A & P (Ch. 32-40) Flashcards
What do the immune system and lymphatic system work together to do?
-protection from pathogens
What is the immune system made up of?
- lymphatic system
- specialized cells
- free floating molecules
Antigens
-identifying molecules recognized by the immune system
Self Antigens
-on the surface of cells that are unique to an individual (ex. antigens on an individual’s RBC’s)
Nonself Antigens
-on the surface of foreign cells (ex. pathogens, organ transplants)
Self Tolerance (self antigens)
-immune system attacks abnormal foreign cells, but leaves the body’s own cells alone
Immunocompetence (nonself antigens)
-immune system activates an effective response to a nonself antigen
Categories of Immunity
1) innate (non specific) immunity
2) adaptive (specific) immunity
*work together
Innate (non specific) Immunity
- always present
- general defense against ‘non self’ antigens
- quick, initial response
Adaptive (specific) Immunity
- develops through exposure to nonself antigens
- response in specific (unique to particular antigens)
- slower, developed response (especially if it is the body’s first exposure to the antigen)
Innate (nonspecific) Immunity Cells
- epithelial (skin, mucous)
- phagocytic cells: neutrophils, monocytes, macrophages, natural killer
Phagocytic Cells- Neutrophils
-most numerous
Phagocytic Cells- Monocytes
-large phagocytes (macrophages)
Phagocytic Cells- Macrophages
- kupffer’s cells (liver)
- dust cells (lungs)
Phagocytic Cells- Natural Killer (NK Cells)
-apoptosis (cell suicide)
Adaptive (specific) Immunity
-lymphocytes (b cells, t cells)
Substances that Contribute to Immunity
- cytokines
- complement
- antibodies
- interferon
Cytokines
-chemicals released from cells to trigger/regulate immune response
Examples of Cytokines
- interleukins (ILs)
- leukotrines
- interferons (IFNs)
Complement
- group of 20 inactive enzymes (plasma proteins)
- produce a domino effect (formation of a membrane attack complex)
- end result is lysis of foreign cell
MAC
-membrane attack complex
Antibodies
-plasma protein made of B cells to destroy or inactivate antigens
Interferon
- protein made by cells when they are invaded by a virus
- interferes with virus replication
Immune System 1st Line of Defense (innate/non specific)
- skin
- mucous
- tears, salvia
Immune System 2nd Line of Defense (innate/non specific)
- inflammation (heat, redness, pain, swelling, fever, etc.)
- phagocytes
Imune System 3rd Line of Defense (adaptive/specific)
- phagocytes (APCs)
- specific (customized) immune responses
- natural killer cells
- systemic response
- has memory
- B cells and T cells
What is a response to pathogens that causes tissue damage (heat, redness, pain, swelling, fever)?
-inflammatory response
What does inflammatory response trigger?
- release of immune factors from immune system cells
- attracts WBCs
- increased blood flow
- increased vascular permeability
What is this type of immunity?
“Protection against invaders due to the ability of the body to recognize, respond to, and remember specific harmful substances or bacteria.”
-adaptive/specific
Where do B cells and T cells originate from?
-hematopoietic cells in the red bone marrow
Once formed, where to B cells and T cells circulate to?
- lymph nodes
- spleen
How do B cells and T cells become activated?
-exposure to antigens/chemicals
How do activated B cells form 2 cloned populations of cells?
-mitosis
Plasma Cells
-secrete antibodies into blood to form an ‘army’ of protection against an antigen (up to 2000 antibody molecules/sec)
Memory Cells
-stored in lymph nodes as emergency cells
If exposure to the same antigen occurs, what do memory cells do?
- become plasma cells
- secrete antibodies
B cells
-do NOT directs attack antigens
B cells make antibodies that either…
- attack antigen
- direct other cells to attack antigens
What are B cells referred to as?
- antibody (mediated) immunity
- humoral immunity
Antibodies
- types of immunoglobulins
- protein compounds with specific combining sites
Types of Immunoglobins
- G, A, M, E, D
- lgG
- lgM
What forms a antigen-antibody complex?
-combining sites attach antibodies to specific antigens
Humoral/Antibody Mediated Immunity
-inactivation of antigens by B cells
lgG
-most abundant circulating lg (makes up 75% of all antibodies in the blood)
lgM
-immature B cells make it and insert in their plasma membrane (most predominant)
Antigen-Antibody Complexes May…
- neutralize toxins
- clump or agglutinate enemy cells
- promote phagocytosis
- complement fixation
Complement Fixation
- mechanism of action for antibodies
- cause cell lysis by permitting entry of sodium and water through holes (MACs) created in plasma membrane by complement molecules
Cytolysis
-cells burst due to an increase in internal osmotic pressure
Do T cells make antibodies?
