Post on 05-May-2020
NERVES & HORMONES BIOLOGY
O2 Organisms selectively detect and respond to changes in the internal and external environments.
O2.1 Describe the importance of sensory receptors that detect changes in the external environment.
O2.2 Compare nervous and hormonal communication.
O2.3 Know the relationship between detection and a reflex response for one external stimulus.
O2.4 Explain how the stimulus response model works in the coordination and control of body temperature.
Overview
Receptors detect changes in the environment.
They are connected to sensory nerve cells that take the message to the brain.
Examples
Receptors
Receptors detect changes in the environment.
They are connected to sensory nerve cells that take the message to the brain.
Examples • Eyes: Sight and detecting changes in light • Ears: Sound • Tongue: Taste • Nose: Smell • Skin: Touch – many receptors for heat, pressure, touch
Receptors
Sensory Neurons
Receptors give information from the environment to sensory neurons. Sensory neurons then transmit messages to the brain.
Sight Receptors
Rods and cones
Optic nerve to the brain
Sound Receptors
Taste Receptors
Sensory neurons
Jayaram Chandrashekar, Mark A. Hoon, Nicholas J. P. Ryba & Charles S. Zuker Nature 444, 288-294(16 November 2006)
Smell Receptors
Skin Receptors
INTENDED STUDENT LEARNING
O2.1 Describe the importance of sensory receptors that detect changes in the external environment.
Once our body detect changes in the external environment, it needs to respond! There are two main ways our body can respond to stimulus.
Responding to Change
Hormonal Response
The Endocrine System consists of several glands that release hormones into the bloodstream.
HORMONAL RESPONSE: Endocrine System
The Endocrine System consists of several glands that release hormones into the bloodstream. The pituitary gland is known as the “master gland” – it stimulates other glands as well as releasing growth hormone and ADH (controls water level).
HORMONAL RESPONSE: Endocrine System
The Endocrine System consists of several glands that release hormones into the bloodstream. The pituitary gland is known as the “master gland” – it stimulates other glands as well as releasing growth hormone and ADH (controls water level). The adrenal gland releases adrenalin which prepares the body for danger (“fight or flight”) by speeding up heart rate, breathing and directing blood away from the digestive system.
HORMONAL RESPONSE: Endocrine System
HORMONAL RESPONSE: Hormone Action
Hormonal Response: INSULIN
Hormonal Response: ADRENALIN
Nervous Response
The Nervous System coordinates the movement of muscles and glands.
NERVOUS RESPONSE: Nervous System
The Nervous System coordinates the movement of muscles and glands. The brain has different areas which coordinate different activities including sleep, emotions and movement of different muscles. This includes reflex arcs.
NERVOUS RESPONSE: Nervous System
NERVOUS RESPONSE: Nerve Action
Nervous Response
Nervous System vs Hormonal Control
Communication Pathway Message Site of Action Speed of Action Duration of Effect
Nervous (electrical impulses)
Direct (via axons of neurons)
Electrical and
chemical Highly specific Fast Short term
Hormonal (chemical impulses)
Indirect (carried in bloodstream) Chemical Widespread
(targets organs) Slow Long term
NEED TO KNOW!
INTENDED STUDENT LEARNING
O2.2 Compare nervous and hormonal communication.
A receptor cell sends a message to a sensory neuron. The sensory neuron carries a message through the central nervous system to the spinal cord. Connector, or interneurons, transfer the message through the central nervous system to a motor neuron. A motor neuron carries the message along the spinal cord to an effector cell (muscle or gland).
Reflex Response
Reflex Response
Reflex Response
Reflex Response
Receptor cells
Sensory neurons
CNS (brain + spinal cord)
Motor neuron
Effector cells NEED TO KNOW!
Examples of stimuli:
Reflex Response
Examples of stimuli: – Touching a hot pan – Putting your hand down on a pin – Bright/low level light – Knee jerk “reflex” – Newborn “sucking” reflex – Newborn “grip” test
Reflex Response
Reflex Response
Reflex Response
INTENDED STUDENT LEARNING
O2.3 Know the relationship between detection and a reflex response for one external stimulus.
PAST EXAM QUESTION Have a go! How would you answer this question?
Main Receptor: Hypothalamus (brain)
Stimulus: Too hot Response: Sweating (ê thyroxine) Red face (vasodilation) Lethargic Stimulus: Too cold Response: Shiver (é thyroxine)
Pale (vasoconstriction) Active
EXAMPLE: Regulating Body Temperature
Vasoconstriction
Vasoconstriction: To save heat, less blood flows to the surface capillaries, so a person looks pale.
Vasodilation
Vasodilation: To lose heat, more blood flows to the surface capillaries, so a person looks red.
