits out
pores.
3. Malpighian tubes: remove N waste from hemolymph,
located near digestive tract. Secretes dry waste with feces.
4. Kidneys: compact organs containing tubules surrounded
by capillaries. Functions in water and blood filtration,
excretion of N waste and salt
1.
How to make urine:
 Water and solutes enter filtrate; blood
cells and proteins remain in body
fluid.
 Reclaim glucose, vitamins,
hormones
 Add toxins and excess ions
 Filtrate leaves body as urine
Mammalian Excretory System
Nephrons: functional units of the kidney
• Glomerulus: filtrate forced into
Bowman’s capsule.
• Blood cells and proteins DO
NOT enter filtrate
Processing of blood filtrate:
1. Proximal tubule: secretion & reabsorption change
2.
3.
4.
5.
volume and composition of filtrate
 Bicarbonate, NaCl, water is absorbed
Descending loop of Henle: reabsorb water
Ascending loop of Henle: reabsorb salt
Distal tubule: K+ and NaCl levels regulated
Collecting duct: filtrate becomes more concentrated;
minimize water loss
From blood filtrate to urine
SECRETION
FILTRATION
REABSORPTION
EXCRETION
Hormones
 Antidiuretic Hormone (ADH):
 urine concentration, reduce H2O
loss
 Also called vasopressin
 Renin/angiotensin II: raise
blood pressure
 Aldosterone:  Na+
reabsorption,  H2O retention,
blood volume, pressure
Blood
Pressure
Regulation
 Urine exits kidney
through Ureters
 Bladder: stores urine
 Urethra: urine exits
body
Believe it or not…
 Your kidneys are only 4 in long and weigh about 5 oz (weight of







½ unfinished can of pop)
Usually we urinate 1.5-2.5 liters/day
44 gallons of blood is filtered by kidneys everyday-2 bathtubs
full
Fresh urine is cleaner than spit, cleaner than your hands after
they have been washed and cleaner than the sandwich you will
eat for lunch
Gandhi drank urine every day (Tantric Yoga practice)
Gladiators brushed their teeth with it
Colonial housewives cleaned their home with it
1st football=pig bladder
Thermoregulation:
 Thermoregulation is the process by which animals maintain an




internal temperature within a tolerable range
Conduction is the process by which heat moves from a place of
higher temps to a place with lower temps
Convection is heat transfer caused by airflow
Evaporation is the process by which water leaves our bodies in the
form of water vapor
Radiation is the loss of heat through ejection of electromagnetic
waves
Figure 32.6
Radiation
Convection
Evaporation
Conduction
Endothermy and Ectothermy
 Endothermic animals generate heat by metabolism; birds and
mammals are endotherms
 Ectothermic animals gain heat from external sources; ectotherms
include most invertebrates, fishes, amphibians, and nonavian reptiles
Figure 32.8
Sensor/control
center: Thermostat
in hypothalamus
Response: Sweat
Response:
Blood vessels
in skin dilate.
Stimulus:
Increased body
temperature
Body
temperature
decreases.
Homeostasis:
Internal body
temperature of
approximately
36–38C
Body
temperature
increases.
Stimulus:
Decreased body
temperature
Response:
Blood vessels
in skin constrict.
Response: Shivering
Sensor/control
center: Thermostat
in hypothalamus
Endocrine signals trigger homeostatic
mechanisms in target tissues
 There are two major systems for controlling and coordinating
responses to stimuli: the endocrine and nervous systems
 In the endocrine system, signaling molecules released into the
bloodstream by endocrine cells reach all locations in the body
 In the nervous system, neurons transmit signals along dedicated
routes, connecting specific locations in the body
Figure 32.9
(a) Signaling by hormones
(b) Signaling by neurons
Stimulus
Stimulus
Endocrine
cell
Cell
body of
neuron
Nerve
impulse
Hormone
Axon
Signal
travels to
a specific
location.
Signal
travels
everywhere.
Blood
vessel
Nerve
impulse
Axons
Response
Response
WARM-UP
1. What is the principle of countercurrent
exchange?
2. (Review) What are the 4 classes of
macromolecules?
3. You eat a piece of candy. List the structures
it passes through as it travels through your
alimentary canal.
4. Where does most of the digestion of the
candy in #3 happen?
Chapter 33: Animal Nutrition
What you need to know:
 Major compartments of alimentary canal
(organs) – and their contributions to animal
nutrition.
 Digestive glands: salivary, pancreas, liver,
gall bladder – and their contributions to
animal nutrition.
 Digestion of carbs, proteins, fats, nucleic
acids.
