What is the circulatory system? The circulatory system is the main transport system of the body. Main Functions: 1. Transport gases, nutrients and wastes 2. Regulates internal temperature and systems (by hormones) 3. Protects the organism against blood loss, toxins and pathogens (invaders)
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
What is the circulatory system?
The circulatory system is the main transport system of the body.
Main Functions:
1. Transport gases, nutrients and wastes2. Regulates internal temperature and systems (by hormones)3. Protects the organism against blood loss, toxins and
pathogens (invaders)
Circulatory System
Composed of:
The Heart
Blood VesselsArteries - leaving the heartVeins - returning to heartCapillaries
The Heart - Structure
The mammalian (human) heart has 4 chambers.
This prevents mixing of oxygenated and deoxygenated blood.
Chambers are called Atrium and Ventricles
Blood enters the heart into Atrium and is passed into Ventricles.
Ventricles have thick walled cardiac muscles to pump blood into vessels.
The Septum completely divides the left and right sides of heart
Deoxygenated blood enters RIGHT side
To left lungDeoxygenated blood flows
from the body through to Vena Cava towards the heart.
It enters the Right Atrium then into Right Ventricle
It is pumped through the Pulmonary Artery to the lungs.
From upper body
From lower body
To rightlung
Oxygenated blood enters LEFT side
From left lung
Oxygenated blood flows from the lungs through to Pulmonary Artery towards the heart.
It enters the Left Atrium then into Left Ventricle
It is pumped through the Aorta to the body.
To upper body
To lower body
From right lung
Heart chambers are separated by Valves
Atrioventricular (AV) Valves separate the atrium and ventricle
The Right AV valve is “Tricuspid”
The Left AV valve is “Bicuspid” also called the Mitral Valve
Semilunar Valves separate the ventricle from the outgoing blood vessel
The Right is called the Pulmonary Valve
The Left is called the Aortic Valve
R L
Heart Valves are one-directional
Valves ensure blood flow is one-directional by preventing backflow.
As the ventricle contracts the AV valve closes and pressure forces blood through the semilunar valve into artery.
Valve Animation
The Mitral valve only has 2 flaps and if damaged cannot stop backflow. This is called Mitral Valve Regurgitation.This is a leading cause of Congestive Heart Failure.
Mitral Valve Disease Animation
The Coronary Artery The Coronary Pathway supplies the heart tissue (muscle) with blood. The heart cannot absorb oxygen and nutrients through the layers of tissue in the chambers and must have its own blood supply.
The Left and Right Coronary Arteries branch off from the Aorta
Coronary Bypass Surgery
How the Heart Beats
Cardiac muscle is called Myogenic muscle. It can contract WITHOUT nerve stimulation and instead uses electrical impulses to control contractions.
(unlike other muscles in the body)
The tempo (rate) that the heart beats is controlled by the Sinoatrial (SA) node, the “pacemaker”
The SA node is located at the top of the right atrium
How the Heart Beats
1 .The SA node sends an electrical signal to a second node, called the Atrioventricular (AV) node.
2. As this signal travels from SA to AV node it stimulates contraction of both atria.
3. Then the AV node conducts the electrical signal along two large Purjinke fibres along the septum to the ventricles
4. The signal stimulates contraction of both ventricles.
The changes in Electrical Conduction is measured by an ECG
1 2 3 4 reset
Heart Sounds are made by valves closing
Contraction of the Heart: Systole
The ventricles contract forcing the AV valves SHUT and Semilunar valves OPEN at the same time so blood flows out of the heart.
= “LUB” 1st heart sound
Heart Sounds are made by valves closing
Relaxation of the Heart: Diastole
The ventricles relax, the AV valves OPEN to let blood flow from the atria to the ventricle and the Semilunar valves SHUT to prevent blood flow out of the heart
= “DUB” 2nd heart sound
Systole Diastole
- Contraction - Relaxation
- AV valves close - Semilunar valves close
Heart Sounds
The Cardiac Cycle
Describe the 4 stages of cardiac cycle to a partner, then have them explain it back to you.
1 2 3 4
The Cardiac Cycle
In what stage is the heart in DIASTOLE? SYSTOLE?
1 2 3 4
Blood Vessels
3 types:
Arteries - carry blood AWAY from the heart
Veins - carry blood TO the heart
Capillaries - small vessels where EXCHANGE of nutrients and oxygen occurs
Blood Vessels - ArteriesHave thick, elastic walls - the diameter stretches to accommodate the surge of blood flow from the heart (systole) then snap back to original size during relaxation (diastole)
Pulse: the surge of blood through arteries
ArtherosclerosisArtherosclerosis: hardening of the arteries
Excess fat in the bloodstream clumps together, then Calcium deposits on the fat causing a plaque on the wall of the artery
Overtime this leads to hardened walls that loose elasticity
→ high blood pressure, stroke, heart attack, aneurysm…
Blood Vessels - Artherosclerosis FYI
Risk factors for heart disease:
High fat dietHeavy Alcohol use SmokingLack of exerciseObesityDiabetesFamily historyHigh blood pressure
Most of these are preventable!!!
