Chapter 15

Front 1

Homeostasis

Back 1

Maintenance of the internal environment despite external changes.

Hint 1

It controls internal body temperature, blood glucose concentration, blood salt concentration, blood temperature and carbon dioxide concentration.

Front 2

Sensory Receptors and Effectors in Homeostasis

Back 2

1) SR (sensory receptor) detects changes in internal/external environment.

2) Info is transmitted to brain.

3) Impulses sent along motor neurones to effectors.

4) Effectors react to motor stimulus to restore equilibrium.

Hint 2

Similar to process of reflex arc caused by neuronal communication (but excludes the sensory and relay neurones).

Front 3

Negative feedback mechanisms in homeostasis.

Back 3

These work to reverse change of initial stimulus. SR detect change, effectors restore conditions to base level.

Hint 3

Front 4

Positive feedback mechanism of homeostasis.

Back 4

These increase the original change detected. SR detect change. Effectors reinforce change and increase the response.

Hint 4

Examples are: Childbirth (Oxytocin causes the cervix to contract and is continuously released as the child presses against cervix) and blood clotting (platelets surround cuts and release clotting factors, which in turn attract more clotting factors until wound has clotted completely).

Front 5

Thermoregulation

Back 5

Maintaining a relatively constant core body temperature to maintain optimum enzyme activity.

Hint 5

37.5°C (Humans)

Front 6

Ectotherms

Back 6

Rely on their external environment. They use less food in respiration and use more energy from it for growth. They are less active in colder temperatures.

Hint 6

Coldblooded animals.

Front 7

Behavioural adaptations of ectotherms when body temperature is low.

Back 7

•Bask in sun.

•Press body against warm ground (conduction).

•Warm up as a result of exothermic metabolic reactions.

Hint 7

Conduction, exposure to sun, chemical reactions.

Front 8

Behavioural adaptations of ectotherms when body temperature is high.

Back 8

•Shelter from sun in burrows/cracks.

•Press body to cool ground.

•Move to available water/mud.

•Orientate themselves so the least SA (surface area) is exposed to the sun.

•Minimise body movement.

Hint 8

Shelter, water/mud, small amount of exothermic metabolic reactions.

Front 9

Physiological adaptations of ectotherms for maintaining body temperature.

Back 9

•Dark colours absorb more radiation and light colours absorb less.

•Alter heart rate to increase/decrease metabolic rate.

Hint 9

Fur/skin colour, heart rate,

Front 10

Endotherms

Back 10

Produce their own body heat through metabolism (have a constant body temperature). Peripheral temperature receptors are in the skin, while blood temperature receptors are in the hypothalamus. Use internal exothermic metabolic activities to keep them warm and energy-requiring physiological responses to keep them cool. Less energy from food is used for growth as a lot is required to maintain their constant body temperature. Can inhabit colder temperatures.

Hint 10

Metabolism. Peripheral temperature receptors detect change in surface temperature, while temperature receptors in the hypothalamus detect internal temperature. Need a lot of food.

Front 11

Behavioural adaptations of endotherms when body temperature is high.

Back 11

•Wallowing in water/mud.

•Aestivation.

•Movement to cooler areas.

Hint 11

Mud/water. Dormancy in hotter/dryer seasons. Migration.

Front 12

Behavioural adaptations of endotherms when body temperature is low.

Back 12

•Dig burrows.

•Bask in sun.

•Hibernation.

•Movement to warmer areas.

Hint 12

Burrows. Sun. Dormancy in colder seasons. Migration.

Front 13

Physiological adaptations of endotherms when body temperature is high.

Back 13

•Limited movement.

•More sweat produced by sweat glands.

•Licking body/opening mouths to pant.

•Erector pili muscles relax.

•Pale fur/feathers reflect radiation.

•Glucose removed from bloodstream to reduce respiration rate.

•Vasodilation.

Hint 13

Relax. Sweating OE. No hair standing. Fur/feather/skin colour. Glucose removed. Vessels dilate.

Front 14

Vasodilation

Back 14

Vessels near skin dilate and arteriovenous shunt vessels constrict to force blood into capillaries.

Hint 14

Blood is near skin.

Front 15

Physiological adaptations of endotherms when body temperature is low.

Back 15

•Rapid, involuntary contracting of large voluntary muscles.

•Glycogen broken down into glucose to increase respiration rate.

•Erector pili muscles contract to trap insulating layer of air.

•Moisture/sweat production is reduced and eventually halted.

•Vasoconstriction

Hint 15

Shivering. Glycogen to glucose. Hair standing up. No sweat or moisture. Vessels constrict.

