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Biology > Hormonal communication in animals > Flashcards

Hormonal communication in animals Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

endocrine glands

A

release hormones directly into blood

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2
Q

exocrine glands

A
  • don’t secrete hormones
  • have small duct that carries secretion to where it’s needed eg. salivary glands
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3
Q

how does a hormone cause a response on a target cell?

A
  • cells receiving hormonal signal (target cells) must have complementary receptor on plasma membrane which hormone binds to
  • each hormone is different and has different receptor
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4
Q

protein and peptide hormones

A
  • hydrophillic so cannot pass through plasma membrane
  • secondary messenger needed
  • eg. adrenaline, insulin, glucagon
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5
Q

steroid hormones

A
  • derived from cholesterol
  • lipid soluble so can pass through plasma membrane and attach to receptors in cytoplasm or nucleus
  • they are transcription factors - act to facilitate or inhibit transcription of specific gene
  • eg. testosterone
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6
Q

adrenal glands structure and location

A
  • each gland divided into cortex on outside and medulla on inside
  • located on top of each kidney
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7
Q

adrenal glands and adrenaline function

A
  • release adrenaline in response to stress eg. pain or shock
  • effect prepares body for action
  • increased heart rate, increased stroke volume, vasocontriction (raises blood pressure), relax smooth muscle in bronchioles, dilate pupils, increase mental awareness, inhibit gut action, hairs erect, converts glycogen to glucose
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8
Q

adrenal cortex function

A
  • uses cholesterol to produce steroid hormones
  • aldosterone - controls salts (potassium and sodium) and water balance in blood - impact on blood pressure
  • cortisol - main stress hormone - helps regulate metabolism by controlling how body converts fats, proteins, carbs to energy
  • androgen - sex hormones
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9
Q

coordinated responses

A
  • an instinct possessed by all animals
  • threat is perceived by autonomic NS, hypothalamus communicates with sympathetic NS and adrenal cortical system
  • effects result in ‘fight or flight’
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10
Q

how does adrenal cortical system stimulate fight/flight in adrenal cortex

A
  • hypothalamus releases CRH which stimultes the pituitary gland to secretes ACTH which arrives at adrenal cortex and releases about 30 cortisol hormones to bloodstream
  • fight or flight
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11
Q

coordination of fight or flight in sympathetic NS

A
  • hypothalamus activates sympathetic NS
  • this activates glands and smooth muscle
  • it also activates adrenal medulla which releases noradrenaline and adrenaline to the bloodstream
  • fight or flight
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12
Q

how is cell signalling used by hormones - adrenaline effect on liver cells?

A
  • adrenaline (first messenger) binds to specific receptor on liver cell plasma membrane
  • this activates the enzyme adenylyl cyclase to turn ATP into cAMP
  • cAMP- secondary messenger, binds and activates a protein kinase enzyme which activates another enzyme which acivates another enzyme
  • this enzyme breaks glycogen down into glucose
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13
Q

pancreas exocrine function

A
  • secretes alkaline pancreatic juices which pass into duodenum via pancreatic duct
  • alkaline because of sodium carbonate - helps neutralise contents which have left acidic stomach
  • pancreatic juice contains enzymes such as:
    lipase - hydrolysis of lipids to fatty acids and glycerol
    amylase - hydrolysis of starch to maltose
    trypsin - hydrolysis of proteins to amino acids
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14
Q

acinar cells

A
  • groups of them surround tiny tubules that produce digestive juices
  • make up most of the pancreas
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15
Q

pancreas endocrine function

A
  • islets of Langerhans - endocrine cells- made up of beta or apha cells - make up 5% of volume of pancreas
  • they secrete peptide hormones which control glucose levels
  • endocrine cells are close to lots of capillaries which they can secrete hormones into
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16
Q

alpha cells in pancreas - how is glucagon released and why

A
  • manufacture and secrete glucagon to increase blood glucose levels
  • alpha cells detect glucose level falling
  • glucagon binds to receptors in liver cell plamsa membrane activating enzyme which breaks down glycogen into glucose - glycogenolysis
  • this glucose is transported out liver cells by facilitated diffusion
  • gluconeogenesis - new glucose made from amino acids and glycerol
  • this causes blood glucose levels to rise
17
Q