EXAMPLE: Regulating Body Temperature
NEED TO KNOW!
INTENDED STUDENT LEARNING
O2.4 Explain how the stimulus response model works in the coordination and control of body temperature.
PAST EXAM QUESTION Have a go! How would you answer this question?
Kahoot Quiz
Nerves vs Hormones
Homework
Independent content revision
ACTIVITY TIME NERVES AND HORMONES
KNEE JERK REFLEX
Hit your leg, just below your knee using the side of your hand Your leg must be relaxed
• Cross your legs • Sit with your legs hanging over the edge of a table
Activity #1
“EYE OPENER”
Cover one eye with your hand. Wait for a few minutes. Find a partner and remove your hand. Ask your partner to observe your eyes and look for differences in the pupils.
Activity #2
FLINCH REFLEX
Find a partner and scrunch up a sheet of paper into a ball. Walk outside the classroom and stand on the other side of the glass wall. Throw the paper ball at a partner and see if they flinch!
Activity #3
Kahoot Quiz
Nerves vs Hormones
EXCHANGE SURFACES AND CAPILLARIES
BIOLOGY
Kahoot Quiz
Nerves vs Hormones
REVISION
O3 The exchange of materials may take place at special structures or organs.
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
O3.3 Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
O3.4 Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Overview
Cells must exchange materials to survive.
Cells take in: 1. 2. 3. 4. 5.
Exchange Surfaces
Cells remove: 1. 2. 3.
Cells must exchange materials to survive.
Cells take in: 1. Oxygen 2. Glucose 3. Amino acids 4. Water 5. Mineral ions
Exchange Surfaces
Cells remove: 1. Carbon dioxide 2. Urea 3. Lactic acid
Exchange surfaces are made up of a single layer of epithelial cells, and these cells need to be efficient when passively exchanging materials.
Exchange Surfaces
Exchange surfaces are made up of a single layer of epithelial cells, and these cells need to be efficient when passively exchanging materials. Therefore EXCHANGE SURFACES MUST:
1. Be thin – for rapid exchange 2. Be moist – to remain permeable 3. Have a large surface area – to maximise exchange
* Be close to blood capillaries – for transport around the body
Exchange Surfaces
Thin exchange surfaces mean that there is less tissue for the moving molecules to pass through. Exchange surfaces are moist because molecules diffuse more efficiently through a liquid medium. If exchange surfaces were dry, cells would die and become impermeable. Having a large surface area means that there is a lot of area molecules can pass through – aiding in the efficiency of exchange.
Exchange Surfaces
NEED TO KNOW!
INTENDED STUDENT LEARNING
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
Humans, and all vertebrates, have a closed circulatory system composed of:
• The heart: acts as a pump to circulate the blood.
• Blood vessels: carry the blood to and from the organs and muscles.
Circulatory System
Heart
Arteries
Veins
The blood vessels found in vertebrates are:
• Arteries: carry blood away from the heart.
• Arterioles: smaller arteries entering a capillary bed.
• Capillaries: transport blood through the organs and tissue.
• Venules: collect blood leaving a capillary bed and carry it to the vein.
• Veins: carry blood to the heart.
Blood Vessels
Capillaries
Capillaries are very small blood vessels that connect arterial and venous circulation and enable exchange of nutrients and wastes between blood and tissues.
Capillaries are composed of a single layer of endothelium (made up of squamous epithelial cells). They form networks or beds and are abundant where metabolic rates are high.
Capillaries
Exchange in Capillaries
Capillary wall
The capillary itself has a diameter 4-10 µm
Tissue cells Large proteins remain in the capillary in solution
Red blood cell with diameter of 7 µm just squeezes through
Blood flow is slow (<1 mm per second)
Blood coming from the arteriole into a capillary is under pressure. Tissue fluid leaks from the capillaries.
Exchange in Capillaries
Blood coming from the arteriole into a capillary is under pressure. Tissue fluid leaks from the capillaries. Small chemicals, such as nutrients (glucose, amino acids, oxygen, ions, water) and wastes (carbon dioxide, etc) are exchanged via diffusion across the capillary wall, travelling through the tissue fluid.
Red blood cells and proteins remain in the capillaries.
Exchange in Capillaries
Capillaries Summary
The lymphatic system is a network of vessels that drains lymph fluid from the tissues back into the circulatory system.
Lymphatic System
Spleen
Lymph nodes
Lymphatic vessels
Thymus gland Tonsils and adenoids
Thoracic duct
Bone marrow
The lymphatic system is a network of vessels that drains lymph fluid from the tissues back into the circulatory system. This network is part of the immune system and is one of the body’s major defences against infection and cancer.
