Bio B Exam 3
What is the body's response to cold temps in terms of blood flow?
Vasoconstriction to reduce heat conductance. Increased heat transfer from arteries to veins and decreased heat transfer from skin to environment.
What is the body's response to high temps in terms of blood flow?
Vasodilation to increase heat conductance. Reduced heat transfer from arteries to veins and increased heat transfer from skin to environment.
What hormones does the skin produce and secrete?
Vitamin D
True or false: Vitamin D is very active.
Vitamin D itself is not very active, but in the liver it receives an -OH group, and in the kidneys another -OH to become (1, 25) Dihydroxyvitamin D (1,25 dihydroxycholcalciferol), the active form
Describe an organ that includes all four tissues types. (pg 820)
WALL OF A GUT -lined with a sheet of columnar epithelial cells, which secrete hormones or digestive juices or absorb nutrients from the gut -connective tissue called mucosa, which has blood vessels, neurons and glands -smooth muscle tissue enables the gut to mix food with digestive juices -a network of neurons between the muscle layers controls these movements
In convection, is the value of K greater for water or air?
Water
Why do humans blush?
We have evolutionary adaptations to give us heat-loss portals on non-furred areas, such as our hands, feet and face. In these areas, specialized blood vessels can open up and act like radiators to disperse heat. (pg 815)
Describe skeletal muscle
responsible for locomotion and other body movements (e.g., breathing, shivering, facial expressions).
How much of the total body protein does collagen make?
25% (pg 818)
Intracellular fluid is __ of total body water
66% Exchanges molecules with interstitial fluid
Interstitial fluid
80% of extracellular fluid that bathes the cells of the body
What percent of water that goes through the kidneys gets reabsorbed?
99%
What statement about brown fat is true? A)It produces heat without producing too much ATP. B)It insulates animals acclimated to cold. C)It is a major source of heat production for birds. D)It is found only in hibernators. E) It provides fuel for muscle cells
A
Q10=3. What does this mean?
A Q10 of 3 means that the reaction's rate triples with each 10 degrees celsius rise in temperature.
What does a Q10 value of 1 mean? 2?
A Q10 value of 1 means the reaction is not temperature-sensitive. A Q10 of 2 means that the reaction's rate doubles with each 10 degrees celsius rise in temperature.
The total balance of heat production and heat exchange is referred to as what? (pg 823)
An energy budget, based on the simple fact that if the body temperature of an animal is to remain constant, the heat entering the animal must equal the heat leaving it. -gives us the ability to quantify and compare the thermal adaptations of animals by determining what component of the energy budget is affected.
How does hormonal control work in insects having complete metamorphic (larva to pupa to adult)?
An example is the silkworm moth. The egg hatches into a 1st instar larva that has a high amount of juvenile hormone in its body. As long as the level of juvenile hormone stays high, larvae molt into the next (larger) larval stage; when the juvenile hormone level decreases, pupae are formed. No juvenile hormone is produced in the pupae, so they molt into adults.
What is the growth stage between each insect molt called?
An instar
What human feature makes complex multicellular organisms possible?
An internal environment meakes complex multicellular animals possible by making it possible for an animal to occupy habitats that would kill its cells if they were directly exposed to external conditions. As long as conditions in the body's internal environment are held within certain limits, cells are protected from the changes and harsh conditions of the external environment. (pg 816)
At what temperature does an object lose heat via radiation?
Any object above absolute zero (0K) loses heat via radiation.
How does aspirin affect fevers?
Aspirin lowers the set point, in addition to being an analgesic (pain killer).
Which of the following would cause a decrease in the hypothalamic temperature set point for metabolic heat production? A)Entering a cold environment B)Taking an aspirin when you have a fever C)Arousing from hibernation D)Getting an infection that causes a fever E) Cooling the hypothalamus
B
What type of heat exchange involved heat transferring directly between two objects at different temperatures when they come into contact? Example? (pg 823)
Conduction An icepack on a sprained ankle
What hormones do adipose tissue produce and secrete?
Hormone: Leptin (inhibits desire to eat)
What hormones do the heart produce and secrete?
Hormone: atrial natriuretic peptide
How are hormones formed and circulated?
Hormones are secreted by endocrine cells (often aggregated in endocrine glands). In the case of circulating hormones, the hormones diffuse into the extracellular fluid, and are distributed by the circulatory system, ultimately affecting their target cells.
How are hormones classified by structure?
Hormones can be classified into three main groups based on structure: Peptides or proteins, Steroid hormones, and Amine hormones
Do hormones work slower or faster than nerve impulse?
Hormones work more slowly than nerve impulses and therefore are less useful for controlling very rapid actions. Among many other things, hormones coordinate longer-term developmental processes such as reproductive cycles.
What causes Diabetes mellitus?
Diabetes mellitus is a disease caused by a lack of the protein hormone insulin (Type I), or a decreased number or sensitivity of insulin receptors on target cells (Type II).
What is the source of calcium in chicken eggs?
Diet and medullary bone (only found in "laying" females, formation stimulated by estrogens and androgens).
What are side effects of Diabetes mellitus?
EXCESSIVE URINE PRODUCTION
What behaviors can some animals use to regulate body temperature in the natural environment?
Ectoderms, such as lizards, use behaviors include basking in the sun, seeking shade, burrowing, or orienting the body with respect to the sun. Endotherms also use behavioral thermoregulation. Most animals select the best thermal environment whenever possible, for example by seeking shade, breezes, etc. Lizards are an example.
Why is the ability to control blood flow to the skin an important adaptation for an ____ such as the marine iguana of the Galapagos archipelago? (pg 824)
Ectotherm. The Galapagos are volcanic islands that lie on the equator but are bathed by cold ocean currents. The iguanas bask on hot black lava rocks on the shore, but they periodically enter the cold ocean water to feed on seaweed. When iguanas are feeding, they cool to the temperature of the sea. This cooling lowers their metabolism, making them slower, more vulnerable to predators, and incapable of efficient digestion. They therefore alternate between feeding in the cold seawater and basking on the hot rocks. It is advantageous for iguanas to retain body heat as long as possible while swimming and to warm up as fast as possible when basking. They can accomplish these results by changing their heart rate and thus the rate of blood flow to their skin. The rate of warming is greater than the rate of cooling.
Animals may also be classified according to the sources of heat that determine their body temperature: what are they?
Ectotherms and Endotherms:
How do honeybees, which are _____, regulate their temperature? (pg 826)
Ectotherms. During winter, they regulate temperature in the hive by group clustering by worker bees to produce metabolic heat so the brood (eggs and larvae) temperature stays at about 34°C even as temperatures outside of the hive drop well below freezing.
What is the electromagnetic spectrum?
Electromagnetic spectrum: showing range of wavelengths where various objects radiate by virtue of their surface T's. (Note: objects are also radiating in the longer infrared, not shown.)
What is endocrine?
Endocrine refers to cells or glands that do not have ducts leading to the outside of the body; they secrete their products directly into the extracellular fluid. (Exocrine glands have ducts that release their secretions into the gut, onto the skin, etc.)
When environmental temperatures fall below the lower critical temperature, what must occur? ( pg 827)
Endotherms must produce heat to compensate for the heat they lose to the environment. -mammals can use shivering and/or non shivering heat production; birds use only shivering heat production -increased muscle tone and increased body movements
What hormones do the kidney produce and secrete?
Erythropoietin, renin
What type of heat exchange involves heat transferring away from a surface when water evaporates on that surface? Example? (pg 823)
Evaporation Ex: the effect of sweating
Explain how blood is cooled to the brain
Evaporation of water in nasal passages leads to cool venous blood from nasal passages. Cooled arterial blood then goes to the brain at around 40C.
What is the line of conformity?
Extent to which a conformer will conform to its environment
What are the temperature ranges for freshwater environments?
FW: 0C (can be colder in small bodies of water) to ~100C (thermal hot springs).
What does rate of transfer for convection depend on?
Factors controling the rate are similar to those for conduction (T gradient, surface area, "K" value of the fluid, etc). "K" greater for water than for air. Free vs forced (movement of the fluid) convection - wind chill factor
Effect of freezing on organisms
Freezing of body water is lethal for most organisms. - except "freeze tolerant" spp. - "freeze avoiding" species must produce antifreeze, etc.
How do furred mammals control blood flow to the skin? (pg 825)
Fur acts as insulation to keep body heat in, making it possible for mammals to function in cold environments. Why they are active, however, mammals must get rid of excess heat, and it does little good to transport that heat to the skin under the fur. Thus, mammals have specialized blood vessels for transporting heat to their hairless skin surfaces. Heat loss from these areas is tightly controlled by the opening and closing of these blood vessels. When you are cold, the blood flow to your hands and feet decreases and they feel cold, but when you exercise, these same surfaces can get hot quickly.
What are 3 types of corticosteroids?
Glucocorticoids, Mineralocorticoids, Sex Steroids
How do long bones grow?
Growth Hormone (via insulin like growth factors) stimulates long bone growth (cartilage), increasing thickness of the epiphyseal plate. Testosterone eventually closes the epiphyseal plate, stopping long bone growth.
How do multicellular organisms meet their body needs?
Have developed specialized cells that help maintain an internal environment consistent with a more advanced lifestyle.
What exactly is negative feedback?
Information used to counteract the influence that created an error signal, which is a difference between optimal body temperature and actual body temperature. (pg 816)
What is Rathke's Pouch?
Inpocketing of the roof of the mouth that forms the anterior pituitary
What are the approximate percentages of animal species?
Insects: 70% Vertebrates: 4% Mammals: 1%
How is blood cooled by evaporated cooling of mucus membranes?
Inspiration: incoming air is warmed and humidified, cooling the nose. The air then passes to the lungs. Expiration: Outgoing air is cooled and loses water, wetting the nose.
Where are insulin and glucagon produced?
Insulin and glucagon are produced in the pancreas in cell clusters called islets of Langerhans.
True or false: Insulin is required for glucose uptake by all cells.
Insulin is required for glucose uptake by most cells, but not nerve cells.
What hormones does skeletal muscle produce and secrete?
Irisin
What is the advantage of the freely flying sphinx moths raising thoracic temperatures before flying?
It increases flight muscle power, efficiency, etc.
What happens to blood flow to animal ears as core temperature increases?
It increases, leading to an increased ear temperature. Thus, heat loss from ears is higher as the core temperature increases
What is a fever?
It is a rise in body temperature in response to pyrogens (substances that raise set point). It is an adaptive response the helps the body fight pathogens.
How is arterial blood cooled to 40C prior to entering the brain?
It is cooled by countercurrent heat exchange prior to entering the brain.
Why is it crucial that the cells of epithelial tissue be densely packed into tight sheets? (pg 817 and Figure 40.3)
It is crucial for creating boundaries between the inside and outside of the body and between body compartments.
What is evaporative cooling? What are the associated problems?
It is the major adaptation as TB rises above set point. Problems: - costs energy - water loss - loss of effectiveness at hi humidity 1. Sweating (salt: Na+ and Cl- loss) 2. Panting
In humans, one study found less brown fat activity in obese than in lean individuals. What does this mean? (pg 828)
It led to the hypothesis that individual differences in propensity for weight gain may be related to the amount of brown fat in an individual.
