Midterm 2 Flashcards
What is homeostasis?
Ability to maintain a consistent internal environment so cells can function properly, even if the external environment changes
All organs work to maintain the internal environment
What is a homeostatically regulated variable?
The regulated variable has a sensor within the body, kept in range by physiological mechanisms (blood pressure) , operate continuously
Example of non-homeostasis variable
Heart rate
Parts of a negative feedback system? (5)
Set point, sensor, error detector, integrator, effector
Set point?
Normal range for regulated variable
Sensor?
Detects value, tranduces into some kind of stimulus
Error detector?
Compares actual value to set point
Integrator?
Interprets error and determines output of effectors
Effector?
Change value of regulated variable
Example of loss of homeostasis?
Diabetes, When homeostasis lost for one variable, it can trigger changes in other variables
Negative feedback?
returns variable to set point
Positive feedback?
pushes variable away from set point
Feed forward control?
anticipatory, minimizes changes to variable
What is the ANS?
Consists of motor neurons that innervate smooth muscle, cardiac muscle, glands
Makes adjumesnts to body as needed (shunts bloods, heart rate, digestive process)
Subconscious, also called involuntary nervous system or visceral motor system
ANS is part of the ______ pathway
Efferent, Motor
Both somatic and autonomic contain motor fibers but differ in?
Effectors, Efferent pathways/ ganglia, Target organ responses
Somatic nervous system?
Skeletal muscle, Cell body in CNS, myelinated axon travels in spinal/ cranial nerves to skeletal muscle
All somatic neurons release Ach (always stimulatory)
Autonomic nervous system?
Cardiac, smooth muscle, glands
Preganglionic: CNS: thick myleinated axon (ganglion)
Postganglionic: PNS: non-myleinated to effector
Pregang. Release AChm postgang. Release NE or ACh
What does dual innervated mean?
Visceral organs served by both divisions, with opposite effects
Parasympathetic?
Rest and digest, conserves energy, maintenance,
Sympathetic?
Fight or flight, mobilizes body, emergency
Anatomy of parasympathetic?
Crainoscaral, brain stem, sacral spinal cord
Long preganglionic, short postganglionic
Glangia near visceral effector organ
Anatomy of sympathetic?
Thoracolumbar, thoracuic, lumbar spinal cord
Short preganglionic, long postganglionic
Glanglia close to spinal cord
Para/sym. in sex?
Parasympathetic fibers cause erection or penis/ clitoris, sympathetic fibers cause ejactualtion of semen or contraction of vagina
Sympathetic tone?
BVs only innervated by sympathetic fibers, controls blood pressure, continual state of partial constriction
Blood goes where needed, Vasoconstriction of skin BVs minimizes bleeding during injury
Parasympathetic tone?
Tone slows heart, dictates activity of digestive tracts, activates most glands
Sympathetic can override during stress, some drugs block parasympathetic responses
3 other features of the sympathetic system?
Thermoregulatory in response to heat
Release renin from kidneys
Metabolic effects
Localized vs. diffuse effects?
Para.- short lived, ACH destryoed by ACHe
Symp- longer, NE and epinephrine take long time to come down
Brain stem and SC?
Reticular formation, medulla, relflexes
Hypothalamus?
Main integrative center, Heart rate, BP, emotional responses, activates fight or flight
Cerebral cortex?
Cortical input may modify ANS, works through limbic system
Disorders of the ANS? (2)
Hypertension (high blood pressure), ulcers (decreased blood to stomach wall)
What is smooth muscle?
alls of most hollow organs (respiratory, digestive, urinary, repoprductive, not in heart)
Sheets of tightly packed fibers
2 layers of smooth muscle?
Longitudinal- Run length of organ, when shortened shorten length
Circular layer- fiber runs arounds diameter of organ, when shortened shorten diameter
Gives contraction of GI tract to pass food
Components of muscle cells?
Thinner, shorter, Single nucleus, No striations, not alot of extracellular matrix tissues
Muscle cell axons contain…
varicosities, swellings which store and release NT’s into synaptic cleft/diffuse junction
2 types of muscle?
Unitary/ visceral, or multiunit
Unitary muscle?
All hollow organs minus heart
Has spontaneous action potentials, can contract on its own/ depolarize without external stimuli
Electrically coupled by gap junction, chemically stimulated
Multiunit muscle?
