Session 6 Lecture Notes - H & E Flashcards
What is found in the red and white pulp of the spleen?
Red pulp = sinuses lined by endothelial macrophages and cords
White pulp = lymph tissue material made of WBCs
Through which artery does blood enter the spleen?
Splenic artery
Which blood cells pass through red and white pulp?
WBCs and plasma pass through the white pulp
RBCs pass through the red pulp
What are the 4 main functions of the spleen?
- Sequestration and phagocytosis (removal of old or abnormal RBCs by macrophages)
- Blood pooling (platelets and RBCs are mobilised by spleen during bleeding)
- Extramedullary haemopoiesis (spleen can make stem cells if bone marrow is failing)
- Immune function (large number of WBCs are present in spleen)
Give a few examples of what causes splenomegaly
- Portal hypertension in liver disease
- Overworking red or white pulp
- Infiltration of cancer cells
- Infiltration of other cells that shouldn’t be there (eg Sarcoidosis and Gaucher’s disease)
- Extramedullary haemopoeisis
What is pancytopenia?
Low blood cell count (of all blood cells)
What is thrombocytopenia?
Low platelet levels
What could cause MASSIVE splenomegaly?
Malaria or chronic myeloid leukaemia
What could cause MODERATE splenomegaly?
Glandular fever (caused by the Epstein Barr virus) or portal hypertension with liver disease eg cirrhosis
What could cause MILD splenomegaly?
Hepatitis or endocarditis
Autoimmune disorders
Or infiltrative disorders e.g. sarcoidosis
What is hyposplenism? Which patients might be this?
Lack of functioning spleen tissue
Patients with sickle cell may be functionally asplenic because they have had repeated infarctions within the spleen due to loss of blood supply via small capillaries (RBCs are sickle)
In a patient who is hypospenic what might you see on a DNA film?
Howell Jolly Bodies (DNA remnants)
What is anaemia?
Low RBC levels
What is luecopenia?
Low WBC levels
What is neutropenia?
Low neutrophil levels
What is erythrocytosis?
High RBC level
What is leucocytosis?
High WBC levels
What is neutrophilia?
High neutrophil levels
What is lymphocytosis?
High lymphocytosis
What is thrombocytosis?
High platelet levels
How many lobes does a neutrophil have?
3-5
It is multi-lobed
How long do neutrophils typically survive in the bloodstream?
1-4 days
What does the hormone G-CSF do?
Increases production of neutrophils and decreases the time it takes for them to be released from bone marrow
In the stages of neutrophils maturation, which precursor cell could we see in peripheral circulation as well as the mature neutrophil?
Band cells (these mature in neutrophils)
What could we give a patient suffering with severe neutropenia?
Neutropenia = low neutrophil levels
You could give them the hormone G-CSF which increases neutrophil production and release from bone marrow
What neutrophil level is considered neutropenia?
Neutrophil count of <1.5 x 10 to the power of 9/L
What is benign ethnic neutropenia?
Low neutrophil levels in people of Afro-Caribbean descent - important to know this to prevent unnecessary referrals
Give some examples of reduction production of neutrophils which could lead to neutropenia
- VIRAL infections
- Radiation of bone marrow
- Infiltration of bone marrow
- B12 or folate deficiency
- Drugs
- Aplastic anaemia (empty bone marrow)
What are you at risk of in neutropenia?
- Life threatening fungal or bacterial infection (e.g. neutropenic sepsis)
- Mucosal ulceration
What is monocytosis?
Increased levels of monocytes
When are you likely to see increased levels of eosinophils?
- After an allergic response
2. After a hypersensitivity reaction eg to drugs, asthma or skin inflammation
What is eosinophilia?
High eosinophil level
What is basophilia?
Increased basophil level
What could cause lymphocytosis?
Chronic lymphocytic leukamia (CLL)
Bacterial and viral infections
Post-splenectomy (following spleen removal as more WBCs are spending time in circulation)
What are the symptoms of pancytopenia?
Symptoms of anaemia = shortness of breath, fatigue, dizziness
Symptoms of thrombocytopenia = bleeding and bruising
Symptoms of neutropenia = infection, ulcers and fever
As well as symptoms of underlying cause
In a control system what is the name of the pathway going into the control centre and the one coming out?
Afferent pathway = going IN
Efferent pathway = going OUT
What is the name of our biological rhythm?
Circadian rhythm
Where region of the hypothalamus controls our Circadian rhythms?
Suprachiasmatic nucleus
Which hormone, released from which gland is responsible for setting our biological body clock?
Melatonin released from the pineal gland
At what time can we expect levels of cortisol to peak?
First thing in the morning - around 8am
What monitors osmotic pressure of blood pressure in the hypothalamus?
Give quantities for fluid in the body
Osmoreceptors
Fluid = 60% of our body weight 70kg person = 42L of fluid 1/3 = extracellular (14L) 2/3 = intracellular (28L) Of the extracellular fluid 11L = interstitial fluid 3L = blood plasma Blood = 5L (3L plasma and 2L cells)
What is hyponatraemia?
Low levels of sodium in the blood
What is the normal serum/ blood osmolality?
275-295 mOsmol/kg
What are the stages that occur if the blood has a high osmolality?
High osmolality = increased levels of solutes and decreased water
- This is detected by osmoreceptors in hypothalamus
- ADH is secreted by the posterior pituitary gland
- This results in increased absorption of water from urine in the kidney
- Osmoreceptors also stimulate thirst centres to try and increase fluid levels
What are the stages that occur after eating a meal?
Eating a meal increases plasma glucose levels
- Pancreatic beta cells release insulin
- Insulin stimulates glucose uptake into tissues via the GLUT4 receptors
- Insulin stimulates glycogenesis in the liver (increased formation of glycogen from glucose)
What are the stages that occur after fasting?
Fasting lower plasma glucose levels
- Pancreatic alpha cells secrete glucagon
- Glucagon stimulates glycogenolysis in the liver (breakdown of glucagon to glucose)
What are steroid hormones synthesised from? What are they soluble in?
Synthesised from cholesterol
Examples are cortisol, aldosterone and testosterone
They are lipid soluble so can cross the plasma membrane
What do thyroid hormones bind to in the blood for transport?
Thyroxine binding globulin (TBG)
What 2 receptor types can water soluble receptors act on?
G protein coupled receptors
Tyrosine kinase receptors
What 2 types of receptors do lipid soluble receptors act on? What is the end result?
Cytoplasmic receptors
Receptors on DNA (in cytoplasm)
End result = promotion or repression of gene transcription
What is area of the hypothalamus responsible for controlling appetite?
Arcuate nucleus
Which stimulatory neurones promote hunger?
Neuropeptide Y (NPY) Agouti-related peptide (AgRP)
Which inhibitory neurones promote satiety? (fullness)
Pro-opiomelanocortin (POMC)
which contains several neurotransmitters including alpha-MSH and beta-endorphins
What hormone is released from the stomach wall when hungry to stimulate appetite?
Ghrelin
What hormone is released by the ileum and colon to suppress appetite?
Peptide tyrosine tyrosine (PYY)
What happens when leptin is released into the blood by adipocytes?
It effects the arcuate nucleus in the hypothalamus in 2 ways:
- Stimulates inhibitory POMC neurones (which promote satiety)
- Inhibits stimulatory NPY and AgRP neurones (which promote hunger)
It also induces expression of uncouplers in mitochondria = energy is dissipated as heat
What happens when amylin is secreted by beta cells in the pancreas?
It suppresses our appetite
We are not sure how yet