No.
Which cells to T cells react to?
-cells that are already infected or have engulfed antigen
Which cells can only react to protein fragments on the surface of APC’s or infected cells?
-T cells
Can antibodies made by B plasma cells react to soluble antigens in blood plasma?
Yes.
Adaptive/Specific Immunity can also be referred to as…
- cell mediated immunity
- cellular immunity
How do T cells carry out cell to cell direct contact?
- kill APCs/infected cells by poison
- release chemicals that attract/activate macrophages to destroy APCs/infected cells by phagocytosis
T Cell Development
- similar to B
- T cell is activated by antigen
- forms 2 types of clones of original T cell
2 Types of Cloned Populations of the Original T Cell
1) effector
2) memory
Memory T Cells
- in red bone marrow until needed
- produce active T cells
Effector T Cells
-release cytokines and use contact to kill APCs/infected cells
Interleukins (ILs)
-cytokines involved in immunity
Lymphotoxins
-posions
Cytotoxic T Cells
-aka killer T cells
What do cytotoxic T cells release?
-lymphotoxins
What do helper T cells and suppressor T cells regulate?
-adaptive immunity
Helper T Cells
- secrete cytokines: stimulate B cells and cytotoxic T cells, phagocytes and leukocytes
- activate TH form clones TH cells and memory TH cells
Suppressor T Cells
- aka regulator cells (T-regs)
- suppress B cells into plasma cells
- regulate other T cells (reduce T cell reactions with self antigens)
Humoral Immunity
- action of antibodies
- activated by B cells (plasma and memory)
Cell Mediated Immunity
- action of cells
- activated T cells kill APCs directly
How do activated T cells kill APCs?
- releasing toxins
- releasing cytokines to attract and activate macrophages
Adaptive/specific immunity can be either…
- natural
- artificial/acquired
Natural Immunity
- exposure to pathogen is not deliberate
- can be active or passive
Artificial Immunity
- exposure to pathogen is deliberate
- can be active or passive
Natural Immunity (inherited or inborn immunity)
- inherited immunity to certain diseases at birth
- exposure to pathogen is not deliberate
- can be passive or active
Active (natural immunity)
-promotes immunity (production of antibodies)
Passive (natural immunity)
-mother passes immunity (antibodies) to fetus through placenta or breast milk
Immunization
- exposure to pathogen is deliberate
- artificial/acquired
Active (artificial/acquired immunity)
- vaccination stimulates antibody production leading to immunity
- longer lasting
Passive (artificial/acquired immunity)
- immune material (antibodies) developed in another individual is given to a non immune person via an injection
- shorter
Respiratory Organs
- nose
- pharynx
- larynx
- trachea
- bronchi
- lungs
- alveoli
Respiratory Functions
- air distribution
- gas exchange
- homeostasis
- filters, warms and humidifies air for breathing
- speech and sound
- olfaction
Upper Respiratory Tract
-outside of thorax
- nose
- pharynx
- larynx
What kind of cold would an upper respiratory tract infection cause?
-head cold
What kind of cold would a lower respiratory tract infection cause?
-chest cold
Lower Respiratory Tract
-within thorax
- trachea
- bronchial tree
- lungs
What is the frame of the nose?
-bone and cartilage covered by skin with sebaceous glands
What forms the frontal root of the nose?
-nasal bones (2) meet and are surrounded by the frontal bone
What is the nose surrounded by?
-maxilla
What is the the internal structure of the nose referred to as?
-nasal cavity
What separates the nasal cavity?
-palantine bones
Where is the nasal cavity?
-lies over roof of mouth
What does the cribiform plate separate?
-roof of nose from cranial cavity
Septum
-separates nassal cavity into Lt and Rt
Which part of the nose gets broken?
-nasal bone
Cleft Palate
- palantine bones don’t close/join
- nose and mouth are only partially separated
- difficulty swallowing
How is each nasal cavity divided?
- superior
- middle
- inferior meatus
Nostrils (external nares)
- external openings into nasal cavities
- entrance for air
Paranasal Sinuses
-frontal, maxillae, sphenoidal, ethmoidal and lacrimal sacs that drain into nose
Conchae
-fold like structures that increase surface area in nasal cavity
Respiratory Muscosa
- membrane that lines air distribution tubes
- covered with ‘mucus blanket’
- rich blood supply
How much muscus is produced each day?
125ml
What does air purification/filtration do?
-traps inspired irritants
Where is cilia found?
-on mucosal cells
What does cilia do?
-beat in one direction to propel mucous and trapped irritants toward the pharynx for expulsion
What can paralyses cilia?