Lymphatic System
Spleen
Lymph nodes
Lymphatic vessels
Thymus gland Tonsils and adenoids
Thoracic duct
Bone marrow
Lymphatic System Summary
Lymph Exchange
Venule Arteriole
Blood flow inward
Lymph vessel
Blood flow outward
Lymph nodes are oval or bean shaped structures scattered throughout the body.
Lymph Nodes
LYMPH NODE
Valve
Blood vessel
Incoming lymph vessel
Outgoing lymph vessel
Medulla
Capsule
Trabeculae
Lymph nodule (contains T and B lymphocytes)
Lymph nodes are oval or bean shaped structures scattered throughout the body. • Lymph nodes filter lymph by trapping
foreign particles in a meshwork of elastic and reticular fibres inside the node.
• Once trapped, the foreign substances are phagocytosed by macrophages and destroyed.
• Lymph nodes are also a store of lymphocytes (T cells and B cells), which circulate to other parts of the body via the outgoing lymph vessel.
Lymph Nodes
LYMPH NODE
Valve
Blood vessel
Incoming lymph vessel
Outgoing lymph vessel
Medulla
Capsule
Trabeculae
Lymph nodule (contains T and B lymphocytes)
The movement into and out of a capillary depends on the balance between the blood pressure and the osmotic pressure at the end of a capillary bed.
Blood and Lymph Exchange
At the beginning of a capillary bed: blood pressure is higher than osmotic pressure. Therefore, there is a net movement of plasma and nutrients (from capillaries) into the extracellular space.
Blood and Lymph Exchange
During exchange: • Glucose, amino acids, oxygen, ions and water diffuse from capillaries
to the surrounding cells. • Carbon dioxide and other wastes diffuse from the surrounding cells
into the capillaries.
Blood and Lymph Exchange
Plasma proteins and red blood cell concentration increases at the end of a capillary bed. Here: osmotic pressure is higher than blood pressure. Therefore, there is a net movement of water (from tissue fluid) back into the capillaries.
Blood and Lymph Exchange
Most, but not all of the fluid is returned to the capillaries. Excess fluid is collected by the vessels of the lymphatic system and becomes lymph.
Blood and Lymph Exchange
Blood and Lymph Exchange hhh
Arteriolar end of a capillary bed there is a net outward pressure:
water and solutes leave the capillary.
Venous end of a capillary bed there is net inward pressure: water and solute re-enter the
capillary.
At the arteriolar end of a capillary bed, hydrostatic (blood) pressure
(HP) forces fluid out of the capillaries and into the tissue fluid.
Glucose, water, amino acids, ions, and oxygen
At the venous end of a capillary bed, hydrostatic pressure drops
and most (90%) of the leaked fluid moves back into the capillaries.
Water, CO2, and other wastes. 90% of leaked fluid
As fluid leaks out through the capillary walls, it bathes the
cells of the tissues.
10% of leaked fluid is collected by lymph vessels and returned to the
circulation near the heart
NEED TO KNOW!
PAST EXAM QUESTION Have a go! How would you answer this question?
Lymphedema
INTENDED STUDENT LEARNING
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
Practice Questions Biology: Levels of Life Study Questions 1 – 4
Page 108
Homework
Biology Levels of Life Textbook (2nd Ed.) Questions: 1 – 4, page 108
Independent content revision
ALVEOLI AND VILLI BIOLOGY
Kahoot Quiz
Exchange Surfaces and Capillaries
REVISION
O3 The exchange of materials may take place at special structures or organs.
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
O3.3 Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
O3.4 Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Overview
O3 The exchange of materials may take place at special structures or organs.
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
O3.3 Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
O3.4 Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Overview
The paired lungs of mammals, including humans, are located within the thorax.
The Respiratory System
Right lung
Trachea
Larynx
Diaphragm
Left lung
Bronchioles
Bronchus
DID YOU KNOW? The lungs of an average
adult weigh about 1kg and have a volume between 4 – 6L!!
The paired lungs of mammals, including humans, are located within the thorax. They are connected to the outside air by way of a system of tubular passageways:
• Trachea • Bronchi • Bronchioles
The Respiratory System
Right lung
Trachea
Larynx
Diaphragm
Left lung
Bronchioles
Bronchus
DID YOU KNOW? The lungs of an average
adult weigh about 1kg and have a volume between 4 – 6L!!
The paired lungs of mammals, including humans, are located within the thorax. They are connected to the outside air by way of a system of tubular passageways:
• Trachea • Bronchi • Bronchioles
The diaphragm is a dome-shaped sheet of skeletal muscle.
The Respiratory System
Right lung
Trachea
Larynx
Diaphragm
Left lung
Bronchioles
Bronchus
DID YOU KNOW? The lungs of an average
adult weigh about 1kg and have a volume between 4 – 6L!!
The trachea divides into two bronchi, each of which leads to one lung.
