The human heart will undergo over 3 billion contraction cycles, as shown in
Figure 5, during a normal lifetime.
The heart beats in a rhythmic cycle. A complete cardiac cycle is one round of
the heart pumping blood.
The
top half of the heart works as one unit.
The
bottom half of the heart works as one unit.
The sino-atrial node (pacemaker) starts and regulates the process.
The
cardiac cycle consists of two parts:
systole (contraction of the heart muscle) and
diastole (relaxation of the heart muscle).
Atrial systole (0.1s)
Atria contract simultaneously, pushing blood into the ventricles
Ventricles are relaxed
Atrio ventricular valves open
Semi lunar valves close
Ventricular systole (0.3s)
Atria relax
Ventricles contract simultaneously
Blood enters aorta and pulmonary artery
Semi lunar valves open
Atrio ventricular valves close
Diastole (0.4s)
Atria and ventricles relax
Atrio ventricular valves open
Blood enters atria and ventricles
Semi lunar valves close
Back flow in arteries prevented
The heart beat can be heard as a sound that the valves make when they close. The
‘lub’ sound is made when the atrio ventricular valves close and the‘dub’ sound is made when the semi lunar valves close.
Figure 5
from mindset – (please check permission from this, found it in Biology 6th
edition Campbell and Reece)
Cardiac Cycle: flow of blood through the heart
Excellent simple video illustrating the heart cycle.
The blood pressure is produced by the left ventricle contractions.
The rhythm of ventricle diastole, often just referred to as diastole, causes the
pulse, which can be felt by holding two finders to the side of the throat.
Blood pressure oscillates with the contraction of the left ventricle.
Ideal blood pressure for an adult is:
Systolic pressure: 120 mm HG
Diastolic blood pressure: 80 mm HG
A usual rule is that systolic pressure should be 100 plus your age but nevermore than 140 and diastolic pressure should not be over 90.
Figure 6 The cardiac cycle. Image from Purves et al.,
Life: The Science of Biology , 4th Edition, by Sinauer Associates (
www.sinauer.com ) and WH Freeman (
www.whfreeman.com ),(please get permission)
Blood from the lungs is pumped into the pulmonary arteries.
From the pulmonary arteries the vascular system branches into smaller and
smaller vessels until the blood is flowing through thin pulmonary capillaries.
These capillaries surround the alveoli in the lungs.
At this point there are only two layers of cells separating the blood from the
air.
Carbon dioxide in deoxygenated blood diffused out of the blood.
Oxygen in the lungs diffuse in to the blood oxygenating it Oxygen is absorbed.
Oxygenated blood then returns to the heart vial the pulmonary veins.
Questions & Answers
differentiate between demand and supply
giving examples
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
ok
Shukri
how do you save a country economic situation when it's falling apart
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product