-cigarette smoke
How many pair of paranasal sinuses are there?
-4 pairs
Where do paranasal sinuses open to?
-nasal cavity
what are paranasal sinuses lined with?
-respirator mucosa
Function of the Nose
- passageway for air to and from lungs
- filters, warms and mostens inhaled air as it flows over conchae
- aids speech
Where are olfactory receptors found?
-nasal mucosa
How long is the pharynx?
12.5 cm
Where is the pharynx located?
-base of skull
What is the pharynx made of?
-muscle
What are the 3 segments of the pharynx?
- nasopharynx
- oropharynx
- laryngopharynx
What is the common name of the pharynx?
-throat
What are pharyngeal tonsils referred to when they become enlarged?
-adenoids
Where are pharyngeal tonsils?
-nasopharynx
Where are palantine tonsils and lingual tonsils located?
-oropharynx
What do eustachian/auditory tubes connect?
-middle ears with nasopharynx (allowing equalization of air pressure between the middle and exterior ear)
What is lining of tubes continuous with?
- nasopharynx and middle ear
- this means a sinus infection can develop from an ear infection
What 2 functions does the pharynx have?
- digestive (passageway for food and liquids)
- respiratory (passageway for air)
Where is the larynx located?
-below the pharynx
What is the framework of the larynx?
-several pieces of cartilage
What is the lining of the larynx?
-ciliated mucous lining
Thyroid Cartilage
- largest
- adams apple
What does the epiglottis cover?
-opening of larynx
What does the epiglottis prevent?
-food from entering trachea
Vocal Cords
-2 fibrous bands that stretch across the interior of the larynx
Functions fo Larynx
- air distribution (passageway for air to move to and from lungs)
- voice production
How is a voice produced?
-muscles attached to larynx cartilage pull on the vocal cords
What sound happens when cords are tense?
-high pitched
What sound happens when cords are relaxed?
-high pitched
What is the trachea known as?
-windpipe
How long is the trachea?
11cm
Where does the trachea run from?
-larynx to primary bronchi
What holds the trachea open?
-C shaped rings of cartilage
What is the lining of the trachea?
- mucous
- ciliated epithelium
What is the main function of the trachea?
-passageway for air to move to and from lungs
What traps airborne irritants in the trachea?
-ciliated mucous lining
What does complete occlusion of the airway cause?
-death in minutes
Heimlich Maneuver
-lifesaving technique used in cases of tracheal obstruction
How many deaths happen per year in the US due to tracheal obstruction?
-over 4000
What does the trachea branch into?
-Lt and Rt bronchi (primary bronchi)
What do the bronchi lead into?
-lungs
What do the primary bronchi branch into in the lungs?
- smaller secondary bronchi which eventually lead to bronchioles
- 23 LEVELS OF BRANCHING***
What are the walls of bronchioles made of?
- smooth muscle
- no rings of cartilage
What do bronchioles divide into?
-microscopic tubes called alveolar ducts (look like a stem of grapes)
What do alveolar ducts end in?
-clusters of microscopic alveolar sacs
What are the walls of alveolar sacs made of?
-alveoli
How many alveoli are in each lung?
-millions
What are bronchi and bronchioles a passageway for?
-air to move to and from alveoli
Alveoli
-site of exchange of oxygen and carbon dioxide between blood in lung capillaries and air in alveoli
What are the walls of alveoli?
- thin
- single layer of cells
what are alveoli in direct contact with?
-blood capillary
What is the thin membrane that lies between the blood in capillaries and the air in each alveolus?
-alveoli
What is alveoli covered with?
-surfacatant (reduces tension to prevent collapse of alveoli as air moves in and out)
Where are the lungs located?
-chest cavity (except mediastinum) from diaphragm to above the clavicles
How many lobes does the Rt lung have?
3
How many lobes does the Lt lobe have?
2
Hilum of Lungs
-where primary bronchi and pulmonary blood vessels enter
Base of Lungs
- broad lower part of each lung
- rests on diaphragm
Apex of Lungs
- narrow upper part
- under collarbone
Costal Surface of Lungs
-lies against ribs
Pleura
-moist, smooth, slippery membrane that lines chest cavity and covers outer surface of lungs
Parietal Pleura
-lines walls of thoracic cavity
Visceral Pleura
-covers lungs
Intrapleural Space
-lies between parietal and visceral
Pleurisy
-inflammation of the pleura
Pneumothorax
-lung collapse
What causes pneumothorax (lung collapse)?