As environmental temperature rises within an endotherm's thermoneutral zone, what will the animal do? (pg 829)
It will get rid of more of its metabolic heat by increasing blood flow to the skin, seeking shade and cool breezes, and decreasing activity.
What is the equation for the Rate of heat transfer via conduction?
KA(T1-T2) - temperature gradient between the two (T1-T2) - surface area in contact (A) -coefficient of thermal conductivity (K, an expression for the ease of heat flow in a material) which is high for metals, etc.; low for fur, feathers, etc.
Does heat transfer between solids go from the higher temperature solid to lower temperature or from the lower temperature to the higher temperatures?
always from higher to lower T
What are ectotherms?
animals that depend on external heat sources to maintain body temperature (a turtle basking in the sun, or not). -most animals except mammals and birds
What are endotherms?
animals that regulate body temperature by producing heat metabolically - regulate it by (1) generating more metabolic heat and (2) controlling heat loss.
Endogenous pyrogens
are produced by cells of the immune system when they are challenged.
When will a species wake up from hibernation? (pg 830)
arousal from hibernation occurs when the hypothalamic set point returns to a normal level.
Which 2 corticosteroids can have similar properties?
Mineralocorticoids and glucocorticoids
Where do most biological Q10 values lie?
Most biological Q10 values are between 2 and 3, meaning that reaction rates double or triple as temperature increases by 10°C.
Where does most calcium in the body lie?
Most calcium in the body is in the bones (99%). About 1% is in the cells, and only 0.1% is in the extracellular fluids.
What is the link between physiological processes and temperature?
Most physiological processes are temperature-sensitive, going faster at higher temperatures (as long as the T is not lethal).
What are the most abundant tissues in the body?
Muscle tissue
What tissues are the most prominent examples of effectors?
Muscle tissue because they affect changes in the internal environment (pg 818)
Animal physiology encompasses what?
Organisms Organ Systems Organs Cells Organelles Membranes
What do osteoblasts do?
Osteoblasts secrete the protein matrix and use circulating calcium to build new bone. As the bone is laid down the osteoblasts are surrounded and develop into osteocytes.
What do osteoclasts do?
Osteoclasts break down bone and release calcium to the blood.
Describe the typical ("cold") fish circulatory system. (pg 825)
Oxygenated blood from the gills collects in a LARGE dorsal vessel, the aorta, and travels through the center of the fish, distributing blood to all organs and muscles.
Describe the "hot" fish circulatory system. (pg 825)
Oxygenated blood from the gills collects in a SMALL central dorsal aorta. Most of their oxygenated blood is transported in large side vessels just under their skin. The cold oxygenated blood leaving the gills is thus kept close to the surface of the fish as blood flows posteriorly to the swimming muscles. Smaller vessels transport this cold blood into muscle mass, and these small vessels run parallel to the vessels carrying warm blood from the swimming muscles back toward the heart. Because the vessels carrying the cold blood into the muscles are in close contact with the vessels carrying the warm blood away, heat flows from the warm to the cold blood by conduction and is therefore retained in the muscle mass. -This adaptation is called countercurrent heat exchange. It keeps heat within the muscles, enabling these fish to have an internal body temperature considerably higher than the water temperature. This allows "hot" fish to swim faster.
Why don't paracrine cells generally get into the circulatory system?
Paracrine hormones are released in tiny amounts, or are inactivated rapidly by enzymes, and therefore are taken up efficiently only by local cells.
What type of hormonal regulation for calcium causes the blood concentration of calcium to rise?
Parathyroid hormones and vitamin D PTH increase bone turnover by activating both osteoblasts and osteoclasts, which shifts calcium from bone to blood and also stimulates calcium retention by the kidneys Vitamin D increases calcium absorption in the kidneys and the guts.
What are some vascular controls of body temperature?
Peripheral vasoconstriction and dilation Heat exchangers Heat sinks (Thermal Windows)
What is an example of physiological color change using chromatophores?
Pigment aggregation and dispersal within black-pigmented chromatophores (melanophores) from the skin of a codfish (Gadus morhua)
What are examples of endocrines?
Pineal, thyroid gland, parathyroid glands, adrenal gland, gonads, hypothalamus, anterior pituitary, posterior pituitary, thymus, pancreas
Behavioral adaptations to cold
Postural (decrease SA / Volume) Huddling (several small rodents have communal nesting, but only in the winter) Microhabitat selection
What are the adjustments to increasing Tb and Ta?
Remember time frames. 1. Increase heat loss via conduction, convection and radiation: - insulation changes - vascular - behavioral (posture, etc) 2. Metabolic Rate 3. Evaporative water loss 4. Heat Storage
What are the two major differences between endotherms and ectotherms? (pg 822)
Resting metabolic rates- the sum total of all energy expenditures in their bodies when at rest Responses to changes in environmental temperature
What are examples of unexpected endothermic homeotherms?
SOME LARGE INSECTS AND HONEYBEES -The flight muscles of some, generally large, insects (Sphinx moth, Manduca sexta, and bumblebees, Bombus sp.) must be warmed to 35-40°C before flight can occur. This is achieved by (1) flight muscle contractions (which in some species can operate at hundreds of contraction per second), that generate heat in a manner similar to shivering in mammals and (2) vascular control of heat loss (can stop heart to keep heat in thorax) -Honeybees (Apis mellifera) take this a step further and regulate temperature in the hive by group clustering to produce metabolic heat so the brood temperature stays at about 34°C even as temperatures outside of the hive drop well below freezing.
Components of a negative feedback system
Sensor- monitors the variable Control center- compares the magnitude of variable to the set-point value, integrates the information, and controls the response Effector system- controls the magnitude of the variable, bringing it back to set-point (zero error signal).
What could result from daily, seasonal, etc. temperature changes, given that not all of the Q10's of the various metabolic pathway reactions are identical?
Since not all of the component reactions in a pathway have the same Q10, temperature change can disrupt physiological function, throwing off the balance and integration that cell processes require.
What affect does skin color have on the temperature of the radiating surface?
Skin color doesn't matter much for the radiating surface. However, absorbance of solar radiation (with peak intensity in the visible range) is dependant on surface color.
How do endocrine cells aggregate?
Some endocrine cells aggregate into secretory organs called endocrine glands. In vertebrates, several major endocrine glands make up the endocrine system.
How are endocrine cells distributed?
Some endocrine cells are distributed as single cells within an otherwise non-endocrine tissue. -Digestive hormones, for example, are secreted by isolated endocrine cells in the wall of the stomach and small intestine.
Where does most non-shivering heat producting occur? (pg 827)
Specialized adipose tissue called BROWN FAT
Prefix "eury-" describes what types of organisms?
Species that are extremely tolerant of a wide range of a particular environmental parameter
Prefix "steno-" describes what types of organisms?
Species that are not tolerant of a wide rage of environmental conditions
What are steroid hormones?
Steroid hormones are derived from cholesterol and are therefore lipid-soluble (non-polar) and can diffuse out of the cell that made them, but in the blood they must be bound to carrier proteins. Because they can diffuse through the cell membrane their receptors are usually in the cytoplasm of the target cells.
What is heat transfer via convection?
Takes place between a solid and a fluid (air or water), or between two fluids.
How does heat transfer via conduction occur?
Takes place between two solids in contact with one another (always from higher to lower T) -Direct transfer of the kinetic energy of molecular motion
What is the role of aspirin in combatting fevers? (pg 830)
Taking aspirin lowers your set point back to normal. Now you feel hot, take off clothes, and even sweat until your elevated body temperature returns to normal.
What is the most important parameter controlling the range of organisms?
Temperature
Besides the hypothalamus, what other sensors register environmental temperature? (pg 829)
Temperature sensors in the skin. For example, a change in skin temperature is feedforward information that shifts hypothalamic set points; the set point for metabolic heat production is higher when the skin is colder and lower when the skin is warm.
How do organisms maintain general homeostasis?
To maintain general homeostasis, organisms must either compensate for, or prevent, temperature change.
How do we group animals based on how they deal with changes in environmental temperature? (pg 822)
The classification system is based on the source of heat that predominantly influences the body temperature of the animal.
What does the cytoplasmic domain in water soluble hormones usually do?
The cytoplasmic domain usually initiates the target cell's response, often by activating G-proteins and signal transduction cascades.
Where are the four parathyroid glands at, as they relate to the regulation of calcium levels?
The four parathyroid glands are embedded in the posterior surface of the thyroid gland.
Generally explain the process of homeostasis:
dependent on information received by the control center, specifically feedback information that signals any discrepancy between the set point (the particular desired condition or level) and the actual conditions present.
How do single-celled organisms and simple multicellular animals meet their body needs?
by direct exchange of substances with the external environment.
Ways to decrease convective and radiation heat loss and their time scales?
- insulation (evolutionary, seasonal, immediate via piloerector muscles) - blood flow (immediate, seasonal?, evolutionary) - behavior, posture etc. (immediate) - body size and shape (evolutionary)
Exogenous pyrogens
come from foreign substances such as invading bacteria or viruses.
Examples of microhabitat selection
- out of wind - sunny slope (basking, etc.) - burrow - subnivean (under snow) - burrowing in snow
Peptide YY
- released by cells in small and large intestine. Also a brain neurohormone and neurotransmitter. - inhibits appetite (activity similar to leptin)
What does rate of transfer for conduction depend on?
- temperature gradient between the two (T1-T2) - surface area in contact (A) -coefficient of thermal conductivity (K, an expression for the ease of heat flow in a material) which is high for metals, etc.; low for fur, feathers, etc.
Who developed the hand cooling unit and where?
developed by Craig Heller and colleagues at Stanford
What is the basal lamina?
extracellular matrix that the basal side of epithelial tissue rests on
What hormones do the stomach produce and secrete?
gastrin
What are the challenges that active fish face when trying to conserve metabolic heat? (pg 825)
he muscles of active fish produce a lot of metabolic heat, but they have difficulty retaining any of that heat. Blood pumped from the fish heart goes directly to the gills, where it must come very close to the surrounding water to exchange respiratory gases. So any heat that the blood picks up from metabolically active muscles is lost to the water flowing across the gills.
Advantage of brown fat
hi heat yield with no build-up of toxic metabolites, etc. (only water, carbon dioxide and heat produced)
Describe cardiac muscle
makes up the heart and is responsible for the heartbeat and the pumping of blood.
Main systems involved in homeostasis
nervous system and the endocrine system.
Nervous tissue is composed of:
neurons and glial cells.
Describe how hormones circulate.
"Classical" hormones diffuse into the blood, which distributes them throughout the body. When the hormone message encounters a cell with the proper receptor, it binds and triggers a response. The position of the receptor, either on the outside surface of the cell membrane or in the cytoplasm of the target cell, depends on the nature of the hormone. Size? Water or lipid soluble? Basically, can it diffuse across the cell membrane?
What does the internal environment of multicellular organisms consist of?
(1) the extracellular fluid that bathes every cell, and (2) cells that exchange materials with the extracellular fluid and form tissues and organs.
What is the active form of vitamin D?
