BIOS 1310 Lab Quiz #5

Circle of Willis

ring of arteries

manages delivering life- sustaining, oxygen-rich blood to the brain

encircles the optic chiasm and hypothalmus

forms a bridge between the internal carotid arteries and the vertebral arteries

Internal carotid arteries

nourish the front of the brain

vertebral (vertebrobasilar) arteries

supplies the back of the brain

A complete circle of Willis exists in…

Less than half of the population

Cerebral Aneurysm

weak spot in vessel walls that can rupture and cause hemorrhage

The Hepatic Portal Vein

directs blood rich with absorbed nutrients, glucose, AAs, vitamins but also toxins, bacteria, and metabolic byproducts to the liver (where it undergoes essential processing).

Sinusoids

within the liver

hepatocytes metabolize nutrients, detoxify harmful substances, regulate blood glucose levels, and prepare vital compounds for storage or release

Cirrhosis

scarring of liver tissue and increase resistance to blood flow

leads to portal hypertension

Portal hypertension

elevated pressure within the portal vein

can result in complications such as varices and ascites (fluid accumulation)

Dural venous sinuses

endothelium-lined spaces located between the periosteal and meningeal layers of the dura mater

lack both valves and muscular walls

structural design allows blood to flow freely, guided by pressure gradients rather than pumps

brain’s essential outflow system

• low-pressure but high-importance

• ensures circulation remains balanced within cranial cavity

Dural venous sinuses function

collect deoxygenated blood from the cerebrum, cerebellum, and brainstem to return to the heart through cerebral veins

absorbing cerebrospinal fluid (CSF) from subarachnoid space

• helps regulate intercranial pressure

Venous blood flow

superior sagittal sinus—→ inferior sagittal sinus—→ straight sinus—→confluence of sinuses—→transverse sinuses—→sigmoid sinuse—→internal jugular veins—→ return of deoxygenated blood to the systemic circulation

Cavernous sinuses

paired

lie on either side of the sella turcica of the sphenoid bone

receive blood from the ophthalmic veins and form connections w facial veins

Infections from the face or nasal region…

spread to the cavernous sinus and pose serious health risks

Dural venous sinus thrombosis( DVST)

consequences are severe if this drainage network becomes obstructed

clot within the sinus can impair venous outflow

• raise in interacranial pressure

• symptoms such as headache, nausea, and visual disturbances

Lymphatic system

one way circulation of vessels, ducts and organs that works in constant partnership with the cardiovascular and immune systems

body’s additional drainage network

Blood plasma

filters from capillaries to nourish tissues

not all returns to bloodstream

• ~3 liters remain behind the spaces between cells

What happens if blood plasma is left behind the spaces between cells?

swelling and disruption of normal function

Lymph

leftover interstitial fluid

collected by tiny lymphatic capillaries

moved through progressively larger vessels w one way valves

eventually emptied into

• thoracic duct

• right lymphatic duct

rejoins the blood stream at the subclavian veins

• due to low pressure and easier entry

Thoracic duct

drains the entire lower body, abdomen, left chest, left arm, and left side of the head/neck

Right lymphatic duct

drains the right thorax, right arm, and right head/neck region

Lymph nodes

lymph passes through

small

bean shaped

clustered in the neck, armpits, and groin

Filter out

• pathogens

• damaged cells

• debris

house lymphocytes

lymphocytes

specialized white blood cells that identify and destroy

• bacteria

• viruses

• abnormal cells

What supports lymphocytes?

bone marrow

• blood cells produced

Thymus

• T cells mature

Spleen

• filters blood and removes old RBCs

Mucosa associated lymphoid tissue (MALT)

• tonsils

• Adenoids

• Peyer’s patches of intestine

Peyer’s patches

intestine

guard entry points to the body

Lacteals

specialized lymphatic capillaries in the small intestine

absorb dietary fats and fat soluble citamins that are too large to enter blood capllaries directly

Lymphedema

infection due to blocked vessels

causes swollen lymph nodes

Lymphoma

due to uncontrolled lymphocyte growth

Immunoglobulins

specialized proteins

designed to recognize and neutralize invading threats

aka antibodies

patrol bloodstream and tissues in search of antigens

• bacteria

• viruses

• parasites

• other foreign substances

5 classes of Ig

IgG

IgA

IgM

IgE

IgD

IgG

most abundant (75-80% of antibodies in blood)

long-term protector

targets pathogens in tissues and found circulating in the blood

only antibody capable of crossing the placenta

• provides newborns w passive immunity during first months

IgM

rapid responder

produced first during an initial infection

circulates as a pentamer

• 5 antibody units joined together

  • highly effective at binding and eliminating pathogens early in response

IgA

guards body’s entry points

found in high conc along mucosal surfaces

• respiratory tracts

• gastrointestinal tracts

• saliva

• tears

• breast milk

prevents pathogens from attaching to and penetrating tissues

IgE

plays a dual role

protects against parasitic infections but is also responsible for allergic reactions

triggers the release of histamine

• symptoms suchs as itching swelling and inflammation

IgD

important regulatory function

located mostly on surface of B cells

helps initiate and regulate immune responses

High levels of Ig

chronic infection

autoimmune disease

certain cancers

Low levels of Ig

immunodeficiency

• leads to recurrent infections of sinuses, ears, lungs

Immunity

layered system composed of innate and adaptive components

guards against disease

Innate immunity

protection we are born with

acts immediately and non-specifically

Physical barriers:

• skin

• muscus linings

  • block pathogens from entering

Immune cells:

• macrophages

  • patrol tissues

  • engulf and destroy invaders

Adaptive immunity

highly specific and capable of memory

produces antibodies and specialized T and B cells that target a pathogen

Natural active immunity

infection

Artificial active immunity

vaccination

Passive immunity

body receives antibodies from another source

Natural passive immunity

occurs when a mother passes antibodies to her baby through the placeta or breast milk

temporary

Artificial passive

medical treatments

• immunoglobulin injections

  • antivenom

Herd immunity

when a high percentage of people are immune the pathogen struggles to spread

Antigen presenting cells (APCs)

link between body’s first line of defense and its specialized response

Ex) dendritic cells, macrophages, and B cells

patrol tissues

engulf pathogens

break them down into small antigen fragments