-presence of air in the intrapleural space on one side of the chest will increase the pressure on that side of the lung
Function of Lungs
-pulmonary ventilation (breathing)
Function of Pleura
-reduced friction between the lungs and chest wall during breathing
External Respiration
- pulmonary ventilation
- pulmonary gas exchange
Pulmonary Ventilation
-air moving in and out of the lungs (breathing)
Pulmonary Gas Exchange
-exchange of oxygen and carbon dioxide between the air in the lungs and the blood
Internal Respiration
-exchange of gases between the blood and the cells of the body/systemic tissue
Cellular Respiration
-use of oxygen by cells in the process of metabolism
Where does cellular respiration occur?
-mitochondria
Pulmonary Ventilation
-breathing
What are the 2 phases of air moving in and out of the lungs?
- inspiration
- expiration
Inspiration
-movement of air into lungs
Expiration
-movement of air out of lungs
What causes changes in air pressure within the thoracic cavity and the lungs?
-change in the size and shape of thorax (ex. diaphragm)
What do air pressure changes cause?
-air to move in and out of lungs
When does inspiration happen?
-when the pressure within the alveoli of the lungs is lower than atmospheric pressure
When does expiration happen?
-when pressure in the alveoli of the lungs is higher than atmospheric pressure
Respiration Muscles
- diaphragm
- internal intercostals
- external intercostals
Tidal Volume (TV)
-amount of air exhaled after normal inspiration
Expiratory Reserve Volume (ERV)
-amount of air that can be forcibly exhaled after a normal expiration
Inspiratory Reserve Volume (IRV)
-amount go air that can be forcibly inhaled after normal inspiration
Residual Volume (RV)
-air left in lungs after the most forceful expiration
Vital Capacity (VC) =
IRV + TV + ERV
-largest amount of air that can be breathed out in one respiration/pulmonary ventilation
What are pulmonary volumes and capacities measured with?
-a spirometer
What does regulation of ventilation permit?
-the body to adjust to varying demands for oxygen supply and carbon dioxide removal
What stimulates muscles of respiratory system with nervous impulses?
-respiratory control centres
Where are respiratory control centres located?
-medulla and pons
What are the most important respiratory control centres and where are they located?
- inspiratory centre
- expiratory centre
- in medulla
normal rate/resting =
12 to 18/min
What are the medulla’s respiratory control centre influences by?
- cerebral cortex
- voluntary, but limited
Ventilation Receptors
- chemoreceptors (involuntary)
- pulmonary stretch receptors
Where are ventilation chemoreceptors located and what do they respond to?
- in carotid and aortic bodies
- respond to changes in oxygen, carbon dioxide and pH blood levels
Where are pulmonary stretch receptors located?
-throughout the pulmonary airways
what do pulmonary stretch receptors prevent?
-lungs from overinflating
Eupnea
-normal breathing
Hyperventilation
-rapid and deep respirations
Hypoventilation
-slow and shallow respiration
Dyspnea
-difficult respiration
Apnea
-stopped respirations
Respiratory Arrest
-failure to resume breathing after a period of apnea
Pulmonary Gas Exchange
- exchange of gases in the lungs
- takes place between the alveolar air and blood flowing throat lung capillaries
What affects the amount of oxygen that diffuses into the blood?
1) oxygen pressure gradient between alveolar air and blood
2) total functional surface area of the respiratory membrane
3) respiratory minute volume (ml of air moved/min)
4) alveolar ventilation (volume of blood inspired air that reaches the alveoli) and alveolar function
How does pulmonary gas exchange occur?
-passive diffusion due to the pressure gradient of oxygen and carbon dioxide between blood and lung capillaries surrounding alveoli
Which was does oxygen move alone a pressure gradient?
-area of high concentration to area of low concentration
Which way does carbon dioxide move along a pressure gradient?
-in the opposite direction of the pressure gradient
When oxygen leaves alveoli, where does it go to?
-lung capillaries
Oxyhemoglobin
-hemoglobin combined with oxygen
What does carbaminohemoglobin break down into?
-carbon dioxide and hemoglobin
What does the exchange of gases in tissue occur from?
-pressure gradient between the tissue capillaries and the tissue cells
Internal Respiration
-exchange of gases between blood in tissue capillaries and body cells
What does oxyhemoglobin break down into?
- oxygen
- hemoglobin
What state are oxygen and carbon dioxide transported to blood in?
-dissolved or combined with other chemicals
Why do dissolved oxygen and carbon dioxide rapidly form a chemical union with some other molecule (ex. hemoglobin)?
-because fluids (ex. blood) can only hold small amounts of gas in solution
What happens when oxygen and carbon dioxide are bound to another molecule?
-concentration decreases and more gas can diffuse into the plasma allowing concentration decreases and more gas can diffuse into the plasma allowing comparatively lg volumes of these gases to be transported
What is the majority of oxygen transported by blood in the form of?
