Circulatory System Flashcards
Arteries vs. Veins
Arteries carry blood under high pressure away from the heart, while veins return the blood to the heart after its pressure has been reduced in the capillaries. Arteries differ from veins in that they have a thicker, more flexible wall designed to handle the high pressure, while veins have a thinner wall and larger lumen to accommodate a greater volume of slower moving blood. Both have three layered walls. The inner layer, or endothelium, of both is a layer of smooth cells that minimizes friction on the flowing blood, but in arteries it is often folded like an accordion during diastole, allowing it to stretch during systole. The middle layer, which is made up of smooth muscle and elastic fibres, is much thicker in arteries, allowing it to expand as a pulse goes through and to contract afterwards, pushing the blood forward. The outer layer, which consists of both elastic and rigid connective tissues, provides protection against ballooning and rupture.
Veins have internal valves, which are lacking in arteries. These valves produce a one way flow when the veins are squeezed, allowing muscular action such as walking and breathing to pump blood toward the heart.
Arteries (arterioles)
A blood vessel that carries blood under high pressure away from the heart. It exerts pressure with its thick walls so high pressure doesn’t burst the walls. Pressure is the force caused when a molecule hits a wall, the # times it hits a wall is proportional to pressure/force.
Arteries branch so that they can send blood to different parts of the body.
Arteriole
The smallest artery, that gives rise to capillaries
Capillary
A tiny blood vessel consisting of only one layer of epithelial cells, where exchange of materials occurs. It is the thinnest structure that carries blood cells . The size of vessel gets smaller as it branches. It is very low in pressure, and allows efficient exchange by diffusion.
Capillary bed
An anastomosing network of capillaries that supplies a particular tissue
Venule
The smallest vein, collecting blood from capillaries
Vein
Any blood vessel that carries low-pressure blood back toward the heart. It is looser to expand more and stores great quantities of blood.
History
Hippocrates was the first physician to view the body as a whole. This dates back to the Greeks and Romans: Hippocrates and Galen. They had similar views on what the circulatory was. At the time they believed the body contained fluids known as humorous, there were 4 of them. If you had an imbalance of these fluids in your body, it meant you sick. This is how surgical techniques like blood letting were introduced. The Hippocratic oath is something all doctors take promising that if anyone is sick, they will treat them.
William Harvey is a doctor who first correctly described that blood circulated through the body. His conclusions were based on vivisection. Blood is circulated, not consumed by the body.
Cardio
Heart
Vascular
Vessels
Vivisection
learning exploratory surgeries on the living
Disection
Surgery done on the dead
Systems in the Body
Since the systems are subjected to natural selection over time and have evolved to gain their structure and function through NS and other agents of evolution, all of them solve a problem in the environment. There is a challenge in the environment that is posed that the systems we have in our bodies will address. This is related to what cells need from the environment.
Cellular Respiration
Cells need oxygen and glucose to produce energy.
Unicellular organisms
Do not have a circulatory system so they use diffusion
Multicellular Organisms
Diffusion is too slow to supply substances like glucose and oxygen to all of the cells in the deep layers of the skin. This is why we have different systems.
Functions of the System
- Transport
* O2, CO2, hormones and wastes, nutrients moved around efficiently - Regulation
* helps control pH and body temperature (homeostasis) - Protection
* from blood loss through clotting, and against infection by pathogens
Pathogens
disease causing organisms (bacteria, fungi, virus)
Homeostasis
the ability to maintain a constant internal environment in response to environmental changes
Main Components of the System
- Pathway of transport -> Blood Vessels
- Pump to move medium along pathway -> Heart
- Medium/Substance that carries things -> Blood
Not all organisms have the exact 3 components, but everything needs a pathway, a medium of transport (like hemolymph), and a pump to move substance around a circuit.
