SUGER Flashcards by Bryony Hawkins

Briefly describe the mechanism of a skin flare-up.

Allergens penetrate the skin, where they are met by lymphocytes which release chemicals that induce inflammation.

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Briefly describe the formation of acne.

Corneodesmosomes block the entrance to hair follicles.
Increased production of sebum.
Sebum trapped in narrow hair follicle.
Sebum stagnates at the pit of the follicle.
No oxygen at the pit = anaerobic conditions.
Bacteria can multiply in stagnant sebum.
Bacteria breakdown triglycerides in sebum into free fatty acids resulting in irritation, inflammation, and attraction of neutrophils.
Pus formation & further inflammation.

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What is a renal corpuscle?

The whole unit of the glomerular tuft and Bowman’s capsule.

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Which cells in the renal collecting ducts secrete acid?

Alpha intercalated cells

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Which cells in the renal collecting ducts secrete bicarbonate?

Beta intercalated cells

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What is the total renal blood flow rate?

1L/min

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What is the total urine flow rate?

1ml/min

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What percentage of nephrons project into the medulla?

15%

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What is the surface area for glomerular filtration?

1m2

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Which protein is normally found in the urine and why?

Tamm Horsfall Protein

It is produced by the thick ascending limb of the loop of Henle.

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What determines Kf (the filtration coefficient)?

Permeability of the filtration barrier.

Surface area available for filtration.

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What is the equation used for working out the filtration fraction?

Filtration fraction = GFR/Renal plasma flow

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What is the renal plasma flow per minute?

600ml/min

(Blood flow is 1L/min but only 60% is plasma).

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How does the clearance compare to the GFR if a substance is freely filtered, not secreted, and not reabsorbed?

It is equal

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What is the equation used to work out renal clearance?

Clearance = (urine concentration x urine volume)/plasma concentration

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What substance is released by macula densa cells in response to a decrease in Na+ concentration?

Prostaglandins

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How is water reabsorbed in the proximal convoluted tubule?

Passively by osmosis

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How is the reabsorption of ions driven in the proximal convoluted tubule?

By the basolateral Na+/K+ ATPase

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How are amino acids reabsorbed in the proximal convoluted tubule?

Cotransport with Na+

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How is Cl- absorbed in the proximal tubule?

It follows sodium through leaky tight junctions.

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How is NaCl reabsorbed in the loop of Henle?

Simple diffusion in the thin ascending limb.

Actively transported in the thick ascending limb.

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How do the vasa recta maintain the medullary osmolarity?

Descending part reabsorbs salts and gives out water.

Ascending part reabsorbs water and gives out salt.

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Is the distal convoluted tubule permeable or impermeable to water?

Impermeable

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How does atrial natriuretic peptide decrease sodium reabsorption from the nephron?

Blocks ENaC channels in the collecting duct.
Dilates afferent arteriole - increased GFR.
Inhibits aldosterone secretion.

Describe the relationship between K+ and aldosterone.

Aldosterone stimulates K+ secretion. | Increased K+ in the ECF stimulates aldosterone release.

What is the anion gap?

The difference between measured cations and measured anions.

Where do the urinary phosphate and ammonium buffers have their action?

Proximal tubule

What is the innervation of the adrenal glands?

Splanchnic nerves

Which enzyme is present in the adrenal gland that is required to make aldosterone?

Aldosterone synthase

Which hormone produced by the adrenal glands will not be affected by a problem with the hypothalamus or pituitary gland?

Aldosterone (not stimulated by ACTH).

Define 'stress' in terms of when it stimulates cortisol release.

A real or perceived threat to homeostasis.

What is normal catecholamine synthesis dependent on?

High local cortisol levels

Does the adrenal medulla produce more adrenaline or more noradrenaline?

Adrenaline

What is the rhabdosphincter also known as?

The external urethral sphincter

Briefly describe the bladder stretch reflex.

Bladder walls stretch. Sensory afferent nerves transmit stretch to spinal cord. Interneurons relay signals to parasympathetic efferents (pelvic nerve). Detrusor muscle contraction = micturition.

What are the spinal roots of the hypogastric nerve?

T12-L2

How does the bladder hold urine under low pressure?

Receptive relaxation

Between which vertebral levels does the thyroid gland lie?

C5-T1

When in embryonic life goes the thyroid gland first appear, and when does it begin producing thyroxine?

First appearance = 3-4 weeks | Thyroxine production = 18-20 weeks

What is the name of the portal circulation which connects the hypothalamus and the anterior pituitary gland?

Hypothalamo-hypophyseal portal system

What inhibits the release of growth hormone?

Somatostatin

What receptors do hypothalamic and pituitary hormones act on?

G-protein coupled receptors

Why is C peptide released when insulin is released?

Proinsulin is cleaved from C peptide to form insulin, but C peptide remains in the secretory granules with insulin.

What are the short-term mechanisms of glucose homeostasis?

Glycogenesis/glycogenolysis

What are the long-term mechanisms of glucose homeostasis?

Lipogenesis/gluconeogenesis

What are the two major incretins?

Glucagon-like peptide 1 (GLP-1) | Glucose-dependent insulinotropic peptide (GIP)

What is produced from testosterone which influences the development of the male external genitalia?

Dihydrotestosterone (DHT)

Which surface of the testis is covered by the tunica vaginalis?

Anterior surface

What is the difference between spermatogenesis and spermiogenesis?

Spermatogenesis is the process of sperm production. | Spermiogenesis is the maturation of spermatids to spermatozoa.

What cells surround the primordial germ cells in the ovary?

Stromal cells

What are three differences between spermatogenesis and oogenesis?

1. Spermatogenesis produces 4 spermatozoa but oogenesis only produces 1 ovum. 2. Both divisions of spermatogenesis occur in the testes, whereas in oogenesis one division occurs in the ovary and one in the fallopian tube. 3. Spermatogenesis is a continuous process but oogenesis is a disjointed process.

Which enzyme converts androgens to oestrogens?

Aromatase

Describe progesterone secretion at the start of the menstrual cycle.

Very small amounts are released.

How does oestrogen affect cervical mucous?

Makes it clear and watery.

How does progesterone affect cervical mucous?

Makes it thick and sticky.

Which cells produce human chorionic gonadotropin (hCG)?

Trophoblast cells

What is the role of relaxin?

Limits uterine activity, softens the cervix, and is involved in cervical ripening.

What is cervical ripening?

Growth and remodelling of the cervix of the cervix prior to labour.

What is the role of prostaglandins in pregnancy?

Initiation of labour | enhances the actions of oxytocin