- oxyhemoglobin
- only 1.5% is dissolved as oxygen
Hemoglobin Molecules
-lg proteins containing 4 iron containing heme components, each capable of combining with an oxygen molecule
2 Forms of Oxygen in the Blood
1) dissolved oxygen
2) oxyhemoglobin (majority)
Deoxygenated blood is ___% saturated with oxygen and is found in _______ veins and _______ arteries?
- 75%
- systemic
- pulmonary
What is carbon dioxide a by product of?
-cellular metabolism
What does carbon dioxide contribute to?
-pH
Why and how is excess carbon dioxide released?
- excess can be toxic
- enters alveoli and is expelled during expiration
In order to expel carbon dioxide via expiration, it must be transported in the blood to the lungs as either…
- dissolved carbon dioxide
- carbaminohemoglobin
- bicarbonate ions
Dissolved Carbon Dioxide
-10% of total carbon dioxide transported in blood
Carbaminohemoglobin
carbon dioxide + hemoglobin + plasma proteins
- 20% of total carbon dioxide transported in blood
- formation is accelerated by an increase in PCO2 and slowed down by a decrease in PCO2
Bicarbonate Ions
-70% of total carbon dioxide transported in blood
Structure of Digestive System
- irregular tube
- open at both ends
- aka alimentary canal or GI tract
Functions of Digestive System
- digestion
- absorption
- metabolism
What are the walls of GI Tract from deep to superficial?
- mucosa
- submucosa
- muscularis
- serosa
Mucosa Wall of GI Tract
- mucus lined
- secretion of digestive enzymes and hormones
- absorption of end products of digestion
- protection against pathogens
Submucosa Wall of GI Tract
- CT
- glands, blood vessels, lymphatic vessels and parasympathetic nerves
- elastic fibres, especially in stomach (allow tubes to stretch and recoil)
Muscular Wall of GI Tract
- mixes/churns food
- peristalsis
2 or 3 Layers:
- inner circular (lots of sphincters)
- outer longitudinal
- oblique
Serosa Wall of Digestive Tract
- protective, outer layer
- visceral and parietal peritoneum in abd cavity
Mouth (oral/buccal cavity)
- where digestion begins
- hollow chamber
- 3 parts: roof, floor, walls
Roof of Mouth
Hard Palate
- 2 maxillary bones
- 2 palatine bones
Soft Palate
- arch shapes muscle
- separates mouth from nasopharynx
Uvula
-projection of soft palate
What part of the roof of the mouth prevents food and liquids from entering the nasal cavity?
-uvula and soft palate
Floor of the Mouth
- tongue (skeletal muscle)
- tip, body and root
What anchors the tongue to the floor of the mouth?
-frenulum
Papilla of Tongue
- small nipple like projections on tongue
- where taste buds are
Tongue Tied (ankyloglossia)
- frenulum is short and thick
- can be mild (bands)
- can be complete (entire tongue is attached to floor of mouth)
- affects eating, swallowing, oral hygiene and speech
- may recede on it’s own or may need surgery
What forms the lateral walls of the mouth?
- cheeks (buccinator muscle)
- contains mucous secreting glands
What forms the anterior wall of the mouth?
- lips
- skin on outside and mucous membrane on inside (junction is sensitive)
Oral Fissure
-line of contact between closed lips
Function of Salivary Glands
-secrete 1 L of saliva (salivary amylase and mucous) everyday
3 Salivary Glands
1) parotid
2) submandibular
3) sublingual
Parotid Glands
- largest
- bottom of ear, at jaw angle
- ducts secrete into mouth cavity
- produce watery saliva (containing enzymes)
Submandibular Glands
- below mandible
- ducts secrete on either side of lingual frenulum
- contain enzyme and mucous producing substances
Sublingual Glands
- below tongue
- anterior to submandibular glands
- ducts secrete into floor of mouth
- produce a mucous type of saliva
Section of a Tooth
- crown
- neck
- root
Crown of Tooth
- visible part
- covered with enamel
Enamel
hardest tissue in body
-perfect for withstanding the abrasion of chewing food
What does the pulp cavity in the centre of the tooth contain?
- CT
- blood
- lymphatic tissue
- sensory nerves
Neck of Tooth
- joins crown to root
- surrounded by pink/gingival tissue (aka gums)
Root of Tooth
- fits in socket/jaw bone
- socket lined with periodontal membrane (anchors tooth to bone)
How many deciduous teeth (baby teeth) are there?
20
When do we get our first deciduous (baby) teeth?
- 6 months
- 8 incisors first
When do we get our complete set of deciduous (baby) teeth?
