Studied by 7 peopleDescribe the three major types of nutrients: carbohydrates, fats/lipids, and proteins
Carbohydrates
digested into small pieces usually glucose, sometimes other easily digestible sugars
stored in limited quantities- body eager to use
liver stores some excess also stored in muscles and nervous tissues
Fats
broken down into fatty acids that can travel in the blood freely
stored as triglycerides in fat cells
typically provides more than half the body’s energy needs
excess carbs stored as fatty acids
Proteins
broken down into amino acids that are used to build new proteins
can also yield energy if needed
Discuss the ways in which carbohydrate metabolic pathways, glycolysis, and the citric acid cycle interrelate with protein and lipid metabolic pathways
Describe the absorptive state and the major events associated with this state
called the fed state and lasts about 4 hours after eating
anabolism exceeds catabolism
excess nutrients stored as fats and sometimes carbs
glucose → glycogen for storage
triglycerides are used for energy by adipose tissue, the liver, and skeletal and cardiac muscles
triglycerides → glycerol and fatty acids → triglycerides for storage
removal of the amino group produces keto acids- energy in the citric acid cycle
amino acids → fat in the liver
amino acids are used for protein synthesis
absorptive state controlled by insulin
Describe the post-absorptive state and the major events associated with this state
fasting state
gi tract is empty, energy sources are supplied by the breakdown of body reserves
catabolism exceeds anabolism
maintains blood glucose
glucose sparing
proteins → amino acids
glycogen → glucose
triglycerides → glycerol and fatty acids
sympathetic nervous system- controlled by several hormones (more complex)
Sources of blood glucose in the post-absorptive state
glycogenolysis in the liver- the first reserve used
glycogenolysis in skeletal muscle- 2nd
lipolysis in adipose tissue and liver- 3rd
catabolism of cellular protein- not good, usually starving
Describe the process of insulin use during the absorptive state
insulin secreted by beta cells in the pancreas
insulin release is stimulated by elevated blood glucose levels and amino acids
parasympathetic stimulation
brings glucose into cells from the blood
brain and liver take up glucose without insulin
insulin is a hypoglycemic hormone
inhibits glucose release from liver and gluconeogenesis
Describe how the catabolic-anabolic steady state is associated with these two metabolic states and how it helps to maintain homeostasis
dynamic state in which organic molecules (except DNA) are continuously broken down and rebuilt
the body uses nutrient pools available for immediate use
anabolic- simple → complex, requires energy
catabolic- complex → simple, releases energy
the intermediates in the metabolic pathways are used for other processes
keeps the energy needs in our body consistent as long as both processes occur
Describe glucose sparing especially regarding nutrients for the brain
during prolonged periods of fasting the body uses more non-carbohydrate sources to conserve glucose
the brain uses a bulk of glucose while other body cells switch to fatty acids as fuel
glucose sparing saves glucose for organs such as the brain
after 4-5 days ketone bodies are used by the brain if needed
Discuss the roles of the nervous and endocrine systems in homeostasis
Nervous system—Autonomic system
Sympathetic—arouses body for “fight or flight”
Neurotransmitter released by sympathetic neurons is norepinephrine (similar to adrenaline)
Parasympathetic—predominates during relaxation, “rest and digest”
Neurotransmitter is acetylcholine—the same neurotransmitter used at the neuromuscular junction
Endocrine system
Hormones involved in blood glucose regulation
Insulin and glucagon
Both are produced by the pancreas
Discuss homeostatic imbalances, specifically diabetes mellitus
Type 1
inadequate insulin production
Type 2
abnormal insulin receptors
both result in
proteins and fats are used for energy
unavailability of glucose to most body cells
excessively high blood glucose levels (hyperglycemia)
glucose loss in urine
can lead to metabolic acidosis, protein wasting, weight loss
may lead to coma and death
Why isn’t it sufficient to reduce only dietary fat intake to prevent new fatty deposits from forming in the body?
Acetyl CoA is a starting point for fatty acid synthesis.
TRUE OR FALSE. The preferred energy fuel for the brain is fat.
False
TRUE OR FALSE. Carbohydrate and fat pools are oxidized directly to produce cellular energy, but amino acid pools must first be converted to a carbohydrate intermediate before being sent through cellular respiration pathways.
True
When proteins undergo deamination (removal of amino group), the waste substance found in the urine is mostly ________.
urea
Glycogen is formed in the liver during the ________
absorptive state
Lipogenesis occurs when ________.
cellular ATP and glucose levels are high
Which of the following statements is FALSE?
