Homeostasis and Endocrine Signaling
Tissues• Figure 32.2
• 4 major types:• Epithelial – found on outside of the body and lining organs and
cavities.
• Muscle – 3 types• Cardiac – heart tissue, involuntary• Smooth – involuntary actions in body, organs, blood vessels• Skeletal – muscle that moves, attaches to bone, voluntary
• Nervous tissue – the neuron, sends impulses, communication• Glia cells are nerve helping cells to the neurons
• Connective tissue – diverse group of tissues scattered throughout body and extracellular matrix• Bone – calcified hard matrix• Blood – liquid matrix• Cartilage – ear, nose, gel like matrix• Dense fibrous – tendons and ligaments• Adipose - fat• Areolar – loose fibrous connecting tissue
Regulator or Conformer?• Animals that are regulators uses internal mechanisms to
control internal change – endothermic, homeothermic, warm blooded
• Animals that are conformers – internal condition changes in accordance with external changes, ectothermic, cold blooded
• Homeostasis – maintenance of a constant internal balance• examples,- body temp, blood glucose levels…• Negative feedback – when body is out of homeostasis and it is
brought back.• Positive feedback – when body is brought out of homeostasis
purposely for a short period of time, childbirth and oxytocin
Thermoregulation (heat)• Figure 32.3
Figure 32.4
Sensor/control center:Thermostatturns heater off.
Sensor/control center:Thermostatturns heater on.
Stimulus:Room
temperatureincreases.
Stimulus:Room
temperaturedecreases.
Roomtemperatureincreases.
Roomtemperaturedecreases.
Set point:Room temperature
at 20C
Response:Heating stops.
Response:Heating starts.
Endocrine system• Endocrine system – communication via hormones that are
released by endocrine glands into the blood stream.• Hormones – chemical messengers• Exocrine glands – figure 32.11
• Exocrine glands – integumentary system, release product to cavity or outside the body, sweat.
• Nervous system – rapid communication using neurons and nerve impulses
• All run by Stimulus/Response mechanism
Figure 32.11a
PancreasInsulinGlucagon
Testes(in males)Androgens
Parathyroid glandsParathyroid hormone (PTH)
Ovaries (in females)EstrogensProgestins
Thyroid glandThyroid hormone(T3 and T4)Calcitonin
Pineal glandMelatonin
Major Endocrine Glandsand Their Hormones
Hypothalamus
Pituitary gland Anterior pituitary
Posterior pituitaryOxytocinVasopressin(antidiuretichormone, ADH)
Adrenal glands(atop kidneys)
Adrenal medullaEpinephrine and norepinephrine Adrenal cortexGlucocorticoids Mineralocorticoids
Figure 32.8 Sensor/controlcenter: Thermostatin hypothalamus
Stimulus:Decreased body
temperature
Bodytemperatureincreases.
Bodytemperaturedecreases.
Homeostasis:Internal body
temperature ofapproximately
36–38C
Response:Blood vesselsin skin dilate.
Response: Shivering
Sensor/controlcenter: Thermostatin hypothalamus
Response:Blood vesselsin skin constrict.
Stimulus:Increased body
temperature
Response: Sweat
Figure 32.9
Cellbody ofneuron
Response
Hormone
Nerveimpulse
Signaltravelseverywhere.
Signaltravels toa specificlocation.
Response
Stimulus Stimulus
Nerveimpulse
Blood vessel
Endocrinecell
(a) Signaling by hormones
Axons
Axon
(b) Signaling by neurons
Osmoregulation (fluids)• How animals control solute concentrations in the interstitial
fluid and balance water gain and loss
• Excretory system – releasing of nitrogenous and metabolic waste products (kidney)
• Osmoconformer – being isoosmotic with its surroundings, marine animals
• Osmoregulator – to control internal osmolarity independent of the environment. Allows animals to live in freshwater/terrestrial habitats.
Nitrogenous wastes in animals• 32.16
Figure 32.16
Most aquaticanimals, includingmost bony fishes
Proteins Nucleic acids
Aminoacids
Nitrogenousbases
Amino groups
Mammals, mostamphibians, sharks,
some bony fishes
Many reptiles(including birds),
insects, land snails
Ammonia Urea Uric acid
Figure 32.16a
Most aquaticanimals, includingmost bony fishes
Mammals, mostamphibians, sharks,
some bony fishes
Many reptiles(including birds),
insects, land snails
Ammonia Urea Uric acid
The excretory process• Urine formation: 32.17
Figure 32.17
CapillaryFiltration
Excretorytubule
Filtrate
Reabsorption
SecretionU
rine
Excretion
The Kidney – figure 32.19
Figure 32.19b
Kidney StructureRenal cortex
Nephron Organization
Nephron Types
Renal medulla
Renal artery
Renal vein
Renal pelvis
Ureter
Renal cortex
Renal medulla
Cortical nephron
Juxtamedullary nephron
Collectingduct
Branch ofrenal vein
Vasarecta
Efferentarteriole
fromglomerulus
Distaltubule
Afferent arteriolefrom renal artery
GlomerulusBowman’scapsule
Proximaltubule
Peritubularcapillaries
Descendinglimb
Ascendinglimb
Loop of
Henle
Figure 32.19bc Nephron Organization
Collectingduct
Branch ofrenal vein
Vasarecta
Efferentarteriole
fromglomerulus
Distaltubule
Afferent arteriolefrom renal artery
GlomerulusBowman’scapsule
Proximaltubule
Peritubularcapillaries
Descendinglimb
Ascendinglimb
Loop of
Henle
Figure 32.20
Filtrate
OUTERMEDULLA
H2OSalts (NaCI and others)HCO3
−
Glucose, amino acids
H
Some drugs
Passive transportActive transport
KeyINNERMEDULLA
CORTEX
Descending limbof loop of Henle
H2O
Interstitialfluid
NH3H
NutrientsHCO3
− K
NaCIProximal tubule
H2O
Thick segmentof ascending limb
H
Urea
HCO3−
K
NaCI
Distal tubuleH2O
Thin segmentof ascending limb
NaCI
H2ONaCI
NaCI
Collectingduct
1
23
5
4
3Urea
Adaptations • Based on where you live, there are adaptations to the kidney
• Hyperosmotic urine (dessert animals) – long loops of Henle that extend deep into the medulla
• Birds – shorter loop of Henle, les concentrated urine compared to mammals – uric acid is product to help conserve water.
Homeostatic regulation of kidney
• 32.23 antidiruretic hormone
Figure 32.23-3
Distaltubule
H2Oreabsorption
STIMULUS:Increasein blood
osmolarity
Drinkingof fluids
Increasedpermeability
Osmoreceptorstrigger release
of ADH.Thirst
ADH
Collecting duct
Homeostasis