Blood Vessels - Arterioles
Are smaller vessels that branch off from arteries
Connect arteries to capillaries
Wrapped in smooth muscle cells
= can contract or relax in response to the autonomic nervous system (involuntary)
Blood Vessels - Arterioles
Nervous system controls blood flow to tissues:
Vasodilation = increase diameter (arterioles relax) MORE blood flow to area
Vasoconstriction = decrease diameter (arterioles contract) LESS blood flow to area
Ex. Blushing is caused by vasodilation
Vasoconstriction in limbs when cold
Blood Vessels - Veins
Have thin, fibrous walls and large diameter(lumen)
Contain one-directional valves to prevent backwards flow of blood
(many veins carry blood upwards against gravity)
Blood Vessels - VeinsBlood is returning to heart at a low pressure so it is ‘squeezed’ forward by muscles in the body
Blood Vessels - Veins FYI
Veins hold ~65% of your total blood volume
If valves and/or walls of the vein are weakened the blood pools in veins and is not returned to the heart properly= varicose veins
Blood Vessels - Artery vs. Vein
Blood Vessels - Capillaries
Only a single-cell thick and have small diameter (only let one blood cell pass through at a time)
Blood Vessels - CapillariesMain site of exchange of nutrients, oxygen, carbon dioxide and wastes between the blood and cells
Heart → Arteries → Arterioles → Capillaries → Venules → Veins
Heart → Arteries → Arterioles → Capillaries → Venules → Veins
Fill In The Chart
Blood Vessel Artery Vein Capillary
Sketch
Structure of wall Thick, Elastic Thin, Fibrous 1-cell thick
Size of lumen Narrow, changes with pulse of blood
Wide Very narrow - only 1 cell at a time
Valves? (Y/N) N Y N
Function Strong and elastic to withstand surges of blood
High pressure
Muscles ‘squeeze’ blood through 1-way valves
Low pressure
Thin walls allow for exchange of nutrients, wastes and gases by diffusion
Cardiac Output
Cardiac Output = amount of blood that flows out of the heart per MINUTE
Stroke Volume = amount of blood that flows out of the heart per BEAT
Heart Rate = number of times the heart beats per MINUTE
Cardiac Output = Stroke Volume x Heart Rate
Cardiac output is adjusted based on your energy demands, so it is used to compare fitness of individuals.
Cardiac Output - Try It!
Estimate your stroke volume
An average Stroke Volume is around 1mL/beat per kilogram (1 kg = 2.2lb)
Take your heart rate by counting your pulse for 30sec and x2
Calculate your Cardiac Output:
Cardiac Output = Stroke Volume x Heart Rate
Blood Pressure
Blood pressure is the force of blood on the walls of arteries during Systole and Diastole.
It is measured with a sphygmomanometer Units are in mmHg
Normal Adult Blood Pressure is
Systolic <120 mmHg
Diastolic <80 mmHg
Blood Pressure
Blood pressure is the highest in arteries (closest to the heart)
Systolic pressure = contraction of ventricles “pulse”
Diastolic pressure = relaxation of ventricles “filling”
Blood Pressure - regulation
Barosensors on the walls of your carotid arteries (sides of your neck) signal the brain when blood pressure is too high
The Autonomic Nervous System lowers blood pressure by:
Vasodilation of arteriolesSlows heart rate
Low and high blood pressure
Hypotension: low blood pressure
can be due to bleeding (blood loss)
Hypertension: high blood pressure
Considered high if >140/90 mmHg
If persistent can lead to heart attack or stroke
Regulation of Body TemperatureThermoregulation: maintaining body temperature in a range that cells can function efficiently
Different animals/species have different temperature ranges
Human normal body temperature 37oC
The hypothalmus coordinates the body’s response to cold or hot temperatures
Capillary Fluid ExchangeCapillaries are the main site of exchange of molecules and fluid between the blood and cells.
Extracellular Fluid or ECF is exchanged between the blood to interstitial fluid to maintain equilibrium in the body
Our bodies are 60% water
Of this total water:80% is intracellular (in cells)
20% is extracellular (interstitial and in the blood)
Capillary Fluid Exchange2 forces regulate the movement of water across the capillary:
OsmosisBlood pressure
Capillary Fluid ExchangeOsmosis - water moves from area of low solute concentration to high solute concentration
Blood has a higher concentration of substances than interstitial fluid so water moves into the blood
Osmotic pressure is
+25 mmHg
(water moves INTO blood)
INTERSTITIAL BLOOD
BLOOD
INTERSTITIAL
Capillary Fluid ExchangeBlood pressure is high on the arterial end and low on the venous end
35 mmHg
15 mmHg
Capillary Fluid Exchange
Water moves from area of high pressure to low pressure
Artery end: blood pressure is 35 mmHg
water moves OUT of the blood = Filtration
Vein end: blood pressure is 15 mmHg
water moves INTO blood = Absorption
Capillary Fluid Exchange
Capillary Fluid ExchangeFluid exchange changes to maintain equilibrium in different conditions, such as:
Dehydration, starvation, inflammation, bleeding …
The Lymphatic SystemProteins leak out of capillaries into the extracellular space.
If too many proteins accumulate in the interstitial fluid the osmotic pressure would reverse, sending water out of the blood and into tissues, causing swelling
To avoid this, the Lymphatic System drains excess proteins from tissue spaces
The Lymphatic SystemExcess fluid is absorbed by open-ended lymphatic capillaries
The Lymphatic SystemLymphatic vessels are similar in structure to veins of the circulatory system.
are low pressure have valves rely on muscle contractions to move fluid through
The Lymphatic System - organs
Lymph nodes- tissue that filters the lymph fluid and stores lymphocytes (a type of blood cell)
Bone Marrow - produces all types of blood cells
Spleen - stores and filters blood and lymph fluid
releases blood in response to low blood pressure or low oxygen levels
Thymus gland - where lymphocytes mature before released into the blood
The lymphatic system runs alongside the circulatory system throughout the body.
Related Documents
