BISC 162 EXAM 1 - Physiology, Homeostasis, and Temperature Regulation PDF

BISC 162 EXAM 1 Jan 22 Ch. 38: Physiology, Homeostasis, and Temperature Regulation ​ Lecture Objectives: ​ Understand what is meant by “homeostasis” and why physiology is integral to it ○​ Homeostasis: the optimal internal physical and biochemical conditions maintain...

BISC 162 EXAM 1 Jan 22 Ch. 38: Physiology, Homeostasis, and Temperature Regulation ​ Lecture Objectives: ​ Understand what is meant by “homeostasis” and why physiology is integral to it ○​ Homeostasis: the optimal internal physical and biochemical conditions maintained by organisms for survival ​ Maintained by physiological systems and processes ○​ Physiology: the study of physical and biochemical processes and functions in living organisms ​ Dumbed down: the study of homeostatic mechanisms ○​ ○​ Receptor puts an input to a control center and the output is sent to an effector which corrects the balance ○​ Why do multiple tissue types evolve? ​ The basic idea is that there were advantages to being large ​ Because they eat smaller things and can’t get eaten ​ Single cells are constrained in the size they can attain ​ Because of the surface area to volume ratio ○​ Surface area is squared while volume is cubed ​ As the cell gets bigger, the surface area relative to its volume is decreasing ○​ Think of mouse vs elephant: overall elephant has more surface area but relative to its volume, mouse has a higher ratio ​ To increase size, number of cells increase ​ When cells increase, they become specialized ​ Be able to describe the fundamental concepts behind the evolution of multicellularity and development of tissue types, and the role of tissue types in homeostasis ○​ ​ Provide details regarding the homeostatic mechanisms involved in temperature regulation Jan 24- friday ​ Levels of organization and types of tissue  ○​ Tissues are distinct groups of cells performing a similar function 1.​ Epithelial 2.​ Muscle 3.​ Connective 4.​ Nervous ​ Epithelial tissues ○​ Used for compartmentalization ○​ Allows separation between internal/ external parts of the organ ​ Stratified squamous epithelium ​ Allows separation between internal/ external parts of the organ ​ Columnar epithelium ​ Lines internal organs like lungs and small intestine. Can have secretory and absorptive functions. Enables movements of substances between body compartments ​ Cuboidal epithelium ​ Makes up tubules and ducts and can have secretory and absorptive functions ​ Secretory cells ​ The stomach lining. Secretes digestive juices and acids. Can also be found in the delivery, sweat, and mammary glands. Also in the pancreas and anterior pituitary ​ Muscle tissues ○​ Generation of force ​ Cardiac muscle ​ Heart contractions ​ Smooth muscle ​ Provides motility to internal organs like the digestive tract. Controls diameter of blood vessels ​ Skeletal ​ responsible for voluntary movements of the body ​ Connective tissue ○​ Provide support ​ Bone tissue ​ Provide support structure for body for muscles to move ​ Adipose tissue ​ White fat cushions and supports organs, provides thermal insulation, and stores energy, brown fat produces heat ​ Blood cells ​ RBC carry respiratory gases. WBC protect against foreign substances and microorganisms invading the body  ​ Ligaments and tendons ​ Connect bones to bones and muscles to bones ​ Nervous tissues ○​ Process information ​ Sensors ​ Cells in the retina Encode information about external environment ​ Glia ​ Support neurons in many ways and modulate their signaling; insulate neuronal processes. Provides immune functions for the central nervous system ​ Neurons ​ Communicate information from sensors to the central nervous system, store and integrate information, communicate commands to muscles and glands ​ Organs consist of multiple tissue types ○​ ​ Homeostasis ○​ Multicellular organisms require a stable internal environment ○​ Cells in multicellular organisms exist in very different environments and are subject to large differences in: ​ Temp ​ Available nutrients ​ Metabolic wastes ​ General physiological mechanisms to maintain homeostasis 1.​ Negative feedback- negates deviations from some set point a.​ ex. Regulation of many hormones 2.​ Positive feedback- increases deviation from some set point, but culminates in an event that resets the system  a.​ ex. parturition(act of giving birth) 3.​ Feedforward information(anticipatory)- the set point changes in anticipation of changing conditions a.​ ex. Stress response ​ An analogy using the heating/cooling system of a house ○​ The thermostat knows to raise the temp: after the night and cool down during the night ○​ Thermostat is anticipating to raise or lower the temperature ​ Animals exchange heat with the environment ○​ Conduction- direct transfer of heat when diff temps come into contact ○​ Radiation- warmer objects lose heat to cooler objects by radiation ○​ Convection- heat is lost when stream of air is cooler than body surface temp ○​ Evaporation- water leaves body from surface to cool down temp ​ Environmental temps can fluctuate dramatically and present problems for all organisms ○​ Why do varying Q10 values in different systems often pose a problem ○​ Why do extreme temperatures threaten survival ​ Classification of animals based on thermoregulatory characteristics ○​ Homeotherms- maintain constant body temps ex humans, birds ○​ Poikilotherms- fluctuating body temps ex lizards ○​ Endotherms- lots of internal heat generated- produce heat to compensate for loss to environment ex mammals ○​ Ectotherms- dependent on environment sources of heat (external heat acquired) ex insects reptiles ○​ Heterotherm- recent term arising from realization that some ectotherms can produce a lot of metabolic heat and some endotherms may not produce heat (at least sometimes) ex. Bear in hibernation Jan 27 Diabetes- insulin from pancreas ​ Body temp ○​ Ectotherm, as temp increases, an ectotherm will also increase ○​ Endotherms maintain constant body temperature ​ Metabolic rate: ○​ As environmental temp increases, ectotherm metabolic rate increases ○​ Metabolic rate of mouse is much greater than the lizard all of the time ​ Thermoneutral zone in endotherm, range of temp where a metabolic rate is low and ind of fluctuation of environmental temps, does not exist in ectotherms ​ Endotherms alter metabolic rate to regulate temperature ○​ General idea- some physiological process is activated when too cold or too hot and this increases metabolic rate  ○​ It is possible that positive feedback “kicks in” and creates a problem, could occur in the ○​ Increases metabolic rate to maintain a constant body temperature ​ Thermoregulatory adaptation and considerations 1.​ Antifreeze- deep sea fish and frogs, body hair fur 2.​ Heat shock proteins- proteins produced by many cells that bind to other proteins to allow other proteins to maintain their structural integrity, so they don't denature 3.​ Isozymes- snake, different forms of enzymes, produces different enzymes in order to stay 4.​ Blood “shunts”- ways to delivery blood to other parts of the body to disperse heat 5.​ Sweat/pant 6.​ Shivering 7.​ Integument- ex polar bear has fur dolphin has adipose both used to helping in the cold 8.​ Behavior ​ Acclimatization- refers to alterations in physiological processes to cope with environmental changes (seasonal changes in temp) production of different enzymes (isozymes) is a good example ​ Dinosaurs- ectortherms that maintain constant body temps and homeotherms because of their size ​ Brown fat and non shivering heat production ○​ Thermogenin uncouples movement of protons from ATP production (it is also referred to as uncoupling protein or UCP) ○​ Brown is brown because of how many mitochondrias it has ○​ Instead of normal proton gradient, brown fat has protons that move down concentration gradient through UCP that doesn't generate heat from lack of atp production ○​ Brown fat (adipose tissue) produces and generates heat ○​ Found mainly in newborn infants ​ Disproportional amount of brown fat when born ​ Because theres a lot of surface area due to size, minor changes have a big impact, so theres more brown fat to keep heat ​ Behavioral regulation ○​ Ectotherms can still maintain constant body temps through behavioral regulations ○​ Blood flow to skin in marine iguanas- galapagos islands ​ Marine iguanas dive into water and feed of seaweed but then eat it on the rocks ​ Ocean is freezing but galapagos islands are very hot  ​ Heart rate drops quickly and temp decreases when dives into the ocean, this preserves heat (less blood flow so) decreases flow of blood through skin on surface of the body ​ Back on land, heart rate increases to increase body temperature ​ Smooth muscles get cut off when diving in water ​ Countercurrent heat exchange ○​ Cold fish ​ Body reflects temp of water ​ Concurrent exchange mechanism, fluids exchange heat in tubes and equilibrate, parallel and touching ​ Blood is oxygenated and cooled to water temp in the gills ​ Cold blood flows through the center of the fish in the large dorsal aorta(oxygenated still) ​ Arteries carry blood to tissues ​ Veins return blood to the heart( heated and deoxygenated) ​ Heart pumps blood through the gills ​ Overall cant maintain body temps ○​ Hot fish ​ Ex tuna and great whites ​ Maintain temps that are higher than water temps ​ Predators are more active than the fish they eat ​ Blood oxygenated in gills, goes through arteries just under the skin ​ Hot fish tubes are arranges countercurrently ​ Countercurrent exchange, running opposite directions, they create random numbers because countercurrent always has a temp gradient associated across the tubes ​ In the heat exchangers arterial blood flows into the muscle and is warmed by venous blood flowing out of the muscle Wed Jan 29 ​ Body size, metabolism, and heat ○​ Larger animals are subject to overheating so they have lower metabolic rate ​ Geographic variation in morphology of closely related species because of temperature ○​ Bergmann’s rule: animals tend to be larger in colder climates ○​ Allen’s rule: limbs tend to be shorter and thicker in colder climates ​ Ex arctic hare and jack rabbit ​ We have focused largely on responses to temp changes( effectors) but where are the sensors, receptors, and the control center ○​ Located largely in the base of the brain ○​ The hypothalamus acts as the primary control center, and to some extent the sensor, though it receives input from other sources (skin)  ​ How do we know hypothalamus acts as a thermostat ​ When hypothalamus was cooled, metabolic heat production increased and the squirrels body temp rose ​ When hypothalamus is heated, squirrels metabolic rate and temp fell ​ Torpor, hibernation, and heterothermy (regulated hypothermia) ○​ On a 24 hour basis, not months/weeks at a time ○​ humming birds have such a high metabolic rate that during sleeping hours, they lower their body temp and metabolic rate (torpor) to get through the night Chapter 39: Animal Hormones ​ Homeostasis requires coordination of multiple systems ○​ Hormones: sending out a chemical message to any part of body to instruct what to do, chemical messengers that affect the function of some target cell ○​ The only cells that respond to the hormone are the cells that possess a sensory/ receptor ○​ Target cell: possesses the receptor for the hormone ​ Forms of hormones: ​ Endocrine mediation: secrete chemicals into blood-stream, where they may travel to distant target cells ​ Autocrine mediation: autocrine substances feed back to influence the same cells that secreted them ​ Paracrine mediation: paracrine cells secrete chemicals that affect adjacent cells ​ Ectocrine mediation: ectocrine substances such as pheromones, are released into the environment by individuals to communicate with others (effects mating behavior) ​ Classification of hormones ○​ Protein hormone; peptide bond forming a complex protein ○​ Steroid hormone: formed from cholesterol (testosterone, estrogen) modified by enzymes but all steroids have the cholesterol backbone ○​ Amine hormone: single amino acid, not a chain, can have multiple copies of one amino acid (ex adrenaline aka epinephrine) ​ Different classes of hormones affect cells via various types of receptors ○​ Steroids are nonpolar molecules, solid in lipids but not in water ○​ Protein hormones are polar and water soluble ○​ Amine hormones may be either ○​ Hormones are involved in signal transduction, that is, converting some extracellular signal into an intracellular response ​ A nonpolar signal can diffuse directly across the lipid bilayer of the cell membrane to encounter its receptor in the cytoplasm or nucleus  ​ A signal that is polar/large cannot diffuse through the cell membrane. Its receptor is embedded in the membrane ​ Signal transduction ○​ A steroid receptor acts as a transcription factor ○​ Cortisol (stress hormone) ​ The receptor chaperone complex cant enter the nucleus ​ Cortisol enters the cytoplasm and binds to the receptor, causing the receptor to change shape and release the chaperone which allows the receptor and the cortisol ligand to enter the nucleus ​ Steps: ​ The three units of a g protein coupled receptor, receptor, inactive effector protein ​ Activation of the g protein ​ Activation of the effector protein- activated g protein subunit activates an effector protein that causes changes in cell function, the GTP on the G protein subunit is hydrolyzed to GDP ​ Cellular responses to hormones can vary because of receptors ○​ An example using “fight or flight” endocrine response: seeing a snake 1.​ The brain detects danger and signals the leg muscles to jump back 2.​ The signals and adrenal glands to release epinephrine and norepinephrine into the blood, triggering a number of effects 3.​ The liver breaks down glycogen to supply glucose (fuel) to the blood 4.​ The heart beats faster and stronger, blood pressure rises 5.​ Blood vessels to the gut and skin constrict shunting more blood to the muscles 6.​ Fat cells release fatty acids (fuel) to the blood Friday Jan 31 ​ Endocrine and nervous systems work together ○​ Hypothalamus- consists of neurosecretory cells ​ Hypothalamic neurons produce antidiuretic hormone and oxytocin and transport them to the posterior pituitary ○​ Pituitary- consists of anterior (adenohypophysis- endocrine cells) and posterior lobes (neurohypophysis- neuroendocrine cells) ​ The human pituitary gland is the size of a blueberry, yet it secretes many hormones ○​ Posterior pituitary produces neurohormones ​ Antidiuretic bromine (ADH, or vasopressin) ​ Oxytocin ○​ The neurohormones are released FILL IN LATER ​ Actions of ADH ○​ ADH present: collecting duct is highly permeable to water, recruits aquaporins, thus you retain water and prevent loss of water, results in a small volume of concentrated water ○​ No ADH: collecting duct is not permeable to water, so there is no water taken back up and comes out with your urine ○​ Why do you urinate more when you drink water? ​ There's no ADH present ○​ Oxytocin: induces labor for birth ​ Recall positive feedback ex from ch 38 ​ How could you induce labor in a late term pregnancy ​ How could you stop premature labor contractions ​ Baby drops lower in uterus to initiate labor and stretch the cervix, Cervical stretch: stimulates, oxytocin releases and causes uterine contractions, delivering the baby stops the cycle, if baby wasn't delivered, the baby pushes against the cervix that causes cervical stretch ○​ Two hormones are involved in breastfeeding: ​ Oxytocin: comes from posterior pituitary and is described as a milk letdown ​ Prolactin: anterior pituitary, promotes production of milk ​ Sucking stimulates nerves in the nipple and areola that travel to the hypothalamus ​ In response, the hypothalamus stimulates the posterior pituitary to release oxytocin and the anterior pituitary to release prolactin ​ Oxytocin stimulates lobules in the breast to let down (release) milk from