Essential Nutrients: required by cells,
obtained through food
 Four classes of essential nutrients:
 Essential amino acids (8)
 Essential fatty acids
 Vitamins (13) - fat-soluble, water-soluble
 Minerals
Dietary Deficiencies
 Undernourished: diet is deficient in calories, not
enough energy
 Malnourishment: missing 1+ essential nutrients
Herbivore licks exposed salts and
minerals lacking in plants.
The main stages of food processing:
1. Ingestion: eating
2. Digestion: breakdown of food into small


3.
4.
molecules
Mechanical (chewing, grinding)
Chemical (enzymes) amylase in saliva
Absorption: cells take up nutrients
Elimination: pass undigested materials from
digestive system
Digestive Compartments
 Most animals process food in specialized
compartments
 Intracellular: digestion of food inside cells by
food vacuoles
 Ex. phagocytosis, pinocytosis, sponges
 Extracellular: food broken down outside of cells
 Gastrovascular cavity (simple) or alimentary
canal (complex)
Specialized organs for digestion in Humans
 Digestive system = alimentary canal + glands
 Glands = salivary glands, pancreas, liver, and
gallbladder
Q: Can you name the organs of the human
alimentary canal in order?
 Peristalsis: push food through rhythmic
contractions of muscles in the wall of the canal
 Esophageal Sphincters: valves (trapdoors)
regulate the movement of material between
compartments
Digestion of Macromolecules:
 Mouth = carbs
 Stomach = proteins
 Small Intestine = carbs, proteins, fats, nucleic
acids
Digestion in the Mouth
 Oral cavity: mechanical, chemical digestion
 Salivary glands: saliva lubricates food
 Teeth chew food into smaller particles
 Salivary amylase: breakdown glucose polymers
 Saliva contains mucus, a viscous mixture of
water, salts, cells, and glycoproteins
 Pharynx: back of throat
 Epiglottis: flap of cartilage, covers trachea when
swallowing
 Esophagus: food tube (pharynx  stomach)
Digestion in the Stomach
 The stomach stores food and secretes gastric
juice, which converts a meal to acid chyme
 HCl: pH 2, kills bacteria & denatures proteins
 Pepsin: enzyme (protease) that hydrolyze
proteins into smaller peptides
 Pepsinogen (inactive)  pepsin (active) by HCl
 Mucus: protects lining of stomach
 Gastric ulcers: lesions in the lining, caused mainly
by bacterium Heliobacter pylori
Digestion in the Small Intestine
 SI = major organ of digestion and absorption
 Pass through the Panama Canal of the body: the
PYLORIC SPHINCTER
 Duodenum: first section, digestive juices,
major chemical digestion
 Digestive juices:
 Pancreas: bicarbonate (basic), trypsin &
chymotrypsin (proteases); lipase (fats);
amylase (carbs); nuclease (DNA, RNA)
 Bile: made in liver, stored in gall bladder
 Emulsify fats (make smaller droplets)
Hormones that coordinate digestion:
Gastrin: produced by stomach, production of gastric
juices
Entrogastrin: produced by SI (duodenum),
peristalsis to allow time for fat digestion
Secretin & CCK (cholesystokinin): secreted by SI
(duodenum), flow of digestive juices from pancreas &
gall bladder
Absorption in the Small Intestine
 Villi and microvilli increase surface area
 Villi  capillaries  hepatic portal vein  liver 
heart
 Liver: distribute nutrients, detox, glucose storage
(glycogen)
Absorption in the Large Intestine
 LI = colon
 Function = compact waste,
reabsorb water
 Cecum: pouch where SI & LI
meet, ferment plant material
 Appendix = extension of
cecum, role in immunity
 Rectum: end of LI, feces
stored until elimination
Evolutionary adaptations of vertebrate digestive
systems correlate with diet
 Dentition: teeth correlate with diet
 Herbivores: longer alimentary canal, longer
cecum
Mutualistic Adaptations
 Many herbivores have fermentation chambers,
where mutualistic microorganisms digest
cellulose (ruminants)
Homeostatic Mechanisms
 Vertebrates store excess calories as glycogen in
the liver and muscle cells, and as fat in adipose
tissue
 Overnourishment can lead to obesity
 Leptin: hormone, suppresses appetite
Glucose Homeostasis
Closing questions
List the locations where each of the 4 macromolecules are
chemically digested.
2. Where do vertebrates store excess calories?
3. Draw and label the structure of a human heart.
4. List the pathway of a single red blood cell through the heart.
1.