The amino acid pool is the body's total supply of amino acids in the body's proteins.
Fats and carbohydrates are oxidized directly to produce cellular energy.
Amino acids can be used to supply energy only after being converted to a citric acid cycle intermediate.
Excess carbohydrate and fat can be stored as such, whereas excess amino acids are oxidized for energy or converted to fat or glycogen for storage.
The amino acid pool is the body's total supply of amino acids in the body's proteins.
If you were to jog one kilometer a few hours after lunch, which stored fuel would you probably tap?
liver glycogen and muscle glycogen
A fasting animal whose energy needs exceed those provided in its diet will draw on its stored resources in which order?
liver glycogen, then muscle glycogen, then fat
Humans store glucose in the form of ________________; plants store glucose in the form of ________________.
glycogen; starch
Which of the following glucose storage forms is the most difficult for human digestive systems to break down?
cellulose
In general metabolic terms, food digestion is a form of _______, while building new protein molecules is a form of _______.
catabolism; anabolism
The process whereby excess glucose is stored in cells is called _______.
glycogenesis
What is the primary process by which insulin is released after ingesting a meal?
Insulin is secreted in direct response to blood glucose.
What is the primary objective during the post-absorptive state?
To maintain blood glucose (typically around 70–110 mg/100 mL blood)
Describe the fibrous skeleton of the heart and its major functions.
structural support for the heart
gives the muscle cells something to pull against
electrical insulation that helps regulate the heartbeat
Describe intercalated discs and their components: desmosomes and gap junctions.
desmosomes
provide a physical connection
allows muscle cells to pull on each other without damaging membrane
gap junctions
provide cytoplasmic connection between cells
electrically connects the heart
Allow waves of depolarization to spread rapidly from cell to cell—all heart muscle cells contract almost simultaneously
Identify the major anatomical features of the heart and major blood vessels.
Arteries carry blood away from the heart
Veins carry blood toward the heart
Tricuspid valve= right atrioventricular valve
pulmonary and aortic valves= semilunar valves
bicuspid valve= left atrioventricular valve
Describe the blood flow through the heart and identify where oxygen and deoxygenated blood flows in the heart.
start at right ventricle
deoxygenated
out of right ventricle through pulmonary semilunar valve
through pulmonary arteries to the lung
gas exchange in capillary beds of lungs
oxygenated
return from lungs through pulmonary veins into left atria
through bicuspid (left AV) valve into left ventricle
out of the Aorta into the body
deoxygenated
returns from the body through the superior and inferior vena cava into the right atria
Through tricuspid (right AV) valve into right ventricle
repeat process
Which of the following structures is associated with oxygen-rich blood?
A. Right AV valve
B. Pulmonary vein
C. Right ventricle
D. Pulmonary artery
B. Pulmonary vein
Which of the following structures does blood flow into AFTER the left ventricle?
A. Right AV valve
B. Aorta
C. Right ventricle
D. Pulmonary artery
B. Aorta
Which of these vessels supplies blood to the heart (myocardium)?
A) Aorta
B) Vena cava
C) Pulmonary artery
D) Pulmonary vein
E) None of the above
E) None of the above
actually the coronary arteries
Why are the walls of the ventricles thicker than the walls of the atria?
Under higher pressure to get the blood farther away from the heart (either to lungs or the body)
Describe the four major structures of the conduction system and where they are related to in terms of anatomy of the heart.
SA node- Pacemaker cells coordinate the heartbeat, signal the atria to contract together first and then the ventricles contract together second
the upper wall of the right atrium and the opening of the superior vena cava
excited roughly 75 times per minute
AV node- conduct the action potential to additional conductive cells of the ventricles
Without SA node, excited roughly 50 times per minute
AV bundle cells- conduct the action potential to the base of the ventricles
Without SA node or AV node, excited roughly 40 times per minute
Purkinje fibers- conduct the action potential to muscle cells of the ventricle walls
Without SA node, AV node, or bundle action potential, excited roughly 30 times per minute
How is the connection between heart muscle cells different than between two neurons or a neuron and a skeletal muscle cell?
A. All of the above have synapses between the cells but no need for neurotransmitters
B. All of the above have synapses and need neurotransmitters
C. Heart cells do not have synapses but still need neurotransmitters
D. Heart cells do not have synapses and no need for neurotransmitters
D. Heart cells do not have synapses and no need for neurotransmitters
Describe the relationship between volume and pressure.
