blood and lymphatic systems

blood and lymph are…

(fluid) connective tissues

blood

• composed of formed elements & plasma

  • plasma, red blood cells, white blood cells, and platelets (cell fragments)

• plasma forms fluid matrix (fluid, proteins)

lymph

• composed of lymphocytes & lymph fluid

• A dilute solution of proteins & excess interstitial fluid

  • collects extra fluid from extra body fluids. very important job!

functions of blood

• Distributes nutrients, oxygen and hormones to body cells

• Carries metabolic wastes away from cells, primarily to the kidneys for excretion

• Carries carbon dioxide away from tissues to lungs

• Transports cells of the immune system that provide protection against infection and disease

blood makeup

• Volume in body

  • 5-6L in average male

  • 4-5L in average female

  • Normovolemic (normal blood levels) vs. hypovolemic/hypervolemic (low/high blood levels)

• pH = 7.35 – 7.45

• Temperature = 38℃

• 55% plasma

• <1% buffy coat (leukocytes and platelets)

• 45% erythrocytes

components of plasma

• 7% plasma proteins

• 1% other solutes

• 92% water

what are plasma proteins for?

• to transport things (blood cells, nutrients ions, electrolytes, waste, etc.

• to provide osmolarity (keeps blood in its vessels)

plasma proteins from most to least

• albumins 

• globulins

• fibrinogen

• regulatory proteins

other solutes in plasma from most to least

• electrolytes

• organic nutrients

• organic wastes

formed elements in blood

• Red blood cells (erythrocytes)

• White blood cells (leukocytes)

  • Neutrophils

  • Eosinophils

  • Basophils

  • Monocytes

  • Lymphocytes

• platelets

function of red blood cells (erythrocytes)

• to carry O2 and CO2 (99% of cells in the blood), and other nutrients

• gets rid of all organelles and are just a bag of protein

function of platelets

blood clot formation

function of the white blood cell neutrofil

destroys bacteria

• big population, destroys invaders. engulfs and digestts them or release toxins and destroy them

function of the white blood cell eosinophils

anti-parasitic, allergic response

function of the white blood cell basophil

inflammatory response

• LOTS of granules for secretion. secretion stimulates the immune system and generates inflammatory responses

function of the white blood cell monocytes

becomes macrophages

• pac man cells: engulfs/eats things that shouldn’t be there

function of the white blood cell lymphocytes

immune response

the innate immune system

forms defense system (fights intruders, clean messy cells, generate immune response. NOT creating a specific response.

• created by neutrophils, eosinophils, basophils, and monocytes

the adapted/acquired immune system

immune response mediated by outside influence

red blood cells

• Biconcave disc-shaped cells

• Plasma membrane surrounds cytoplasm containing water (66%) and proteins (33%)

  • Intracellular structures, including nucleus, are ejected from cell during development – not needed for main purpose of gas transport

  • proteins are mainly hemoglobin (iron binding proteins)

platelets

• Formed from large stem cells called megakaryocytes in the red bone marrow and lung

• membrane-bound enzyme packets that pinch off from the cytoplasm of the megakaryocyte

blood vessels

• Pathways for blood to circulate throughout the body

• Blood flows in two directions:

  • Away from heart

    • Arteries, arterioles (artery branch), capillaries (blood reaches here and its where, gas, nutrient and waste exchange happens and collects in larger veins)

  • Toward the heart

    • Veins, venules, capillaries

structure of blood vessels

• adventitia (outermost)

• media (middle)

• intima (innermost)

adventitia

Composed of connective tissue, attaches vessel to surrounding tissue

media

Composed of elastic fibers & smooth muscle (thin or thick), regulates diameter.

• elastic fibers: ECM with elastin. makes it so BV can adapt to incresse pressure, capacity, and can shrink back down when it needs it

• proportion of these two components vary

intima

• Composed of simple squamous epithelium (endothelium) & thin layer of connective tissue

• lines the vessel that forms the surface in which blood flows. equiv of endocardiuum

differences in artery and vein structures

• Media is largest layer in arteries.

• Adventitia is largest layer in veins.

elastic (conducting) arteries

• Largest diameter arteries (almost an inch!). gets smaller the closer it gets to capillaries

• Media contains high density of elastic fibers, not so much smooth muscle

  • Can have additional elastic layers internal and external to media in very large vessels

• Stretch & recoil in response to pumping of heart

• Even out pressure surges

  • Needs to be able to absorb pressure and be expandable. without it, it cant handle the pressure and blood entry so damage happens and blood flow is not maintained

muscular (distributing) arteries

• Medium-sized arteries

• Distribute blood to skeletal muscles & internal organs

• Media contains predominantly smooth muscle (elastic recoil not as important here)

• Able to vasoconstrict (close) & vasodilate (open) to redirect blood flow

  • smooth muscle can extract or expand amount of blood inside

what does NOT have an internal elastic layer?

muscular (distributing) arteries

arterioles

• Small to microscopic vessels

• Poorly defined adventitia

• Media composed of scattered smooth muscle cells

• Deliver blood to capillaries

• Change in luminal diameter (vasoconstriction/vasodilation) to regulate blood pressure

• narrow to make sure blood is distributing

capillaries

• Smallest blood vessels, connect arterioles to venules

• Have an endothelium and basement membrane

• Mediate exchange between blood and surrounding tissues

capillary function

Mediate exchange in different ways, depending on what we are exchanging. can exhange through:

• diffusion (things just pass thru — O2 and CO2 can do this)

• active transport (things taken into another — proteins)

• gaps between cells or holes in cells (fenestrations)

  • making things leak out

sinusoids

• expanded capillaries in the liver, spleen and bone marrow.