(1, 25) Dihydroxyvitamin D (1,25 dihydroxycholcalciferol), the active form.
What is thermogenin?
(Uncoupling protein-1) is a protein in mitochondria of brown fat that uncouples proton movement from ATP production so heat is released without ATP
Terrestrial temperature ranges
- -95oC (-140F) to ~85oC (180F)
What is the function of adipose cells in connective tissue? (pg 819)
- Adipose cells form loose connective tissue that stores lipids. -Adipose tissue, or "fat", is a major source of stored energy. -It also cushions organs -and layers or adipose tissue under the skin can provide a barrier to heat loss.
What are growth factors?
- Growth factors, which stimulate growth and differentiation of cells, are a major class of paracrine hormones. - Growth factors may also act as autocrine hormones: Some of the hormone influences the cell that secreted it, preventing the cell from secreting too much hormone.
Why doesn't high body temperature result in neural problems of animals?
- Heat exchanger cools blood perfusing the brain. - Found in numerous species, especially those capable of long term running (antelope, caribou, wolf, etc) and/or duration of hi TA (camel, orynx, etc, especially if water stressed).
What targets does epinephrine act on?
- In the heart, it stimulates faster (increases HR) and stronger (increases stroke volume, SV) heartbeat to increase cardiac output. CO = HR x SV -Blood vessels in some areas (gut, skin, etc.) constrict to send more blood to skeletal muscles. -In the liver, glycogen is broken down to glucose that is released to the blood to provide quick energy. -In fat tissue, fats are mobilized into the blood as another energy source. -up-regulates nervous system
Aquatic temperature ranges
- Marine: -2 to ~30oC (100+ in and near deep sea vents) - FW: 0oC (can be colder in small bodies of water) to ~100+oC (thermal hot springs)
3 types of receptors for NE and E.
- α-adrenergic, -β-adrenergic -γ (Gamma) Norepi acts mostly on alpha and epi acts mostly on beta
What is the Krogh principle?
-"For every physiological problem there is an animal optimally suited to yield an answer" -use the best model system to study the phenomenon of interest. ex) Optimal animal: i.e., giant axons of squid, polar spp. for lo temperature, desserts for hi T and/or dry conditions, size of animal, etc.
Who was Krogh?
-1874-1949 -Danish physiologist -University of Copenhagen (1916-1945) -Nobel prize in 1920 -Respiratory and vascular physiology, etc. of many different animals
What are the temperature ranges for marine environments?
-2 to about 30C (100+ in and near deep sea vents)
Significance of shivering in humans
-A last stop for heat production -Will cause hypothermia over time -controlled by the hypothalamus
Activation of alpha-2 receptors?
-Activation of alpha-2 receptors inhibits adenyl cyclase
Anterior pituitary
-Adenohypophysis -forms from an inpocketing of the roof of the mouth -secretes tropic hormones
What are the adrenal glands made up of?
-Adrenal medulla (inner) -Adrenal cortex (outer)
What happens after a meal in relation to insulin?
-After a meal, blood glucose levels rise and stimulate the β cells to release insulin. -Insulin (indirectly) stimulates cells to metabolize glucose and/or to convert it to glycogen and fat.
What are organs composed of? (pg 820)
-An epithelium and one or more other kinds of tissue. -Most organs include all four tissue types
Give an example of positive feedback. (pg 817)
-An example is sexual behavior, in which a little stimulation causes more behavior, which causes more stimulation, and so on. -Another example is birth. Contractions of the uterus stretch the birth canal, and stretching stimulates more contractions until the baby is delivered, at which time contractions cease.
What is adaptive hypothermia?
-Animals can save energy by turning down the thermostat to below normal (hypothermia). -Strategy to survive periods of cold and food scarcity -especially useful in small animals
What is elastin?
-Another protein fiber common in connective tissue -It recoils after being stretched, so elastin fibers are abundant in tissues that are regularly stretched such as the walls of the lungs and large arteries -can be stretched to several times its resting length and then recoil.
What hormones are released by the posterior pituitary?
-Antidiuretic hormone (vasopressin) -Oxytocin
How do queen bumblebees thermoregulate?
-As air temperature falls, incubating queens thermoregulate by increasing metabolic rate and thus the rate at which they generate heat -In the cold they swarm closer and in the summer they swarm less tightly -As temps increase they bring water and do evaporative cooling by fanning their wings
How does a fish cope with seasonal changes in temperature?
-Between summer and winter, a slow process of acclimatization compensates for seasonal temperature changes. -ptheir metabolic functions are less sensitive to long term changes in temperature than to short-term changes -One possibility is that a fish may express isozymes with different temperature optima for the summer and winter
Significance of blubber and vasoconstriction/vasodilation?
-Blubber has an advantage b/c blood can be shunted outside of it.
Primary example of a heat sink
-Bunny/rabbit ears -Vasoconstriction during lo temps dilation during high temps
How are posterior pituitary hormones synthesized?
-By neurons in the hypothalamus (and therefore are neurohormones), and are packaged in vesicles. -The vesicles are transported down the axons of the neurons that made them and are stored in the nerve endings of these same neurons, in the posterior pituitary
Explain how a change in body temperature can disrupt physiological processes.
-Changes in body temperature can disrupt an animal's physiology because not all of the biochemical reactions that constitute the metabolism of an animal have the same Q10. Because of this, changes in tissue temperature will shift the rates of some reactions more than others, disrupting the overall network.
Describe physiological color change to control body temperature.
-Chromatophores (cells containing pigments that can control pigment dispersal) are typically found in layers of chromatophores containing different colored pigments. -Usually melanophores overlie lighter colored chromatophores. -Dispersal of melanin in melanophores blocks underlying cells; dark color -Aggregation of melanin in melanophores permits underlying cells to show, lighter color. -Pigment granule dispersal is controlled by both neural and hormonal input.
What happened to Paula Radcliffe?
-Collapsed when her body temp rose above normal just 6 km from the finish in the women's 2004 Olympic marathon in Athens on a hot and humid day
What are ways that cold-climate endotherms decrease blood flow to the skin?
-Constriction of blood vessels in the skin, and especially in appendages, greatly improves an animal's ability to conserve heat. -countercurrent heat exchange in "hot" fish, wolfs, caribou and birds; heat is transferred from the outgoing to the returning blood, thus retaining heat in the animal's core.
What are effectors?
-Controlled systems -Cells, tissues, and organs that respond to commands from regulatory systems -Hormones and neurons relay info to these cells and organs
What is the main glucocorticoid?
-Cortisol which helps to control blood levels of glucose and other energy sources, and to mediate the body's response to stress.
What processes regulate blood calcium levels?
-Deposition and reabsorption of bone (a calcium phosphate mineral) -Excretion of calcium by the kidneys -Absorption of calcium from the digestive tract
Describe insulation
-Done on all time scales (evolutionary, seasonal, immediate via piloerector muscles) -Fur, feathers, blubber -Fur and feathers trap air (lo "K") -Insulation lowers conductive, convective and radiative heat loss (conductance). -Better insulation lowers the LCT and decreases the slope of the MR vs TA line.
What are the hibernation patterns in a ground squirrel?
-During most of the year it regulates its body temp at 37 degrees C -During winter months bouts of hibernation are interrupted by brief returns to body temp -Hibernation begins with a drop in MR followed by a drop in body temp, arousal from hibernation begins with a large rise in MR followed by a rise in body temp
What are the relationships between cells, tissues, and organs? (pg 817)
-Each physiological system is composed of discrete organs (stomach, lungs, heart). Organs are made of assemblages of similar cells called tissues, which are made of of cells.
Why is hypothermia advantageous?
-Endothermic homeothermy at lo TA is very energetically expensive. By turning down the set point the animal saves considerable energy, at a time when food is often limiting.
What are ways that endotherms use behavioral thermoregulation? (pg 822)
-Endotherms usually select the most comfortable thermal environment possible. -They may change posture, orient to the sun, move between sun and shade and move between still air and moving air. -More complex thermoregulatory behaviors include nest construction and social behaviors such as huddling -humans put on or remove clothing and burn fossil fuels to generate the energy to heat or cool buildings
What is an example of the epithelial tissues selectively transporting ions and molecules from one side of an epithelial membrane to the other. (pg 817)
-Ex: The gut epithelium absorbs nutrients from the gut and secretes digestive juices in the gut.
Explain the fever experiments done on lizards
-Experiments done in poikilotherms such as lizards show that decreasing their body temp after an infection decreases their chances of survival
Why study non-human, non-mammalian species (comparative physiology)?
-Gain an evolutionary perspective -Basic knowledge of nature -Krogh principle
What are pituitary gigantism and dwarfism?
-Gigantism is the result of overproduction of GH in children. -Underproduction of GH causes pituitary dwarfism. GH is now produced by genetically engineered bacteria, harvested, and used to treat this problem.
How does Diabetes Mellitus cause excessive urine production?
-High glucose levels in the blood result in such high (glucose) in the kidney tubules that significant amounts of glucose are not reabsorbed, resulting in an increased osmotic pressure in the tubules that in turn inhibits water reabsorption and causes excessive urine volume. -The term "diabetes" refers to this high urine output which in untreated individuals results in dehydration. -Diabetes insipidus is caused by hypo-secretion of antidiuretc hormone.
What is the "Hunting Response" in animals?
-Humans lack heat exchangers in the limbs. -However, vasoconstriction reduces blood flow, and therefore heat loss, to the hands when core T drops. -Flow is periodically opened and closed to control heat loss, but not allow hand T to drop too far. -Vasoconstriction and dilation and use of heat sinks fluctuates with Ta
What does hyperthyroid goiter result from?
-Hyperthyroid goiter results when the negative feedback mechanism fails even though blood levels of thyroxine are high. -A common cause is an autoimmune disease in which an antibody to the TSH receptor is produced. This antibody binds to and stimulates the TSH receptor, causing the thyroid cells to release excess thyroxine. -The thyroid remains maximally active (even though TSH levels are low) and grows larger, causing symptoms associated with high metabolic rates.
What does hypothyroid goiter result from?
-Hypothyroid goiter results when there is insufficient functional thyroxine to turn off TSH production. -The most common cause is a deficiency of dietary iodine, once fairly common in the interior regions of the continents where access to seafood was restricted. -With high TSH levels, the thyroid gland continues to produce nonfunctional thyroxine and becomes very large.
How does ADH affect the kidneys?
-If there is a high level of ADH secretion, the kidneys reabsorb more water, decreasing urine output. -If there is a low level of ADH secretion, the kidneys reabsorb less water producing a dilute, high volume urine.
What are physiological mechanisms that animals use to control body temperature?
-In addition to behavioral means, some animals we generally consider to be poikilotherms/ectotherms may use physiological mechanisms to control TB - vascular, i.e., marine iguana - color change: darker to increase radiation gain, lighter to decrease radiation gain. - chromatophores (special skin cells designed for rapid color change) They may even be endotherms (some insects and large fish such as tuna and large sharks).
How does brown fat generate heat?