Front 16

Vasoconstriction

Back 16

Vessels near skin constrict and arteriovenous shunt vessels dilate.

Hint 16

Blood is away from skin.

Front 17

Heat loss centre in the hypothalamus.

Back 17

Activates when temperature if blood flowing through increases. Signal is sent to autonomic motor neurones. Effectors trigger responses that lower core body temperature.

Hint 17

High blood temperature. Autonomic NS. Lower core body temperature.

Front 18

Heat gain centre in the hypothalamus

Back 18

Activates when temperature of blood flowing through hypothalamus decreases. Signal sent along autonomic motor neurones. Effectors trigger responses that increase core body temperature.

Hint 18

Low blood temperature. Autonomic NS. Increase core body temperature.

Front 19

General structure of the liver.

Back 19

•Makes 5% of body mass.

•Contains 13% of total blood in the body at any one time (1dm^3 flows through it every minute).

•Damaged areas regenerate quickly.

•Uses 20% of total energy in the body.

Hint 19

Uses lots of energy. Can act as blood reservoir for small changes in blood volume. Fast growing.

Front 20

The liver's blood supply.

Back 20

It has a dual blood supply. The hepatic artery supplies oxygenated blood, while the hepatic vein removes deoxygenated blood. The hepatic portal vein carries blood from the intestines and contains products of digestion.

Hint 20

Front 21

Lobes of the liver

Back 21

2 lobes make up the liver, they are surrounded by a fibrous capsule. They are made of hexagonal lobules.

Front 22

The lobules of the liver.

Back 22

Each lobule divides into 6 liver acinus that forms its hexagonal shape. In the center of the lobule is the central vein which leads to the hepatic vein.

Hint 22

Front 23

The liver acinus of the lobules.

Back 23

They contain sinusoids, in which blood from the hepatic artery and hepatic portal vein mix. They also contain the bile canaliculus (separate from the sinusoids, in which bile constituents into the hepatic bile ductules, which delivers to the duodenum, diverting through the gall bladder.

Hint 23

Mixture of HPV and HA blood. Channel for bile. Bile ductule➡Duodenum➡Gall bladder.

Front 24

Sinusoids of liver acinus.

Back 24

•Contain Kupffer cells.

•Surrounding hepatocytes have microvilli and release proteins/lipoproteins and absorb glucose/insulin/minerals/vitamins/blood-borne toxins for detox.

Hint 24

Absorbs molecules required by body and toxins. Releases proteins.

Front 25

Bile canaliculus of liver acinus.

Back 25

•Bile is secreted into it by hepatocytes.

•Surrounding hepatocytes contain lots of Golgi vessels for the transport of bile constituents.

Hint 25

Rich in Golgi vessels.

Front 26

Kuppfer cells of the sinusoids.

Back 26

Phagocytic cells that ingest bacteria and pathogens and breakdown bilirubin.

Hint 26

Bilirubin/bacteria/pathogens.

Front 27

Hepatocyte structure.

Back 27

•Single nucleus or binucleated. Nuclei are round/large.

•Metabolically active (contain lots of mitochondria).

•Active in synthesis of proteins/lipids for export (contain lots of ER and Golgi apparatus).

Hint 27

1 or 2 nuclei. Lots of mitochondria. Lots of Golgi apparatus and endoplasmic reticulum.

Front 28

Carbohydrate metabolism in the liver.

Back 28

Hepatocytes interact with insulin and glucagon to help maintain blood glucose concentration.

Hint 28

Interaction with hormones produced in the pancreas.

Front 29

Gluconeogenesis

Back 29

Synthesis of glucose from amino acids, glycerol and other non-hexose sugars. Triggered by adrenaline in fight or flight response.

Hint 29

Occurs during starvation/fasting. Creation of glucose. Adrenaline.

Front 30

Glycogenesis

Back 30

Hepatocytes respond to beta cells releasing insulin by taking up more glucose. Glycogen will be formed.

Hint 30

High blood glucose concentration. Insulin. Glucose➡Glycogen.

Front 31

Glycogenolysis.

Back 31

Hepatocytes respond to alpha cells releasing glucagon by converting glycogen into glucose.

Hint 31

Low blood glucose concentration. Glucagon. Glycogen➡Glucose.

Front 32

Protein metabolism in the liver.

Back 32

Creation of soluble globular proteins in the blood are created in the liver. The most important synthesise proteins are albumin, prothrombin and fibrinogen. However, the body cannot store excess proteins and amino acids.

Hint 32

Prothrombin/albumin/fibrinogen.