storage. Prolactin stimulates additional milk production ○​ The anatomy and relationship between the hypothalamus and anterior and posterior pituitary are very different ○​ Negative feedback loops typically regulate hormone secretion ​ external/internal conditions go to hypothalamus that produce releasing/release-inhibiting hormones to go to anterior pituitary into tropic hormone into endocrine gland into hormone. Hypothalamus to tropic hormones is a “short-loop” negative feedback ​ There are exceptions: think about posterior pituitary hormones we just talked about!!!! ​ Taking steroids inhibits the anterior pituitary and stops tropic hormones ○​ “Stress” response ​ Numerous environmental factors can trigger the response ​ Involves epinephrine/norepinephrine release ​ Glucocorticoid production (cortisol/corticosterone)  ​ Elevated cortisol inhibits release of CRH by hypothalamic neurosecretory cells ​ Elevated cortisol inhibits release of corticotropin by anterior pituitary corticotrophs ​ Adrenal gland produces two ​ Medullary cavity: produces epinephrine ​ Adrenal cortex: produces steroids ​ Glucocorticoids ​ Protein catabolism (breakdown) ​ Lipid catabolism (breakdown) ​ Those products are then used by liver to produce glucose (via gluconeogenesis) ​ Also inhibits immune system and reproductive system ​ How is any of this good (adaptive) ○​ Thyroid hormones ​ Cross section of a thyroid gland ​ Follicle ​ Epithelial cells of follicles ​ Inside of the lumen is a stored form of the thyroid hormone ​ Synthesis of thyroid hormones requires iodine in diet ​ Follicle cells take up iodide by Na cotransport ​ Must have receptors ​ Iodine (from salts in food) forms the mature thyroid hormone ​ Cells begin forming thyroglobulin ​ Colloid: immature thyroid hormone Mon February 3 ​ Regulation of thyroid hormone production ○​ Negative feedback loop ​ Goiters ○​ May be associated with underproduction (hypothyroidism) or overproduction of thyroid hormones ( hyperthyroidism) ○​ Inflamed thyroid gland in the neck ○​ In the US, where iodine is not in short supply, a goiter is usually associated with hyperthyroidism ○​ If not enough iodine, functional hormone never forms ○​ Mainly found in high elevation populations and places far from oceans ​ Many hyperthyroid patients have “LATS” in blood (long acting thyroid stimulators) and a class of immunoglobulins or auto-antibodies. They mimic the actions of TSH(thyroid stimulating hormone). believed to be pathopsychological factor leading to Graves disease and hyperthyroidism  ○​ Overproduction of thyroid hormones (Graves disease) ​ Blood glucose regulation by the pancreas ○​ Acinar cells- digestion- exocrine pancreas (acinar and duct cells) ○​ Islets of Langerhans- consist of alpha(secretes glucagon) and beta(secretes insulin) cells- endocrine ○​ Difference between type 1 and 2 diabetes ​ Type 1: not making enough insulin, autoimmune response, can be genetically based ​ Fixed by injecting insulin ​ Type 2: can be developed, insulin resistance due to cells lacking receptors ​ very difficult to resolve, only special diet and exercise ○​ Is not under hypothalamic- pituitary control ​ What controls production of insulin and glucagon ​ Glucose levels inside of pancreas ○​ Glucose stimulates beta cells and inhibits alpha cells ​ Insulin controls glucose uptake via glucose transporters ○​ When insulin binds to its receptor, cytoplasmic vesicles release glucose transporters that move into the cell membrane ​ Gonadal hormones ○​ Gonadal hormones play a central role in gamete production, reproduction, and behavior(ex aggression, mating behavior) ​ These are activational effects of gonadal hormones ○​ Gonadal hormones also play a major role in the differentiation and development of the external genitalia ○​ These organizational effects of gonadal hormones ○​ How does variation in these structures arise? This is where he talked about penis and vaginal growth Chapter 43: Neurons, Glia, and nervous system ​ Nervous systems encode, process, and store information from the external and internal environments and regulate physiology and behavior ○​ Cell body, stems off of cell body are dendrites ​ Dendrites receive info from other neurons ​ Cell body contains nucleus and most cell organelles ○​ Information collected by dendrites is integrated in the axon hillock, which generates action potentials ○​ The axon conducts action potentials away from the cell body ○​ Axon terminals synapse (the connector) with a target cell ○​ Presynaptic vs postsynaptic cell: postsynaptic cell cna become presynaptic , depends on the way its ordered ​ The other cells found in vertebrae nervous systems include glia  ​ Unlike neurons, glia don't generate and conduct electrical signals ​ Glia support and modulate neural function or provide immune defenses ○​ Oligodendrocytes: located in brain and spinal cord (CNS); wrap, insulate and prevent “electrical leakage” with myelin ○​ Schwann cells: myelin insulation in periphery ​ Wrap around the axon insulating it against electrical leakage ○​ Ependymal cells: line fluid chambers and produce cerebrospinal fluid ○​ Astrocytes: contribute to blood-brain barrier, can alter neural communication ( ○​ Microglia: phagocytosis/immune defense Wed feb 5 ​ Neurons, like all cells, have an electrical charge ○​ The charge is due to the