Body Systems L5 Flashcards
State 2 characteristics all tissues have
Arterial supply
Venous drainage
State the characteristics of blood vessels?
- Resilience
- Flexibility
- Constantly remain open
Name each of the layers in the structure of a blood vessel (Inner -> Outer)
Lumen
Tunica intima
Tunica media
Tunica adventitia
Describe the Tunica intima
Endothelium -> simple squamous epithelium
Basal lamina of epithelial cells
Subendothelial connective tissue
Describe the Tunica media
Smooth muscle fibres -> loose connective tissue
May contain elastic fibres
Describe the Tunica adventitia
Connective tissue
Merges -> surrounding connective tissue
May contain vaso vasroum
What are the characteristics of arteries?
High pressure -> thick muscular walls Small lumen Maintains shape -> elastic Resilient No valves
What are the characteristics of veins?
Low pressure -> thin walls
Wide lumen
Less elastic & resilient
Valves -> prevent backflow.
Name the types of arteries
Elastic -> conducting
Muscular -> distributing
Arterioles -> resistance
Describe the characteristics of the elastic arteries. Include examples.
1. Elastic -> conducting Diameter -> Up to 2.5cm Withstand pressure changes Continuous blood flow Thick tunica media Many elastic fibres Smooth muscle cells • Eg. Aorta, brachiocephalic & common carotid
Describe the characteristics of the muscular arteries. Include examples.
Diameter -> 0.5mm-0.4cm
Distribute blood -> muscles & organs
Vasodilation & vasoconstriction -> control rate of blood flow to organ
Smooth muscle cells -> tunica media
Distinct internal (IEL) & external (EEL) elastic laminae
Thick tunica externa
Eg. Brachial & femoral arteries
Describe the characteristics of the arterioles.
- Arterioles -> resistance
Diameter -> 30 micrometres or less.
Vasoconstriction & vasodilation -> control blood flow to organs
Involved -> control of blood pressure
1-2 layers smooth muscle -> tunica media
Poorly defined tunica externa
Describe the characteristics of the capillaries
• Capillaries:
- Connect arterioles & venules -> microcirculation
- Site of gaseous exchange
- Thin walls -> lined with endothelial cells -> enable diffusion
- Slow blood flow
- Structure -> enables 2-way exchange
- Diameter -> 8 micrometres
- Near almost every cell
Name the types of capillaries
Continuous
Fenestrated
Sinusoidal
Describe the continuous capillaries
Most common/majority
Skeletal & smooth muscle
Connective tissue & lungs
Describe the fenestrated capillaries
Pores penetrate endothelial lining
Rapid exchange water & large solutes -> small peptides
Absorption -> kidney, chorid plexus & endocrine glands
Describe the sinusoidal capillaries
Spaces between endothelial cells
Incomplete/absent basement membrane
Exchange of large solutes -> plasma proteins
Specialised lining cells in liver -> phagocytic cells engulf damaged red blood cells.
Slow blood flow
What are capillary beds?
Groups of organized capillaries
What are the functions of metarterioles?
Supplies -> single capillary bed
Continues as a route-connecting channel
Leads directly to vein
Numerous capillaries leading off it.
Constriction -> reduces blood flow to entire capillary bed
Describe the role of the precapillary sphincter
Guards entrance -> each capillary
Contraction -> narrows entrance -> reduces bloodflow
Relaxation -> dilates entrance -> increases bloodlfow
Describe the role of the arteriovenous anastomases
Direct communication arteriole -> venule
When dilated -> blood bypasses capillary bed -> directly flows -> venous circulation.
Describe venules & their role within the body
Collect blood -> capillary beds Delivers blood -> small veins Diameter -> Avg. 20 micrometres Small endothelium -> basement membrane Large -> incr. numbers -> smooth muscle cells -> outside endothelium.
Describe the characteristics of veins
• Veins -> capacitance vessels Classified according to size (diameter) Small: <2mm Medium: 2-9mm Large: >9mm -> Eg. superior & inferior vena cavae Low pressure Easily distensible (capacitance) Thin walls Predominant tunica externa Valves -> aid blood flow
What are the function of valves?
-> prevent backflow of blood -> low pressure
What works alongside the valves to prevent backflow of blood, and what is it’s function?
Musculovenous pump
->contracts to close valves & ensure constant blood flow
What tissues prevent backflow of blood?
Valves
Musculovenous pump
How much blood distribution does the systemic venous system have?
65-70% blood distribution
What venous system holds the most amount of distributed blood?
Systemic venous system
What is the anatomical position?
Position of the upright body -> arms at sides -> palms facing forwards.
What is the underside/front of the body called?
Anterior/ventral
What is the behind/upperside of back of the body called?
Posterior/dorsal
What is the name of the direction towards the head?
Superior
What is the name of the direction towards the feet?
Inferior
What is the name of the direction towards the core/centre?
Medial
What is the name of the direction towards the side/away from core/centre?
Lateral
What is the name of the direction closer towards the trunk?
Proximal
What is the name of the direction further away from the trunk?
Distal
What is the name of the plane that divides into front & back planes?
Coronal/frontal
What is the name of the plane that divides into anterior/ventral & posterior/dorsal ?
Coronal/frontal
What is the name of the plane that divides into top & bottom planes/ above & below waist?
Horizontal/transverse
What is the name of the plane that divides into superior & inferior planes? ->
Horizontal/transverse
What is the name of the plane that divides into right & left halves?
Midsagittal
What is the name of the plane that divides into medial & lateral planes?
Midsagittal
Outline the transfer circuit of blood through the blood vessels from the heart.
• Aorta -> artery -> arterioles -> capillaries -> venules
-> vein -> vena cava
What is the vaso vasorum?
Vessels supplying blood vessels -> thick walls
What is the endothelium?
Inner layer of cells lining tissues & organs