Human Biology 2 Exam 2

immunity

ability to resist and defend against infectious organisms and other damaging substances

resistance

ability for body to maintain immunity

immune response

reaction to infectious agents and other abnormal substances

four classes of pathogens

• extracellular bacteria

• instracellular bacteria

• viruses

• parasitic worms

2 layers of immune system protection

1. innate branch (if this fails then acquired actiavted)

2. acquired/adaptive branch

innate branch

• present from birth

• nonspecific → protects against all pathogens in the same way

• has limited diversity - recognizes a lot of things but things can still slip through

• no memory → doesn’t become more efficient on subsequent exposure to same organisms

• responds quickly → presence of pathogen triggers a response instantly

• 3 nonspecific barriers

  • mechanical

  • chemical

  • biological

innate branch - mechanical

• skin (external covering of body) and mucous membranes (covers lining of many things inside body)

• tight junctions between cells in epithelial sheets prevent entrance of microorganisms

innate branch - chemical

• sebum → made by skin, oil residue put on skin, makes it hard for bacteria to survive

• mucin → viscous when hydrated and forms mucus that covers respiratory and gastrointestinal tract

  • protein made in cells, secreted and H2O attracted because it has sugar → creates mucous; easy for bacteria to get trapped in

  • stick of protein with carbohydrates on it → hydrophilic so sticks onto things

• HCl results in low pH of stomach contents → neutralizes most pathogens

• lysozyme → enzyme in our saliva that degrades peptidoglycan

lysozyme

enzyme in our saliva that degrades peptidoglycan (outer coat on all bacteria species, body doesn’t digest it so we know that it needs to be destructed)

innate branch - biological

• normal flora: 10 times more bacterial cells than human cells in your body

• take up space that pathogens might otherwise occupy → create competition for space and food

• sometimes make antibiotics → bacteria get possessive of their space and make antibodies to kill other bacteria

cells of innate immune response

• phagocytes: attack and remove dangerous microorganisms

  • neutrophils and eosinophils: enter peripheral tissues to fight infections

  • macrophages: reside in tissue rather than blood stream where monocyte is, large phagocytic cells derived from monocytes

  • dendritic cells: live in tissue but more around a lot in lymph system, present to T-cell

neutrophils

• large reserves of neutrophils are stored in the bone marrow and released when needed to fight an infection

• travel to and enter the infected tissue, where they engulf and kill bacteria

• neutrophils die in the tissue and are engulfed and degraded by macrophages as they can’t be reused

• enter tissue through spaces in endothelial cells

macrophages

• seeded throughout all body tissues

• clean by debris from old/dead cells or damaged tissue (garbage collection)

• phagocytosis of garbage or invading pathogens

• bacteria interacts with macrophage, gets engulfed and degraded OR bacteria interacts with macrophage and it releases cytokines (chemicals)

Macrophages constantly remove:

• dead cells

• old cells

• small debris

This happens all the time.

No danger → no cytokines because cytokines cause inflammation, and we don’t want inflammation all the time.

cytokines

• proteins released by immune cells to trigger immune response

• chemical messengers released by cells once activated or triggered

cytokine induced inflammation

• surface would introduces bacteria which activate resident effector cells to secrete cytokines (macrophage phagocytoses bacteria and releases cytokine)

• vasodilation and increased vascular permeability to allow fluid, protein, and inflammatory cells and to leave blood and enter tissue

  • cytokine causes gap formation of capillary bed and allows things to enter

• swelling = cytokine releases, gaps in endothelial layer → more fluid to come in bringing other things → associated with redness because RBC can enter gaps

• neutrophils come in through gaps also and phagocytose

hallmarks of inflammation

• swelling: fluid leakage from blood into tissue

• redness: increased blood flow and leakage of RBC

• pain: stimulation of nerves sending pain signals to brain

• heat: increased cellular activity in fat and muscle cells

dendritic cell

• present in every tissue/organ

• antigen presenting cells

  • antigen = anything on surface of membrane

  • take bacteria → chew → present parts of it for T-cells to recognize

• important for activating T-cells through antigen presentation → initiating the adaptive immune response

acquired immune response

• specific: exposure to an organism or a unique chemical derived from that organisms confers immunity to only that organism

  • requires that we have had initial exposure

• great diversity: can response to almost any organism or foreign macromolecule

• has memory (vaccines)

  • responds slowly to first exposure to a pathogen and then following exposures are faster

cells of adaptive immune response

• T cells

• B cells

• NK cells (natural killer cells)

general steps of adaptive/acquired immunity

• chemical targets that stimulate immune response

• when lymphocyte contacts appropriate antigen it becomes activated

• activated lymphocyte divides to produce a clone

• rapid expansion of identical lymphocytes to increase antigen detecting ability

B lymphocytes

• born in bone marrow, move out and live inside lymphatic tissue

• each B cell has unique receptor anchored to its surface with the capacity to bid to unique chemical structure (antigen)