distribution of ions and large charged molecules on either side of the cell membrane. It establishes the “membrane potential” (aka voltage of the cell). The voltage difference is important because it represents the “force” exerted on ions to move between two points. The “resting potential” above is on -60v (inside of cell is negatively charged relative to the outside) ​ What creates the membrane potential? ○​ The difference in the voltage on either side of the neural membrane is mostly regulated by ​ Distribution of ions, established largely by the sodium-potassium pump ​ The permeability (leakiness) of the ions ​ Why is ion permeability important? ○​ Let's consider a neuron at rest where the ion concentrations are differentially distributed inside and outside the cell as a result of the Na/K pump ○​ Now imagine that the cell membrane is leaky (more permeable) to Na ​ What happens to Na? ​ Na will move down the concentration gradient ​ This is because na will move from higher concentration to lower concentration and equilibrate across the membrane. This is called equilibrium potential for Na ○​ What will this do to the membrane potential of the cell ​ Membrane potential is governed largely by Na if the cell is leaky to Na ​ In reality, neurons are leaky to K+ and the resting membrane potential is most closely related to the equilibrium potential of K+ ○​ Equilibrium of K inside and outside the cell is complicated by the electrochemical gradient which is the crux of the nernst equation (you do not need ot know the details of that). You can think of the equilibrium potential in terms of how much pos or neg charge needs to be applied to the inside of a cell to prevent movement of the ions  ○​ Potassium moves against the concentration gradient thats est by NaK pump; potassium leaves the cell once it becomes “leaky” causing the cell to be negative ​ Neurons process information and communicate via electric potentials ○​ Action potentials are sudden, large, transient changes in the membrane potential ○​ They result from changes in the permeability to ions, because ion channels open and close ​ Lets dissect an action potential to understand what is going on ○​ Ion channels act as gates: they open (or close) in response to specific stimuli ○​ Na+ flowing into the cell depolarizes (becomes more positive) ​ Voltage gated Na+ channels open ○​ More K+ flowing out of the cell hyperpolarizes it (becomes more negative) ​ Voltage gated K+ channels open ○​ Cell is extremely permeable to potassium ○​ Details of each “phase” of an action potential ​ Leak K+ channels create the resting potential. Gated channels are closed ​ Some voltage gated Na channels open, depolarizing the cell to threshold ​ Additional voltage gated Na channel activation games open, causing a rapid spike of depolarization- an action potential ​ Na channel inactivation gates close; gated K channels open repolarizing and even hyperpolarizing the cell ​ All gated channels close. The cell returns to its resting potential. Na inactivation gates reopen. ​ Directions nd propagation of action potential ○​ An action potential cannot go the other way because of the refractory period of the Na channels (they are inactivated) ○​ Voltage gated na channels open in response to spreading membrane depolarization but have inactivation gates that close quickly ○​ A depolarizing current spreads to adjacent areas of the membranes ○​ Upstream na FINISH LATER ​ Significance of myelin ○​ Myelin insulates ○​ Saltatory conduction ○​ Nodes of ranvier ​ Na channels open, generating action potential ​ Spreading current from the upstream node and brings membrane at the next nod threshold ​ Upstream na channels inactivate making the membrane refractory. Voltage gated k channels open, repolarizing the axon ​ The action potential jumps to the new node and continues form node to node  ○​ Speed of transmission ○​ SKIPPED THIS DAY: see if margaret will send me feb 7 ○​ significance of myelin: -​ myelin insulates (insulates against loss of electricity/diffusion of ions) -​ wrapping of myelin prevents loss of ions -​ saltatory conduction -​ nodes of Ranvier -​ speed of transmission -​ multiple sclerosis ​ synapse: junction between pre synaptic neuron &... ​ types of synapses: types of communication between cells: 1.​ chemical synapse: type of synapse @ which neurotransmitter molecules released from a presynaptic cell induce changes in a postsynaptic cell -​ most common type of synapse in vertebrate nervous system -​ voltage gated calcium channels 2.​ electrical synapse: type of synapse @ which action potentials spread directly from presynaptic cell to postsynaptic cell -​ are common among invertebrates ​ neuromuscular chemical synapse:  ​ chemical synapse between 2 neurons: -​ extent of depolarization in postsynaptic cell depends on amount of ACh released from presynaptic cell & # of receptors activated in postsynaptic cell -​ presynaptic input to postsynaptic cell may not be sufficient to elicit an action potential -​ this is the idea behind graded potentials 2/8: ​ not all inputs to postsynaptic cells are excitatory:  -​ there are many different neurotransmitters & many types of receptors. Thus far, we’ve focused on ACh & acetylcholine receptors -​ however, consider GABA (gamma aminobutyric acid) & its receptor shown to right ​ 2 general types of receptors: + 1.