NERVES & HORMONES...O2 Organisms selectively detect and respond to changes in the internal and...

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).


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: 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!


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

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


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!


O2.4 Explain how the stimulus response model works in the coordination and control of body temperature.

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!

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.


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.


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.


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.


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.


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 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!

Lymphedema

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


ALVEOLI AND VILLI BIOLOGY

Kahoot Quiz

Exchange Surfaces and Capillaries

REVISION







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


Right lung

Trachea

Larynx

Diaphragm

Left lung

Bronchioles

Bronchus



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.


Right lung

Trachea

Larynx

Diaphragm

Left lung

Bronchioles

Bronchus



The trachea divides into two bronchi, each of which leads to one lung.


Pho

to: K

P

ryor

Bronchioles

Cross section of lung

showing bronchioles


Each bronchus divides many times into respiratory bronchioles.


Pho

to: K

P

ryor

Bronchioles


showing bronchioles


Each bronchus divides many times into respiratory bronchioles.

Each bronchiole gives rise to 2-11 alveolar ducts and numerous ALVEOLI.


Pho

to: K

P

ryor

Bronchioles


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.


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.



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.



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.


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.


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


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




Crypt of Lieberkuhn


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




Crypt of Lieberkuhn


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




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



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



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


Colon




before elimination.




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


Colon




before elimination.




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

Practice Questions Biology: Levels of Life Study Questions 5 – 7

Page 108

Homework



KIDNEY NEPHRON BIOLOGY

Kahoot Quiz

Alveoli and Villi

REVISION







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.).


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.).


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.


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.


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


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


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


O3.3

Know the structural features of nephrons in the kidney, and understand the importance of filtration and reabsorption.

Practice Questions Biology: Levels of Life Study Question 9 Page 108

Homework



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


NERVES & HORMONES...O2 Organisms selectively detect and respond to changes in the internal and...

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