QUIZ 3 Flashcards
What substances do we find in circulation?
- Respiratory gases (oxygen and carbon dioxide)
- Hormones
- Nutrient
- Immune cell
- Intracellular waste
What sorts of animals do not have a circulatory system? What are some disadvantages to not having one?
Example: jellyfish
Disadvantage: limits the size of the animal
How do open and close circulatory systems differ? What are some of the advantages and disadvantages of each?
OPEN:
* Doesn’t have vessels
* Contains hemolymph
* Hemolymph circulates through heart and out to the hemocoel (cavity)
CLOSED:
* Has vessels that separate blood from interstitial fluid blood doesn’t come in contact with organs
* Arteries carry blood away from the heart, whereas veins carry blood to the heart
* Exchange of substances occurs at capillaries
How does the number of chambers within an animal’s heart influence its circulatory system?
- 2-chambered (fish): two chambers limit the circulatory system to one circuit creates a low-pressure system animal needs to constantly move to keep blood flowing
- 3-chambered (frogs): with the addition of an extra atrium, we create two circuit high/low oxygen blood mixes in the ventricle decrease blood oxygen level in the animal (not efficient)
- 4-chambered (humans): eliminates blood mixing so we have a side that is dedicated to dealing with oxygenated blood and a side that deals with deoxygenated blood; four chambers create a high-pressure system
What phases occur during the cardiac cycle? Label the phases below. What stimulates these phases too occur?
Systole: heart is contracting
1. Atrial systole
2. Ventricular systole
Diastole: heart is relaxing
Action potentials stimulate contraction contraction will decrease the volume of the chamber pressure then increases blood moves
What creates the heart sounds we hear when we put a stethoscope to a mammal’s chest?
Heart sounds are caused by valves closing
1. Sound 1 “Lub”: AV closing
2. Sound 2 “Dub”: Semilunar valves closing
How does cardiac muscle tissue differ from our other muscle tissues?
Cardiac muscle cells are joined by gap junctions which increase speed of action potential traveling across chambers.
While skeletal muscle cells are voluntary (somatic), cardiac muscle cells are involuntary (autonomic).
How do myogenic and neurogenic hearts differ? Which do we find in humans?
Myogenic hearts do not need nervous input to contract because they have autorhythmic cells. human hearts!!
Also, rhythm can be altered by autonomic nervous system
Neurogenic hearts require nervous innervation to function.
What allows a myogenic heart to depolarize on its own, without neural input
Autorhythmic cells (SA node, AV node, intrinsic conduction system)
SA node has the fastest rate and thus sets the pace.
Explain what is occurring during each of the phases included in the image below.
- Depolarization: Na+ voltage channels open allowing for Na+ to rush into the cell and then they become inactive.
- Plateau: Initially K+ voltage channels open allowing for K+ to rush out of the cell, but closely after Ca2+ channels open allowing for Ca2+ to rush into the cell. The Ca2+ channels become inactive which concludes the plateau.
- Repolarization: K+ voltage channels remain open, allowing for more K+ to rush out of the cell.
Describe the journey of an action potential from the SA node to a cardiac muscle fiber in the left ventricle.
SA node (R. atrium) generates action potential (AP) AP spreads across atria causing them to contract to… AV node (R. atrium) – impulse is delayed because of fewer gap junctions AP sent down bundle branches and out to purkinje fibers embedded in ventricle wall
What are the extrinsic and intrinsic factors that control heart rate and force of contraction?
Extrinsic Controls
Hormonal
* Norepinephrine and epinephrine from adrenal medulla increase SA node rate
* Thyroxine (T4) increases heart rate and enhances effects of norepinephrine and epinephrine
Neural
* Sympathetic: stimulatory
o Increase rate of SA node
o Enhance force and speed of ventricular contraction
* Parasympathetic: inhibitory
o Decrease rate of SA node
Intrinsic Control
Frank-Starling Mechanism
* Defines the normal relationship between the length and tension of the myocardium. The greater the stretch on the myocardium before systole, the stronger the ventricular contraction.
* Serves to have the heart match its output with its input
How are cardiac output, BP and peripheral vascular resistance related to one another?
BP = CO x PVR
In the space below draw out what mechanism would ensue if baroreceptors detected elevated BP.
When BP is high, baroreceptors detect this in the carotid sinus and rely this information to the medulla via the glossopharyngeal and vagas nerves.
The cardioinhibitory center response to this information by increasing parasympathetic signals along the vagas nerve to the SA node. This causes a decrease in heart rate, leading to a decrease in BP.
Where do we see higher BP, arteries or veins? How does their anatomy support either high or low pressure?
BP is higher in arteries as they are first to receive blood pumped out of the heart. To be able to withstand this high pressure, arteries have relatively thick muscular walls. Veins have lower BP. Because they do not have to combat high pressure blood against their internal walls, veins have a relatively thin layer of smooth muscle.
To prevent backflow against gravity, we see that veins have valves. Venous valves work in conjunction with the musculoskeletal system.
Muscles constantly contract and release, causing the blood to flow toward the heart. The valves open, allowing the blood to flow, and close, stopping the blood from flowing backwards.
How is it that lymph fluid is created by blood?
Lymph is formed from fluid that seeps through the thin walls of capillaries into the body’s tissues. This fluid contains oxygen, proteins, and other nutrients that nourish the tissues. Some of this fluid reenters the capillaries and some of it enters the lymphatic vessels becoming lymph.
Is blood flow to structures consistent throughout the course of a day?
No! Depending on the demands that we place on tissues we increase/decrease blood flow to them. An example of this is after eating food when blood is shunted to the digestive viscera to fuel digestion.
What is EPO and what role does it play in maintaining blood homeostasis?
EPO is erythropoietin, a hormone produced by the kidneys. EPO is released in response to low oxygen or red blood cell (RBC) levels. Once released into the blood, EPO targets and stimulates the red bone marrow to manufacture more RBCs.
You are training for a marathon and so when your family takes a vacation to Boulder, Colorado, you figure it’s a great opportunity to fit in some scenic long runs. You don’t get far into your run when you have to stop and walk because you’re so winded. You’re very confused because back at home in Chicago you haven’t any episodes like this.
Why are you having such a tough time running while on vacation? If you trained in Colorado for an extended period of time, how would your body adapt?
Your breathing difficulties are brought on by the higher altitude in Colorado. At higher elevations, there’s less oxygen in the air since atmospheric pressure is lower. Consequently, it’s harder for your body to take in oxygen. Your workout will feel more difficult, and you’ll get tired more quickly as a result.
It is thought that high altitude training forces your body to adapt to the lack of oxygen by releasing EPO and producing more RBCs.
Carbohydrates
Monosaccharides,
Short term energy
proteins
Amino acids
Contractile muscle fibers,
amino acid-based hormones