The Respiratory System
Pho
to: K
P
ryor
Bronchioles
Cross section of lung
showing bronchioles
The trachea divides into two bronchi, each of which leads to one lung.
Each bronchus divides many times into respiratory bronchioles.
The Respiratory System
Pho
to: K
P
ryor
Bronchioles
Cross section of lung
showing bronchioles
The trachea divides into two bronchi, each of which leads to one lung.
Each bronchus divides many times into respiratory bronchioles.
Each bronchiole gives rise to 2-11 alveolar ducts and numerous ALVEOLI.
The Respiratory System
Pho
to: K
P
ryor
Bronchioles
Cross section of lung
showing bronchioles
Ciliated, mucus-secreting epithelium lines the trachea and bronchi. It traps and removes dust and pathogens before they reach the gas exchange surfaces of the alveoli.
The Respiratory System
EII
Ciliated cells lining a bronchus.
The alveoli are the site of oxygen and carbon dioxide exchange in the lungs.
Alveoli DID YOU KNOW? Each lung contains more
than 150 million alveoli!
The alveoli are the site of oxygen and carbon dioxide exchange in the lungs. A phospholipid surfactant lines the inside of each alveolus. The alveoli tend to recoil inward (deflate) after each breath. The surfactant prevents complete collapse after deflation.
Alveoli DID YOU KNOW? Each lung contains more
than 150 million alveoli!
The alveoli are the site of oxygen and carbon dioxide exchange in the lungs. A phospholipid surfactant lines the inside of each alveolus. The alveoli tend to recoil inward (deflate) after each breath. The surfactant prevents complete collapse after deflation.
Alveoli DID YOU KNOW? Each lung contains more
than 150 million alveoli!
Istock
O2 in, CO2 out
The walls of the small bronchioles lack
cartilage but have a large amount of smooth muscle.
Blood capillaries
The smallest respiratory bronchioles
subdivide into the alveolar ducts
(between 2-11). These give rise to numerous alveoli.
0.3mm
There is a close physical relat ionship between the alveolar membranes and the surrounding capillaries. Phagocytic monocytes and macrophages are also present to protect the lung tissue. Elastic connective t issue enables expansion and recoil of the alveoli.
Internal Structure of Alveoli
There is a close physical relat ionship between the alveolar membranes and the surrounding capillaries. Phagocytic monocytes and macrophages are also present to protect the lung tissue. Elastic connective t issue enables expansion and recoil of the alveoli.
Internal Structure of Alveoli
Alveolar space
Alveolar space
Alveolar macrophage
Red blood cell in capillary
Nucleus of epithelial cell
Surfactant
Connective tissue containing
elastic fibers
Monocyte
Respiratory membrane
Connective tissue cell
The respiratory membrane is the term for the layered junction between:
• The alveolar and epithelial cells.
• The endothelial cells of the capillary.
• T h e a s s o c i a t e d b a s e m e n t membranes (thin, collagenous layers that underlie the epithelial tissues).
Gases move freely across the membrane.
Respiratory Membrane
The respiratory membrane is the term for the layered junction between:
• The alveolar and epithelial cells.
• The endothelial cells of the capillary.
• T h e a s s o c i a t e d b a s e m e n t membranes (thin, collagenous layers that underlie the epithelial tissues).
Gases move freely across the membrane.
Respiratory Membrane
Red blood cell
Interstitial space Surfactant is a
phospholipid produced by cells in the
alveolar walls.
Alveolar epithelial wall
Epithelial basement membrane
Capillary basement membrane
Capillary endothelium
0.5 µm
O2
CO2
Nucleus of endothelial cell
Deoxygenated blood is pumped from the heart to the lungs.
Blood Flow to the Lungs
Deoxygenated blood is pumped from the heart to the lungs. Oxygen from the lungs diffuses into capillaries and is pumped back to the heart.
Blood Flow to the Lungs
Deoxygenated blood is pumped from the heart to the lungs. Oxygen from the lungs diffuses into capillaries and is pumped back to the heart. This oxygenated blood is then pumped throughout the body where it is taken in by cells for use in cellular respiration.
Blood Flow to the Lungs
Gas Exchange at an Alveolus Deoxygenated Blood
Oxygenated Blood
NEED TO KNOW!
Alveoli are the site of gas exchange in the lungs:
• The air sac increases the surface area.
• They have thin, moist membranes that are close to blood vessels.
• Oxygen diffuses into the blood, and into the haemoglobin of red blood cells.
• Carbon dioxide diffuses from the blood into the air sac.
Alveoli Summary NEED TO KNOW!
Oxygen Transport Video
PAST EXAM QUESTION Have a go! How would you answer this question?