• They are fenestrated, discontinuous, and have an incomplete basement membrane.

control of blood flow in capillary bed

• Precapillary sphincters control blood flow through capillaries

  • can open and close capillaries depending on what the needs of the tissue are

• Metarterioles (final branch of arterioles) connect arterioles to capillaries. When sphincters are closed, they shunt blood to venules via throughfare channels (straight to vein)

veins

• Collect blood from organs & tissues & return it to the heart

• Contain 65-70% of the blood in the body

• Veins have larger capacity to stretch than arteries and therefore can act as a blood reserve.

medium and large veins

Slender media, adventitia is thickest layer

venules

• Collect blood from capillaries

• Wall composed primarily of intima

venous valves

• One way valves in the walls of peripheral veins prevent the backflow of blood in arms and legs.

  • Looks a lot like tricusps valve in heart just with two cups instead of three.

• Venous compression caused by contraction of adjacent muscles aids in maintaining blood flow

• tdlr: often veins are sandwiched between muscles, so when muscles contracted it helps push that blood

arteries of thorax

• arch of the aorta

• ascending aorta

• descending aorta

posterior intercostal arteries

• arteries under each rib that supply the thorax

• ____ _____ _____ numbers 3-11 arise from the descending aorta

anterior intercostal arteries

• comes from the subclavian arteries and the right and left internal thoracic arteries (internal mammary arteries, IMA)

• On top of each rib.

Anterior and posterior intercostal arteries ___ with one another.

anastomose (link together)

parts of the common carotids

• internal carotids

• external carotids

• carotid sinuses

internal carotid arteries of the common carotid arteries

the primary blood supply to the brain.

external carotid arteries of the common carotid arteries

supply the neck and face.

carotid sinuses of the common carotid arteries

• swollen region at base of internal carotid

• contains baroreceptors that measure blood pressure

vertebral arteries

branches of the subclavian arteries. They are also an important blood supply to the brain.

Subclavian, Axillary, and Brachial Arteries

• litearlly all one artery just with different names at different points

subclavian artery

the first part of that long ahh artery

• Emerges from aorta (left)/brachiocephalic artery (right) and travels under clavicle

the axillary artery

the second part of that long ahh artery

• Starts after artery crosses first rib, passes through armpit (axilla)

brachial artery

• the last part of that long ahh artery

• Starts after artery crosses teres major muscle, travels through upper limb until branches into radial and ulnar arteries (which are differnet vessels so they’re not apart of this long artery)

common iliac arteries

• Descending aorta (front / beside vertebral column) divides into left and right common iliac arteries, which each divide into external and internal iliac arteries.

• left and right external iliac arteries are headed down to the legs, and turn into the femoral arteries

• left and right internal iliac arteries supply the pevic organs

the common iliac veins (and therefore the femoral veins) drain their blood into…

the inferior vena cava

femoral arteries

• External iliac arteries become femoral arteries when it passes below the inguinal ligament and travels into the lower limb.

inguinal ligament

major route for vasculature at the lower limb

veins…

trace similar paths to arteries and typically have the same name (e.g., facial artery, facial vein). However, there are some exceptions.

veins of the thorax

• left and right internal jugular veins (blood from brain, head and neck)

• left and right subclavian veins (blood from upper extremities)

• left and right brachiocephalic veins (blood from arms, forearms, hand)

• superior vena cava (collecting blood from upper part of body (head, upper limbs, thorax). combo of the brach veins.)

inferior vena cava

receives blood from lower part of the body (abdomen, pelvis, lower limbs)

renal veins

drains kidney blood into the inferior vena cava. LOTS of blood goes here and comes out, like 20% of cardiac output. good for regulating BP

hepatic portal system

All blood returning from the abdominal GI system is directed / drained into the hepatic portal vein, which distributes it to the liver for processing. From the liver, the blood is transported to the IVC via hepatic veins and thereby returned to systemic circulation.

body fluids

• Intracellular fluid – cytoplasm, nucleoplasm, etc.

