Chapter 20: Tissues & Organ Systems
The Importance of Homeostasis The maintenance of a relatively constant internal environment, i.e., homeostasis, is essential for life.
Cellular conditions that need to be maintained within a narrow range include:
Temperature pH concentrations of: minerals, nutrients, wastes
Negative Feedback Homeostasis is largely maintained by what is known as Negative Feedback:
• counteracting a change in body state to restore the original state e.g. • sweating to cool an overheated body • releasing insulin to lower blood sugar • accelerated breathing, pulse to increase oxygen
**various sensory systems in the body detect changes and trigger negative feedback responses**
1 Organization of the Animal Body
Cells Tissues Organs Organ Systems
The 4 Basic Tissue Types
All tissues in the animal body fall into one of 4 basic tissue types:
Epithelial Tissue
Connective Tissue
Muscle Tissue
Nerve Tissue
Epithelial Tissue Sheets of cells that line body surfaces, cavities: skin; digestive, urinary, reproductive tracts; vessels; glands
Epithelial cells come in 3 basic shapes… • squamos (flattened) • cuboidal (cube-shaped) • columnar (elongated) …and in single or multiple layers: simple or stratified epith.
2 Examples of Epithelial Tissue
simple squamous epithelium (lung) stratified squamous epithelium (lining the esophagus)
simple cuboidal dead cells epithelium (kidney) rapidly dividing cells Colorized SEM
stratified squamous epithelium simple columnar epithelium (intestine) (human skin)
Connective Tissue
Tissue that supports, binds, “fills” or provides structure. • contains few cells, mostly extracellular matrix (ECM)
Connective Tissue (CT) comes in 3 basic types: Loose CT – underlies epithelium, loosely woven fibers, “gel-like”
Fibrous or Dense CT – densely packed fibers as in tendons & ligaments
Specialized CT – bone, cartilage, blood & lymph, adipose (fat) tissue
Examples of Connective Tissue
Fat droplets
Cartilage- forming cells
adipose tissue Matrix
Cell nucleus cartilage (end of a bone)
Collagen fibers
Central fibrous connective canal White blood tissue (tendon) cells Matrix Bone- Red blood forming cell cells
Plasma bone loose connective tissue (under the skin) blood
3 Muscle Tissue Made of cells that contract, comes in 3 types: Skeletal Muscle (striated, voluntary – moves skeleton) Cardiac Muscle (striated, involuntary – heartbeat) Smooth Muscle (unstriated, involuntary – visceral org., vessels)
Muscle Unit of fiber muscle Junction between contraction Muscle two cells fiber Nucleus
Nucleus
Muscle fiber Nucleus cardiac muscle
skeletal muscle
smooth muscle
Nerve Tissue Tissue that transmits electrical signals.
neuron Contains 2 basic cell types: Neurons – cells that generate, transmit electrical signals Glial cells (glia)– metabolic support, insulation for neurons
Organs and Organ Systems Organs = multiple tissues that comprise a physically & functionally distinct structure
Organ systems = multiple organs that work together to perform a common function
• each tissue and organ has a distinct role
e.g. – Integumentary System (skin, nails, etc)
• skin, nails, hair each have different roles
• each contains multiple tissues (epithelium, connective tissue, muscle, nerve) with diff. roles
4 Organs are made of all Tissue Types
Lumen Small intestine (cut open)
Lumen epithelial tissue (columnar epithelium)
connective tissue
smooth muscle tissue (2 layers)
connective tissue epithelial tissue
10 Major Organ Systems (11 if you count the Integumentary System)
The Circulatory System (blood & vessels, heart) • nutrient & waste transport • temperature control • pH balance • movement of cells, hormones Lymphatic/Immune System (lymph & vessels, lymphocytes) • fluid balance, transport • fat transport • immune responses
Organ Systems cont’d…
The Endocrine System (endocrine glands) • hormone production • physiological control
The Nervous System (brain, spinal cord, nerves) • internal, external sensation • behavioral control • physiological control
5 The Digestive System (esophagus, stomach, liver, intestines, pancreas) • food breakdown, absorption • waste disposal
The Urinary System (kidneys, bladder) • blood-borne waste disposal • salt & water homeostasis
The Respiratory System (pharynx, trachea, lungs) • gas exchange • pH balance
The Muscular System (all 3 muscle types) • movement of skeleton • movement in hollow organs • heartbeat The Skeletal System (bones, cartilage, tendons…) • structural support • blood production • calcium, phosph. storage The Reproductive System (ovaries, uterus, testes…) • gamete, production • hormone production • nurturing offspring
Key Terms for Chapter 20