INTENDED STUDENT LEARNING
O3.4
Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
The small intestine (SI) is a long, narrow tube about 7 metres long. Food is digested into small soluble forms including glucose, amino acids, and fatty acids. The main function of the SI is to absorb these nutrient molecules into the blood and lymphatic system.
The Small Intestine
The SI is lined with finger-like projections called villi, which absorb nutrient molecules form the SI.
Villi DS
Villi along surface of the small intestine
Section through small intestine
Gut lumen
Villus
Villi
Epithelial cells divide and migrate toward the top of the villus to replace lost and worn cells
Epithelial cells
Capillaries surround a central lymph vessel
Nutrients are transported away
Alkaline fluid and mucous
Crypt of Lieberkuhn
The intestinal villi project into the gut lumen and provide an immense surface area for nutrient absorption.
Villi
Epithelial cells divide and migrate toward the top of the villus to replace lost and worn cells
Epithelial cells
Capillaries surround a central lymph vessel
Nutrients are transported away
Alkaline fluid and mucous
Crypt of Lieberkuhn
The intestinal villi project into the gut lumen and provide an immense surface area for nutrient absorption.
The villi are lined with epithelial cells and each has a brush border of many microvilli which further increase the surface area.
Villi
Epithelial cells divide and migrate toward the top of the villus to replace lost and worn cells
Epithelial cells
Capillaries surround a central lymph vessel
Nutrients are transported away
Alkaline fluid and mucous
Crypt of Lieberkuhn
The intestinal villi project into the gut lumen and provide an immense surface area for nutrient absorption.
The villi are lined with epithelial cells and each has a brush border of many microvilli which further increase the surface area.
Enzymes bound to the surface of the epithelial cells break down peptides and carbohydrate molecules.
Villi
Epithelial cells divide and migrate toward the top of the villus to replace lost and worn cells
Epithelial cells
Capillaries surround a central lymph vessel
Nutrients are transported away
Alkaline fluid and mucous
Crypt of Lieberkuhn
Crypts of Lieberkuhn secrete mucous and alkaline fluid. The products broken down by the enzymes in the surface of microvilli are absorbed into the underlying blood and lymph vessels.
Villi and Microvilli
Villi and Microvilli
Absorption in the Small Intestine
Cross section through a villus showing how the various breakdown products of digestion are absorbed across the intestinal epithelium into the capillaries of lacteals of the lymphatic system. These vessels eventually deliver these nutrients to the liver for processing.
Lumen of gut
Intestinal epithelial cell
Goblet cell
Capillary
Vein Lacteal
Clumps of bile salts aid passage of lipids
across the membrane of epithelial cells.
Protein coated aggregations of fats are formed in the Golgi of
the epithelial cells.
Fructose
Glucose/galactose
Amino acids Dipeptides
Tripeptides
Active transport
Short chain fatty acids
Diff
usio
n
Long chain fatty acids
Monoglycerides
Fat soluble vitamins
After most of the nutrients have been absorbed in the small intestine, the remaining fluid contents is passed to the large intestine (LI).
The Large Intestine
Appendix
Cecum
Colon
Rectum Anus
Taenia coli (longitudinal bands of smooth muscle running the length of the the LI)
Haustra (pouches along the colon)
After most of the nutrients have been absorbed in the small intestine, the remaining fluid contents is passed to the large intestine (LI). The f luid contains undigested material, bacteria, loose dead cells from the gut wall, mucous, bile, ions and a large amount of water.
The Large Intestine
Appendix
Cecum
Colon
Rectum Anus
Taenia coli (longitudinal bands of smooth muscle running the length of the the LI)
Haustra (pouches along the colon)
After most of the nutrients have been absorbed in the small intestine, the remaining fluid contents is passed to the large intestine (LI). The f luid contains undigested material, bacteria, loose dead cells from the gut wall, mucous, bile, ions and a large amount of water. In humans, the LI’s main function is to reabsorb water and electrolytes.
The Large Intestine
Appendix
Cecum
Colon
Rectum Anus
Taenia coli (longitudinal bands of smooth muscle running the length of the the LI)
Haustra (pouches along the colon)
The semi-solid waste from the colon is passed to the rectum where it is stored before being expelled (egested).
The Large Intestine
Cecum
Transverse Colon
Small intestine
Ascending Colon Descending
Colon
Colon: Absorbs water, Na+ and some vitamins. Also incubates bacteria
(which provide vitamin K)
Rectum: Feces are stored and consolidated
before elimination.
Anus: Two anal sphincters control elimination. One is under involuntary control: stretching of
the anus triggers its reflex relaxation. The other is under voluntary control allowing the reflex activity to be modified.
Appendix: a blind sac that may have a minor immune function.