-In brown fat cells, a protein called thermogenin uncouples proton movement from ATP production, which allows protons to leak across the inner mitochondrial membrane rather than having to pass through ATP synthase and generate ATP. -Thus, metabolic fuels are consumed without producing ATP, but heat is still released -A hydrogen ion leakage pathway -H+ moves down its electrochemical gradient, releasing all this energy as heat, rather than ATP. -UCPs-2 and -3 are structurally similar to UCP-1, but their functions are not involved with brown fat.
Explain the effects of the release of epi and norepi
-Increased in response to stress (fight or flight) (1) the cardiovascular system (i.e., increased heart rate and stroke volume and elevated blood pressure) and respiration (increased breathing rates) to enhance gas exchange and nutrient delivery. (2) increased glucose and fatty acid availability for metabolism.
Insulation graph
-Insulation varies from animal to animal but also within the animal, areas that require more heat a more insulated -Insulation can also fluctuate from winter to summer
What is the importance of insulin for glucose uptake?
-Insulin binds to receptors on the cell membrane and this stimulates glucose uptake. -This glucose is then used as an energy source, stored as glycogen or converted to fat. -Without insulin or the receptors, glucose accumulates to very high levels in the blood, and is lost in urine. -Insulin also (1) inhibits lipase (lipid breakdown) in adipose tissue, and (2) stimulates amino acid uptake by cells.
What do feedforward information signals do?
-It anticipates a change in the internal environment before the change occurs. Ex: "on your mark" raises your heart rate in anticipation of running
What does a hand cooling unit do?
-It permits increased heat loss to the hand. The hand is closed in a sealed glove that holds TA at a constant low, but not too low, temperature that is optimal for heat loss.
Explain the release of aldosterone?
-It's release is stimulated by angiotensin-II. -Recall that the kidneys release renin (a proteolitic enzyme) into the blood. Renin cleaves a peptide, angiotensin-I, from circulating angiotensinogen. Angiotensin converting enzyme (ACE) (released into the blood by endothelial cells) converts angio-I to angiotensin-II. -Renin release is stimulated by lo blood Na+ and /or lo blood pressure.
Why does the classification of animals as "cold-blooded" or "warm-blooded" not work? (pg 822)
-Mammals that hibernate become cold -many reptiles and insects can have body temperatures similar to ours when they are active
What is the relationship between Growth Hormone and blood glucose?
-Many of the actions of growth hormone are antagonistic to those of insulin and similar to those of glucagon. -GH inhibits glucose uptake which raises blood sugar
What are Additional Means of Heat Transfer outside of the traditional types?
-Metabolism (always a gain) -Evaporation (loss, except for a wet sauna) - respiratory surface - general body surface
How did the Energetic Costs of T Control Vary?
-Metabolism and evaporation (mobilization of water) are energetically expensive. -Insulation and vascular changes are relatively inexpensive. -Some behaviors are costly (increase activity, etc.) while others are not (postural)
What is the function of the adrenal medulla?
-Neural tissue controlled by the brain (sympathetic) -Produces epinephrine and norepinephrine
How is the anterior pituitary controlled?
-Neurohormones from the hypothalamus -hypothalamus obtains data about body conditions and the external environment through both neuronal and hormonal signals
Posterior pituitary
-Neurohypophysis -an extension of the hypothalamus and therefore is neural tissue. -Hormones are synthesized in the hypothalamus and travel down through the neurons to be released directly onto capillaries
How do neurons function?
-Neurons are extremely diverse in size and form. -They encode and conduct information as electrical signals -Release chemical signals received by target cells, which can be other neurons, muscle cells, or cells that secrete hormones and other molecules and substances, such as saliva
Briefly explain the importance of PTH on the kidneys.
-PTH acts on the kidneys to increase the elimination of phosphate to reduce the possibility of calcium phosphate salt precipitation. -Normal levels of calcium and phosphate in the blood are close to the concentration that could cause them to precipitate as calcium phosphate salts. -Calcium phosphate salts are involved in the formation of kidney stones and hardening of artery walls.
Characteristics of a heat sink
-Poorly insulated -Controlled blood flow -Can bypass heat exchanger -Thin -High surface area -Highly vascularized
How are pyrogens involved in fevers?
-Pyrogens increase hypothalamic set point, and body temperature rises until it matches the new set point.
What are the four avenues of heat exchange between the bodies (of ectotherms and endotherms) and their environments? (pg 823)
-Radiation -convection -conduction -evaporation
What is hibernation?
-Regulated hypothermia lasting days or weeks, with drops in set point and TB to very low temperatures -reduction in metabolic rate results in enormous energy savings.
Processes that are involved in homeostasis:
-Regulation of a parameter in the internal environment in spite of external fluctuation. -Occurs in the extra- and/or the intra-cellular spaces. The latter is especially well controlled. -Homeostasis often, but not always, involves a negative feedback system.
Downsides of cortisol
-Remember the time lag in cortisol effects, especially compared to epi-. -Cortisol also blocks the immune system reactions, which temporarily are less critical. Cortisol can therefore be used to reduce inflammation and allergic reactions.
Examples of epithelial tissue functions?
-Secretion of hormones, milk, mucus, digestive enzymes, sweat -Some have cilia to move substances. -Some are modified to be chemoreceptors for taste, smell, etc. -Some may have protective, absorptive, or transport functions. -Some create boundaries
Why is honey important for Bees?
-Serves as an energy source for bees to generate metabolic heat in the winter -Center of hive/huddle is the warmest but bees keep hive temps relatively constant
3 types of muscle tissue
-Skeletal -Cardiac -Smooth
Which animals experience daily torpor?
-Some small birds like Humming birds -Some small mammals -(lo MR and TB during inactive period of the day)
What is brown fat?
-Specialized adipose tissue whose sole function is heat production
What are regulators (homeo-)?
-Species that control their internal environment to a particular set-point for a given parameter even though the external environment varies. -Regulators have a zone of stability where homeostasis is maintained
What are conformers (poikilo-)?
-Species that match their internal environment to the external conditions as regards a particular parameter ex) temp, ion concentration etc.
Thyroxine's role in metabolism
-Stimulates the transcription (cytoplasmic receptors) of many genes for enzymes of energy pathways, transport proteins, and structural proteins. -elevates metabolic rates in most cells and tissues (important in thermoregulation -raises blood (glucose) and promotes the use of carbohydrates over fats for fuel. -promotes amino acid uptake and protein synthesis and so is critical for growth and development -Insufficient thyroxine after the 4th month of human fetal life results in inadequate formation of the myelin sheath around the axons of neurons resulting in irreversible neural damage and retardation, cretinism
The powerful flight muscles of many insects must reach 35C-40C before the insects can fly, and they must maintain these high temperatures during flight. How do some ectotherms, such as a fly, regulate their metabolic heat production? What is the most impressive case of this?
-Such insects warm up to fly by contracting their flight muscles in a manner analogous to shivering in animals. Some also can stop their heart to keep heat in thorax. -most impressive case is a species of scarab beetle that lives mostly underground in mountains north of Los Angeles, California. These beetles come aboveground to mate, with males flying in search for females. They undertake this mating ritual at night, in winter, and only during snowstorms. (pg 826)
What type of control are the hypothalamus and anterior pituitary under?
-The anterior pituitary cells and hypothalamus are under negative feedback control by the hormones of the glands that they stimulate.
What is the outer surface of epithelial tissues?
-The apical side. -They face the air (skin, lungs) or a fluid-filled organ cavity (the lumen of the gut) -may have cilia or be highly folded to increase surface area.
What is the inner surface of epithelial cells?
-The basal side. -it rests on an extracellular matrix called a basal lamina
How are the anterior pituitary and the hypothalamus connected?
-The hypothalamus and the anterior pituitary are connected by portal blood vessels. -Secretions from hypothalamic nerves are transported by these blood vessels to the anterior pituitary.
What is the one species of bird that goes through adaptive hypothermia?
-The poorwill (Phalaenoptilus nuttallii)
Why are the actions of lipid-soluble hormones generally slower than water soluble hormones?
-The receptors for lipid-soluble hormones are generally intracellular, either in the cytoplasm or in the nucleus. -The action of lipid-soluble hormones is mediated by intracellular hormone receptors that usually alter gene expression (i.e., initiate transcription). -Therefore, they are generally slower acting than water soluble hormones, but their effects typically last longer (perhaps as long as the protein product persists.
When thinking about the thermostat in our homes, what is the set point, what is the feedback, and what would be feedforward information? (pg 816-817 and figure 40.2)
-The set point is the desired temperature on the thermostat -The feedback is the thermostat sensor, which responds to the temperature of the air, providing information that is compared with a set point -A timer provides feedforward information, changing the set point at different times of the day (raising temp in morning, lowering it at night).
Why is the fight or flight response effective?
-The stress (fight-or-flight ?) response ensures that muscles have adequate glucose for immediate response (due to epinephrine), but then cortisol spares glucose for the brain and switches other tissue to fat (and amino acid) metabolism.
Explain how skin temperature affects the hypothalamus
-The temperature of the skin can be considered feedforward information that adjusts the hypothalamic set point. -For example, cooling the skin allows the system to anticipate potential cooling of the core, and therefore set-point(s) may be increased slightly.
What are examples of feedforward information? (pg 817)
-The timer on a thermostat provides feedforward information by changing the system's temperature set point, usually lowering it in the evening and raising it in the morning. -Hearing the words "on your mark", raises your heart rate in anticipation for running.
Relationship between weight, metabolic rate (MR), and animal size?
-The weight specific MR (MR/Body Mass) increases in smaller animals. (MR varies inversely with body mass.)
How can large fish such as giant bluefin tuna and great white sharks maintain temperature differences as great as 10C to 15C between their bodies and surrounding water despite the fact that metabolic heat is difficult to maintain? (pg 825)
-They are "heterothermic (spatial)" fish -Are able to use countercurrent heat exchange through red swimming muscles to generate heat -The heat comes from their powerful swimming muscles, and the ability of these "hot" fish to conserve that heat is based on the remarkable arrangement of their blood vessels. -The cold blood from gills is transported to the muscles by small vessels. These vessels come off the dorsal aorta and run parallel to vessels carrying warm blood toward the heart. Thus, the cold blood is warmed by conduction and is retained in the muscle mass. -this adaptation is called countercurrent heat exchange. -Each 10C rise in muscle temperature increases the fish's sustainable power output almost threefold, giving it a faster swimming capability -Compared to most fish whose blood is usually the same as water temp bc of contact with water
Significance of penguin flippers?
-They are able to shunt blood to bypass the exchange if necessary. -When Tb > Tset
What makes collagen so good for connective tissue? (pg 818)
-They are strong and resistant to stretch, giving strength to the skin and the connections between bones and between bones and muscles. - collagen fibers provide a netlike framework for organs, giving them shape and structural strength
What is the basic primary function of the epithelial cells? (pg 817)
-They control which molecules and ions can move between different body compartments, such as blood and the interstitial fluid. -They selectively transport ions and molecules from one side of an epithelial membrane to the other.
Control of Thyroxine
-Thyrotropin (thyroid-stimulating hormone, TSH): from the anterior pituitary activates thyroid gland cells to produce thyroxine. -Thyrotropin-releasing hormone (TRH): from the hypothalamus activates TSH-producing cells in the anterior pituitary. -In a negative feedback loop, thyroxine inhibits the response of pituitary cells to TRH. Therefore, less TSH is released when thyroxine levels are high, and more is released when levels are low -Thyroxin also feeds back to reduce TRH from the hypothalamus.