- 2 years
- no premolars (2 pairs of molars per jaw)
When do we lose our deciduous (baby) teeth?
6 to 13 years old
How many permanent teeth are there?
32
At what age do we get our permanent teeth?
6 years
When do we get our complete set of 32 permanent teeth?
-between 17 and 24 years age
Pharynx
-tube like structure
made of muscle
-lined with mucous membrane
-3 divisions
Function of Pharynx
- digestion
- respiration
What passes through the pharynx?
- air to lungs
- food to stomach
Esophagus
- muscular
- mucous lined
- connects pharynx to stomach
- sphincters at both ends
- mucous secretions help pass food
- collapses when not moving food
Stomach
- in upper abd cavity (under diaphragm and liver)
- temporary storage for chewed food
Where does chemical digestion of protein begin?
-stomach
How big is the stomach?
- size of a lg sausage when empty
- expands after a lg meal
- 1 to 1.5 L capacity
Divisons of the Stomach
- cardia
- fundus
- body
- pylorus
Cardia (stomach)
-collar like region at junction with esophagus
Fundus (stomach)
-enlarged portion to the Lt and above the opening of the esophagus into the stomach
Body (stomach)
-central portion
Pylorus (stomach)
-lower part
Cardiac Sphincter (LES- lower esophageal sphincter)
- ring of muscle at end of esophagus
- prevents stomach contents from refluxing back into esophagus
Hiatal Hernia
- due to weakening of esophageal hiatus
- end of esophagus bulges
- stomach bugles upward
- leads to GERD
Pyloric Sphincter
-controls emptying of stomach into duodenum
4 Parts of Stomach Wall
1) gastric mucosa
2) gastric submucosa
3) gastric muscularis
4) gastric serosa
Gastric Mucosa (stomach wall)
- epithelial lines
- rugae
- gastric glands below gastric pits (secrete gastric juice)
What is gastric juice made of?
- chief cells: secrete enzymes
- parietal cells: secrete HCl, intrinsic factor, B12
- endocrine cells: secrete hormones (gastrin and ghrelin)
Gastrin Muscularis (stomach wall)
- thick muscle layer
- 3 different directions (oblique, circular, longitudinal) that allow the stomach to churn
Function of Stomach
- holds food until is can be moves along GI tract
- secrets gastric juice (aids in digestion)
- breaks food into small particles and mixes wit gastric juice
- secretes intrinsic factor
- absorption
- produces gastrin and ghrelin
- protects body from swallowed bacteria
What is the man digestive organ?
-sm intestine
Where does the sm intestine run from, and how big is it?
- pyloric sphincter to ileocecal valve
- 6 to 8 m lone
- 2.5 cm wide
What are the 3 divisions of the sm intestine?
- duodenum
- jejunum
- ileum
Peristalsis
-smooth muscle fibres in wall of sm intestine
Lining of Sm Intestine
- mucus membrane
- secretion and nutrient absorption
Plicae
- circular folds in sm intestine
- covered with villi
Villi
- blood capillaries and lymph lacteals for nutrient absorption
- covered by microvilli
What cells are on microvilli? (lining of sm intestine)
- mucous secreting cells
- enteroendocrine cells
- tuft cells
What increases the surface area of the sm intestine hundreds of times?
- villi
- microvilli
Where are intestinal crypts located?
-valley’s between villi
What is the last part of the GI tract?
-lg intestine
How big is the lg intestine?
- 1.5 to 1.8 m long
- 6 cm wide
Lg Intestine
- smooth muscle
- mucous membrane: absorption of water, salts and vitamins
- no villi: less surface area (less absorption than sm intestine)
Divisons of Lg Intestine
- cecum
- colon
- rectum
- anus
Cecum
- pouch like
- 1st section of lg intestine
- at iliocecal valve
Colon
- ascending
- transverse
- descending
- sigmoid
Rectum
- last 17 to 20 cm
- holding tank before exit
Anus
- opening to exterior
- inner anal sphincter (involuntary)
- outer anal sphincter (voluntary)
Vermiform
-worm shaped
Vermiform Appendix
- blind tube off cecum
- lymphatic tissue
- reservoir/bredding ground for beneficial gut bacteria
Peritoneum
- lg
- sseroud membrane
- lines abd cavity
- covers abd organs
Mesentery
- fan like extensions of parietal peritoneum
- attaches most of sm intestines to lumbar area of posterior abd wall
- keeps sm intestine in place
- fans out from 15/20 cm from to 6 m
Greater Omentum
- apron
- pouch like extensions of visceral peritoneum (greater curvature to 1st part of duodenum)
- hangs down from lower edge of stomach and transverse colon over intestines
Lesser Omentum
-from liver to lesser curvature of stomach/1st part of duodenum
What is the largest gland in the body?