beta cells in pancreas - how they secrete the hormone

A
  • manufacture and secrete insulin to decrease blood glucose levels
  • usually K+ channels are open so K+ diffuses outside the membrane, maintaining -70mV on inside of cell
  • Ca2+ usually closed
  • when glucose moves inside the cell by a transporter, it’s phosphorylated by glucokinase then metabolised into ATP
  • ATP sensitive K+ channels close when ATP binds to them, reducing electrochemical grad to -30mV inside the cell
  • this causes voltage gated Ca2+ channles open and Ca2+ floods into the cell - depolarisation
  • Ca2+ help form and move the vesicles containing insulin so insulin can be released by exocytosis
18
Q

normal blood glucose level

A

3.5-7 mmol/dm3

19
Q

hyperglycaemic blood glucose level, why it’s a problem and symptoms

A
  • 15 mmol/dm3
  • cells have higher water potential than the blood and lose water to the blood
  • symptoms - extreme thirst, blurred vision, ketoacidosis
  • ketoacidosis - ketone bodies are formed by fatty acids in the liver causing an acidosis that can be fatal
20
Q

hypoglycaemic blood glucose level and why it’s a problem

A
  • below 3mmol/dm3
  • can lead to inadequete glucose for respiration in cells
  • symptoms: dizziness, feeling weak, nausea
21
Q

glycogen

A
  • store of glucose in liver and muscle cells
  • large insoluble polysaccharide linked by alpha 1-4 glycosidic bonds and alpha 1-6 side branches
22
Q

insulin effect on muscle cell

A
  • insulin binds to receptor on plasma membrane
  • receptor signals to cell to make vesicles with transporter protein (GLUT4) merge with the plasma membrane
  • allows glucose to enter the cell and reduce the blood glucose level
  • the cell can then utilise the glucose for respiration
23
Q

how does insuin cause glycogenesis?

A
  • driven by raised insulin level
  • insulin binds to receptors on plasma membrane of liver cells, activating enzyme called glucokinase
  • glucokinase phosphorylates glucose, trapping it inside the cell as it can’t pass through the membrane tranporters
  • phosphofructokinase and glycogen synthase catalyse formation of glycosidic bonds between glucose to make glycogen
  • as glucose levels drop, beta cells reduce amount of insulin reduced
24
Q

type 1 diabetes

A
  • usually occurs in childhood
  • destruction of beta cells, usually as an autoimmune response
  • insulin not produced at all
25
Q

type 2 diabetes

A
  • onset later in life
  • insulin resistance - it’s released but receptor on cell doesn’t respond correctly
  • beta cells don’t release enough insulin
  • link to high BMI and high visceral fat
26
Q

symptoms of diabetes

A
  • urine with glucose level over 9 mmol/dm3
  • tired (cells can’t respire as glucose can’t get in), thirsty (low water pot. compared to glucose level in blood), urinary frequency (drinking more water bc low water pot.)
27
Q

how do you monitor diabetes?

A
  • clinistix or diastix - urine dip sticks
  • blood testing - spot test with biosensor
28
Q

treatment of type 1 diabetes

A
  • insulin from pig or genetically engineered injected at regular intervals (not in tablet form because insulin is peptide hormone so would be digested)
  • infusion pumps
  • planning diet
  • regular exercise
29
Q

treatment of type 2 diabetes

A
  • diet control
  • exercise
  • insulin injections
  • drugs that affect glucose absorption - reduce glycogenesis and enhance insulin production eg. metformin prevents glucose being absorbed
30
Q

how does the body know there needs to be a heart rate change?

A
  • baroreceptors in the aorta, vena cava or carotid arteries detect a blood pressure change
  • chemoreceptors in carotid artery, aorta and medulla detect a chemical change eg. carbon dioxide levels
  • baroreceptors send nerve impulse along sensory neurones to cardioregulatory centres in the medulla oblongata
31
Q

what happens when high bp is detected?

A
  • cardioinhibitory centre sends nerve impulse along parasympathetic neurones to the SAN
  • acetylcholine is secreted at the parasympathetic neurone and binds to receptors in the SAN
  • this reduces the rate of impulses sent from the SAN to heart muscle to reduce heart rate
32
Q

what happens when low bp is detected?

A
  • cardioacceleratory centre sends nerve impulse along sympathetic neurones to SAN
  • noradrenaline is secreted by sympathetic neurone and binds to receptors on SAN
  • this increases the rate of impulses sent from the SAN to the heart muscle so heart rate increases
33
Q
A

Biology (17 decks)

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