What types of tissues have abundant elastin?
-Tissues that are regularly stretched, such as lung walls and artery walls
What is modern physiology?
-Traditional physiology plus biology, physiological ecology, biochemistry, and molecular biology -Located in the center of the hierarchy of biological disciplines -Other disciplines require an understanding of physiology
Thyroxine structure
-Two active forms of thyroxine, T3 and T4, are made from tyrosine. T3 (triiodothyronine) has three iodine atoms. T4 has four iodine atoms -More T4 is produced, but it can be converted to T3 by an enzyme in the blood. T3 is the more active form of the hormone.
What is some evidence for the functionality of fevers?
-Ubiquitous nature of fever (behavioral or physiological fever found in all animals), why wouldn't evolution remove it? -When they are infected ectotherms demonstrate a behavioral fever (choose a higher TB if possible).
What is the function of the adrenal cortex?
-Under hormonal control -Mainly by adrenocorticotropin (ACTH) especially for glucocorticosteroids from the anterior pituitary
What happens when blood glucose levels fall?
-When blood glucose levels fall, the pancreas decreases the release of insulin, and cells switch to fat (stored and/or delivered by blood; remember that insulin inhibits lipid uptake by cells) or stored glycogen for energy. -
Explain thermoneutral zone (TNZ)
-Within this narrow range, the metabolic rates of endotherms (birds and mammals) are at low levels and independent of temperature. -Within this zone body temp is regulated by energetically cheap mechanisms such as heat loss through the skin. -As Ta (ambient temp) increases from the LCT to the UCT the animal uses means that gradually increase the rates of conductive, convective and radiation heat loss. As Ta decreases from the UCT to the LCT the animal employs means that gradually decrease conductive, convective and radiation heat loss
Growth Hormone (GH)
-acts on many tissues to promote growth -GH stimulates cells to take-up amino acids, and stimulates the liver to produce chemical messages (insulin-like growth factors) that stimulate bone and cartilage growth.
What is daily torpor?
-an adaptive hypothermia that can drop body temperature 10-20°C and save considerable metabolic energy. Hummingbirds.
What happens to an animal if the temp gets below the LCT?
-below the LCT (Lower critical temp) animals expend energy to produce metabolic heat and maintain a constant Tb
Gonadotropin-releasing hormone (GnRH)
-causes certain anterior pituitary cells to release tropic hormones that control gonad activity (follicle stimulating hormone and luteinizing hormone).
Most common protein in extracellular matrix of connective tissues and what does it do?
-collagen -a very strong fiber prevalent in tendons and ligaments. - It also forms a netlike framework for organs, to give shape and strength. - It has low density as loose strands when it fills in between organs.
What do tropic hormones do?
-control (stimulate) activities of other endocrine glands. -All are peptide and protein hormones; each is produced by a different type of pituitary cell.
How does the vertebrate thermostat work in endotherms
-cooling the hypothalamus causes the core body temperature to rise as effectors that raise TB (peripheral vasoconstriction, shivering, etc.) are activated. -Warming the hypothalamus causes TB to drop as effectors that lower TB (peripheral vasodilation, sweating, panting, etc) are activated in attempts to lower body temperature. -experiments done on squirrels showed that metabolic basal rates increased when the hypothalamus was cooled and decreased when it was warmed
Examples of negative feedback
-cortisol is produced by the adrenal gland (adrenal cortex) in response to adrenocorticotropin. -ACTH returns in the blood to the pituitary and inhibits release of adrenocorticotropin. -Cortisol also exerts negative feedback control on the hypothalamus, inhibiting release of adrenocorticotropin-releasing hormone. -In addition, higher brain input to the hypothalamus also controls circulating anterior pituitary hormone levels. ex) stress
What is regional heterothermy?
-describes organisms that are able to maintain different temperature "zones" in different regions of the body. -usually occurs in the limbs, and is made possible through the use of counter-current heat exchangers, such as the rete mirabile. -Limbs used as a heat sink to dump heat when Tb gets too high
What is an organ?
-discrete structure that carries out a specific function in the body -composed of tissues, usually of several different types
Strategies of skunk cabbage (Symplocarpus foetidus)
-endothermy allows them to grow faster and flower in late winter. -Can maintain a T of 15C down to -15C.
What are some other peptide and protein anterior pituitary hormones (influence tissues other than endocrine glands)?
-growth hormone, -prolactin, -melanocyte-stimulating hormone, and -the endogenous opiodes endorphins and enkephalins.
What animals typically have brown fat?
-in newborns of many mammalian species -adults that hibernate -many small, active adult mammals in winter -in humans, brown fat is stimulated by cold exposure; obese people have less brown fat activity. -Brown fat is located so that blood flow carries the released heat directly to the internal organs
Summarized function of the hypothalamus
-integrates thermosensory info -establishes set points for body temp -regulates physiological thermal controls
Describe smooth muscle
-involved in movement and generation of forces in internal organs -Makes up the walls of many hollow internal organs (e.g., gut, blood vessels, uterus, etc.).
How do animals combat overheating as the temperature exceeds the upper critical temperature? (pg 829)
-large mammals wallow in water -evaporation of water by sweating or panting
Pituitary Gland
-link between the nervous system and many endocrine glands and plays a crucial role in the endocrine system. -Made up of anterior and posterior -Attached to hypothalamus
Thyroid gland
-located near the trachea, is another example of an endocrine gland that is controlled by negative feedback. -Produces thyroxine from follicles
What are regulatory systems and what do they do?
-obtain, process, and integrate information, then issue commands to controlled systems, which cause change. -receive information as negative feedback, which causes effectors to counteract the cause of the error signal.
Glial cell function?
-one category of nerve cells -provide a number of critical support functions for neurons. -one class of glial creates a barrier between blood vessels and the neural tissue that protects the nervous system from potentially harmful chemicals circulating in the blood. -communicate information through the release of CHEMICAL SIGNALS, not electric signals
Complex effects of cortisol
-raises blood (glucose) by (a) stimulating gluconeogenesis by the liver and (b) inhibiting peripheral use of glucose (saves glucose for neural tissue). -mobilizes fatty acids from adipose tissue into the blood. -increases blood (amino acid), from muscle etc., for uptake and use in gluconeogenesis by liver.
Explain hypothalamic set point(s)
-rather than one single set-point, there is a hierarchy of set points. Not all effectors are changed at once, rather they are usually activated one at a time, generally beginning with non-energy requiring effectors, as TB slowly changes. The system "tries" to return core T to normal using this sequence of effectors. -Animals have the ability to change the hypothalamic set points. For example, set points are usually higher during the active part of the daily cycle than during sleep, lower during hibernation.
How is the vertebrate thermostat controlled?
-regulator is at the bottom (ventral) of the brain in a structure called the hypothalamus. -The temperature of the hypothalamus itself is the major source of feedback information in many species. Cooling it causes fish and reptiles (ectotherms) to seek a warmer environment, and warming it triggers the reverse behavior.
How are cortisol and other glucocorticoids released under non-stress conditions?
-release is controlled by ACTH from the anterior pituitary which, in turn is controlled by adrenocorticotropin-releasing hormone from the hypothalamus. -Turning off the cortisol stress response is also critical to avoid the consequences of long-term stress. -Cortisol has a negative feedback effect on the hypothalamus that decreases the release of adrenocorticotropin-releasing hormone. -Higher areas of the brain also control ACTH-RH (stress, daily circadian cycle)
What are some behaviorial strategies that a lizard may use to maintain a fairly stable body temperaure? (pg 822)
-spending time in a burrow -basking in the sun -seeking shade -climbing vegetation -changing its orientation with respect to the sun
What causes hypothermia? (pg 830)
-starvation (lack of metabolic fuel) -exposure to extreme cold -serious illness -anesthesia In each of these cases, the drop in body temperature is unregulated.
Function of oxytocin
-stimulate uterine smooth muscle contraction for the birth process. (Pitocin=clinical term) -stimulates milk flow (stimulates smooth muscle contraction for ejection of milk) in the mother's breasts. -Suckling by the baby, or even the sight or sound of the baby, can cause the mother to secrete oxytocin and release milk.
Prolactin
-stimulates the production and, too a lesser extent, secretion of milk in female mammals. -It is also important in pregnancy and, in males, has a role in controlling the endocrine functions of the testes. -Also responsible for pair bonding and nesting behaviors in vertebrates other than mammals --Willingness to sit on eggs --stimulates crop milk for birds to feed young -Migration upstream in fish -Reproductive behaviors
Why are the costs evaporation of water by sweating or panting? (pg 829)
-sweating and panting are ACTIVE processes that require expending metabolic energy. That is why the metabolic rate increases when the upper critical temperature is exceeded. A sweating or panting animal is generating heat in the process of dissipating heat, which can be a losing battle. -Sweat that falls off the body provides no cooling. Thus when the need for heat loss is greatest, water from the internal environment can be squandered with no cooling benefit. -Also, water is heavy so animals do not carry an excess supply of it. In habitats that are hot and dry, sweating and panting are cooling adaptations of LAST RESORTS.
Endorphins and Enkephalins
-the body's natural opiates. In the brain, these molecules also act as neurotransmitters. Both as hormones and neurotransmitters they reduce pain in pain pathways. (Addiction)
What are the 4 tropic hormones released by the anterior pituitary?
-thyrotropin -adrenocorticotropin -two gonadotropins: --luteinizing hormone --follicle-stimulating hormone
What is the function of antidiuretic hormone (ADH)?
-to increase water conservation by the kidney. -ADH stimulates increased aquaporins (water channels) in the collecting ducts.
Thyrotropin-releasing hormone (TRH)
-was the first releasing hormone extracted from the hypothalamus. -causes certain anterior pituitary cells to release thyrotropin, which in turn stimulates the thyroid gland. Remember, target cells must have the appropriate receptor.
What are beta blockers?
-which inactivate only β-adrenergic receptors, can be used to reduce fight-or-flight (stress) responses to epinephrine. -The beta blockers leave the alpha sites open to norepinephrine and its regulatory functions. -Used for people with weak hearts
What is positive feedback?
-which tells a regulatory system to amplify a response, is rare, but does occur. -Positive feedback responses tend to reach a limit and terminate rapidly.
What are the three water-containing compartments of the human body? Why is the ECG crucial to survival in multicellular cells (pg 816 and Figure 40.1)?
-⅔ of water is in cells -⅓ of water is in extracellular fluid, or ECF, which is the internal environment -----plasma, 20% or ECF -----interstitial fluid, 80% or ECF ECG is so crucial because a stable internal environment makes it possible for an animal to occupy habitats that would kill its cells if they were directly exposed to external conditions.
How does a G protein- Linked receptor work?
1) Hormone binding to the receptor activates the G protein, GTP replaced GDP. 2) Part of the activated G protein activates an effector protein that causes changes in cell function. 3) The GTP on the G protein is hydrolyzed to GDP.
What are the roles of thyroxine in regulating metabolism?
