6.2 blood system Flashcards
what gets transported via blood?
nutrients & gas: Nutrients, Oxygen
waste: carbon dioxide, urea
communication: hormones
immune: Leukocytes, Antibodies
homeostasis: heat, hormones
myoarteries
convey blood AWAY from the heart, to lungs to be oxygenated
High pressure. Result of a:
- Narrow lumen (interior)
- A muscular & elastic wall.
- Can stretch when a pulse of blood is ejected from the heart into the arteries. Then, when the artery returns to it original size, blood is propelled forward.
- Can contract to narrow the lumen, increasing blood pressure.
- An outer layer made of collagen which provides structure and prevents rupturing
veins
convey blood to the heart (valves regulate direction)
-Low pressure, transporting blood to the heart
-Large lumen
-Non-elastic.
-Has valves to increase pressure and prevent backflow of blood.
systole
the active phase of the heart’s movement. contraction of atria then ventricle.
capillaries
-Very low pressure
-Narrow (red blood cell width)
-One cell thick to facilitate diffusion/osmosis.
-Highly branched
Two events occur:
1. Exchange of fluid (plasma & interstitial fluid)
2. Diffusion of molecules (gases, nutrients, ions, etc.)
Two forces influence the movement of fluid in capillaries
Hydrostatic pressure (blood pressure - pushes fluid out of capillaries).
Osmotic pressure (water moves from a low solute conc. to high solute conc.)
The net force between the two forces determines the direction of movement.
* Hydrostatic pressure = Osmotic pressure → no net movement in or out of the blood.
* H.P > O.P → movement of fluid out of capillaries
* H.P < O.P → movement of fluid into capillaries
interstitial fluid
Fluid surrounding capillaries & cells
the 3 blood vessels
arteries, veins, capillaries
right vs left side of heart
The right heart contains deoxygenated blood. It accepts blood from the body and pumps to the lungs for oxygenation.
The left heart contains oxygenated blood. It accepts blood from the lungs and pumps it to the body.
sinoatrial (SA) node
The heart beat is controlled by the sinoatrial (SA) node. It is a group of specialised muscle cells in the right atrium that signals to the heart muscles.
The SA node acts as a pacemaker. It controls the rate at which the heart beats.
heart beat process
The SA node sends out an electrical impulse that causes the immediate contraction of the atria.
The impulses then travel along the septum via a nerve bundle (Bundle of His or atrioventricular (AV) bundle).
Purkinje fibers transfer the impulses to the left and right ventricular walls.
The ventricles contract.
There is a delay between the contraction of the atria and the ventricles.
Basal heart rate is controlled by the SA node (pacemaker) but can be influenced by the:
Autonomic (involuntary) nervous system & hormones
how does Autonomic (involuntary) nervous system influence heart rate
Two nerves from the medulla oblongata signal the heart directly by releasing neurotransmitters. They can:
- Increase heart rate via the release of norepinephrine/noradrenaline (sympathetic)
- Decrease heart rate via the release acetylcholine (parasympathetic)
how do hormones influence heart rate?
High levels of epinephrine/adrenaline in the blood stream can increase heart rate. This epinephrine is released by the adrenal glands which are located atop the kidneys (endocrine system)
Exercise results in high concentrations of epinepherine.
2 parts of cardiac cycle
systole and diastole