The semi-solid waste from the colon is passed to the rectum where it is stored before being expelled (egested). Infection or disease can result in n o t e n o u g h w a t e r b e i n g absorbed, causing diarrhoea.
The Large Intestine
Cecum
Transverse Colon
Small intestine
Ascending Colon Descending
Colon
Colon: Absorbs water, Na+ and some vitamins. Also incubates bacteria
(which provide vitamin K)
Rectum: Feces are stored and consolidated
before elimination.
Anus: Two anal sphincters control elimination. One is under involuntary control: stretching of
the anus triggers its reflex relaxation. The other is under voluntary control allowing the reflex activity to be modified.
Appendix: a blind sac that may have a minor immune function.
The semi-solid waste from the colon is passed to the rectum where it is stored before being expelled (egested). Infection or disease can result in n o t e n o u g h w a t e r b e i n g absorbed, causing diarrhoea. Too much water being absorbed can lead to faeces becoming hard and diff icult to pass, resulting in constipation.
The Large Intestine
Cecum
Transverse Colon
Small intestine
Ascending Colon Descending
Colon
Colon: Absorbs water, Na+ and some vitamins. Also incubates bacteria
(which provide vitamin K)
Rectum: Feces are stored and consolidated
before elimination.
Anus: Two anal sphincters control elimination. One is under involuntary control: stretching of
the anus triggers its reflex relaxation. The other is under voluntary control allowing the reflex activity to be modified.
Appendix: a blind sac that may have a minor immune function.
Villi increase the surface area.
Epithelial cells that line the villi have microvilli.
Inside the villi there is a network of capillaries surrounding a lacteal (lymph) vessel.
Glucose and amino acids go into the capillaries by diffusion and active transport.
Villi Summary NEED TO KNOW!
The larger fat molecules are engulfed into the lacteal vessel (via endocytosis) to be carried back into circulation.
The capillary carries the blood with the soluble food to the liver to be stored, used, or broken down.
Amino acids can’t be stored by the liver and are broken down to urea.
Villi Summary NEED TO KNOW!
Food Breakdown and Villi Video
INTENDED STUDENT LEARNING
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Practice Questions Biology: Levels of Life Study Questions 5 – 7
Page 108
Homework
Biology Levels of Life Textbook (2nd Ed.) Questions: 5 – 7, page 108
Independent content revision
KIDNEY NEPHRON BIOLOGY
Kahoot Quiz
Alveoli and Villi
REVISION
O3 The exchange of materials may take place at special structures or organs.
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
O3.3 Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
O3.4 Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Overview
O3 The exchange of materials may take place at special structures or organs.
O3.1 Explain why exchange surfaces in the body must be thin and moist, and have a large surface area.
O3.2 Explain the role of blood capillaries and lymph capillaries in the exchange of materials.
O3.3 Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
O3.4 Know the structural features of alveoli in the lungs, and describe how gases are exchanged through this surface.
O3.5 Know the structural features of villi in the digestive system, and describe how nutrients are absorbed.
Overview
The urinary system consists of the kidneys and bladder, and their associated vessels and ducts.
The Urinary System
The Urinary System
Vena cava returns blood to the heart. Dorsal aorta supplies oxygenated
blood to the body’s tissues and organs.
Kidney produces urine (blood filtration, the removal of waste products, and the regulation of blood volume).
Adrenal glands are associated with, but not part of, the urinary system.
Renal artery carries blood from the aorta to the kidney.
Renal vein (at back)returns the blood from the kidney to the venous circulation.
Bladder stores the urine before it passes out of the body. It can expand to hold about 80% of the daily urine output.
Urethra conducts urine from the bladder to the outside. The urethra is regulated by a voluntary sphincter muscle.
Ureter carries urine to the bladder.
The urinary bladder is a hollow organ located in the pelvic cavity.
The Bladder Istock
Transitional epithelium lines the bladder. This type of epithelium is layered, or stratified, and can be stretched without the outer cells breaking apart from each other.
Lumen
Epithelium
EII DID YOU KNOW? The average capacity of
the urinary bladder is about 750mL
The urinary bladder is a hollow organ located in the pelvic cavity. The shape of the urinary bladder depends on how much urine it contains.
• It is collapsed when empty, spherical when slightly distended, and pear shaped when fully distended.
The Bladder Istock
Transitional epithelium lines the bladder. This type of epithelium is layered, or stratified, and can be stretched without the outer cells breaking apart from each other.
Lumen
Epithelium
EII DID YOU KNOW? The average capacity of
the urinary bladder is about 750mL
The kidney filters about 180L of plasma every day.
• Most of this is reabsorbed, leaving a daily urine output of about 1L.
• The kidneys help maintain the body’s internal chemical balance by adjusting the composition of the fluid excreted.
The Kidney
The kidney filters about 180L of plasma every day.