• homeostasis • epithelium – squamous, cuboidal, columnar simple & stratified • connective tissue – loose, fibrous, specialized • skeletal, smooth & cardiac muscle • neurons & glial cells
Relevant Review Questions: 2-14
6 Chapters 21-23, 25: Organ Systems of the Body
1. Circulatory System 2. Respiratory System 3. Digestive System 4. Urinary System
1. The Circulatory System
Organs of the Circulatory System Heart pumps the blood
Blood vessels veins, arteries, capillaries Blood red & white blood cells, blood plasma
(we’ll also look at lymph and lymphatic vessels) Roles of the Circulatory System
• deliver O2, remove CO2 • transport nutrients, wastes, hormones • regulate temperature & pH • immune protection (antibodies, white blood cells)
7 Vertebrate Circulation Fish have a 2 chambered heart Reptiles & amphibians have a 3 chambered heart
Mammals & birds have a heart with 4 chambers
left right atrium atrium The Human Heart
semilunar semilunar valve valve
atrioventricular (AV) valve atrioventricular (AV) valve
right left ventricle ventricle
The Cardiac Cycle 1 2 3
oxygenated vs deoxygenated 1. Atria contract, forcing blood from right atrium & left atrium into ventricles systole 2. Ventricles contract, forcing blood into aorta (fr. LV) and pulmonary artery (fr. RV)
3. Atria & ventricles relax (diastole), cycle repeats…
8 superior capillaries of vena cava 8 head, chest, and arms
pulmonary artery pulmonary artery 9 aorta capillaries of left lung capillaries 2 7 of right lung 2
3 3
4 5 10 pulmonary 4 vein pulmonary 6 1 vein right atrium 9 left atrium left ventricle right ventricle aorta
inferior vena cava capillaries of 8 abdominal region Blood Circulation and legs
Control of the Heartbeat The synchronous contraction of cardiac muscle cells is controlled by the sinoatrial (SA) & atrioventricular (AV) nodes. • ea beat starts at the SA node, stimulates AV node (delayed)
Specialized Pacemaker muscle fibers (SA node) AV node
Right ventricle 1 23Apex 4
ECG
Oxygen Transport Oxygen is transported by red blood cells (RBCs) • aka erythrocytes • don’t have a nucleus! • vast majority of blood cells (~99%) are RBCs
Oxygen binds to hemoglobin in RBCs
• each hemoglobin
molecule binds 8 O2 • vast majority of protein in RBCs is hemoglobin
9 Other Blood Cells Blood also contains: Platelets • essential for blood clotting • “pinch off” from cells in bone marrow called megakaryocytes
White Blood Cells • collective term for all cells of immune system • B cells, T cells, monocytes, neutrophils…
Blood Vasculature Arteries, arterioles: • conduct blood flow away from the heart • usually oxygenated blood
Veins, venules: • conduct blood flow toward the heart • usu. deoxygenated blood Capillaries: • smallest vessels • where “exchange” occurs
Capillaries Unlike larger vessels, capillary walls are only 1 cell thick, barely wide enough for RBCs to pass through • allows diffusion of gases, nutrients, wastes between blood & tissues • some fluid (plasma) “leaks out” as well
10 The Lymphatic System A vascular system distinct from the circulatory system • conducts fluid “leaked” from the blood called lymph • returned to blood at vena cava
• lymph is filtered through structures called lymph nodes • full of immune cells, important part of the immune response • also transports fats from digestion in small intestine
Lymphatic Vessels
Fluid leaked from capillaries is taken up by “lymph capillaries”
• lymph is conducted into larger lymphatic vessels
• lymph passes through lymph nodes before being “dumped” into the blood at the vena cava
2. The Respiratory System
11 The Respiratory System
Respiratory System function :
• facilitate O2 uptake, waste CO2 removal
Respiratory System Organs Nasal Cavity warms & moistens air
Pharynx passage for air, food/water Larynx vocal chords; where air, food separate
Epiglottis blocks airway when swallowing
Trachea connects airway to lungs
Lungs site of gas exchange
Diaphragm muscle used for “inhaling”
Inhalation & Exhalation
Rib cage expands as Rib cage gets rib muscles air smaller as air contract inhaled rib muscles exhaled relax
lung
diaphragm
Diaphragm contracts Diaphragm relaxes (moves down) (moves up) Inhalation Exhalation
12 The Lungs The bronchi of the lungs branch into smaller and smaller bronchioles which terminate in alveoli.
• alveoli are the sites of gas exchange
• arrangement maximizes the surface area for gas exchange
Gas Exchange in the Alveoli
O2 and CO2 simply diffuse from higher to lower concentration across the capillary, alveolar epithelia
• O2 is more concentrated in the lungs than in the blood
• CO2 is more concentrated in the blood than in the lungs
*situation reversed in body tissues*
Summary of Gas Exchange
Deoxygenated blood from tissues returns to the right atrium & lungs ventricle of the heart which pumps it to the lungs.
