Download Human Circulatory System 1

Quaestio: What structures transport
substances throughout the human body?
Nunc Agenda:
What are 3 parts of a circulatory system?
What are they called in the human body?
Function of the Circulatory System
• To transport oxygen, nutrients, and other
dissolved substances throughout the body
• Remove wastes from cells
• Maintain body temperature by distributing
heat
Vertebrate circulatory system overview
• Heart  pumps blood
– Atrium – collects blood from veins
– Ventricle – pumps blood out to the body
• Blood Vessels
– Arteries – carry blood away from the heart
– Capillaries – tiny vessels where exchange of
materials between blood and body cells occurs
– Veins – carry blood toward the heart
Other vertebrate hearts
• Fish – 2 chamber heart
– 1 atrium, 1 ventricle
• Amphibians – 3 chamber heart
– 2 atria, 1 ventricle
• Birds / mammals – 4 chamber
– 2 atria , 2 ventricles
– Prevents oxygenated and deoxygenated blood
from mixing, allows for more efficiency and ability
to be warm-blooded
The Developing
Heart of a
Zebrafish Embryo
http://bioimaging.caltech.edu/index_content.ht
ml
Note: In Crocodilians, heart is actually
completely separated. They can prevent
blood from flowing through the
pulmonary circuit while underwater by
using a muscular valve.
Overview of
Vertebrate
Circulatory
Systems
Interesting…
• Average adult body contains about 5 L of blood
• On average , your blood circulates from your
heart, throughout your body and back about
every 60 seconds.
• Everyday your heart beats about 100,000 times
• First heartbeat in human embryo occurs about 45 weeks after conception
• The leading cause of death in the US is heart
disease
The heart is a muscular double-pump
• Pulmonary circulation – right side of the heart
pumps deoxygenated blood to the lungs
– Heart  lungs
– Pulmo = “lung” (latin)
– -ary = “belonging to or connected with”
• Systemic circulation – left side of the heart
pumps oxygen rich blood to the rest of the
body
– Heart  brain and body
Blue=Deoxygenated
blood.
Red = oxygenated
blood
Lungs
replenish the
blood with
oxygen.
How it works:
RBCs pick up
O2 through
diffusion
across the
capillary
membrane.
Pericardium – a tough membrane that covers the
heart and protects it
The Heart
• The heart consists of four chambers:
–
–
–
–
1. Left Atrium
2. Left Ventricle
3. Right Atrium
4. Right Ventricle
• Atria: Upper, thin-walled chambers.
• Ventricles: Lower, thick-walled chambers.
• Septum: A wall that separates the left and right
sides of the heart.
• Valves: flaps of tissue that prevent blood from
flowing backwards
The heart
• Composed almost entirely of cardiac muscle
– Cells are connected together in an electrical
network that stimulates contraction
– When one cell is stimulated, all of the fibers
contract at the same time
– Can work continuously without getting tired
Cardiac Muscle Cells
Human Heart Beat
• 2 contractions
1. Atria contract “lub”
•
•
Begins at the SA node (sinoatrial) a.k.a. “the pacemaker”
Electrical impulse spreads causing both atria to contract
2. Ventricles contract “dub”
•
•
Impulse is picked up by the AV node (atrioventricular)
Split-second delay then both ventricles contract, pumping
blood out of the heart
–
(allows both atria to contract and ventricle to fill with blood)
Circulation Pathways (1)
• Steps:
– 1. Deoxygenated blood enters the right atrium of the
heart from the body tissues.
• This blood reaches the heart through the superior and inferior
vena cava veins.
– 2. Deoxygenated blood is pumped from the right atrium
to the right ventricle through a valve.
– 3. Deoxygenated blood is pumped out of the heart to
the lungs by the right ventricle.
• This blood is pumped out through the pulmonary artery.
– 4. The lungs replenish the blood with oxygen. It is now
oxygenated blood.
Circulation Pathways (2)
• Steps:
– 5. Oxygenated blood enters the left atrium of the heart
from the lungs.
• This blood reaches the heart through the pulmonary veins.
– 6. Oxygenated blood is pumped from the left atrium to
the left ventricle through a valve.
– 7. Oxygenated blood is pumped out of the heart to the
body tissues by the left ventricle.
• This blood is pumped out through the aorta.
– 8. The body tissues use the oxygen carried by the red
blood cells. The blood then becomes deoxygenated and
must be returned to the heart where the cycle repeats.
Simplified Sequence
• Blood flows from
Right Atrium  Right Ventricle  Lungs  Left Atrium
Left Ventricle Rest of Body  Right Atrium again.
Pulmonary Circuit:
Right Ventricle  Lungs  Left Atrium
Systemic Circuit:
Left Ventricle  Body  Right Atrium
Questions
• The left ventricle is the largest chamber of the
heart. How is its size related to its function?
• If the valves in the right ventricle do not close
properly, where in the body might circulation be
affected the most?
• Why is it important to have two separate
pathways for circulation?
• Describe some of the adaptations of the
mammalian heart that allow it to be efficient and
coordinated.