L5: Functions of sympathetic supply to thorax, abdomen, and pelvis

Question 1

What is the origin of sympathetic supply to the thorax?

Answer 1

• LHCs of upper 4 or 5 thoracic segments of the spinal cord.

Question 2

What is the relay o the sympathetic supply to the thorax?

Answer 2

• 3 cervical ganglia and upper 4 thoracic ganglia.

Question 3

What is the sympathetic supply to the thorax directed to?

Answer 3

Heart and lungs

Question 4

What is the function of the sympathetic supply to the thorax?

Answer 4

1-Heart

A- It ↑ the heart rate, the force of contraction, conductivity, and excitability →↑ the effectiveness of the heart as a pump.

B- Coronary vessels:
• Direct effect → vasoconstriction. (For few seconds)
• Indirect effect → vasodilatation (due to accumulation of metabolites).

2-Lungs

a. Inhibition of the smooth ms of the bronchi → bronchodilatation.
b. Inhibition of the mucus secretion of air passages.
c. Vasoconstriction of the pulmonary blood vessels.

Question 5

What is the origin of the sympathetic supply to the abdomen?

Answer 5

LHCs of T6-T12 segments of the spinal cord (splanchnic nerves).

Question 6

What is the relay of the sympathetic supply to the abdomen?

Answer 6

• collateral (prevertebral) ganglia (celiac, superior mesenteric, aortico-renal).

Question 7

What what are the organs that are affected by the sympathetic supply to the abdomen?

Answer 7

1- GIT
2- Liver
3- Gall bladder
4- Pancreas
5- Spleen
6- Blood vessels
7- Kidneys
8- SRM

Question 8

What is the effect of sympathetic supply on the GIT?

Answer 8

(Stomach, small intestine, and proximal part of large intestine):

• Relaxation of their walls and contraction of their sphincters → inhibition of digestion and delayed evacuation of their contents.

Question 9

What is the effect of the sympathetic supply on the liver?

Answer 9

• Stimulation of glycogenolysis → ↑ed blood glucose.

* Stimulation of fibrinogen synthesis.( for blood clotting)

Question 10

What is the effect of the sympathetic supply on the gall bladder?

Answer 10

• Relaxation of its wall and contraction of sphincter of Oddi → retention of bile and delayed emptying of gall bladder.

Question 11

What what is the effect of the sympathetic supply on the spleen?

Answer 11

• Contraction of smooth muscles in splenic capsule and trabeculae → pouring of about 250 ml (especially in cases of hemorrhage) of stored blood into the general circulation.

Question 12

What is the effect of the sympathetic supply on the pancreas?

Answer 12

• It inhibits both endocrine and exocrine pancreatic secretion.

Question 13

What is the effect of the sympathetic supply on the blood vessels?

Answer 13

• Mixed supply (vasoconstriction and vasodilatation)

Question 14

What is the effect of the sympathetic supply to the kidneys?

Answer 14

• Stimulation of juxtaglomerular cells → ↑ed renin secretion.
• ↓es renal blood flow.
• ↓es urine output.

Question 15

What is the origin of the sympathetic supply to the SRM?

Answer 15

• LHCs of T10 and 11segments of the spinal cord.

Question 16

What is the relay of the sympathetic supply to the SRM?

Answer 16

• SRM is supplied by sympathetic preganglionic nerve fibers (with no postganglionic nerve fibers) which relay directly with the SRM cells (chromaffin cells).

Question 17

What is the function of the sympathetic supply to the SRM?

Answer 17

• Stimulation of sympathetic nerves to SRM →releases adrenaline (80%) and noradrenalin (20%) into the circulating blood.
• These hormones have prolonged action due to their slow clearance from the circulation.

Question 18

What is the function of both adrenaline and noradrenaline?

Answer 18

• Adrenaline → acts more on metabolic actions of the body while noradrenalin→acts more on blood vessels.

Question 19

What happens in stress conditions regarding SRM and the sympathetic nervous system?

Answer 19

In stress conditions, SRM acts together with the sympathetic nervous system (sympathoadrenal system).

Question 20

What is the origin of the sympathetic supply to the pelvis?

Answer 20

LHCs of L1, L2, and L3 segments of the spinal cord.

Question 21

What is the relay of the sympathetic supply to the pelvis?

Answer 21

• Inferior mesenteric or hypogastric ganglia.

Question 22

What are the organs affected by the sympathetic supply to the pelvis?

Answer 22

Urinary bladder, rectum, and sex organs.

Question 23

What are the functions of the sympathetic supply to the pelvis on the Urinary bladder?

Answer 23

Relaxation of its wall and contraction of internal urethral sphincter → urine retention.

Question 24

What is the effect of sympathetic supply to the rectum?

Answer 24

• Relaxation of its wall and contraction of internal anal sphincter→ retention of feces.

Question 25

What is the effect of the sympathetic supply on sex organs?

Answer 25

In male:

a) Contraction of smooth ms in the walls of the seminal vesicle, epididymis, vas deferens, and ejaculatory duct
→ ejaculation of semen.
b) VC of blood vessels of pelvic viscera including external sex organs → shrinkage of the penis.

In female:

a) VC of blood vessels of external sex organs → shrinkage of the clitoris.
b) Variable effects on the uterus, mainly inhibitory but may be excitatory in late pregnancy.

Question 26

What is the origin of the sympathetic supply to the somatic structures?

Answer 26

􏰀 Upper limb from LHCs of T2-9.
􏰀 Lower limb from LHCs of T10-L2.
􏰀 Thoracic and abdominal walls from LHCs of T1-L2.

Question 27

What is the function of the sympathetic supply to the somatic structures?

Answer 27

1- Skin
􏰀 VC of blood vessels.
􏰀 Hair erection.
􏰀 Sweat secretion.

2-Skeletal muscles
􏰀 VD of skeletal muscle blood vessels.

Question 28

What is the Orbelli phenomenon?

Answer 28

-Better contraction, delayed onset of fatigue, early recovery after fatigue due to V.D. of blood vessels which supply O2 and nutrients to contracting muscles and remove CO2 and waste products from muscles so prevent or delay fatigue.