Circulation & Gas Exchange
Chapter 34
What you need to know:
 Circulatory vessels, heart chambers, route of mammalian







circulation
Evolution of the heart from 24 chambers
How RBC’s demonstrate structure/function
Blood pressure
Cardiovascular disease (Roles of diet, BP, genetics)
General characteristics of a respiratory surface
How O2 and CO2 are transported in blood
Pathway of O2 from airRBCtissues
Transport systems (circulation) linked with gas
exchange (respiration)
 Diffusion of gases only rapid across small distances
Basic:
Cells in direct
contact with
environment
Ex. sponges
Gastrovascular
Cavity:
For digestion &
distribute substances
Ex. jellies, flatworms
Circulatory System:
Moves fluid to
tissues & cells for
exchange
Ex. larger animals
Circulatory System = Blood + Vessels + Heart
Open circulatory system: blood
bathes organs directly
• Blood + lymph = hemolymph
• Heart pumps hemolymph into sinuses
• Ex. arthropods, mollusks
Closed circulatory system: blood
contained in vessels & pumped around
body
• Blood and fluid separate
• Ex. annelids, cephalopods,
vertebrates
Figure 42.10a
Valve
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Capillary
Smooth
muscle
Connective
tissue
Artery
Vein
Arteriole
Venule
Types of Blood Vessels
arterioles
venules
ARTERIES
CAPILLARIES
VEINS
 Blood away
 Connect
 Blood back
from heart
 High
pressure
 Thick,
strong
walls
 Pulse
arteries
 Single-cell
thick walls
 Exchange of
O2/CO2
heart
 Low pressure
 Thin-walled,
large
diameter
 Valves prevent
backflow
 Blood enters through an atrium and is pumped out through a
ventricle
 Fish = single circulation pathway, 2 chambers
 Double circulation: amphibians, reptiles, mammals
Double circulation pathways in vertebrates
Pathway of blood through heart
Figure 42.6
Capillaries of
head and forelimbs
Superior vena cava
Pulmonary
artery
Capillaries
of right lung
Pulmonary
vein
Right atrium
Right ventricle
Pulmonary
artery
Aorta
Capillaries
of left lung
Pulmonary vein
Left atrium
Left ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and hind limbs
Cardiac cycle
 Systole: contraction or pumping phase
 Diastole: relaxation or filling phase
 Heart rate: # beats/minute (72 bpm resting)
 Stroke volume: amount of blood pumped by L. ventricle during
contraction (~70 ml)
Figure 42.8-3
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
Valves: prevent backflow of blood
 The atrioventricular (AV) valves (tricuspid, bicuspid)
separate each atrium and ventricle
 The semilunar valves control blood flow to the aorta and
the pulmonary artery
 “Lub-dup” sound = blood against closed AV valves (lub) /
the semilunar (dup) valves
 Heart murmur: backflow of blood through a defective
valve
Sinoatrial (SA) node: pacemaker of heart, in right
atrium
 The pacemaker is regulated by two portions of the nervous
system: the sympathetic and parasympathetic divisions
 The sympathetic division speeds up the pacemaker
 The parasympathetic division slows down the pacemaker
 The pacemaker is also regulated by hormones (epinephrine)
and temperature
Blood Pressure
 BP = systolic/diastolic
pressure
 Systolic: heart contracts
 Diastolic: heart relaxed
 Normal: 120/70
 Pulse: rhythmic bulging of
artery walls with each
heartbeat
Using a Sphygmomanometer
Blood pressure reading: 120/70
1
3
2
120
120
70
Artery
closed
Sounds
audible in
stethoscope
Sounds
stop
Figure 42.13
Direction of blood flow
in vein (toward heart)
Blood returning
to heart
through veins
and venules
Valve (open)
Skeletal muscle
Valve (closed)
Lymphatic System: returns lost fluid and proteins to
blood as lymph
 Lymph Nodes: filter
lymph, house WBC’s
 Immune system role
Blood
 Plasma (55%) – water, ions, proteins, gases, nutrients, wastes,
hormones
 Cells (45%) – RBC, WBC, platelets
 Develop from stem cells in bone marrow
 Red blood cells (erythrocytes): O2 transport via hemoglobin
 White blood cells (leukocytes): fight infection
 Platelets (cell fragments): blood clotting
Figure 42.17
Cellular elements 45%
Plasma 55%
Constituent
Water
Solvent for
carrying other
substances
Ions (blood
electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering,
and regulation
of membrane
permeablity
Plasma proteins
Albumin
Fibrinogen
Leukocytes (white blood cells)
Separated
blood
elements
5,000–10,000
Functions
Defense and
immunity
Lymphocytes
Basophils
Eosinophils
Neutrophils
Osmotic balance,
pH buffering
Monocytes
Platelets
250,000–400,000
Clotting
Immunoglobulins Defense
(antibodies)
Substances transported by blood
Nutrients
Waste products
Respiratory gases
Hormones
Number per L
(mm3) of blood
Cell type
Major functions
Erythrocytes (red blood cells)
5–6 million
Blood
clotting
Transport
of O2 and
some CO2
Figure 42.18
2
1
3
Collagen fibers
Platelet
plug
Platelet
Fibrin
clot
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Enzymatic cascade
Prothrombin

Thrombin
Fibrinogen
Fibrin
Red blood cell
Fibrin clot formation
5 m
Cardiovascular Disease
 Atherosclerosis: buildup of plaque deposits within arteries
 Heart attack (myocardial infarction): blockage of one or
more coronary arteries
 Stroke: rupture or blockage of arteries in the head
 Hypertension: high blood pressure; promotes
atherosclerosis and increases the risk of heart attack and stroke
Figure 42.20
Lumen of artery
Endothelium
Smooth
muscle
1
LDL
Foam cell
Macrophage
Plaque
2
Extracellular
matrix
Plaque rupture
4
3
Fibrous cap
Cholesterol
Smooth
muscle
cell
T lymphocyte
Closing questions
How does the heart beat?