• Most of this is reabsorbed, leaving a daily urine output of about 1L.
• The kidneys help maintain the body’s internal chemical balance by adjusting the composition of the fluid excreted.
The Kidney
Left kidney of cadaver showing renal vein and artery and ureter.
Anatom
ist90 CC
3.0
Renal artery
Renal vein
Ureter
The functional unit of the kidney is the nephron.
• The striated appearance of the kidney tissue is due to the alignments of the nephrons.
Internal Kidney Structure Nephron
Outer cortex
Inner medulla
The urine collects in a space near the ureter called the renal pelvis before flowing out of
the kidney via the ureter. Urine flow
Ureter
Nephrons are selective filter elements, which regulate blood composition and pH, and excrete wastes and toxins.
The Nephron
Proximal convoluted tubule
Glomerulus
Afferent arteriole (enter glomerulus)
Venule Ascending limb of the loop of Henle
Blood vessels (the vasa recta)
Loop of Henle
The collecting duct drains to the renal pelvis
Descending limb of the loop of Henle
Distal convoluted tubule
Bowman’s capsule
Efferent arteriole (leaves glomerulus)
They are involved in three processes:
1. Filtration 2. Absorption 3. Secretion
The Nephron
Filtration occurs in the glomerulus. The passage of water and solutes into the nephron and the formation of the glomerular filtrate depends on the pressure of the blood entering the afferent arteriole.
Filtration
Filtration occurs in the glomerulus. The passage of water and solutes into the nephron and the formation of the glomerular filtrate depends on the pressure of the blood entering the afferent arteriole. If blood pressure increases, filtration rate increases. If blood pressure decreases, filtration rate decreases.
Filtration
All the small chemicals (glucose, urea, minerals, water) go through the glomerulus into the tubule under pressure.
Filtration
Blood flow
Filtrate
Glomerulus
Loop of Henle
Bowman’s capsule
Collecting duct
Bowman’s capsule is a double-walled cup, lying in the cortex of the kidney.
It encloses the glomerulus (a capillary network).
Filtration: Bowman’s Capsule
DID YOU KNOW?
Bowman’s capsule
+
Glomerulus =
Renal corpuscle
PH
OTO
: EII
Capsular space
Glomerulus
Bowman’s capsule
Visceral layer
Parietal layer
Capsular space Glomerulus
Bowman’s capsule
Visceral layer Parietal layer
Diagrams of glomerulus and Bowman’s capsule
Convoluted tubules
Bowman’s capsule is a double-walled cup, lying in the cortex of the kidney.
It encloses the glomerulus (a capillary network).
The outer (parietal) layer of Bowman’s capsule is separated from the inner (visceral) layer by the capsular space.
Filtration: Bowman’s Capsule
DID YOU KNOW?
Bowman’s capsule
+
Glomerulus =
Renal corpuscle
PH
OTO
: EII
Capsular space
Glomerulus
Bowman’s capsule
Visceral layer
Parietal layer
Capsular space Glomerulus
Bowman’s capsule
Visceral layer Parietal layer
Diagrams of glomerulus and Bowman’s capsule
Convoluted tubules
Selective reabsorption occurs with some chemicals moving from the tubule back into the capillary. Glucose and amino acids move by diffusion THEN active transport.
Absorption
Selective reabsorption occurs with some chemicals moving from the tubule back into the capillary. Glucose and amino acids move by diffusion THEN active transport. Materials left in the tubule go to the bladder. Some water is reabsorbed and some goes out as urine.
Absorption
Nephron Substance Movement The filtrate that enters the proximal convoluted tubule contains both wastes and useful substances (ions, glucose, amino acids, etc.).
Nephron Substance Movement The filtrate that enters the proximal convoluted tubule contains both wastes and useful substances (ions, glucose, amino acids, etc.).
Useful substances MUST be returned to the blood from the filtrate.
Nephron Substance Movement The filtrate that enters the proximal convoluted tubule contains both wastes and useful substances (ions, glucose, amino acids, etc.).
Useful substances MUST be returned to the blood from the filtrate.
The cells l ining the tubules transport these substances from t h e t u b u l e s o u t i n t o t h e extracellular space from where they are absorbed into the capillaries.
Nephron Substance Movement
K+
Na+
B W
G
U
Key
Na+, Cl-
K+ and H+
HCO3-
Glucose, amino acids Urea
H2O Na+
K+
B U
G
W Reabsorption (active)
Reabsorption (passive)
Secretion (active)
The filtrate that enters the proximal convoluted tubule contains both wastes and useful substances (ions, glucose, amino acids, etc.).
Useful substances MUST be returned to the blood from the filtrate.
The cells l ining the tubules transport these substances from t h e t u b u l e s o u t i n t o t h e extracellular space from where they are absorbed into the capillaries.