• B cells have potential to recognize almost any microbial antigen

  • each B-cell is different but all receptors on an individual B-cell are identical

  • most B-cells never encounter the right antigen

steps for activation of B lymphocyte

1. activation of B cell by appropriate antigen leads to clonal expansion of B cell that has the right receptor

2. some cells differentiate into plasma cells that secrete antibodies that bind antigen (must be activated before it becomes a plasma cell)

   1. have large endoplasmic reticulum to make these proteins (antigens)

3. other cells of clone differentiate into memory B cells waiting until same antigen infects us again

actions of antibodies

• neutralization: binding of antibodies to a region of pathogen stops it to attach to other cells

• agglutination: binding of multiple pathogen into large immune complexes that become insoluble

  • lots of antibodies bind to pathogen and create large clumps which then call macrophages to come degrade it

• attraction of phagocytes/inflammation and opsonization: other immune cells are attracted to antibody coated pathogens, the antibody coat may help cells phagocytosis the pathogen

opsonization

to mark something to signal that it needs to be degraded

T lymphocytes

• born in bone marrow, go to mature in the thymus and then move to lymphatic tissue (live side by side with B cells)

  • in order to fully mature, go and live in thymus gland to fully develop T-cell receptor, then once matured go and live with B-cells in lymph tissues

• have receptors on their surface (called TCRs - T cell Receptor) that can bind microbial antigens

  • can only recognize protein components

  • not good at detecting pathogens on their own, need to be presented a piece of antigen from a dendritic cell

  • other cells in our body use molecular trays calls MHCs to display antigens to T cells

T Cell Function

• once activated, T cells don’t secrete their receptors unlike B cells do with antibodies

• go through clonal expansion (some become memory T cells)

  • T cells themselves leave lymph tissue and circulate through blood to find the pathogen

two types of T cell function

CD8 T cells: cytotoxic T cells, assassins → will kill other cells potentially infected with pathogens

CD4 T cells: helper T cells

CD8 Cells Process

• an infected cell presents a foreign antigen with a Class 1 MHC proteins

  • if cell gets infected it shows proteins pathogen is making and T cells identifies it and then CD8 kills the cell

• if CD8 receptors binds antigen, then CD8 cell is activated

• activated CD8 cell releases chemicals that kill infected cells

  • destruction of plasma membrane

  • stimulation of apoptosis

  • disruption of cell metabolism

CD4 T cells

• helper T cells

• complex set of functions

• interact with other immune cells through Class 2 MHC receptor (only specialized immune cells have this)

  • sensitized B cells → required for full activation of B cell

  • to have B cell fully activated you need to present some of the pieces of killed pathogen to a helper T cell

  • Because T cell acts like a safety check. B cell alone could be wrong.

• activated CD4 T cells then send signals to infected cell that help it eliminate the pathogen rather than killing the cell

lymphatic fluid (lymph)

is interstitial fluid that enters a lymphatic vessel, often helped alone by swelling

lymphatic system

• interstitial/extracellular fluid is the fluid that surrounds all cells and tissues

• lymphatic fluid (lymph) is interstitial fluid that enters a lymphatic vessel, often helped alone by swelling

• series of small vessels and nodes that drain lymph into venous system

• lymph nodes connected to each other through lymphs which T and B cell monitor

lymph nodes

• at junctions of body

• soluble microbial antigens and antigen presenting cells with loaded MHC trays use lymphatic vessels to get to lymph nodes

• ex. dendritic cell phagocytoses a pathogen then leaves tissue in lymph and travels to lymph node where it T cells look at it and see if right T-cell gets activated

  • B-cells are also here but mostly looking for free flowing ones

ventilation

(breathing), moving of air in and out of lungs for it to be in gas exchange

respiration

allow gas exchange between air and circulating blood

internal respiration

gas exchange within body in capillary beds

external respiration

occurs in the lungs, where oxygen moves from alveoli into pulmonary blood and carbon dioxide moves

functions of respiratory system

1. ventilation

2. respiration

3. protection from external environment

4. producing sound and speech

5. facilitating smell

upper respiratory system

oral and nasal cavity

lower respiratory system

bronchiole tree, alveoli

conducting zone

movement of air, no gas exchange in this region, anatomical dead space

nasal cavity → terminal bronchioles

respiratory zone

site of actual gas exchange in alveoli

how is respiratory system anatomically divided

upper and lower respiratory system

how is respiratory system functionally divided

conducting zone and respiratory zone

mucous membrane

line organs of conducting zone

function of respiratory mucosa

conditioning process, warming, purification, and humidifying air

epithelium at back of throat, oral and nasal cavity

stratified squamous

epithelium at trachea and major bronchi

pseudo stratified epithelium

epithelium at smaller tubules/bronchioles

simple cubodial

epithelium at alveoli

simple squamous

lamina propria

connective tissue

mucous cell

spread between pseudo stratified epithelium of trachea and major bronchi are mucous cells that produce mucin

function of cilia in the respiratory airway

creates mucous elevator, move mucous up and away from alveoli to prevent blockage of gas exchange, moves to mouth and we swallow it

upper respiratory system

nose, nasal cavity, sinuses, and pharynx

nasal cavity

highly vascularized because blood carries heat and this is where we begin to warm up the air, lots of hairs to trap debris

nasal conchae

bony ridges, increase SA to trap bacteria, also direct flow to nasal epithelium where the olfactory receptors are