Front 33

Deamination

Back 33

Nitrogen (amine) group from amino acids is used to form ammonia, which goes on to form urea. Urea is excreted by the kidney and the rest of the amino acid can be fed into cellular respiration/converted into lipids for storage.

Hint 33

Front 34

Transamination.

Back 34

Converting 1 type of amino acids into another (excludes the 8 essential amino acids). This is useful as the diet does not always provide the required balance of amino acids.

Hint 34

Change from one to another.

Front 35

Ornithine cycle

Back 35

Hint 35

How ammonia is transformed into urea.

Front 36

Detoxification in the liver.

Back 36

Most harmful ubstances are detoxified in the liver.

Front 37

Detoxification of hydrogen peroxide in the liver.

Back 37

Hydrogen peroxide is the toxic byproduct of many metabolic pathway. Hepatocytes contain catalase which breaks it down into water and oxygen.

Hint 37

Catalase.

Front 38

Detoxification of ethanol in the liver.

Back 38

Ethanol is an active drug in alcoholic drinks. Hepatocytes contain alcohol dehydrogenase which breaks it down into ethanal. Which is then converted into ethanoate, which canbe used to build up fatty acids or in cellular respiration.

Hint 38

Alcohol dehydrogenase.

Front 39

Breakdown of haemoglobin.

Back 39

It is broken down into heamm and globin in the liver and spleen. •Kuppfer cells ingest haemoglobin and remove the iron, which is combined with transferrin. This complex is taken to the bone marrow to create new haemoglobin or stored in hepatocytes.

•The non-iron part of beam is converted into bilirubin and is released into the bile. •Globin is hydrolysed to make amino acids.

Hint 39

Performed by Kupffer cells. Iron+transferrin. Non-iron part of haem➡bilirubin. Globin is hydrolysed.

Front 40

Bile

Back 40

It is made in the liver and stored in the gall bladder between meals and then released into the small intestine via the bile duct.

Hint 40

Liver➡Gall bladder➡Bile duct➡Small intestines.

Front 41

Function of bile.

Back 41

•They contain bile salts that help emulsify fats.

•Bile is important for absorption of fat and soluble vitamins.

•Bile helps neutralise excess acidity in the stomach.

•Bile has a bactericidal role.

Hint 41

Bile salts. Absorption. Neutralisation. Defence mechanism.

Front 42

General structure of the kidneys.

Back 42

•Attached to the back of the abdominal cavity.

•Surrounded by a layer of protective fat and layer of fibrous connective tissue.

Front 43

Blood supply of the kidneys.

Back 43

•Supplied by renal artery (branches from abdominal aorta).

•Removed by renal vein (drains into inferior vena cava).

•90-120cm^3 passes through every minute (all of the blood in the body passes through in 1 hour).

•180dm^3 is filtered and 1-2dm^3 of urine is produced a day.

Front 44

Urine transport in the kidney.

Back 44

Nephrons make up the kidney. They act as filtering units and produce urine. Urine passes out the kidneys through the ureters and stored in the bladder. When the bladder is full the sphincter opens and urine passes out through the urethra.

Hint 44

Nephrons(Kidney)➡Ureters➡Bladder➡Urethra

Front 45

Cortex of the kidney

Back 45

The dark outer layer where filtering of the blood occurs. It is surrounded by capillaries carrying blood from the renal artery.

Hint 45

Blood filtering.

Front 46

Medulla of the kidney.

Back 46

Lighter. Contains the tubules of the nephrons and the collecting ducts.

Front 47

Pelvis of the Kidney.

Back 47

Central chamber, where urine collects before passing through the ureter.

Hint 47

Front 48

Bowman's capsule.

Back 48

Contains glomerulus and is where ultrafiltration occurs.

Front 49

Proximal convoluted tubule.

Back 49

In the cortex and is where reabsorption occurs.

Front 50

The Loop of Henle.

Back 50

Creates a high concentration of solutes within the tissue fluid of the medulla.

Front 51

Distal convoluted tubule

Back 51

Fine-tuning of water balance and ion and pH balance occurs here.

Front 52

Collecting duct.

Back 52

Passes urine from the medulla to the pelvis and is where fine-tuning of water balance.

Front 53

Ultrafiltration.

Back 53

This results in the formation of tissue fluid.

Front 54

Glomerulus (ultrafiltration).

Back 54

A bundle of capillaries, blood is supplied by a wide afferent areteriole and blood leaves through a narrower efferent arteriole. This results in a high pressure in the capillaries in the glomerulus.

Hint 54

High pressure inside.