​ ionotropic receptor cell: stimulus opens a 𝑁𝑎 channel 2.​ metabotropic receptor cell: stimulus affects a receptor molecule that initiates a G protein-mediated cascade that controls an ion channel via second messenger ​ these gated ion channels may be sensitive to various stimuli ​ major divisions of peripheral nervous system: 1.​ somatic 2.​ autonomic ​ organization of autonomic nervous system: ​ comparison of somatic & autonomic systems: -​ if a neuron produces acetylcholine as a neurotransmitter it is referred to as a “cholinergic” neuron. If it produces epinephrine/norepinephrine it is referred to as a “adrenergic” or “noradrenergic” neuron Mon Feb 10 ​ Organization of autonomic nervous system ○​ Parasympathetic vs sympathetic divisions ○​ parasympathetic ​ Mostly consists of neuron coming out of the stem of the brian and sacral part of the spinal cord ○​ Sympathetic ​ Comes out of the cervical, thoracic, and lumbar sections of the spinal cord ○​ Both contain preganglionic and postganglionic neurons ○​ Cholinergic ​ Both have this type of preganglionic but parasympathetic also has this type of postganglionic ○​ noradrenergic releases noradrenaline ​ On sympathetic side ○​ Have opposing effects because of different neurotransmitters ​ Comparison of somatic and autonomic systems ○​ If a neuron produces acetylcholine as a neurotransmitter it is referred to as a “cholinergic” neuron. If it produces epinephrine/norepinephrine is it referred to as “adrenergic” or “noradrenergic” neuron ○​ What causes opposing effects of sympathetic and parasympathetic ​ Different neurotransmitters that have different receptors, therefore having different effects on the cell’s organs ○​ Chromaffin are the postganglionic neurons of the sympathetic nervous system ​ Modified adrenal gland ○​ Not all reactions to stimuli involve processing by the brain: spinal reflexes  ​ Stimulus is not sent up to higher brain centers ​ Involves input to the spinal cord, the motor output to the muscles ​ Ex hammer tap on knee cap Chapter 48 Circulatory system ​ Open and closed circulatory systems ○​ Open systems: ​ Blood referred to as hemolymph, the extracellular fluid in the blood is plasma which is separated from intracellular fluid ​ blood/ hemolymph, is pumped throughout the whole body cavity, not inside of a vessel system ○​ Closed systems have advantages: ​ More rapid ​ More control and selective delivery ​ But, that does not mean that a closed system would be “better” for all organisms. Closed systems evolved with increased multicellular complexity ​ Vasculature associated with closed systems ○​ Heart is central system ○​ Heart - arteries - arterioles - capillaries - venules - veins - back to heart ​ Vessels, pressure and valves ○​ Reinforcement associated with arteries than veins ​ Arteries have more elastin/connective tissue that gives it more structural integrity and more smooth muscle wrapped around them ​ More pressure exerted on arterial walls from being closer to heart pump ​ Because they operate under low pressure, some veins have velves to prevent backflow of blood  ​ Muscle contraction and relation effects valves open and closing and therefore blood flow/ blood pressure ​ Capillary network is very fragile because it is one layer thick, if there was too much pressure within the network, it would rupture, there has to be a great lowering of pressure before entering the capillary ​ Capillaries have higher total area in comparison to other networking systems causing the lower in blood pressure ​ Velocity of the blood increases once reaching the venules but the blood pressure remains low ​ Valves facilitate movement back to the heart ​ The structure of capillaries (and necessary drop in pressure) ○​ Capillary walls consist of a single layer of endothelial cells. Fluids can squeeze through the spaces between the cells ​ Composition of blood ○​ Plasma portion: mostly water with solutes, proteins, clotting fibers, nutrients, waste, hormones ○​ Cellular portions: mostly RBCs with buffy coat that contains WBCs and platelets ​ Rbcs - erythrocytes ​ Wbc- leukocytes ​ platelets - cell fragments that are important in blood clotting ​ Lets walk through the diversity of circulatory systems beginning with vertebrates that lack lungs ○​ One of the biggest modifications to the circulatory system of vertebrates has to do with the evolution of lungs and pulmonary vs systemic circuits ○​ Most fish have a heart with four chambers: sinus venosus, an atrium, a ventricle, and a bulbus arteriosus ​ Gills involved with oxygen exchange from the surrounding water ​ Lungfish ○​ the lungfish heart has a partially divided atrium. The left side receives oxygenated blood from the lung; the right side receives deoxygenated blood from the body ○​ A dual circuit system involves lungs ​ First occured in lungfish( where lungs first arrived) ​ Need to understand environment ​ Tend to live in ponds that dry up ​ Have to go through heart twice to get the oxygenated blood into the systemic circuit ○​ Oxygen exchange still in the gills, but only occurs in the oxygen exchange gills and not throughout the gills ○​ Only posterior gills have ○​ This is when a pulmonary circuit was first evolved  ○​ Deoxygenated blood goes through the posterior gills (oxygen exchange gills) for where the fish will