In the alveoli of the lungs blood is oxygenated and flows back to the left atrium & ventricle of the heart, from which it is pumped back to the body.
tissues
13 3. The Digestive System
Digestive System Functions 1) Digest food and absorb nutrients • mechanical breakdown • physical breakdown of food into smaller particles • chemical digestion • breakdown of large molecules (polymers) into smaller ones (monomers) • absorption • transfer of digested material into blood & lymph 2) Waste removal • undigested material & waste from liver
Organs of the Digestive System Digestive Tract • mouth • pharynx • esophagus • stomach • small intestine • large intestine
Accessory Organs • liver • gall bladder • pancreas
14 Early Digestion Mouth & Pharynx • chewing (mastication) of food, Muscles contract mixing with saliva Muscles contract, • swallowing of food bolusconstricting Muscles relax Bolus of passageway food and pushing • starch digestion via amylasebolus down
Muscles relax, allowing Muscles contract Esophaguspassageway • muscularto open tube conducting food bolus from pharynx to stomach Muscles relax StomachStomach • mechanically “churns” food • adds pepsin (digests protein) and HCl (kills microbes, activates pepsin)
Completion of Digestion Small Intestine • 3 sections: duodenum > jejunum > ileum • digestion is completed in the duodenum • absorption of nutrients Pancreas • secretes “pancreatic juice” (enzymes, bicarbonate) to complete digestion Liver & Gall Bladder • bile from liver added to duodenum via gall bladder • bile helps emulsify fats for better digestion
Nutrient Absorption Nutrients are absorbed throughout small intestine. • nutrients are transferred to the blood or the lymph (fats)
Vein Lumen of Intestine nutrient nutrient with blood absorption absorption into en route to the liver epithelial cells microvilli
epithelial amino fatty cells acids and acids and sugars glycerol lumen muscle fats layers blood large capillaries circular folds blood lymph villi vessel nutrient lymph absorption Epithelial Cells
Villi
Intestinal Wall
15 Folds, Villi & Microvilli
Folds in the intestinal wall as well as villi & microvilli greatly increase surface area for nutrient absorption.
• villi are multicellular finger-like projections
• microvilli are projections on individual cells
Waste Removal Large Intestine: cecum > colon > rectum
• absorption of water, minerals, vitamins
Large • compaction, elimination intestine (colon) of waste (undigested material, fiber, bacteria)
Small • houses a variety of intestine Sphincter beneficial bacteria End Rectum of small (aka “probiotics”) intestine Anus
Nutrient flow ***bacteria need to be kept Appendix OUT of small intestine*** Cecum
4. The Urinary System
16 The Urinary System
Kidneys • removal of waste, excess in blood Ureters • conduct urine from kidneys to bladder Bladder • holds, expels urine Urethra • conducts urine from bladder “out”
The Kidney Organized into functional units called nephrons
Nephron Structure
glomerulus
17 Filtration in the Kidney 1. Dissolved substances leave the blood in the glomerulus, enter glomerular capsule > tubule
2. Needed H20, salt, nutrients reabsorbed from tubule
*maintains pH, salt & water tubule 3 homeostasis*
1 2 4 glomerulus
3. Additional wastes added to urine 4. H2O reclaimed
Water & Salt Homeostasis Antidiuretic Hormone (ADH) regulates water resorption in the kidneys: • released by the pituitary gland • “sensors” in brain and heart regulate ADH release • increases permeability of kidney tubules, greater water resorption
Aldosterone released from the adrenal cortex regulates “salt” levels: • stimulates retention of sodium ions (Na+), excretion of potassium (K+) in kidneys
Key Terms for Chapters 21-23 & 25 • atrium, ventricle, aorta, vena cava • sinoatrial, atrioventricular nodes • hemoglobin, white blood cells, platelets • arteries, arterioles, veins, venules, capillaries • lymph, lymph nodes • pharynx, larynx, epiglottis, diaphragm, alveoli • villi, microvilli, • nephron, glomerulus, tubule Relevant Review Questions: Ch. 21: 1 Ch. 22: 1, 2, 5, 7 Ch. 23: 1, 2, 4, 5 Ch. 25: 2, 4
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