Na+ Na+
Na+
Na+
K+
G B B W
W
W
W
Na+
U
Nephron Video
Practice Questions Biology: Levels of Life Study Question 8 Page 108
Variations in salt and water intake, and in the environmental conditions to which we are exposed, contribute to fluctuations in blood volume and composition.
Control of Urine Output
Hem
era
Variations in salt and water intake, and in the environmental conditions to which we are exposed, contribute to fluctuations in blood volume and composition. The primary role of the kidneys is to regulate blood volume and composition (including the removal of nitrogenous wastes), so that homeostasis is maintained.
• This is achieved through varying the volume and composition of the urine.
• Two hormones: antidiuretic hormone (ADH) and aldosterone are involved in the process.
Control of Urine Output
Hem
era
Variations in salt and water intake, and in the environmental conditions to which we are exposed, contribute to fluctuations in blood volume and composition. The primary role of the kidneys is to regulate blood volume and composition (including the removal of nitrogenous wastes), so that homeostasis is maintained.
• This is achieved through varying the volume and composition of the urine.
• Two hormones: antidiuretic hormone (ADH) and aldosterone are involved in the process.
Control of Urine Output
Hem
era
Aldosterone produced by the adrenal cortex ADH released from
the posterior pituitary
Hypothalamus (osmoreceptors) detect fall in plasma volume.
ê
Hypothalamus (neurosecretory cells) synthesise and secrete ADH (hormone).
ê
ADH moves to the posterior pituitary and is released into the blood.
ê
ADH increases permeability of kidney collecting duct. ê
More water is reabsorbed and urine volume decreases.
ADH and Aldosterone
ADH
Hypothalamus (osmoreceptors) detect fall in plasma volume.
ê
Hypothalamus (neurosecretory cells) synthesise and secrete ADH (hormone).
ê
ADH moves to the posterior pituitary and is released into the blood.
ê
ADH increases permeability of kidney collecting duct. ê
More water is reabsorbed and urine volume decreases.
Aldosterone acts on distal tubules and collecting ducts of the nephron, causing conservation of sodium ions and
secretion of potassium ions.
ADH and Aldosterone
ADH
Aldosterone
The body’s fluid and electrolyte balance is critical to metabolic function.
Fluid Balance
40% solids
60% fluids
66% intracellular
fluid
33% extracellular
fluid
80% interstitial
fluid
20% plasma
Fluids and solids in an average person
The body’s fluid and electrolyte balance is critical to metabolic function. Water makes up around 60% of the body and is found within two main fluid compartments.
Fluid Balance
40% solids
60% fluids
66% intracellular
fluid
33% extracellular
fluid
80% interstitial
fluid
20% plasma
Fluids and solids in an average person
The body’s fluid and electrolyte balance is critical to metabolic function. Water makes up around 60% of the body and is found within two main fluid compartments.
1. The intracellular fluid makes up 60-66% of the water in the body and is found within the body’s cells.
2. The extracellular fluid makes up the rest of the body’s water and can be divided into intravascular fluid (mostly blood) and extravascular f luid (interstitial fluid around the cells).
Fluid Balance
40% solids
60% fluids
66% intracellular
fluid
33% extracellular
fluid
80% interstitial
fluid
20% plasma
Fluids and solids in an average person
Animation
Kidney Nephron
Model the movement of substances through a kidney nephron Draw a kidney nephron on an A3 piece of paper (see next slide). Use different coloured skittles to model the movement of ions, water, glucose and amino acids, and urea. Use your phone or other device to take pictures of each stage of movement. You can use your photos to make a movie, or use them for revision later on!
ACTIVITY
Nephron Substance Movement
K+
Na+
B W
G
U
Key
Na+, Cl-
K+ and H+
HCO3-
Glucose, amino acids Urea
H2O Na+
K+
B U
G
W Reabsorption (active)
Reabsorption (passive)
Secretion (active)
Na+ Na+
Na+
Na+
K+
G B B W
W
W
W
Na+
U
INTENDED STUDENT LEARNING
O3.3
Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.
PAST EXAM QUESTION Have a go! How would you answer this question?
Practice Questions Biology: Levels of Life Study Question 9 Page 108
Homework
Biology Levels of Life Textbook (2nd Ed.) Questions: 8 – 9, page 108
Independent content revision
KIDNEY NEPHRON BIOLOGY
Kahoot Quiz
Kidney Nephron
REVISION
KIDNEY DISSECTION
PRACTICAL
PRACTICAL
Ellen Feedback Form
h"ps://goo.gl/forms/bUwdAriR3AZjt1oq1
Kahoot Quiz
ORGANISMS
MEGA QUIZ!
Homework
Independent content revision