-For a fixed volume of fluid, the pressure depends on the volume of the space it occupies
-Pressure and volume are inversely proportional
Large volume = lower pressure
Small volume = high pressure
As the size of the space changes, so does the pressure
Define systole and diastole.
systole- contraction
diastole- relaxation
During systole the space of the chamber decreases, the volume of fluid is the same – What happens to pressure?
A – Increases
B - Decreases
A – Increases
During Diastole the space of the chamber increases, the volume of fluid is the same - What happens to pressure?
A – Increases
B - Decreases
B - Decreases
Explain how contraction and relaxation of the chambers of the heart create pressure gradients and how these gradients cause the flow of blood in relation to anatomy.
All chambers in diastole
– Blood flows passively through atria and into ventricles
– Both AV valves open
– Note both atria and ventricles fill with blood
– But not all blood leaves atria
Atrial systole
– Ventricles (still in diastole) swell with extra blood that has been pumped in by atria
Ventricular systole (atrial diastole)
– Right and left AV valves pushed shut
– Blood forced into arteries through pulmonary and aortic semilunar valves
– ventricles contract from the bottom up
Now back to all chambers in diastole
– as ventricles enter diastole, a little blood sucked back in
– however right and left semilunar valves snap shut
Explain what the first and second heart sounds are.
Bicuspid and tricuspid valves are pushed shut during ventricular systole (first heart sound—“lub”)
Pulmonary and aortic semilunar valves snap shut when reentering all chambers in diastole (second heart sound—“dub”)
Where would pressure be greater?
A) coming out of the right ventricle (pulmonary circuit—heading to lungs)
B) coming out of the left ventricle (systemic circuit—to the rest of the body)
B) coming out of the left ventricle (systemic circuit—to the rest of the body)
Which set of valves are involved with the second heart sound?
A. Pulmonary and right AV valves
B. Pulmonary and aortic valves
C. Right and left AV valves
D. Aortic valve and left AV valve
B. Pulmonary and aortic valves
Define a brain center.
a collection of interneurons that receive sensory input about a specific function and create motor output to alter that function
“Cardiovascular control centers” include:
Cardiac control (heart)
Cardioacceleratory neurons
Cardioinhibitory neurons
Vasomotor control (vessels)
Together they regulate blood pressure and heart function
Describe the action potential in the pacemaker cells/SA node and how it contributes to the autorhythmicity of the heart.
Have leak-like channels that allow cations to diffuse into the cell
Channels result in depolarization to threshold without neuronal excitation
no Na+/K+ pump needed to return to Resting Membrane potential
Analyze how the major regions of an EKG correlate with the conduction system function and contraction
P wave- SA node excitement and atrial depolarization
PR segment- atrial depolarization is complete, the impulse is delayed at the AV node
QRS complex- ventricular depolarization, atrial repolarization
ST segment- ventricular depolarization is complete
T wave- ventricular repolarization begins at the apex
after the T wave- ventricular repolarization is complete
A patient visits a physician for a second opinion about a diagnosed heart murmur affecting the right AV valve. Heart murmurs are caused by valve prolapse (the valve turns inside out). Which of the following symptoms could the physician check to confirm the heart murmur?
A. A missing QRS complex on an EKG
B. A weak/missing second heart sound
C. A missing T wave on an EKG
D. A weak/missing first heart sound
D. A weak/missing first heart sound
What is happening in the lower EKG?
A. No atrial contraction
B. No ventricle depolarization
C. No ventricle contraction
D. No AV node activity
A. No atrial contraction
Define stroke volume and cardiac output.
stroke volume- the amount of blood pumped out of each ventricle in one pump (both ventricles pump the same amount). normally between 70-80mL
cardiac output- the amount of blood the heart pumps per minute INTO ARTERIES
heart rate (beats/min) x stroke volume (mL/beat)= cardiac output (mL/min)
Describe blood vessel anatomy, especially the differences seen in arteries, veins, and capillaries.
Arteries are thicker than veins because they carry blood under a higher pressure
Arteries transport blood away from the heart
Veins return the blood back to the heart
Capillaries surround body cells and tissues to deliver oxygen, amino acids and glucose, and return carbon dioxide and wastes
The capillaries also connect the branches of arteries to the branches of veins.
In capillaries, the arterial end blood pressure is higher than the osmotic pressure, and net pressure out
The venous end has higher osmotic pressure than blood pressure, net pressure in.
Describe blood pressure and how it is controlled.
-the force blood exerts against an arterial wall (most commonly the brachial artery)
-Neural circuits in the brain also regulate heart rate, the strength of contraction, vasoconstriction, and dilation throughout the entire body
Three main variables that affect blood pressure? what do they do?