Structure of Blood Vessels:
Direction of Blood
Artery: away from heart
Vein: back to heart
Structure of Blood Vessels:
Lumen
Artery: small
Vein: large
Structure of Blood Vessels:
Wall thickness
Artery: thicker
Vein: thinner
Structure of Blood Vessels:
Valves and Muscles Around
Artery: no valves or muscles
Vein: present
Structure of Blood Vessels:
Tunica Interna
Artery: folds
Vein: no folds
Structure of Blood Vessels:
Tunica Intermedia
Artery: thicker/more muscles
Vein: thinner/less muscle
Arteries need thicker muscle layers because high pressure would rip the thinner walls.
Structure of Blood Vessels:
Tunica Externa
Artery: thicker
Vein: thinner
Epithelial Cells
Specialized cells that surround tissue
Tunica Interna
The inner layer has flat, smooth, flat epithelial cells and is known as the endothelium on a thin layer of connective tissue. Has the lowest amount of friction and is quite strechy. Produces protein elastic collagen. In arteries, this layer is folded like an accordion so it can expand for pressure/
Tunica Intermedia
Surrounding layer of smooth muscle can stretch to accommodate passing blood, or contract to resist blood flow. Blood won’t travel as far with low pressure. Covered in connective tissue.
Tunica Externa
This is a layer of connective tissue produced by elastic and rigid collagen proteins. This has a stretch limit. The tough layer will prevent walls from ballooning when pressure is high.
Varicose veins
abnormal valve during atrial contraction
Open circulatory system
- most common in invertebrates
- haemolymph is the transport medium (from open-ended vessels to cavities)
- transports nutrients by diffusing in cells
- gases are not transported
Insects and crustaceans have an open circulatory system, in which the blood (technically called haemolymph) leaves the blood vessels and surrounds the tissues. They lack a venous system. They lack a lung or gill, and distribute gases by a series of tubes
Tracheal System
system of tubes that carry air for each cell of the body, the circulatory system is not responsible for transporting gases
a) Superior (anterior)
b) Inferior (posterior)
c) Dorsal (back)
d) Ventral (front)
Closed circulatory system
- keeps everything inside of the veins
- when you close vessels, you can control substances and you will have more efficiency because you control directions of fluid and send things to certain places
- you can generate pressure so the system doesn’t need to work as hard
more loops=more oxygen=more efficient
One loop and two loop systems
Fish and their relatives have a heart that is a single pump, and their blood flows through first the gills and then the body systems. This “single loop system” is efficient, except that the movement of blood through the gill capillaries slows it down and reduces blood pressure to the other organs. Blood pressure is required for rapid delivery of resources.
The higher vertebrates (mammals, birds, crocodiles, probably dinosaurs) have a “double loop system” in which the heart consists of two parallel pumps. One pump sends deoxygenated blood to the lungs, and returns it to the other pump, which sends it to the body systems. Thus, every system gets high pressure, oxygenated blood
The heart of a mammal has ______ chambers. The chambers that produce the main pumping action of the heart are called __________.
The heart of a mammal has ____4__ chambers. The chambers that produce the main pumping action of the heart are called _____ventricles_____.
A membrane sac called the __________ surrounds the heart.
A membrane sac called the _____pericardium_____ surrounds the heart.
The main artery leaving the left side of the heart is called the _____. The first branches from it are the coronary arteries, which supply blood to the __________.
The main artery leaving the left side of the heart is called the ___aorta__. The first branches from it are the coronary arteries, which supply blood to the ______heart muscle (myocardium)____.
How does a heart valve work? How do the chordae tendineae contribute to this function?
Valves are one-way gates that open if there is pressure on one side and close if there is pressure on the other side. They typically consist of two or more flaps of tissue.
The chordae tendineae are tough bands of connective tissue that attach the AV valves (tricuspid and bicuspid) to the opposite wall of the ventricle. They help to pull the AV valves open when the ventricle relaxes, but their main function is to support the AV valves during ventricular systole (contractions) so they don’t get blown inside out.
The Heart
The heart is mostly muscle and the pump part of the circulatory system. It moves blood by contracting. Its longest length is when its relaxed and when it contracts it gets shorter. When it contracts the volume inside lowers so that pressure is higher so blood can be pumped around. The function of the heart is to pump blood.
Coronary
takes blood to all the muscles of the heart