-liver
What separates Lt and Rt lobes of the liver?
-falciform ligament
What are the anatomical units of the liver?
- hepatic lobules
- each has a hepatic vein through it
Hepatocytes
- liver cells
- around each central vein (aka interloper vein)
Portal Triad
Consists of:
- interlobular artery
- interlobular portal vein
- interlobular bile duct
-on the outside corner of each lobule
What forms the Rt and Lt hepatic ducts?
-small bile ducts
What do the Rt and Lt hepatic ducts form?
-1 hepatic duct
What forms the CBD, and where does it open into?
- hepatic duct and cystic duct
- into duodenum
Liver Functions
- detoxification
- bile secretion
- metabolism (proteins, fats, carbohydrates)
- storage (iron, vitamins)
- production (plasma proteins)
What are bile salts formed from?
-cholesterol in liver
How much bile does the lover secrete per day?
1 pint
What is the GB shape and size?
- pear shaped
- 7 to 10 cm long
- 3 cm wide
What are the layers of the GB wall?
- serous
- muscular
- mucous
What allows the Gb to expand?
- rugae in mucous lining
- allows GB to store 30 to 50 ml of bile
Function of GB
- stores bile
- concentrates bile (5 to 10x)
- moves concentrated bile to duodenum
What happens in bile is too concentrated?
-gallstones
When does jaundice occur? (in regards to the GB)
- when bile flow to duodenum is blocked
- bile is absorbed into blood instead of being eliminated via feces
- excess bile pigments get deposited in body tissues
Where does the main pancreatic duct empty into?
-duodenum
Where is the pancreas located?
- being stomach
- from duodenum to spleen
- in the C of duodenum
How long is the pancreas?
12 to 15 cm long
Exocrine Portion of Pancreas
- majority
- compound acing arrangement (cluster of cells)
- tiny ducts unite to form main pancreatic duct (empties into duodenum)
Endocrine Portion of Pancreas
- embedded between exocrine
- called pancreatic islets
- 2% of pancreatic mass
- made of alpha and beta cells
- pass secretions to capillaries
Functions of Pancreas
- acinar units secrete digestive enzymes: lipase, protase, amylase
- beta cells secrete insuin
- alpha cells secrete glucagon
Primary Function of Digestive System
-bring nutrients to body
Ingestion
-food is taken into body through the mouth
Digestion
-complex nutrients are broken down into simple nutrients
Motility of the GI Wall
-mechanical breakdown ad movement of food through GI tract
Secretion
-digestive enzymes to chemical digestion
Absorption
-movement of nutrients from Gi mucosa to internal environment
Elimination
-excretion of unabsorbed material
Regulation
-coordination of all digestive system functions
Mechanical Digestion
-physically breaks chunks of food into smaller pieces
Chemical Digestion
-breaks molecules apart and chemically changes the food
What does mechanical digestion involve?
- mastication (chewing)
- deglutition (swallowing)
- peristalsis and segmentation
- regulation of motility
- intestinal motility
Mastication (chewing)
-reduces size of food particles and mixed food with saliva to prepare for deglutition
Deglutition (swallowing)
-complex process involving several stages: oral, pharyngeal, esophageal
Oral Stage of Deglutition
- mouth to oropharynx
- voluntary
- food bolus is formed, pushed against palate by tongue, then moved back into the oropharynx
Pharyngeal Stage of Deglutition
- oropharynx to esophagus
- involuntary
- requires blockage of mouth, nasopharynx and larynx
- accomplished by contractions and gravity
Esophageal Stage of Deglutition
- esophagus ot stomach
- involuntary
- accomplished by contractions and gravity
What are the 2 main types of motility produced by smooth muscle of the GI tract?
- peristalsis
- segmentation
Gastric Peristalsis
- wave like ripple of muscle layer or a hollow organ
- moves matter forward in GI tract
- triggered by presence of food
Gastric Segmentation
- forward and backward mixing movement within a single segment of the GI tract
- mixes food with digestive juices and brings in contact with intestinal mucosa where absorption takes place
How is chyme formed?
- food in stomach is churned and mixed (via peristaltic contractions called propulsion and retropropulsion) with gastric juices
- exits stomach every 20 sec
How long does the stomach take to empty after eating a meal, and what is it controlled by?
- 2 to 6 hours
- hormonal or nervous mechanisms
Hormonal Mechanisms of Gastric Motility
-presence of fat in the duodenum stimulates a hormone that slows down the passage of chyme into the duodenum
Nervous Mechanisms of Gastric Motility
- presence of acid and distention picked up by receptors in duodenal mucosa
- impulses travel through vagus nerve
- inhibits gastric peristalsis
What does intestinal motility include?