Large airways of lungs, large arteries, iris
No gap junctions, no spontaneous depolarization
Controlled by ANS, hormones
What is the intermediate filament network?
No contractile proteins, form lattice-like network
Transmit tension generated by contractile proteins to the sarcolemma
When actin and myosin contract energy is transmitted to IFN
How are filaments arranged?
Thin/ thick filaments arranged diagonally, connected by dense bodies to eachother and to intermidate filaments, for every thick filament their are 13 thin
How is contraction regulated? (4 steps)
Contraction regulated by Ca, but no T tubular system, less complicated SR
SR stores Ca but also comes from outside
Caveolae contain voltage gated Ca channels
Ca entry triggers Ca release form SR
4 steps of contraction?
Ca binds to calmodulin (CaM)
Causes inactive mysoin light chain kinase (adds phosphate group to something)
Binds to myosin, makes it active
Phosphorylates with mysoin cross bridge (can bind with actin)
What stimulates contraction?
Neural (nervous control/action potential), hormones
If you stretch smooth muscle it will…
immediately contract (stretch activated channels)
Contracts briefly, adapts to new length (allows organ to have huge volume changes)
Contraction speed of smooth muscle? (3 reasons)
Contraction speed: Slower to contract and relax
Slower ATPases
Each crossbridge lasts longer
Ca pumped more slowly
Elements of the endocrine system?
Activates with NS to coordinate, hormones released into blood with slower responses but longer lasting
Controls and integrates reproduction and development, blood-water nutrient balance, mobilizes body defenses
Examples of endocrine glands
Pituitary, thyroid, parathyroid, adrenal, pineal
Hypothalamus (neuroendocrine)
Pancreas, gonads, placenta (endocrine/ exocrine)
Also found in adipose cells, thymus, kidneys
Functions of hormones?
Long distance travel signals, travel in blood or lymph
Amino acids: derivates, peptides, proteins
Steroids: synthesized from cholesterol
Water vs lipid soluble?
Hormones are water soluble, can not enter cell, act on PM receptors
Lipid-souble, can enter the cell and act on intracellular receptors
Cyclic AMP is produced…
from ATP through the action of Adenylate Cyclase, is rapidly degraded, Stimulates gene transcription via the cAMP response element binding protein
Mechanism of lipid-soluble hormones (5)
- Steroid hormone diffuses through PM, binds intracellular
- Receptor hormone enters nucleus
- Receptor hormone binds to DNA region
- Biniding initiates transcription to mRNA
- mRNA directs protein synthesis
Endocrine glands can be modified by…
NS can modify stimulation or inhibition of endocrine glands to override normal controls (unders stress hypothalamus overrides insulin to allow blood glucose to rise)
Blood hormone levels controled by?
negative feedback
3 factors for target cell activation?
- Blood hormone levels
2.Relative # of receptors on cells
3.Strength of receptor for hormone
-Up regulation has more receptors in response to low levels
-Down regulation has less receptors and desensitivies target cells
Concentration of hormones based of:
rate of release, speed of inactivation/ removal
What is half life/ reaction time?
Half life is time required for level of hormones to decrease by half
Response time can be immediate or hours to days
Response duration can be secs to hrs.
2 parts of hypothalamus?
Posterior pituitary: neural tissue secrets neurohormones, neurohypophysis
Anterior pituitary: glandular tissue, adenohypophysis
3 kinds of endocrine gland?
Humoral- relase due to ion charges
Hormonal- release due to activation of other hormone
Neural- release due to NS stimulus
3 steps of hormone release
- Parvocellullar neurosecretory cells- small neurons project to median eminence, terminals secrete or release hormones
- Hypophyseal portal veins lead to anterior pituitary
- Secondary capillary plexus empties into circulation
Hypothalamic neurons hormones?
GHRH, TRH, SS, CRH, GnRH, PIH
Anterior pituitary hormones?
GH, PRL TSH, ACTH, FSH, LH
How does the posterior pituitary release hormones? (4)
- PVN neurons synthesize oxytocin, SON synthesize ADH
2.Transported down axon of hypothamalmic-hypophyseal tract - Stored in axon terminals
4.Arrivings APs cause release into blood
3 Functions of blood?
Transport, regulation, protection
What is blood composed of?
Composed of fluid connective tissue: matrix (plasma) and cells, erythrocytes (red blood cells), leukocytes (white blood cells), platelets, hemotocrit, buffy coat, and plasma
60% of plasma protein is….