gulp air from the atmosphere and take it to the lungs ​ The blood doesn't become oxygenated until reaching the lungs (for when it is dry) ​ If not dry, posterior gills will get enough oxygen grom water and environment, so the blood becomes oxygenated without going through the lungs and can go straight to the dorsal aorta ○​ The anterior most gills (high throughout gills) do not lose oxygen to surrounding water Wednesday Feb 12 ​ Amphibians ○​ In adult amphibians, the pulmonary and systemic circuits are partially separated. The heart has three chambers ○​ Vena cava brings deoxygenated blood to the rights side of the heart into right atrium- then pumps deoxygenated blood into the ventricle and pumps blood into the pulmonary artery where the blood can become oxygenated in the lungs and then into the pulmonary vein ​ The pulmonary vein then brings the now oxygenated blood into the left atrium and then into the aorta that brings blood to systemic circuit for blood to be spread throughout the body ○​ Can also repair via Cutaneous respiration- respiration through the skin ​ Reptiles (lizards snakes turtle, but not crocs) ○​ 3 chambered heart, left right atrium and partially divided ventricle. Divided by a septum which directs oxygenated blood to the body and deoxygenated blood ot the lungs ○​ Have 2 aortas: left and right ​ When not breathing, the pulmonary artery constricts pushing deoxygenated blood through right aorta ( remember, metabolic rates are low) ○​ Deoxygenated blood returns from the system capillaries and comes into the right atrium through the vena cava and dumps into the right atrium ○​ Then goes into the partially divided ventricle, which pushes blood up into the lung capillaries to become oxygenated ○​ Some blood will be pushed into the right aorta (half oxygenated/half deoxygenated blood) and joined into the left aorta ○​ This blood goes into the left atrium then pushed into the left aorta to be sent back into the systemic capillaries. ○​ Because of the organisms low metabolic rate, some oxygen remains left in the blood after going through the systemic capillaries- this blood pushed up from the  partially divided ventricle and goes straight through the right aorta to join the left aorta in distributing oxygenated blood back to the systemic capillary network ​ Birds and mammals ○​ Complete separation of ventricles prevents mixing of oxygenated and deoxygenated blood ○​ Have four chambered hearts (fully divided ventricle) ○​ Deoxygenated blood in the right ventricle is routed up through the pulmonary artery into the lung capillaries where it becomes oxygenated. This blood then travels through the pulmonary vein and into the left ventricle to be pumped into aorta and sent through systemic capillary system ​ The human heart and circulation ○​ Superior and inferior vena cava brings deoxygenated blood into the heart from capillaries in the body ○​ Deoxygenated blood from tissues in body enters the right atrium, passes through valve( contracts and pushes) into right ventricle ​ Once right ventricle contracts, the blood travels through the pulmonary artery that brings deoxygenated blood to the lungs ​ From the lungs, the now oxygenated blood returns to the left atrium and flows into the left ventricle. Left ventricle pumps blood through aortic valve into systemic circulatory system ○​ Atrioventricular (AV )valves separate atria and ventricles ​ One way valves, contraction causes pressure, keeps motion in one direction and cant have backflow ​ Tricuspid and bicuspid valves: ​ Right is tricuspid- deoxygenated- three flaps ​ Left is bicuspid- oxygenated- two flaps ​ Pulmonary and aortic valves and called semilunar valves ​ Flaps of tissue where pressure from below will cause them to open. Pressure from above will close them shut, causing blood to go in one direction ○​ Cardiac cycle, systole, diastole, and “lub-dup” ​ Near the end of the diastole, the atria contract ​ The first heart sound “lub” marks the beginning of the systole. The ventricles contract, the av valves close and pressure in the ventricles builds up until the aortic and pulmonary valves open ​ Blood is pumped out of the ventricles and into aorta and pulmonary artery ​ “Dup” marks the end of the systole. The ventricles relax; pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut ​ Ventricles are filled with blood  ​ Period of diastole: nothing is happening/ventricle relaxes ​ And the end of diastole, systole is onset of ventricular reaction, causes AV valves to close ​ See graph of systole and diastole (an upside down parabola of pressure once reaching the systole phase- pressure is at a constant low during the stages of the diastole) Friday Feb 14 ​ Blood pressure is measured using a sphygmomanometer and stethoscope ○​ The cuff is inflated to shut off all blood flow to the arm ○​ Pressure in the cuff is gradually lowered until the sound of a pulsing flow of blood through the constriction in the artery is heard. At this time, pressure in the cuff is jut below the peak systolic pressure in the artery ○​ Pressure is further lowered until the sound becomes continuous. At this time, the cuff is just below the diastolic pressure in the artery. This person’s bloof pressure is just below FINISH ​ Electrical stimulation of heart is generated in the heart muscle ○​ Pacemaker cells- muscle