• Extracellular fluid

  • Blood plasma – in the circulatory system

  • Interstitial fluid – bathes the cells of the body

    • Filtrate of fluid and small solutes out of capillaries to the areas surrounding cells

      • not all fluid that leaks out goes back into veins — lymphatic system takes leaked fluid so cells do not swell and swell and swell

    • Called “lymph” when it enters the lymphatic vessels

lymphatic system

• Produce, maintain and distribute lymphocytes

  • Function in the immune response

• Assists with maintaining normal blood volume

  • Vascular pressure forces water and solutes across capillary membrane into interstitial space

  • That fluid is returned to the vasculature by the lymph vessels

  • Alternate route for transport of hormones, nutrients, metabolic waste

  • E.g., Lipids absorbed by digestive tract enter bloodstream via lymph rather than via capillaries of the vasculature

• drained in the brain (meninges)

components of the lymphatic system

• Lymphatic vessels

  • Thin vessels that transport lymph, eventually returning it to blood

• Lymphatic Organs (defined, identifiable structures)

  • Organs where lymphocytes differentiate or reside

  • Enclosed by a fibrous capsule

  • Bone marrow, thymus, lymph nodes, spleen

• Lymphatic Tissue (less defined structures that are still clearly lymphatics)

  • Connective tissue network containing dense aggregates of lymphocytes

  • No capsule

  • E.g., Tonsils, lining of appendix

lymphatic system facts

• Lymph flows passively along a pressure gradient (i.e., no pump).

• Lymphatic system is extremely low pressure, soo vvvv

• Vessels very thin walled

• Lymph nodes are oval

• lymphoid organs 1 – 25 mm in diameter

  • they surveys and checks fluid to make sure its all good.

  • can become swollen in disease scenarios

lymphatic vessels

• ~ 3.6L, 70% of blood volume, enters interstitial fluid every day.

• Lymphatic capillaries absorb fluid through gaps between overlapping endothelial cells. Act like one-way valves so fluid can’t leak back out.

  • simple squam epi makes up the walls of these vessels. has gaps in the walls (where cells overlap but are not stuck together) and allows fluids in but not out (like a one way valve!)

valves in lymphatic vessels

• have many valves to prevent backflow.

• Valves are similar to those in veins, but region around valve bulges, giving _____ _____ a beaded appearance

lymphatic ducts

• thoracic duct

• left and right ducts

• cysterna chyli

function of lymphatic ducts

to collect lymph and empty it into large thoracic veins

thoracic duct

• posterior

• sends lymph to brachiocephalic vein

lymphocytes

a type of white blood cell crucial to the immune system, responsible for fighting infection and disease. all come from stem cells in your red blood marrow, but T cells mature in thymus before reentering the red blood marrow.

• NK cells

• B cells

• mature T cells

NK cells

"Natural Killer” cells

• destoys things (engulf cells or trigger apoptosis). bridges both side of immune systems

• continuously circulates through peripheral tissue

B cells

• come from bone marrow. prduces anti-bodies

• resides in lymph nodes, spleen, lymphoid tissue

mature T cells

• develops in thymus and are selected to recognize foreigners only. reside in diff lymp organs. important in directly attacking something and also tell the B cells to make antibodies

• resides in bone marrow, spleen, and lymphoid tissue

lymphatic organs

• Discrete structures enclosed by a fibrous connective tissue capsule

• Primary – produce, maintain and store lymphocytes

  • contain stem cells that generate B, T, and NK cells

  • E.g., bone marrow, thymus gland

• Secondary (peripheral) structures – where most immune responses are initiated

  • Activated lymphocytes divide to produce additional lymphocytes of same type

  • The front line where invading bacteria first encountered

  • E.g., spleen, lymph nodes

thymus gland

• Lies posterior to manubrium in the superior mediastinum

• Two lobes

• large in early life, it undergoes involution in later life (but still functions)

• Source of T lymphocytes (proliferate, differentiate, mature, and are selected here)

Spleen

• Largest lymphoid organ

• Sits in upper left quadrant of abdomen, against posterior body wall.

• Filters the blood, removing abnormal blood cells and components by phagocytosis

• Stores iron recycled from metabolized RBCs

• Initiates immune response by B and T cells in response to circulating antigens

lymph nodes

• filters the lymph, removing 99+% of antigens

• Resident T cells, B cells and macrophages (major site of immune response to antigens)

• Lymph “glands” – large nodes at base of neck, axillae, groin

• “Swollen glands” – enlarged nodes due to inflammation or infection

• includes capsules

  • Many afferent vessels penetrate fibrous capsule

• One efferent vessel exits nodes

lymphoid tissues

• Connective tissues dominated by lymphocytes (they live here!). Lacks a surrounding capsule, so they are not lymphoid organs

• Often present near external surfaces

• Diffuse

  • mucous membranes of respiratory and urinary tracts

• Nodules

  • Aggregations of densely packed lymphocytes supported by dense reticular fibres

  • Boundaries often indistinct due to lack of fibrous capsule

  • Mucosa of digestive tract — all around larynx

    • wall of pharynx (tonsils)

    • lining of small intestine (Peyer’s patches)

    • appendix – mass of fused lymphoid nodules

    • immune defenses are sometimes overwhelmed ➔ tonsillitis, appendicitis, etc

lymphoid nodules

• Densely packed accumulations of lymphocytes.

• Have germinal centres where lymphocytes are dividing.