2. What are the 3 types of blood cells and their function?
3. What is the function of the lymphatic system?
4. List the pathway of one molecule of O2 from the air into
your pinky toe.
1.
Respiration
 Gas exchange supplies O2 for cellular respiration and
disposes of CO2
 Partial pressure = pressure exerted by a particular gas in a
mixture of gases
 Gases always diffuse from higher partial pressure  lower
partial pressure
 Respiratory media: O2 in air or water
 Respiratory surface: body wall, skin, gills, tracheae, lungs
 Characteristics:
 Moist
 Large surface area-to-volume ratio
 Larger animals: associated with vascular system
Gills in aquatic animals
Coelom
Gills
Parapodium
(functions as gill)
(a) Marine worm
Gills
Tube foot
(b) Crayfish
(c) Sea star
Fish gills: absorb O2 through countercurrent
exchange (blood flows opposite of water)
Tracheal systems in insects
Respiratory system in birds (lungs + air sacs)
Mammalian respiratory system
Pathway of O2
 Nose/mouth: filtered, warmed, humidified
 Pharynx
 Larynx: contains vocal cords
 Trachea: windpipe; lined with cartilage
 Bronchi: branches to lungs
 Bronchioles
 Alveoli: air sacs for gas exchange
 Mucus: traps particles
 Cilia: sweeps particles up to pharynx
Alveoli
Figure 42.30a
1 Inhaled air
8 Exhaled air
Alveolar
epithelial
cells
2 Alveolar
spaces
CO2
O2
Alveolar
capillaries
7 Pulmonary
arteries
3 Pulmonary
veins
6 Systemic
veins
4 Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
5 Body tissue
(a) The path of respiratory gases in the circulatory
system
Diaphragm: dome-shaped muscle
separating thoracic/abdominal cavities
Control of Breathing in Humans
 Control center =
medulla oblongata
 Responds to pH changes in
blood
 High CO2  carbonic acid
forms  lowers pH
 Sensors in the aorta and
carotid arteries
Adaptations for gas exchange
 Hemoglobin: respiratory pigment in vertebrates
 4 subunits, each with heme group with iron (Fe)
 Can carry 4 molecules of O2
 Bohr shift: O2 dissociates from hemoglobin when blood pH is low
 Arthropods, mollusks:
 blue hemocyanin pigment
 contains copper (Cu)
How CO2 is transported
1.
2.
3.
Bicarbonate ions (70%)
Hemoglobin (23%)
Dissolved in plasma (7%)
Respiratory Adaptations of Diving
Mammals
 Diving mammals have evolutionary adaptations that allow
them to perform extraordinary feats
 For example, Weddell seals in Antarctica can remain
underwater for 20 minutes to an hour
 For example, elephant seals can dive to 1,500 m and remain
underwater for 2 hours
 High blood to body volume ratio
 Stockpile O2 and deplete it slowly
 Store oxygen in their muscles in myoglobin proteins
Respiratory Disorders
 Asthma: airways constricted
 Bronchitis: bronchi swollen and clogged
 Pneumonia: inflammation of lung caused by infection
 Tuberculosis (TB): infectious disease caused by M. tuberculosis
 Emphysema: lose elasticity of lung tissue
 Lung Cancer: abnormal cell growth in lungs