Albumin, blood buffer
3 features of RBCs
- Bioconcave chape gives huge surface area for gas exchange
- Hb: 97% cell volume
- RBCs have no mitochondria, consume no O2
What is Hb?
heme pigment bound to globin (composed of 4 polypeptide chains), pigment gives blood color and transports oxygen
What is Hematopieosis?
formation of blood cells in red bone marrow
8 stages of Erythropoiesis
- Hematopoietic stem cell
- Myeloid stem cell
- Pro-erythroblast
- Basophilic Erythroblasts
- Polychromatic erythroblasts
- Orthrochromatic erythroblasts
- Reticulocytes
- Mature erythrocyte
Erythrocyte Disorders?
Anemia, polycythemia
Hemostasis and 3 steps involved?
If a blood vessel breaks, a series of reactions is sent to stop bleeding
Vascular spasm, Platelet plug formation, Coagulation
What is a vascular spasm?
Vessel responds with vasoconstriction
Vascular spasm triggered by injury to muscle cells, chemicals, pain
Reduces blood loss, works best in small blood vessels
Platelet plug formation?
Platelets stick to fibers (prostacyclin and NO prevent platelet sticking)
Von willebrand Factor stabilizes (VWF)
Activated platelets swell, ADP causes more platelets to stick and release contents
Serotonin and thromboxane A2 enhance vascular spasm
What is the Von Willebrand Factor?
Made by megakaryocytes
Monomers assemble to form globular protein, unfold and extend in response to injury
Surface proteins on activated platelets bind
Coagulation
Reinforces platelet plug, blood clots, and effect in sealing larger breaks
Blood locally transformed, series of reactions using clotting factors (procoagulants)
Most proteins are synthesized by the liver
Intrinsic or extrinsic pathway? (Two pathways to Prothrombin activator)
Intrinsic pathway: Negatively charged phospholipids on the surface of platelets , Clotting factors present within blood, triggered by phospholipids (1 min)
Extrinsic pathway: Clotting factors outside of blood, triggered by exposure to tissue factor, Bypasses several steps of intrinsic so faster (15 sec)
Events that prothrombin starts (3)
Prothrombin activator transformed prothrombin to thrombin
Common pathway to fibrin, Thrombin converts fibrinogen to fibrin
Fibrin mesh forms clot structure (3-5 min)
Factors that limit clot formation? (3)
Swift removal, dilation
Inhibition of activated clotting factors (Thrombin restricted by clot fibrin factors, prevent from getting too big)
Undesirable clotting
Hemostasis disorders?
Thromboembolic disorders- undesirable clot formation
Bleeding disorders? (3)
Thrombocytopenia: Deficient # of circulating platelets
Impaired Liver function
Hemophilia
Antigen vs. Antibody?
Antigen: substance that triggers production of antibody by immune system
Antibody: kills or neutralizes or foreign antigen
RH blood types?
RH positive indicates D antigen protein
Rh most common blood type (85% in NA)
Second exposure to Rh blood will result in transfusion reaction
Transfusion Reactions
Occur if mismatched blood infuses
Donor RBC’s attacked by recipient’s plasma agglutinins, reduced O2 capacity, Hb in kidney tubules can lead to renal failure
Who can donate to who?
Group AB can donate to other AB’s but can receive from all others. Group B can donate red blood cells to B’s and AB’s. Group A can donate red blood cells to A’s and AB’s. Group O can donate red blood cells to anybody.
Features of heart?
Heart is a transport system with 2 side-by-side pumps
Right side receives oxygen-poor blood from tissues, pumps to lungs via pulmonary circuit to remove CO2 and pick up O2
Left side receives oxygenated blood and pumps to body via systemic circuit
3 layers of the heart?
Pericardium, Myocardium, Endocardium
Features of Pericardium
Doubled-walled fibro-serous sac, outside layer
The fibrous Pericardium protects and anchors the heart
Serous Pericardium: parietal (outer side) and visceral (inside) layers, space in between
Features of Myocardium
Part that contracts/releases, made of branching bundle branches that: reinforce and anchor, support for big vessels, and spread electrical current
Features of Endocardium
Innermost wall of heart, where blood is, contiunous with endothelium leaving and entering heart
Leaving vs. entering the heart
Leaving the heart, it is a artery, Entering heart, is a vein
Flow of Blood through heart
-Superior and inferior vena cava bring blood from top and bottom of body
-Blood empties into right atrium/ atria (reciving areas)
-As blood fills it drains to right ventricle, which will contract and blood is sent throughpulmonary arteries to lungs
-Comes back into heart through left pulmonary veins to left atrium and into valves and into left ventricle, leave through aorta
-Both atria and then ventricles contract at the same time
2 kinds of heart valves?