1) It stimulates the transcription (cytoplasmic receptors) of many genes in nearly all cells in the body. 2) It elevates metabolic rates in most cells and tissues (important in thermoregulation). 3) It raises blood (glucose) and promotes the use of carbohydrates over fats for fuel. 4) It promotes amino acid uptake and protein synthesis. 5) Insufficient thyroxine after the 4th month of human fetal life results in inadequate formation of the myelin sheath around the axons of neurons resulting in irreversible neural damage and retardation, cretinism.
Blood calcium decrease triggers release of parathyroid hormone (PTH). PTH causes an increase in blood calcium levels by doing what?
1. Causing the osteoclasts to dissolve bone and release calcium. 2. Promoting calcium reabsorbtion by the kidney to prevent loss in the urine. 3. Promoting vitamin D activation, which stimulates the gut to absorb calcium from food.
Why does some epithelial tissue have a high rate of _______ and ________?
1. Cell Division, Replacement 2. Because it gets a lot of wear and tear (ex gut and skin)
How is molting regulated for insects?
1. Cells in the brain produce brain hormone which is stored in a pair of structures attached to the brain called the corpora cardiaca. 2. After appropriate stimulation (e.g., a blood meal for Rhodnius), the c.c. release brain hormone (also known as prothoracicotropic hormone, PTTH), which is caried by the blood to an endocrine gland in the thorax called the prothoracic gland. 3. PTTH stimulates the prothoracic gland to release ecdysone which stimulates molting.
What are some adaptations to cold?
1. Decrease conductive, convective and radiation heat loss* : 2. Decrease evaporative heat loss. 3. Increase metabolic rate
What are general mechanisms for control of body temperature that are based on the control of heat transfer processes and metabolism?
1. Metabolic rate 2. Evaporation (Evaporative water loss) 3. Insulation (conduction, convection, radiation) 4. Vascular control (conduction, convection, radiation) 5. Behavior: postural changes, burrows, huddling, choice of microhabitat (conduction, convection, radiation). Some of the above have a high energy cost, others cost little. Which are used first?
In multicellular animals, what are the two primary types of controls on effectors?
1. NERVE CELLS that produce electrical impulses within the nerve cells and then transmit information between cells via chemicals (neurotransmitters) 2. HORMONES: chemical signals, usually transmitted via the cardiovascular system. -All multicellular animals have chemical communication between cells, even sponges. -Plants also have hormones, mainly to control growth and development.
Advantages for the bluefin tuna (highly evolved for swimming)
1. Red muscle, increased swimming power (Q10 = 3), swimming speed (both maximum and sustained), and efficiency. 2. Gut, speeds up digestion & absorption (permits smaller stomach, more muscle mass per body volume) 3. Retina, visual predator 4. Brain, faster neural processing 5. Allows range expansion to cooler waters.
If a lizard (ectotherm) and a mouse (endotherm) are placed in a closed chamber in which the temperature is gradually raised, what will happen to the body temperature?
1.Body temperature of the lizard will equilibrate with that of the chamber, whereas the body temperature of the mouse will remain constant, up to a point.
What is the rate of calcium deposition and blood circulation of chicken eggs?
A chicken egg shell contains ~2gm of Ca++ (as CaCO3), and is laid down in ~16hrs. Therefore Ca++ is deposited at a rate of ~125mg/hr. Total circulating blood Ca++ is ~25mg. Therefore every 12 minutes for 16 hrs an amount of Ca++ equal to the total circulating Ca++ is laid down in the shell by the shell gland.
What is a goiter?
A goiter is an enlarged thyroid gland associated with either very low (hypothyroidism) or very high (hyperthyroidism) levels of thyroxine. Goiter occurs when thyroglobulin production is above normal and the follicles are enlarged in an attempt to produce more thyroxin.
What is homeostasis?
A narrow range of stable physical and biochemical conditions under which the body functions optimally. (pg 816)
What are the two locations for receptors?
A non polar signal and a polar signal. A non polar signal can diffuse directly across the lipid bilayer of the plasma membrane to encounter its receptor in the cytoplasm or nucleus. A signal that is polar and/or large cannot diffuse through the plasma membrane. Its receptor is embedded in the membrane.
What is a thyroid follicle?
A thyroid follicle is a layer of epithelial cells surrounding a lumen containing a volume of glycoprotein called thyroglobulin which contains iodinated tyrosines. Prior to release of TH, the thyroglobulin is taken-up and broken down by the epithelial cells to make thyroxine.
Why is ADH also called vasopressin?
ADH also causes peripheral blood vessel constriction to help elevate blood pressure, and consequently is also called vasopressin.
ADH and the posterior pituitary
ADH release by the posterior pituitary increases if blood pressure falls or blood osmotic concentration becomes too high.
Differentiate between the types of local hormones.
AUTOCRINE hormones act on the secreting cell itself. JUXTACRINE signals bind to adjacent cells PARACRINE hormones act on cells near the site of release.
Describe the range of temperatures in which cells can function?
About 0C-45C, although there are numerous exceptions (algae in hot springs, archaea, etc.)
What happens to an animal if the temp gets above the UCT?
Above the upper critical temp, the animal expends energy to lose heat by panting or sweating -Animal must use evaporative cooling to maintain Tb constant
Is there a connection between solar radiation absorbance and skin color?
Absorbance of solar radiation (peak intensity in the visible) does depend on skin color. Therefore, dark objects heat-up faster in sun. Light colored feathers or fur absorb less (reflect more) visible wavelength energy, but they may also transmit more to the skin surface (Polar bear: white hair, black skin)
What is the difference between a catalyzed reaction and uncatalyzed reaction? What is the same?
Activation Energy (Ea): greater for catalyzed reactions. Free Energy (Delta G): same between catalyzed and uncatalyzed reactions An uncatalyzed reaction has greater activation energy than does a catalyzed reaction. There is no difference in free energy between catalyzed and uncatalyzed reactions.
What is another word for fat?
Adipose tissue. (pg 819)
What is the main mineralocorticoid?
Aldosterone which stimulates the kidney to conserve (reabsorb) sodium and excrete potassium. Increases blood pressure.
What tissue type do most organs consist of?
All 4 types (epithelial, connective, muscle, and nervous)
Norepinephrine and epinephrine are what type of hormones?
Amine
What are amine hormones?
Amine hormones are derivatives of the amino acid tyrosine, etc. Most are water-soluble (cell surface receptors), but some are lipid-soluble (intracellular receptors).
What are heterotherms?
An animal that sometimes behaves as an endotherm and at other times as an ectotherm. (pg 822) -Ex: animal that hibernates is an endotherm over the summer, but an ectotherm in the winter during hybernation -some ectotherms can produce substantial metabolic heat, thus behaving like endotherms
What are the two predominant proteins in connective tissue?
Collagen and elastin. (pg 818)
Why must insects molt periodically?
Because insects have rigid exoskeletons, they have episodic growth patterns and must molt periodically.
What cell types have been identified in the islets of Langerhands?
Beta (β) cells produce and secrete insulin. Alpha (α) cells produce and secrete glucagon (antagonist of insulin). Delta (δ) cells produce somatostatin.
What connective tissue consists of cells dispersed in the extensive liquid extracellular matrix, the _______ ________?
Blood. The extensive liquid extracellular matrix is the blood plasma (pg 819)
How can physiologists determine an animal's metabolic rate? (pg 826)
By measuring its consumption of O2 or production of CO2
Wigglesworth also demonstrated that another hormone is responsible for determining whether an insect molts into the next juvenile instar or an adult: How did he do this?
By removing only the front part of the head, it was shown that the rear of the brain, containing the corpora allata, releases a substance preventing a molt to the adult stage. The substance is called juvenile hormone. If it is present, Rhodnius molts to another juvenile instar. Normally, during the fifth instar, the corpora allata stop making this hormone and the insect molts to the adult stage.
If the Q10 of an animal's metabolic rate is 2, then A) The animal is better acclimated to a cold environment than if its Q10 were 3. B) The animal is an ectotherm C )The animal consumes half as much oxygen per hour at 20C as it does at 30C D)The animal's Metabolic rate is not at basal levels E) The animal produces twice as much heat at 20C as it does at 30C
C
Which of the following best describes the limits of life on earth? A)The freezing point and boiling point of water B)The Effects of temperature on biochemical rates of reaction C)The freezing point of water and the temperature at which proteins denature D)The ability of the organism to actively produce and dissipate heat E)The effect of temperature on the oxygen content of the environment
C
What do chemical messages do?
Chemical messages, such as hormones, produce and coordinate anatomical, physiological, developmental and behavioral changes.
Where are steroid hormones derived from?
Cholesterol. A six carbon side chain is cleaved from cholesterol to form pregnenolone. Different enzymatic processes produce different specific steroid specific molecules.
How does a sand dab create its camoflage pattern?
Chromatophores
How does calcitonin lower calcium levels in the blood?
Calcitonin decreases osteoclast activity and stimulates the osteoblasts to take up calcium from the blood for bone growth.
What type of hormonal regulation for calcium causes the blood concentration of calcium to fall?
Calcitonin, which inhibits osteoclasts and and stimulates the osteoblasts to take up calcium from the blood for bone growth.
Describe examples heat storage in animals.
Camels can store heat up to 41C (105 F). Orynx can store heat up to 45C (114F) (but only used if water stressed).
What connective tissues offer firm structural support?
Cartilage and bone (pg 819)
Where does countercurrent heat exchange occur?
Cavernous sinus is where the arterial blood flow and venous blood flow exchange heat because the two flows are in immediate juxtaposition. The cool venous blood from nasal passages and the arterial blood from the heart flow opposite.
Why is Diabetes Mellitus described as "Starvation in the midst of plenty"
Cells fail to take up glucose use fat and/or protein for fuel, resulting in the body wasting away leading to tissue and organ damage.
What are tissues?
Cells grouped together with the same characteristics or specializations
What is the result of cells that do not take up glucose?
Cells not taking up glucose use fat and/or protein for fuel, resulting in the body wasting away leading to tissue and organ damage.
Why do endotherms produce more heat than ectotherms? (pg 822)
Cells of endotherms are less efficient at using energy than are the cells of ectotherms. -The cells of endotherms are more "leaky" to ions than are the cells of ectotherms. Therefore Na+ ions are constantly diffusing into the cells and K+ ions are constantly diffusing out. Even at rest, an endotherm must spend considerable amounts of energy to transport Na+ out of cells and transport K+ back in. Because of their leaky membranes, endotherms expend more energy (and thus release more heat) than do ectotherms JUST TO MAINTAIN THE ION CONCENTRATION GRADIENTS ACROSS THEIR CELL MEMBRANES. The faster ions leak, the more metabolic energy that is needed to pump ions back in.
What are target cells and what do they require?
Cells receiving the hormonal message are called target cells and must have appropriate receptors. The binding of the receptor activates a response, usually specific to the target cell.
Where does Chagas disease come from?
Chagas disease is caused by the parasite Trypanosoma cruzi, transmitted by "kissing bugs", Rhodnius prolixus and related (reduvid) bugs. Common in South and Central America. Some occurance in southern U.S.A.