cells, not neurons, that initiate action potentials and muscle contraction ○​ The left and right atria contract in unison followed by contraction of both ventricles. In order for this to happen, pacemaker cells spreads action potential across the cardiac musculature through the cardiac gap junction (between adjacent cells) ​ When the action potential is generated by these cells, a wave of depolarization or action potential spread across all the arterial muscular rally rapidly through these gap junctions ​ Does not spread to the ventricular muscle because there's no gap junctions between atria and ventricles ​ Sinoatrial node id what is generating the action potential (the pacemaker cells in the right atria of the heart) ​ Wave of depolarization is transmitted to the av valve, travels down bundle of HIS and passes through the purkinje fibers that radiates it and spreads it throughout the thick ventricle musculature ​ This causes atrial contraction, followed by ventricular contraction ○​ Spread of action potentials is facilitated by gap junctions ○​ Purkinje fibers ​ Spreading of electrical signals through the ventricular musculature ​ Generation of action potentials in pacemaker cells ○​ Inherent rhythmicity of heart ​ Dont need and outside neural input from the nervous system to regulate the beating of the heart  ​ You can remove the heart from and organic and it will continue to beat outside an organism because of the inherent rhythmicity associated with the pacemaker cells/SA node ○​ Generation of the AP is unique in SA node cells ○​ A key element involves opening of unique na channels cause by the efflux of K+ ​ Permeability of potassium increases during repolarization since its moving out of the cell ​ Trigger sodium channel to open as k+ is moving out of the cell, during phase of repolarization ​ Influx of sodium triggers two different calcium channels ​ Transient and long lasting ​ This is followed by activation of transient and long lasting ca+ channels ​ Transient opened for short period of time ​ Long lasting channel opened for longer ​ Causes gradual increase in the membrane potential until it reached threshold, where the action potential is called buy the L type channels opening ​ The pacemaker potential does not require neural input ​ But neural input form both divisions of the autonomic nervous system can modify the pacemaker potential ​ Norepinephrine- (NE) increases heart rate ​ Acetylcholine (ACh) decreases heart rate ​ Graph if membrane potential ​ See graph ​ Neuroendocrine control of heart rate ​ Higher brian centers signal emotion, anticipation, stress- sympathetic divisions release norepinephrine ○​ Goes through frontal gland to release epinephrine and norepinephrine ​ Chemoreceptors in medulla signal high Pco2 in blood- parasympathetic division releases acetylcholine ​ Regulation of heart rate ​ An electrocardiogram ​ Electrical changes occurring within heart musculature radiates over the skin ​ Typical ECG recording with corresponding arterial pressures and heart sounds ​ P corresponds to the depolarization of the atrial muscle  ​ Q R and S correspond to the depolarization of the atrial muscle and therefore contraction of the ventricles as well as the repolarization of the atria ​ T corresponds to the repolarization and therefore the relaxation of the ventricle ​ Blood clotting ○​ Platelets are fragments of cells produced in bone marrow that contain enzymes and chemicals involved in blood clotting. Inactive enzyme prothrombin is converted to thrombin, which produces the protein fibrin from fibrinogen ○​ An injury to the lining of a blood vessel exposes collagen fibers: platelets adhere and become sticky ○​ Platelets release substances that cause the vessel to contract. Sticky platelets form a plug and initiate the formation of a fibrin clot ○​ The fibrin clot seals the wound until the vessel wall heals ○​ Clotting factors ​ Released from platelets and injured tissue ​ Blood plasma proteins synthesized in liver and circulated in inactive form ​ Cause the conversion of prothrombin which is circulating in the blood plasma to thrombin then converts fibrinogen (which is also circulating in plasma) into fibrin ​ The fibrin then forms a meshlike network that seals off the injured vessel ​ The cells will be replaced over time and wound associated with vessel heals ​ Cardiovascular disease is related to ¼ of all deaths in the US and is often due to hardening of arteries ○​ Damaged endothelial cells attract WBCs ○​ Underlying smooth muscle cells are exposed ○​ Lipids are deposited forming fatty plaque ○​ Connective tissue and calcium deposits/plaques result in hardening and narrowing of vessels ○​ Platelets adhere to the plaque forming a thrombus ○​ The endothelial lining is harmed by something (pathogen or dietary habits) ​ This damage attracts WBCs to come to the endothelial ​ Lipids begin to be deposited in and around cells in surrounding areas ​ This forms the fatty plaque/ cells no longer had the flexibility it used to have and cannot accommodate the changes associated with blood pressure adjustment ​ Build up in a blood vessel and constricts blood flow through them ○​ Platelets adhere to the plaque forming a ‘thrombus’ (blood clot) IF in coronary artery this leads to heart attack. If thrombus breaks loose= embolism which in brain=stroke