Cardiac output
Amount of blood the heart pumps per minute into the arteries
arterial volume is constant but the amount of fluid in arteries is altered
Resistance of vessels
the combined effect of blood composition, vessel diameter, and vessel length
vessel diameter can change (vasomotion)
Blood volume
controlled by the kidneys and hormones
Describe the afferent signals to the brain, including three types of receptors, and how they affect heart rate.
Propriocenters- sensory input from muscles and tendons
informs the brain on changes in physical activity
Baroreceptors- sensory input from blood vessels
informs the brain on changes to pressure in vessels
Chemoreceptors- sensory input from blood vessels
informs the brain on changes in carbon dioxide or oxygen levels in the blood
important in respiratory system but has some affect on heart rate
Compare and contrast the efferent responses that affect heart rate and how they alter the SA node activity including the neurotransmitters associated with these responses.
Sympathetic system
cardioacceleratory system- increased heart rate
Postganglionic neuron secretes norepinephrine (NE)
Adrenergic receptors on cells of the SA node bind to NE
Cause an increased rate of action potentials of SA node
Maximum heart rate is 230 beats/minute
Limit of SA node excitation
Parasympathetic system
cardioinhibitory system- decreased heart rate
Postganglionic neuron secretes acetylcholine (ACh)
Cholinergic receptors on cells of the SA node bind ACh
Allow potassium to leave the cell → hyperpolarizing reaction
The rate of action potentials decrease
Normal heart rate is about 75 beats/minute
Without nervous control, the heart rate would be about 100 beats/minute
Describe the roles of the sympathetic and parasympathetic nervous systems in controlling heart rate.
Sympathetic
blood pressure is too low
visceral motor neurons cause
increase heart rate by activating cardioacceleratory neurons
vasoconstriction which is the constriction of blood vessels regulated by the sympathetic release of norepinephrine or epinephrine
Parasympathetic
blood pressure is too high
visceral motor neurons cause
decrease heart rate by activation of cardioinhibitory neurons
vasodilation which is the dilation of blood vessels due to a decrease in norepinephrine
If the right AV valve does not close completely and allows blood to pass through when it should be shut, then you could expect:
the output of the right ventricle to be decreased.
The semilunar valves prevent blood from flowing backwards into the...
ventricles
Normal heart sounds are caused by which of the following events?
closing of the heart valves
Without SA node activity, what type of heart surgery would be indicated?
inserting an artificial pacemaker
Which of the following develops the greatest pressure on the blood in the aorta?
systole of the left atrium
diastole of the right ventricle
systole of the left ventricle
diastole of the right atrium
systole of the left ventricle
Among the following choices, which organism likely has the highest systolic pressure?
mouse
human
hippopotamus
giraffe
giraffe
The heart muscle (myocardium) receives its nutrients from the blood moving through the left atrium and ventricle.
True
False
False
The left side of the heart pumps the same volume of blood as the right.
True
False
True
The atrioventricular (AV) valves are closed ________.
when the ventricles are in systole
During exercise, which of the following would occur on an electrocardiogram (ECG/EKG) compared to an individual at rest?
the T wave would decrease
the P-R interval would decrease
the time from one R to the R of the next heartbeat would decrease
the S-T segment would decrease
the time from one R to the R of the next heartbeat would decrease
Ultimate goal of plant nutrient uptake
sucrose biosynthesis
During the day what happens to the CO2 in the carbon reactions
what happens at night?
stored as starch in chloroplast or sucrose in the cytosol
at night, co2 assimilation stops, and starch in chloroplast broken down for transport
what is sucrose transported through?
Sucrose transported into vascular tissue to sinks throughout plant
What are sinks and sources?
-Sources synthesize sugars \n –Sinks use sugars
What do the xylem and the phloem do?
Xylem conducts water and dissolved minerals \n upward from roots into the shoots (“xylem up”)
Phloem transports sugars to roots and other parts of \n plant as needed (“phloem down”?)
Where do plants get sucrose from and in which direction can it move?
Plants can use sucrose locally within the leaf or transport it to another part of the plant that needs it
Sucrose can move up OR down in in the phloem, only up in the xylem
Which of the following is most likely to be a source in plants? \n a) immature leaves \n b) developing fruits \n c) roots in the early spring \n d) roots in late summer
d) roots in late summer
Why is sucrose used for carbon transport through the plant rather than glucose?
glucose is smaller than sucrose
need pressure gradient
if glucose builds up there is ketoacidosis so sucrose is better because it is reactive
Note
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