What controls the thermoregulatory mechanisms and adaptations of endotherms? (pg 829)
Controlled by neural regulatory systems that integrate information from mental and physiological sources and then issue commands to the effectors that alter the heat content of the body.
What type of heat exchange involves heat transferring to a surrounding medium such as air or water as that medium flows over a surface? Example? (pg 823)
Convection Ex: the wind-chill factor Heat is lost by convection when a stream of air (wind) is cooler than body surface temperature.
What does thermal conductance encompass?
Convective and radiation heat loss
What types of steroid hormones are produced by adrenal cortex cells?
Corticosteroids from cholesterol which act by stimulating transcription of certain genes.
What shape do plotted Q10 values produce?
Curves. Temperatures increase in additive intervals (10,20,30) whereas reaction rates increase in a multiplicative fashion (2,4,8,16,32, etc). (pg 821)
Which of the following is the most important and general characteristic of endotherms adapted to cold climates compared with endotherms adapted to warm climates? A)Higher basal metabolic rates B)Higher Q10 values C) Brown fat D)Greater insulation E) Ability to hibernate
D
Which has the highest basal metabolic rate per gram of tissue? (pg 826) a)An elephant b)A cat c)A horse d)A mouse
D. Across all of the endotherms, BMR per gram of tissues increases as animals get smaller. Order: mouse, cat, horse, elephant
True or false: A cheetah has a heat exchanger to cool blood perfusing the brain.
False, it is not present in cheetah. The cheetah is a sprinter, and it stops if prey not captured in 40-60 seconds. TB increases by ~3C.)
True or false: PTTH (brain hormone) is released by the CC in insects all the time.
False. In some insects PTTH (brain hormone) is released by the Corpus cardiacum, in others by the Corpus allatum
True or false: a lizard can regulate its body temperature by altering its internal metabolic heat production? (pg 822)
False. It does so by behavioral mechanisms such as seeking shade.
True or false: an endotherm solely uses internal metabolic heat production to regulate its body temperature. (pg 822)
False. They also use behavioral mechanisms, like ectotherms do
True or false: Vitamin D is a true vitamin.
False. Vitamin D is not a true vitamin. It is made in skin cells (from cholesterol, stimulated by ultraviolet light), circulates in the blood, and acts on distant target cells; therefore it is a hormone.
What is adipose tissue?
Fat
What is the advantage of feedforward information?
Feedforward information makes it possible to anticipate a physiological challenge to homeostasis and to take preemptive action by changing a set point or the sensitivity of a regulatory system.
Examples of animals with regional heterothermy?
Fish and birds with rete.
What is plasma?
Fluid portion of the blood 20% of all extracellular fluid
What did British physiologist Sir Vincent Wigglesworth show?
He showed how insect molting is triggered by a hormone from the brain. Initial work was done in the kissing bug, Rhodnius prolixus, because it's relatively large size, the shape of it's head and brain (long, anterior to posterior) and it's growth pattern (only molts a certain number of days after taking a blood meal) made it an excellent model system.
What are concepts behind the idea of homeothermy?
Heat Loss=Heat Gain (exchange of heat with environment) Heat budget -Losses: via conduction, convection, radiation, evaporation -Gains: via conduction convection, radiation, metabolism
What is the energy budget formula/equation? (pg 823)
Heat in=heat out Heat in: metabolism + Rabs Heat out: Rout + convection + conduction + evaporation So: metabolism + Rabs=Rout + convection + conduction + evaporation All components on right side depend on the surface temperature of the animal.
How have endotherms evolved adaptations to reduce their heat loss? (pg 828)
Heat is lost from the body surface, and cold-climate species have anatomical adaptations that given them smaller surface-to-volume ratios than their warm-climate relatives. -These adaptations include rounder body shapes and shorter appendages. -thermal insulation by fur, feathers, or fat Ex: antelope jackrabbit has large ears for heat exchange, thick fur of Arctic hare lowers its surface-to-volume ratio and provides insulation
For the energy budget formula, all components on the ____ ____ side depend on the surface temperature of the animal. What is a way that we can control surface temperature? (pg 824)
Heat loss. One way surface temperature can be controlled is by altering the flow of blood to the skin.
What are countercurrent heat exchangers associated with?
Heat sinks
What do countercurrent exchangers exchange?
Heat, O2, NaCl
What is considered to be a high Calcium concentration? Low?
High: >11 mg/100 mL blood Low: <9 mg/100 mL blood Very narrow range
What is the control system of the brain?
Hypothalamus
What is hypothermia? (pg 830)
Hypothermia is a below-normal body temperature.
What happens if blood glucose falls TOO LOW?
If blood glucose falls too low, the α cells release glucagon which stimulates the liver to convert glycogen back to glucose (glycogenolysis).
What happens if there is inadequate iodine present when thyroglobulin is made?
If there is inadequate iodine present when thyroglobulin is made, the released molecules will be neither T3 nor T4 and will not bind to appropriate receptors (including those in the hypothalamus and anterior pituitary).
What are some ways for animals to increase metabolic rate (heat)?
Increase activity (immediate) Shivering (involuntary contraction of skeletal muscle) (immediate) Non-shivering thermogenesis (immediate, seasonal, evolutionary) - brown adipose tissue - other (thyroid hormone, etc.)
What is the relationship between the release of TSH and thyroxine levels?
In a negative feedback loop, thyroxine inhibits the response of pituitary cells to TRH. Therefore, less TSH is released when thyroxine levels are high, and more is released when levels are low. Thyroxin also feeds back to reduce TRH from the hypothalamus.
How does Vitamin D affect the calcium levels in the bone?
In bone, vitamin D acts like PTH to stimulate bone turnover and the liberation of calcium
How is heat from endotherms released in regards to Ta being lower than the surface temperature?
In endotherms blood carries metabolic heat from its source (mostly in the core) to the body surface where it is released, if TA is lower than surface temperature
How does Vitamin D affect the calcium levels in the kidneys?
In the kidneys, vitamin D acts with PTH to decrease calcium loss in urine.
What are the positive effects of a hand cooling unit?
Keeping the hand at a constant optimal temperature for heat loss does many things. 1) This lowers core T resulting from hi TA and/or exercise, thereby permitting longer, more vigorous exercise, etc. 2) Recovery from an exercise bout is also quicker. 3) Athletic capabilities resulting from training with this device (# push-ups, etc.) are greatly increased (i.e., 2X). 4) Being used by professional and collegiate athletic teams, military.
Difference between Lepus alleni and Lepus arcticus
Lepus alleni is more suited for heat while Lepus arcticus is better suited for cold. -Insulation -Heat sinks
What is the isothermal line?
Line that shows when the water temperature equals red muscle/body temperature.
Example of an organism that performs huddling behavior
Maccaca fuscata (monkeys)
Effect of temp on proteins in the body
Macromolecular structure is disrupted at extremes. - Proteins (enzymes, etc.) begin to unfold at extremes.
Major function of physiological systems?
Maintaining homeostasis in spite of external variation
What happens when a person's internal body temperature rises above 40 degrees Celsius?
Major organs start to fail, a condition known as heat stroke. (pg 815) -Paula Radcliffe at Boston Marathon
How does the fraction of molecules having energy > Ea change with temperature?
Maxwell-Boltzmann Energy Distribution Curves
Effect of temperature on membranes
Membranes are only functional over a limited T range. Addition of more unsaturated fatty acids to membrane phospholipids, etc. shifts functional T range lower. (See page 107 of text.)
Effects of temp on metabolic pathways
Metabolic pathways are disrupted as T affects enzymes and energy available for activation energy of reactions.
Organ systems in the body
Nervous system Endocrine system Muscle Skeletal Reproductive Digestive Respiratory Circulatory (cardiovascular) Lymphatic Excretory Immune Skin
What are all the organ systems?
Nervous system Endocrine system Muscle Skeletal Reproductive Digestive Respiratory Circulatory Excretory Lymphatic Immune Skin
What group of local hormones do neurons fall under?
Neurons may technically be considered paracrine cells because they use chemicals called neurotransmitters to send messages to another cell.
What are the categories of nerve cells, or nervous tissues?
Neurons or glial cells (pg 819-820)
Are lipid soluble hormones polar or nonpolar?
Non-polar
What does the rete in the swimbladder of a fish exchange?
O2
Important components of the extracellular matrix of connective tissue are?
Protein fibers
What is Q10?
Q10 is defined as the rate of a reaction at a particular temperature (RT) divided by the rate of that reaction at a temperature 10°C lower (R(T-10)). Q10 = RT / R(T-10)
How do queen bumblebees promote faster development of their eggs
Queen bumblebee starting her colony in spring forages for nectar and stores it in her "honey pot". She drinks from this to obtain energy, shivers her wings to produce heat and presses her uninsulated ventral abdomen against her eggs to warm them. She is thermoregulating by increasing her metabolic rate as air temperature falls. This promotes faster development of the eggs.
What type of heat exchange involves heat moving from warmer objects to cooler ones via the exchange of infrared radiation? Example? (pg 823)
Radiation. Ex: what you feel when you stand in front of a fire
What do responses to hormones depend on?
Receptors and target cells. The same hormone can cause different responses in different types of receptor cells. An example is epinephrine. The nervous system reacts to an emergency very quickly and stimulates adrenal medulla cells to secrete epinephrine. The result is the fight-or-flight response.
Why do we think the mutation in ectotherms that resulted in faulty or leaky ion channels occured? (pg 822)
Such a mutation in a small ectotherm would have increased its energy expenditure and therefore its heat production. Increased heat production would allow the animal to be active for a longer time after sunset. Being active in the evening would open up a world of ecological opportunities because of the decreased competition.
What does the active form of vitamin D do?
The active form binds to cytoplasmic receptors and forms transcription factors. In the digestive tract cells the transcription factors act to increase synthesis of calcium pumps, calcium channels, and calcium-binding proteins, promoting uptake of calcium.
How is body temperature raised when an animal's body temperature is below the lower critical temperature?
The animal expends energy to produce metabolic heat.
Why is countercurrent heat exchange advantageous?
The animal loses less heat to the periphery
How is body temperature lowered when an animal's body temperature is above the upper critical temperature?
The animal must expend energy to lose heat by panting or sweating.
What does connective tissue consist of?
The cells that make up connective tissues are generally dispersed in an extracellular matrix that these cells themselves secrete. -include bone, blood, and fat
What are the two primary proteins in muscle tissue? What is their role?
The cells that makeup muscle tissues contain long filaments of proteins called actin and myosin. They interact to cause muscle cells to contract and exert force. (pg 818)
What is the error signal(homeostasis)?
The difference between the set point and the feedback information
How are hormone groups distinguished?
The distance over which the signal operates distinguishes hormone groups; some only act close to the release site (local hormones: autocrine, juxtacrine and paracrine factors), others act at distant body locations (true hormones).
Why does having water in contact with skin greatly increase heat loss? (pg 829)
The heat absorbing capacity of water is much greater than that of air.
How does heat typically enter and leave the body? (pg 823)
The heat coming in is usually from metabolism and radiation (Rabs. The heat leaves the body via the four mechanisms listed below. -Radiation (Rout) -convection -conduction -evaporation
Describe the human makeup of the water that makes up the body.