3 parts of pharynx (throat) (from highest to lowest)

1. nasopharynx

2. oropharynx

3. laryngopharynx

separation of upper and lower respiratory system

anything below pharynx = lower respiratory

glottis

opening for air into the larynx

3 cartilages that protect glottis

1. thyroid cartilage

2. cricoid cartilage

3. epiglottis

swallowing

muscles elevate larynx → glottis closes and epiglottis folds over the glottis → food and mucous slides over into esophagous

sound production

air passing through glottis vibrates vocal cords → can manipulate voice by changing orientation of vocal cords. you control tension

what are vocal cords physically attached to

thyroid cartilage

lower respiratory system

trachea, bronchi, bronchioles, alveoli

trachea

windpipe, ringed structure, C-shape cartilage rings on front and soft on back

primary bronchi

right and left branches - out the lungs

secondary bronchi

right → 3

left → 2

one to each lobe

tertiary bronchi

branch into bronchioles

bronchioles

lack cartilage, contain smooth muscle

bronchi vs bronchioles

bronchioles don’t have cartilage and bronchi have cartilage

terminal bronchiole

where it ends

lobule

the alveoli coming off a single terminal bronchiole, open space surrounded by collection of alveoli

terminal vs respiratory bronchiole

terminal = has no alveoli lobule

respiratory = HAS alveoli lobule

alveolar ducts

connect respiratory bronchioles to clusters of alveoli

cartilage in conducting zone

• found from trachea to the tertiary bronchi

• arrangement and amount of cartilage changes

  • trachea - C-shaped rings

  • bronchi = reduced to plate like structure

• bronchioles = no cartilaginous support

smooth muscle

• lines all wind pipes

• found from trachea to terminal bronchiole

  • because of cartilage not a lot of constriction possible

  • bronchiole all lined by smooth muscle, can move air, big changes in air flow

• contraction and relaxation results in changes of airway diameter

• innervated by PNS and SNS and responsive to epinephrine

SNS effect on conduction zone bronchioles

bronchodilation

PNS effect on conduction zone bronchioles

bronchoconstriction

alveolus

each individual ball in making up alveoli, each alveolus surrounded by elastin

purpose of elastin

allows for stretch and recoil of alveolus

what surrounds individual alveoli and how does the gas exchange work

elastin and capillary beds

• gas exchange between air space and plasma

gas are exchanged between alveoli and capillaries

• oxygen in alveoli diffuses into pulmonary capillaries

• CO2 from capillaries diffuses into alveoli

cell types of alveoli

1. Type 1 pneumocytes

2. Type 2 pneumocytes

3. macrophages

Type 1 pneumocytes

gas exchange, responsible for forming respiratory membrane

surfactant

lipid oily residue that lines alveolar sacs to reduce surface tension → breaks up any water residue so alveoli don’t stick together

Type 2 pneumocytes

produce and secrete surfactant; oily mixture containing proteins and phospholipids

macrophages/dust cells

• resident phagocytic cells are present in interstitial fluids near alveoli
  

• resident = already there (not coming from blood)

• phagocytic = they eat things (phagocytosis)

• interstitial fluid = fluid around cells

• alveoli = air sacs where gas exchange happens

compliance

ability for lungs to stretch and fill with air, not enough elastin = decreased compliance

factors that influence compliance

• amount and distribution of connective tissues in the lungs

• mobility of thoracic cage

• amount of surfactant production

if lung volume increases, pressure inside lungs _____

decreases, expanding thoracic cage

if lung volume decreases, pressure inside lungs _____

increases, depress thoracic cage

atmospheric pressure

pressure of atmosphere around us, constant in any moment, set this to 0 and make the other pressures relative to this, equal to 760 mmHg

visceral pleura

attached to lungs

delicate inner serous membrane layer that directly covers the lungs, extending into the interlobar fissures

parietal membrane

attached to diaphragm

pleural cavitiy

space between visceral pleura and parietal membrane

intrapleural pressure

we manipulate this, pressure inside pleural cavity, directly impact this which changes transpulmonary pressure which then changes intra-alveolar pressure

intraalveolar pressure

pressure inside alveoli themselves, don’t directly control what happens in this

transpulmonary pressure

difference in pressure inside alveoli versus intrapleural pressure

breathing in

pressure of alveoli less than atmospheric pressure

breathing out

pressure of alveoli greater than atmospheric pressure

absolute and relative pressure

absolute:

• Patm = 760 mmHg

• Pip = 756 mmHg

relative:

• Patm = 0 mmHg

• Pip = -4 mmHg

air moves from region of ___ pressure to ___ pressure

high; low