- Atrioventricular valves (AV): tri and bi-cuspid valve
Between atria and ventricle - Semilunar valves (SL): pulmonary and aortic
Between ventricle and arteries/ aorta
AV opening and closing?
AV opening: Blood comes to atria, will build up and pressure opens valves (pressure gated)
AV closing: Ventricle contracts and forces blood against cusps, closes valves. Job of capillary muscles to prevent valve from inveriting into atria
SL opening and closing?
SL opening: As blood is pushed valves are forced open (saloon door)
SL closing: Some blood flows back into arteries, filling cusps and closing them
Examples of problems with valves? (2)
Incompetent valve: blood backflows, heart repumps same blood
Valvular stenosis: stiff flaps constrict opening, heart needs more force to pump
What is the pulmonary circuit?
Short, low-pressure circulation
SVA to IVA, right atrium to right ventricle, contracts, moves through pulmonary arteries to lungs
What is the systemic circuit?
Long, high-friction circulation
Left atrium, left ventricle, aorta, circulation
What are coronary arteries?
Branch system reaches different of the heart, feeds the heart muscle
Highly intricate and branched system, enables blood to move even with blockages
What are conary veins?
Bringing blood into interior of heart, removes waste from heart muscle
Coronary Sinus empties into right atrium
Features of cardiac muscle?
Striated cells with one nucleus, involuntary movement
Highly branched with large mitochondria, resistance to fatigue, have pacemaker cells, gap junctions, and desmosones
2 kind of cells in heart?
Contractile cells (responsible for contraction, bulk of myocardium)
Pacemaker cells (noncontractile, spontaneously depolarize without nervous system stimulation)
Heart functions _______ from NS
Independantly
Heart contracts as a ______
Unit
What is the Intrinsic conduction system?
A network of non-contractile cells, pacemaker cells concentrated in the SA node, help to set the pace of the heart
Path of impulse in heart
SA Node, AV Node, AV bundle, bundle branches, purkinje fibers
Heartbeat can be modified by…
modified by ANS via cardiac centers in medulla oblongata
Heart sounds assoicated with…
Valve closing
Cardioaccelatory center?
sends signals through sympathetic trunk to increase rate/force
Stimulates SA/AV nodes, heart muscle, etc.
Cardioinhibitory centre?
Parasymp. Signals via vagus nerve to decrease rate
Inhibits SA/AV nodes via vagus nerves
Areas on an electrocardiogram?
P wave: depolarization of SA node/atria
QRS complex: ventricular depolarization/ atrial repolarization
T wave: ventricular repolarization
P-R interval: beginning of atrial excitation-ventriculae excitation
S-T segment: ventricular myocardium depolarized
Q-T interval: beginning of ventricular depolarization- ventricular repolarization
Issues seen on electrocardiogram? (3)
Junctional rhythm: SA node non-functional, AV node take over, no P waves
2nd degree heart block: AV node fails to conduct SA impulses, more P than QRS
Ventricular fibrillation: Electrical activity is disorganized, AP occur randomly
Systole and Diastole?
Systole: contraction of heart, pumping out
Diastole: relaxing of heart, filling
Heart rate impacted by… (3)
ANS, chemical factors, other
Regulation of stroke volume? (3)
Preload, contractibility, afterload
Preload?
Degree to which cardiac muscles stretch before they contract, Changes in preload cause changes in SV, EDV
If you put lots of blood in heart, heart will be set to pump it (more liquid, stronger contraction) -Frank Starling law
Contractibilty
Contractile strength at given muscle length
Increased lowers ESV, caused by impacted calcium levels in myocardium
Afterload?
Back pressure exerted by arterial blood, pushes on SL valves
Must be overcome by ventricles to eject blood
Cardiac output?
Amt of blood heart pushes in one minute (co= HR x sv)
Stroke volume?
Volume of blood pumped by ventricle in one best
SV=(end diastolic volume- end systolic volume)
Cross talk?
When para activated symp. inhibted etc.