The human body is 60% water. ⅓ of water in the human body is extracellular fluid (ECF) that is our internal environment. 80% of the ECF is the interstitial fluid that bathes every cell of the body. Individual cells get nutrients from this interstitial fluid and dump their waste products in it. (pg 816)
How does the intensity of the heat correlate with the temperature of the radiating surface? the wavelength?
The intensity varies directly with the temperature of the radiating surface. The wavelength varies inversely with surface T. objects at physiological T's emit mostly in the middle and long infrared.
What determines the type of molt of an insect?
The juvenile hormone. JH levels decrease thru the larval to larval molts, are very low at the larval to pupal molt, and when JH is absent the adult molt is permitted.
What is the role of the hypothalamus in mammals? (pg 829)
The major thermoregulatory integrative center of mammals at the base of the brain in a structure is called the hypothalamus. -experiments have shown that slight cooling of hypothalamus stimulates constriction of skin blood vessels and that stronger cooling increases metabolic heat production and vice versa - the temperature of the hypothalamus is the major feedback signal; it generates set points for thermoregulatory responses -hypothalamic set points are higher during wakefulness than sleep, and higher during the active part of the daily cycle than the inactive part
Compare the metabolic rate needed to sustain a regular animal to that needed to sustain a hibernating animal. (pg 830)
The metabolic rate needed to sustain a hibernating animal may be only one-fiftieth its basal metabolic rate, and many hibernating animals maintain body temperatures close to the freezing point.
What is the basal metabolic rate, or BMR? (pg 826)
The metabolic rate of a resting animal at a temperature within the thermoneutral zone is known as the basal metabolic rate, or BMR. -Thus, the BMR is the rate at which a resting animal is consuming just enough energy to carry out its minimal body functions. -It is usually measure in animals that are quiet but awake and not using energy for digestion, reproduction or growth.
If a lizard (ectotherm) and a mouse (endotherm) are placed in a closed chamber in which the temperature is gradually raised, what will happen to the metabolic rates?
The metabolic rates also respond differently. In an ectotherm, metabolism decreases as air temperature decreases (Q10). In an endotherm, metabolic rate increases as temperature decreases below a critical ambient T (below the thermal neutral zone). This increases production of body heat. - in other words; the mouse could regulate its body temperature by increasing its metabolic rate; the lizard couldn't (although it can in true nature by other ways)
What were the observations for the following hypothesis: The substance that controls molting in R. prolixus is produced in the head segment and diffuses slowly through the body?
The observation was on a juvenile bug in its third instar. When decapitated 1 hour after blood meal, it does not molt. When decapitation is 1 week after blood meal, it molts into an adult. However, when decapitating third-instar juvenile bugs at different times after blood meal (1 week and one hour), joining them by a glass tube leads to the bugs molting into adults. CONCLUSION: A blood meal stimulates production of some substance within the insect's head that then diffuses slowly through the body, triggering a molt.
What is the overall action of Vitamin D?
The overall action of vitamin D is to raise blood calcium levels. Vitamin D also acts in a negative feedback loop to inhibit transcription of the PTH gene in the parathyroid glands.
What must a physiologist understand?
The pertinent anatomy, cell biology, biochemistry, molecular biology, genetics, physiological ecology, behavior, evolution, etc. of the organism. Ex) Frog jumping requires anatomy, muscle physiology, neurobiology, cardiovascular and respiratory physiology etc.
What is the only species of bird that has been shown to hibernate? (pg 830)
The poor-will
What does the body do to respond to fevers? (pg 830)
The presence of a pyrogen causes a rise in the body's hypothalamic set point for metabolic heat production. As a result, we shiver, we put on a sweater, or crawl under a blanket and your body temperature rises until it matches the new set point. You no longer feel cold and you may not feel hot, but someone touching your forehead might say "you're burning up". Although modest fevers help the body fight infections, extreme fevers can be dangerous and must be controlled.
What is acclimatization?
The process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), allowing it to maintain performance across a range of environmental conditions.
What is heliothermy?
The process of regulating body temperature primarily by means of heat gain from direct solar radiation, as in reptiles and amphibians.
What do the receptors for water-soluble proteins include?
The receptors for water-soluble proteins are large proteins on the cell surface with three domains: -A binding domain projecting outside the plasma membrane -A transmembrane domain that anchors the receptor in the membrane -A cytoplasmic domain that extends into the cytoplasm of the cell
What is the vertebrate thermostat?
The regulatory system for body temperature in vertebrates (both endo- and ectotherms)
What is traditional physiology?
The study of organisms, organs, and organ systems
What is the effect of insulating clothing and ambient temperature on heat extraction during post-exercise recovery?
The subjects cooled more rapidly in the cool room without insulation than the room with insulation.
What are the symptoms of hypothyroid goiter?
The symptoms of this condition are low metabolic rate, cold intolerance, and physical and mental sluggishness.
Why does brown fat look brown?
The tissue looks brown because of its abundant mitochondria and rich blood supply
Explain peripheral vasoconstriction and dilation
The velocity of blood flow through a blood vessel varies with the diameter of the vessel (all else being equal). Diameter is controlled by smooth muscle lining the vessel. Contraction of the smooth muscle results in vasoconstriction (decreasing flow), while relaxation of the muscle causes vasodilation.
Hypothesis: Strains of mice that become obese lack a satiety factor (or its receptor) in their brains. Describe the conclusion.
The wild-type OB gene codes for a satiety hormone. This hormone is given the name leptin, which inhibits the desire to eat. The Db gene encodes the leptin receptor. Thus, this is why strains of mice become obese.
What are peptides, or proteins?
These hormones are large and water soluble (polar) and transported by vesicles out of the cell that made them. Their receptors are on the outside of the cell membrane of the target cells (they can't get into the cells).
How are the anterior and posterior pituitary related?
They are 2 separate organs
Why are fur and feathers good insulators? (pg 828)
They trap a layer of still, warm air close to the skin surface. However, if that air is displaced by water, insulation is drastically reduced. -In many species oil secretions spread through fur and feathers by grooming are critical for resisting wetting
How do bombus, or Hymenoptera (ants, bees and wasps) retain heat in their thorax?
Through a natural heat exchanger.
What is the role of thyrotropin (TSH)?
Thyrotropin (thyroid-stimulating hormone, TSH) from the anterior pituitary activates thyroid gland cells to produce thyroxine.
What is the role of the thyrotropin-releasing hormone (TRH)?
Thyrotropin-releasing hormone (TRH) from the hypothalamus activates TSH-producing cells in the anterior pituitary.
True or false: When PTH stimulates the release of calcium from bone, phosphate is also released.
True
True or false: Both ectotherms and endotherms can control blood flow to the skin? (pg 824)
True.
True or false: Both ectotherms and endotherms use behavioral thermoregulation.
True.
True or false: Basal metabolic rates correlate with body size. (pg 826)
True. However, although an elephant is more than 100000 times larger than a mouse, the BMR of the elephant is only about 7000 times greater than that of a mouse. That means that a gram of mouse tissue uses energy at a rate greater than a gram of elephant tissue. -Across all of the endotherms, BMR per gram of tissues increases as animals get smaller.
True or false: Birds use only shivering heat production. (pg 827).
True. Mammals can use shivering and/or non shivering heat production, but birds use only shivering heat production
When an environmental temperature is within the thermoneutral zone, how does it affect thermoregulatory responses? What if it is outside the thermoneutral zone? (pg 827)
When an environmental temperature is within the thermoneutral zone, an endotherm's thermoregulatory responses do not require much energy and could be considered passive (changing posture, fluffing fur, and controlling blood flow to skin). Outside the thermoneutral zone, an endotherm thermoregulatory responses are active and require considerable metabolic energy
What is countercurrent heat exchange?
When arteries and veins are close together, some heat lost from arterial blood enters venous blood. Venous blood temp therefore rises as it travels towards the body. Creates a more equal heat distribution between arteries and veins.
How do animals control blood flow to the skin? (pg 824)
When body temperature rises because of exercise, blood flow to the skin increases, and the skin surface becomes warm. The heat that the blood brings from the body core to the skin is lost to the environment through the four avenues of heat transfer, which helps bring the body temperature back to normal. In contrast, when body temperature is too low or environment is to cold the blood vessels supplying the skin constrict, reducing heat loss to the environment.
Explain the difference between positive and negative feedback control mechanisms. (pg 816-817)
While negative feedback is focused on turning a system to a set point, positive feedback amplifies a response(i.e., it increases the deviation from the set point).
What is the key difference between neurons and glia, the two cell types that make up nervous tissue? (pg 819-820)
While neurons code and conduct information as electrical signals, glia do not generate electrical signals. -both do communicate through the release of chemical signals
Why is heat stroke a danger for those who must be active in the heat?
Working muscles generate heat. Humans have normal internal temperatures that are not far from the environmental temperatures that cause heat stress, so they do not have much of a safety zone. Most mammalian skin surfaces are covered by fur, which makes it difficult to lose heat. (pg 815)
Is energy expended when temps go below the LCT or the UCT?
Yes, energy is expended either way
Briefly explain the negative feedback system?
You have a disturbance, in which a change occurs. You have a sensor, or the place where change is detected (neurons). There's a control, which is just a response to the change (hypothalamus). There's an effector, or the effect of the response (neurons and hormones).
What is an organ system?
a group of organs that function together (i.e., the heart and vascular system form the cardiovascular system)
Astrocytes
a star-shaped glial cell of the central nervous system.
What are the temperature ranges for terrestrial environments?
air temperatures range -95C (-140F) to ~85C (180F)
What two hormones work together in insects to regulate molting?
brain hormone and ecdysone (molting hormone)
What three hormones control calcium levels?
calcitonin, parathyroid hormone and vitamin D.
What do bone minerals consist of?
calcium and phosphate.
How do we describe the temperature sensitivity of a physiological process?
can be described as a quotient, Q10
What are muscle tissues made of?
elongated cells capable of contracting and causing movement by a sliding of protein filaments past each other.
Four basic types of tissue:
epithelial, connective, muscle, and nervous
Glucocorticoids
influence (raise) blood glucose concentrations and other aspects of fuel molecule metabolism.
Mineralocorticoids
influence extracellular ionic (especially Na+ and K+) balance.
What temperature range do most cellular functions need?
proteins begin to denature and lose their function when it gets Above 40 degrees celsius. Between 0C and 40C typically (pg 820)
What hormones do the intestines produce and secrete?
secretin, cholecystokinin
What are epithelial tissues?
sheets of densely packed and tightly connected cells that cover inner and outer body surfaces.
Sex steroids
stimulate sexual development and reproductive activity. Under normal conditions these are secreted in only minimal amounts by the adrenal cortex.
How do terrestrial systems vary?
temperature gas content (O2, CO2, N2), humidity, water, mineral availability, light, etc.
How do aquatic systems vary?
temperature, gas content, salinity, pH, hydrostatic pressure, light, etc.
When did scientists fully understand the enzyme-level activity of glycogenolysis?
the 70's
What is homeostasis?
the maintenance of constant conditions in the internal environment of an organism.