- peristalsis
- segmentation
Intestinal Segmentation
- occurs in duodenum and 1st part of jejunum
- mixes chyme with digestive juices from pancreas, liver and intestinal mucose
Intestinal Peristalsis
-moves chyme through the rest of the sm and lg intestine
How many hours does it take for chyme to travel through the sm intestine?
5 hrs
What is intestinal peristalsis regulated by?
- stretch reflexes
- CCK (cholecystokinin)
Digestion
-all changes in chemical composition of food as it travels through the digestive tract
Hydrolysis
- chemical changes in digestion
- digestive enzymes are involved
Where do digestive enzymes function?
- lumen of digestive tract
- extracellular enzymes
Hydrolases
-digestive enzymes breaking down food molecules using water
Digestive Enzymes
- lock and key action
- require specific pH and temp
- continually synthesize since they are continually destroyed/eliminated
Do digestive enzyme actions reverse?
No.
Are digestive enzymes synthesized?
- most are
- secreted as inactive proenzymes
How do polysaccharides form disaccharides?
-hydrolysed by amylases
Where does the final step of carbohydrate digestion happen?
- sm intestine
- disaccharide to monosaccharide
Maltase
maltose = glucose + glucose
Sucrase
sucrose = glucose + fructose
Lactase
lactose = glucose + galactose
fat =
glycerol + fatty acids
What must happen to fats before they can be digested?
-emulsified by bile
Bile
- contains no enzymes
- emulsifies fats
Pancreatic Lipase
-changes emulsified fats to fatty acids and glycerol in sm intestine
Digestive Secretion
- the release of various substances from exocrine glands that serve the digestive system
- ex. saliva, bile, pancreatic juice, gastric juice, intestinal juice
What is saliva secreted by?
-salivary glands
What is saliva made up of?
- mucus
- enzymes (amylase)
What is the min enzyme is saliva and when does it function best?
- amylase
- functions best in an alkaline pH
What is gastric juice secreted by?
-exocrine glands in stomach
Pepsin (gastric juice)
-protease that begins digestion of proteins
What does HCl do in gastric juice?
-decreases pH of chyme to a level that activates and optimizes pepsin activity
Why is the intrinsic factor required in gastric juice?
-for B12 vitamin absorption
What does mucous and water do in gastric juice?
- lubricates
- protects
- mixing of chyme
What makes up gastric juice?
- pepsin
- HCl
- intrinsic factor
- mucus and water
What does pancreatic juice secrete?
Enzymes
- protease
- lipase
- nuclease
- amylase
-sodium bicarbonate
What part of the pancreas is pancreatic juice secreted from?
-exocrine
What does sodium bicarbonate do in pancreatic juice?
- buffers stomach contents that enter duodenum
- increase pH for optimum enzyme function
- maintains pH
Bile
-lecithin and bile salts (emulsify fat in preparation for digestion by lipase)
What initiates the release of bile?
-presence of fat in chyme
What does the detection of fat in chyme stimulate?
-release of the hormone CCK (cholecystokinin) from duodenum
Where is intestinal juice secreted from?
-cells of intestinal exocrine glands
What is salivary secretion controlled by?
- reflex mechanism
- chemical and mechanical stimuli from presence of food in mouth
- olfactory and visual stimuli
3 Phases of Gastric Secretion
1) cephalic
2) gastric
3) intestinal
Cephalic Phase of Gastric Secretion
- sensations of thoughts of food are sent to the brainstem
- parasympathetic signals are sent to the gastric mucosa via vagus nerve
- gastric juice secretion is stimulates
- gastric secretion is stimulated
Gastric Phase of Gastric Secretion
- presence of food in stomach (distension)
- triggers reflexes that increase secretion of gastric juices and gastrin
Intestinal Phase of Gastric Secretion
- occurs as food moves into/through duodenum
- presense of fats, carbs, proteins and acid stimulates hormonal and nervous reflexes that inhibit stomach activity
What is pancreatic secretion stimulated by?
- hormones released in intestinal mucosa
- secretin: stimulates production of pancreatic fluid that is low in enzymes and high in bicarbonate
- CCK: stimulates contraction of GB
Bile Secretion
- continually secreted by liver
- stored in GB
What does CCK do?
-stimulates GB to squeeze out bile
How many days does it take for fecal matter to pass?
3 to 5 days
Constipation
- prolonged time in L.I. leads to more water being absorbed
- feces becomes more solid
Diarrhea
-fecal matter rushes through the L.I. before the water is absorbed
